Chapter 1

Food Processing for Increasing Consumption: The Case of Legumes

Geetanjali Kaushik^*

Poonam Singhal^**

Shivani Chaturvedi^**
*    Mahatma Gandhi Mission’s Jawaharlal Nehru Engineering College, Aurangabad, Maharashtra, India
^**    Indian Institute of Technology Delhi, New Delhi, Delhi, India

Abstract

Food is a basic necessity of life. However, over the past few decades food quality and safety issues have caused serious concern among consumers on account of their direct association with human health. Unsafe food poses serious risk to the health of consumers, particularly in the developing countries where food contamination is high on account of indiscriminate use of food contaminants and food protectants. The presence of harmful antinutrients and pesticide residues in legumes limits the bioavailability of the essential nutrients. Organic farming and other approaches are effective in dealing with pesticide contamination, but it would take significant time for them to be adopted worldwide. Therefore, a simple, as well as effective solution in the transitional phase is offered by domestic processing techniques. Domestic food processing methods, such as washing, cooking, milling, parboiling, and storage, may provide a simple and effective solution in this context. The nature of the processing operation (viz., physical, chemical, or thermal) plays an important role in this; usually, the processes that utilize the higher temperatures have greater effects on dissipation of antinutrients and pesticide residues. It is concluded that a combination of processing techniques renders food grains safe for human consumption.

Keywords

food safety

antinutrients

pesticides

human health

processing techniques

1. Food Legumes: A Boon to Human Nutrition

Legumes are important sources of protein for the human diet (Kaushik et  al.,  2010; Tharanathan and Mahadevamma, 2003). There are more than 13,000 species of legumes, but only 20 are eaten by mankind. The major legumes used as foods include peas, beans, lentils, peanuts, and soybeans. The structure of peas and beans consists of a seed coat (hull), hypocotyl–radicle axis, plummule, and two cotyledons. The seed coat works as a protective barrier during storage and handling. The most consumed varieties of legumes include chickpeas (Cicer arietinum), peas (field or smooth pea and wrinkled pea), broad beans (Vicia faba or field bean), lentils (Lens esculenta), and beans (Phaseolus vulgaris, Phaseolus lunatus, Phaseolus aureus, and Phaseolus mungo) (Fabbri and Crosby, 2016). The nutritional composition of legumes can provide a high proportion of proteins, fats, carbohydrates, dietary fibers, B-group vitamins (thiamin, riboflavin, and niacin), and minerals (Prodanov et al., 2004). This composition can vary according to cultivar, location of growth, climate, environmental factors, and soil type in which legumes are grown (Satya et al., 2010). Starch is the major constituent of available carbohydrates of peas and beans. Lipids consist primarily of triacylglycerol plus di- and monoacyglycerol, free fatty acids, sterols, sterol esters, phospholipids, and glycolipids. Peas and beans are very poor sources of fat-soluble vitamins and rich sources of water-soluble vitamins, as well as excellent sources of minerals, such as calcium, phosphorus, potassium, sodium, manganese, iron, magnesium, copper, cobalt, sulfur, zinc, and fluorine (Karmas and Harris, 1988). In some countries, various terms are often substituted for “legume.” The term “pulse” is commonly used for legumes having a low-fat content, such as beans, broad beans, peas, and lentils. Soybeans and peanuts are sometimes referred to as leguminous oil seeds (Kaushik et al., 2010).

Legumes form the main sources of human and animal nutrition, especially in developing countries because of their high nutritive value (Tharanathan and Mahadevamma, 2003). They are increasingly being used in therapeutic formulations in the treatment and prevention of diabetes, cardiovascular diseases, and cancer of the colon (Singhal et al., 2014).

Nevertheless, apart from having high nutritional value, plant foods are often associated with a series of compounds known as antinutrients, which generally interfere with the assimilation of some nutrients. The effects of these substances may be regarded as positive, negative, or both. In some cases, these can cause undesirable physiological effects, such as flatulence and hence can prove to be toxic (Kaushik et al., 2010). However, recent epidemiological studies have demonstrated that many antinutrients may be beneficial in the prevention of diseases, such as cancer and coronary diseases (Messina, 2014). For this reason they are now termed nonnutritive or bioactive compounds, as they are not always harmful even if they may lack nutritive value (Muzquiz et al., 2000). Several antinutritional factors (ANFs), such as α-galactosides, trypsin and chymotrypsin inhibitors, phytates, lectins, and polyphenols (Satya et  al.,  2010; Srivastava and Srivastava, 2003), impede the availability of nutrients (Fereidoon, 2014).

2. Antinutrients in Legumes and Their Removal

ANFs are chemical compounds present naturally in food and/or feedstuffs of plant origin and can interfere with the optimum utilization or metabolism of nutrients (Gemede and Ratta,  2014; Soetan and Oyewole,  2009). These are also known as “secondary metabolites” in plants and are highly biologically active. One major factor that restricts the wider utilization of many tropical plants as food is the presence of these ANFs, which are capable of producing deleterious health consequences in man and animals (Shanthakumari et  al.,  2008; Singh et  al.,  2015; Ugwu and Oranye,  2006). These are the compounds evolved by plants for their own defense through metabolism and other biological functions. Hence they reduce the maximum utilization of nutrients, especially proteins, vitamins, and minerals, thus preventing optimal exploitation of the nutrients present in a food and decreasing the nutritive value. These ANFs can be divided into protein and nonprotein types. Nonprotein ANFs include alkaloids, tannins, phytic acid, saponins, and phenolics, while protein ANFs include trypsin inhibitors, chymotrypsin inhibitors, lectins, and antifungal peptides (Fereidoon, 2014).

2.1. Enzyme Inhibitors

Enzyme inhibitors are proteinaceous compounds present in pulses and inhibit the hydrolases of enzymes, such as proteases, amylases, lipases, glycosidases, and phosphatases. These can easily be denatured and inactivated by heat treatment.

2.1.1. α-Amylases

They occur in starch and related compounds, and are endoamylases that catalyze the hydrolysis of α-d-(1,4)-glycosidic linkages playing a major role in the carbohydrate metabolism. Amylase inhibitors reduce amylase activity and digestion of starch in the gut. This kind of activity is beneficial in lowering postprandial glucose and thus may also prove to be useful in the treatments of obesity or diabetes mellitus (Singh et al., 2015).

2.1.2. Trypsin inhibitors

They cause pancreatic enlargement and growth depression, inhibiting the metabolism of the trypsin enzyme. Trypsin/chymotrypsin inhibitors from red kidney bean, Brazilian pink bean, lima bean, and soybean are closely related with high homology (Satya et al., 2010).

2.1.3. Protease inhibitors

They are of two types: (1) Kunitz type, single-chain polypeptides that inhibit the enzyme activity of only trypsin but not chymotrypsin, and (2) Bowman–Birk inhibitors, which are also single-chain polypeptides but of different molecular weight, and that inhibit the enzyme activity of both trypsin and chymotrypsin. They interfere with the digestion of trypsin and chymotrypsin in the human digestive tract by irreversible binding. They are resistant to the digestive enzyme pepsin and the stomach’s acidic pH (Kaushik et al., 2010).

2.2. Cyanogenic Glucosides

The cyanogenic glycosides are products of secondary metabolism present in the natural products of plants. These compounds are found in various legumes, and C. arietinum is one of them (Champ, 2002). Cyanogenic glucosides (α-hydroxynitrile glucosides) are derived from five protein amino acids (Val, Ile, Leu, Phe, and Tyr) and from the nonproteinogenic amino acid cyclopentenyl glycine. A number of plant species produce hydrogen cyanide (HCN) from cyanogenic glycosides when they are consumed. These cyanogens are glycosides of a sugar, often glucose, which are combined with a cyanide containing aglycone. Cyanogenic glucosides are classified as phytoanticipins because they defend the plant from herbivore and pathogen attack, as on hydrolysis they yield toxic hydrocyanic acid (aqueous solution of HCN) (Golden, 2009). When the plant product is consumed without proper processing, the cyanide ions inhibit several enzyme systems; they depress growth through interference with certain essential amino acids and utilization of associated nutrients. They also cause acute toxicity, neuropathy, and death in extreme cases.

2.3. Lectins

Lectins are glycoproteins widely distributed in legumes and some oil seeds (including soybeans), which possess an affinity for binding with specific sugar molecules and are characterized by their ability to combine with carbohydrate membrane receptors (Fereidoon, 2014). Lectins have the capability to directly bind to the intestinal muscosa, interacting with the enterocytes and interfering with the absorption and transportation of 0.01% free gossypol within some low-gossypol cotton nutrients (particularly carbohydrates) during digestion and causing epithelial lesions within the intestine. Although lectins are heat labile, their stability varies between different plant species. Many lectins, being resistant to inactivation by dry heat, require moist heat for complete destruction (Boehm and Huck, 2009). They function both as allergens and as hemagglutinins (agglutinate red blood cells) and are present in small amounts in whole-grain food. Lectins have also shown in vivo effects when consumed in excess by sensitive individuals, causing severe intestinal damage, disrupted digestion, and nutrient deficiencies. They can provoke IgG and IgM antibodies, causing food allergies and other immune responses (Boehm and Huck, 2009), and they can bind to erythrocytes, simultaneously with immune factors, causing hemagglutination and anemia. Of the 119 known dietary lectins, about half are panhemagglutinins, clumping all blood types.

2.4. Tannins

Tannins are polyphenolic compounds of intermediate-to-high molecular weight that are astringent and bitter in taste that either bind or precipitate proteins and various other organic compounds, including amino acids and alkaloids (Redden et al., 2005). They are divided into two groups based on their ability to fractionate hydrolytically (with acid, alkali, hot water, or enzymatic action): (1) hydrolyzable tannins (including gallotannins and ellagitannins) more responsible for the color of legume seed coats as in chickpeas or (2) condensed tannins. Tannins are heat stable, and they decrease protein digestibility in animals and humans, probably by either making partially unavailable or inhibiting digestive enzymes and increasing fecal nitrogen. Tannins are known to be present in food products; inhibit the activities of trypsin, chymotrypsin, amylase, and lipase; decrease the protein quality of foods; and interfere with dietary iron absorption (Felix and Mello, 2000). The condensed tannins (proanthocyanidins) are known to bind enzymes and other proteins and to form insoluble tannin–protein complexes that are not readily digestible. Due to this, tannin becomes astringent (in tea and some vegetables and fruits) and thus decreases the palatability. Tannins are known to be responsible for decreased feed intake, growth rate, feed efficiency, and protein digestibility in experimental animals. If tannin concentration in the diet becomes too high, microbial enzyme activities, including cellulose and intestinal digestion, may be depressed. Tannins also form insoluble complexes with proteins, and the tannin–protein complexes may be responsible for the antinutritional effects of tannin-containing foods (Kyriazakis and Whittenmore, 2006).

2.5. Oxalates

Oxalates bind minerals, such as calcium and magnesium, and interfere with their metabolism. The insoluble calcium oxalate has the tendency to precipitate (or solidify) in the urinary tract and form calcium oxalate crystals with sharp edges, leading to the formation of kidney stones when the levels are high enough (Nachbar et al., 2000). Oxalate is an antinutrient that under normal conditions is confined to separate compartments, but when it is processed and/or digested it comes into contact with the nutrients in the gastrointestinal tract (Noonan and Savage, 1999). When released, it binds with nutrients, rendering them unavailable to the body. If food with excessive amounts of oxalic acid is consumed regularly, nutritional deficiencies, as well as severe irritation to the lining of the gut, are likely to occur (Liebman and Al-Wahsh, 2011).

2.6. Phytates

Phytates, also known as inositol hexakisphosphates (InsP6), are the salt form of phytic acid, and are found in plants, animals, and soil. Phytic acid is a major phosphorus storage form in plants, and it regulates various cellular functions, such as DNA repair, chromatin remodeling, endocytosis, nuclear messenger RNA export, and potentially hormone signaling that is important for plant and seed development. The most abundant InsP6 accounts for 77% in chickpeas (Campos-Vega et al., 2009). It has a high ability to chelate multivalent metal ions, especially Zn, Ca, and Fe, forming insoluble complexes and making them unavailable for absorption and utilization in the small intestine (Gemede,  2014; Jukanti et  al., 2012).

Phytic acid also makes complexes with proteins, decreasing protein solubility and therefore its presence in food; this has a negative impact on enzyme activity, such as lipase, α-amylase, pepsin, trypsin, and chymotrypsin. It also binds with starch through phosphate linkages. However, it also exhibits a beneficial role in anticancer (preventive, as well as therapeutic) properties. It reduces cell proliferation and increases differentiation of malignant cells. It also delays postprandial glucose absorption (Campos-Vega et al., 2009).

2.7. Saponins

Saponins are secondary compounds that are generally nonvolatile and surface active; they are widely distributed in nature, occurring primarily in the plant origin. The name “saponin” is derived from the Latin word sapo, which means “soap,” because saponin molecules form soap-like foams when shaken with water. They are structurally diverse molecules that are chemically referred to as triterpene and steroid glycosides. They consist of nonpolar aglycones coupled with one or more monosaccharide moieties. This combination of polar and nonpolar structural elements in their molecules explains their soap-like behavior in aqueous solutions.

Due to the presence of one or more lipid-soluble aglycone and water-soluble sugar chains in their structure (amphiphilic nature), saponins are surface-active compounds with detergent, wetting, emulsifying, and foaming properties and have found wide applications in beverages and confectionery, as well as in cosmetics and pharmaceutical products (Shanthakumari et al., 2008). Saponins were treated as toxic compounds to fish and cold-blooded animals possessing strong hemolytic activity. In high concentrations, saponins impart a bitter taste and astringency in dietary plants. The bitter taste of saponin is the major factor that limits its use. In the past, saponins were recognized as antinutrient constituents, due to their adverse effects, such as growth impairment and throat-irritating activity due to their bitterness. In addition, they also reduce the bioavailability of nutrients by inhibiting various digestive enzymes, such as trypsin and chymotrypsin (Liener, 2003). Recent studies suggest that legume saponins may possess anticancer activity and be beneficial for hyperlipidemia. They are also known to reduce the risk of heart diseases in humans (Campos-Vega, 2009).

2.8. Alkaloids

Alkaloids are diverse compounds that consist of a heterocycle with a nitrogen atom within the cycle. They are mainly present in lupins (Champ, 2002). Alkaloids cause gastrointestinal and neurological disorders. They are also reported to cause fetal malformation, and some plant alkaloids are reported to cause infertility (Soetan and Oyewole, 2009).

Alkaloids are one of the largest groups of chemical compounds synthesized by plants and generally are found as salts of plant acids, such as oxalic, malic, tartaric, or citric acid. They are synthesized by plants from amino acids (Felix and Mello, 2000).

Alkaloids are considered to be antinutrients because they cause gastrointestinal and neurological disorders. For instance, consumption of high tropane alkaloids will cause rapid heartbeat and paralysis, and, in fatal cases, lead to death (Fernando et al., 2012).

3. Processing Techniques to Reduce Antinutritional Factors

Processing techniques bring about changes in the biochemical, nutritional, and sensory characteristics in legumes that enhance their nutritional value by increasing essential amino acids, protein digestibility, amino acid availability, and certain B vitamins. The nutritional profile of legumes is generally improved from approximately 40% up to 98% (El-Adawy, 2002). It also proves beneficial in reducing some antinutritional compounds that otherwise would cause interference in the metabolism of certain essential nutrients. Most ANFs can be easily destroyed with heat, such as α-galactosides, protease inhibitors, and lectins, so cooking would eliminate the ill effects of these nonnutrient compounds before consumption. Tannins, saponins, and phytic acids are more heat stable, but can be reduced by dehulling, soaking, or germination (Schoeninger et al., 2014). Various processing techniques used as a tool for reducing the ANFs are listed in Table 1.1.

Table 1.1

Processing techniques for reducing antinutritional factors (ANFs).

S. No.	Processing Techniques	Detailed Methods	Effects on Antinutrients	Reasons	References
1.	Soaking	Soaking 12 h	Phytic acid content showed loss of 20% due to soaking		El-Tinay et al. (1989)
		Soaking for 9 h	Decreases in α-galactosides; 27% (distilled water), 17% (citric acid),16% (NaHCO3)		Frias et al. (2000)
2.	Boiling	19 h soaking followed by 90-min boiling	Decrease amounting to 99% in phytic acid and 82.27% in TIA	The losses in vitamins were probably due to a combination of leaching and chemical destruction	Alajaji and El-Adawy (2006)
		4 h soaking followed by 90-min boiling	Decreases in TIA, tannins, and phytates amounted to 36, 30, and 23%		Sharma (2006)
		12 h soaked seeds were cooked		Possible hydrolysis of starch and oligosaccharides to monosaccharides on cooking resulting in increased concentration of sugars in cooked legumes; cooking may cause rupturing of starch granules followed by amylolysis that leads to a decreased amount of starch	Jood et al. (1988)
		Soaking (9 h) in citric acid, distilled water, or 0.07% sodium bicarbonate solution followed by boiling for 35 min	Losses in α galactosides Complete elimination of TIA		Frias et al. (2000) Prodanov et al. (2004)
		Soaking (12 h) followed by boiling in water for 60 min	30% loss in phytic acid		El-Tinay et al. (1989)
		Soaking in 0.03% EDTA for 16 h followed by cooking (40 min chickpeas)	Reduction in phytic acid 53% chickpeas Reduction in TIA 68% chickpeas	Greater reduction in phytic acid in chickpeas as these were processed without skin; decrease in phytic acid due to leaching during soaking and cooking; thermal treatment was effective in reducing TIA content	Estevez et al. (1991)
			Cooking chickpeas in water	Trypsin inhibitors, tannins, and oligosaccharide contents were observed to be reduced	Wang et al. (2010)
3.	Pressure cooking	Pressure cooking (120°C/5 min)	Polyphenol content reduced by 50%		Clemente et al. (1998)
		12 h soaked followed by autoclaving (121°C/35 min)	41% reduction in phytic acid, 50% reduction in tannins 84% reduction in TIA	The losses in vitamins were probably due to a combination of leaching and chemical destruction	Alajaji and El-Adawy (2006)
		4 h soaking followed by pressure cooking for 20 min	Decreases in TIA, tannins, and phytates amounted to 58, 63, and 18%		Sharma (2006)
4.	Microwave cooking	12 h soaking followed by microwave cooking on high for 15 min	Reduction in TIA by 81%, tannins 49%, and phytic acid 38%	The increase in crude fiber due to protein–fiber complexes formed after chemical modification induced by soaking and cooking of dry seeds; improvement in vitamin retention in microwave-cooked seeds due to shorter cooking time compared to boiling and autoclaving	Alajaji and El-Adawy (2006); Bressani (1993)
5.	Germination	72-h germination	Complete elimination of raffinose and stachyose		Tewari (2002)
		12-h soaking followed by germination for 3 days	Phytic acid reduced by 56% and TIA by 34%	The reductions were due to hydrolysis of these components to monosaccharides that are used as an energy source during germination; the increase in crude protein was due to use of seed components and degradation of protein to simple peptides during germination; the reduction in phytic acid was due to phytase activity during the process	El-Adawy (2002)
		12-h soaking followed by germination for 2 days	Decreases in TIA, tannins, and phytate amounted to 62, 23, and 45%		Sharma (2006)
		Seeds were soaked for 24 h and then germinated for 0, 24, 48, 72, and 96 h	Germination time up to 48 h significantly reduced the phytic acid content from 1.01% to 0.6% and phenols decreased after 120-h germination	There is an increase of phytase activities, which makes the phytates soluble and releases soluble protein and minerals	Khattak et al. (2007)
		Seeds were exposed to heat treatment and then germinated	The amylase inhibitor activity decreased with increasing germination days and became negligible on the 6th day
6.	Irradiation	Chickpeas were exposed to irradiation (dose levels of 5, 7.5, and 10 kGy)	Reduced levels of phytic acid and tannins		El-Niely (2007)
		Seeds were irradiated (0.05–0.20 kGy) following germination	Maximum destruction (43.8%) of TIA occurred on germination for 120 h of 0.20-kGy sample		Sattar et al. (1989)
		Seeds were exposed to irradiation and soaked at ambient temperatures (25–35°C)	Maximum decrease (30.7%) in TIA occurred during soaking for 12 h of 1.00-kGy sample		Sattar et al. (1989)
7.	Dehydration	Seeds were soaked for 16 h at 20°C and cooked by boiling for 70 min; soaked-cooked seeds were dehydrated in a forced-air tunnel at 75 ± 3°C for 6 h	A decline of phytic acid was observed during dehydration process
8.	Roasting	Seeds were roasted on sand bath at 180°C for 20 min	Decrease in polyphenol content from 315.9 mg/100 g in raw to 218 mg/100 g in roasted seeds		Daur et al. (2008)

EDTA, ethylenediaminetetraacetic acid; TIA, trypsin inhibitor activity.

Legumes were usually processed by two ways: nonheat or heat processing.

3.1. Nonheat Processing

3.1.1. Soaking

This is the first step, followed by a number of subsequent treatments, such as cooking, germination, and fermentation. It consists of hydrating the seeds in water, usually until they reach maximum weight. The medium in which they are hydrated can be discarded or retained, depending on the subsequent procedure. Several studies indicate that soaking can reduce the levels of total sugars, α-galactosides, minerals, phytic acid, and proteolytic enzyme inhibitors due to metabolic processes taking place that usually affect the soluble carbohydrate metabolic processes and riboflavin contents (Satya et al., 2010).

3.1.2. Germination/sprouting

Germinated legumes are consumed in many parts of the world owing to their enhanced nutritional value. Germination causes important changes in the biochemical, nutritional, and sensory characteristics of legumes. It is generally carried out by soaking the legume seeds in water. The water is drained out, and the soaked seeds are then tied in a muslin cloth and hung for 1–2 days, depending upon the ambient temperature. The legume seeds are left as such to respire and synthesize new cell constituents of the developing embryo during germination (Schoeninger et al., 2014; Vidal-Valverde et al., 2002). Germination/sprouting has been reported to increase certain vitamins and minerals and the availability of proteins and to decrease certain antinutrients, such as phytic acid and trypsin inhibitor.

3.1.3. Fermentation

It improves the flavor, color, and texture of legumes. The process increases the digestibility of plant proteins and reduces the ANFs, such as phytate. Fermented legumes are consumed as condiments, such as fermented locust bean (Subuola et al., 2012).

3.2. Heat Processes

3.2.1. Cooking

Cooking is probably the oldest treatment for making legumes edible. Usually it includes a prior soaking of the seeds and subsequent cooking in boiling water until they become tender. Addition of mineral salts to the soaking and/or cooking medium can produce a reduction in the cooking time. In general, cooking brings about denaturation of proteins, inactivation of heat-sensitive factors, such as trypsin inhibitors, and decreases of phytic acid and α-galactoside contents. Generally the legumes are cooked in tap water on a hot plate or cooking stove for 15–120 min or more until they become tender. This is the most common practice in rural habitats. Food legumes are often cooked in a pressure cooker involving both high temperature and high pressure to save time in urban settings. This enhances the digestibility and palatability of legumes considerably (Lemos et  al.,  2015; Satya et  al.,  2010).

3.2.2. Roasting

Roasting of legumes is done in an open frying pan in the presence or absence of salts or ash. Roasting improves the taste and flavor of legumes and thus increases their sensory appeal. It also helps in reducing and eliminating ANFs (Subuola et al., 2012).

3.3. Modern Methods, Including Radiation-Based Technology

3.3.1. Microwave cooking

It is a popular means of cooking in urban areas for saving both energy and time. This form of cooking is even faster than pressure cooking, but in developing countries it is limited to the higher strata of society due to the high cost of the microwave oven and the requirement of electricity for it to work. Presoaked legumes are immersed in water and then cooked in a microwave oven for 4–10 min until tender. As a result of cooking, there is an overall a significant decrease in fat, total ash, carbohydrate fractions (decrease in reducing sugars, sucrose, raffinose, and stachyose, while verbascose is completely eliminated after cooking treatments), and ANFs (trypsin inhibitor, tannins, saponins, and phytic acid) (Bongoni et  al.,  2014; Satya et  al.,  2010).

3.3.2. Irradiation

This process involves exposing food to ionizing radiations, such as gamma rays emitted from radioisotopes 60 Co and 137 Cs, or high-energy electrons and X-rays produced by machine sources. Gamma irradiation has been recognized as a reliable and safe method for improving the inactivation of certain ANFs in foods (Taghinejad et al., 2009).

It is clear from the Table 1.1 that heat, as well as nonheat treatments, such as soaking, boiling, and microwave cooking, help in reduction of the ANF of legumes. Losses in antinutrients are directly proportional to the duration of treatment and their structure. For example, lentils with a soft seed coat require a smaller cooking time than those with a hard seed coat.

Soaking results in a decrease in phytic acid due to leaching (El-Tinay et al., 1989). In a recent study it also resulted in decreases in α-galactosides (Frias et al., 2000). Thermal treatment, such as cooking is effective in reducing the trypsin inhibitor activity (TIA) content, phytic acid, and tannins. Cooking treatment has been accompanied by soaking seeds for a specific duration and then subjecting them to boiling for different periods of duration by different researchers. Pressure cooking also resulted in the decrease of the TIA content, phytic acid, and tannins and was performed on presoaked seeds for different durations. Microwave cooking resulted in a faster degradation of antinutrients as compared to simple cooking and pressure cooking. The losses are mainly due to leaching and destruction of the bigger molecules. Germination also leads to reduction of the ANFs. Increase in phytase activity during germination is responsible for decrease in phytic acid content. Decrease in TIA could be due to their utilization as source of energy during early stages of germination. Loss of tannins is caused by leaching into soak water and is a result of enzymatic hydrolysis by polyphenolase during germination. Irradiation also brought a reduction in the tannins, TIA, and phytic acid when seeds were exposed to different levels of a radiation dose. Roasting seeds on a sand bath at 180°C for 20 min also reduced the polyphenol content (Daur et al., 2008).

4. Food Safety and Quality Issues

In the past few decades safety and quality issues associated with food have received considerable attention from consumers owing to their serious impacts on human health. Recently the incidences of food contamination with harmful pesticide residues, preservatives, synthetic colors, toxins, and the like have increased and have caused significant mortality and morbidity in populations, especially in the developing countries. Therefore, against this background it is important to discuss the concept of food safety (Anzene et al., 2014).

“Food safety” refers to a complete absence of or acceptable, as well as safe levels of contaminants or adulterants, which are either naturally prevalent toxins or other synthetic substances that might make the food harmful for health in an acute or chronic manner. Food safety hence is associated with the presence of microbiological elements and different chemicals in food. Within the microbiological elements are included foodborne pathogens, such as Salmonella, Escherichia coli O157, Campylobacter, protozoa, Cryptosporidium, rotavirus, and the fungal mycotoxins that result in instances of food poisoning. Chemical food contaminants include the heavy metals (such as Hg and Pb), residues of pesticides, and the different food preservatives, as well as synthetic colors. In addition, food may contain other contaminants, such as genetically modified organisms and veterinary residues (Sharma, 2006). Widespread food contamination with harmful chemicals and toxins has highlighted the importance of safe food products that have high nutritional value (Peri, 2006; Satya et  al.,  2010). Unintended food contamination may occur as a result of direct exposure (e.g., pesticide application for pest control at various stages in crop production) or indirect exposure (e.g., utilization of pesticides or chemicals while in storage or during food processing) to toxic chemical compounds (Bai et al., 2006). Therefore, a sustainable alternative to this current situation of unsafe, as well as inferior-quality, food is presented by a paradigm shift within our mind-set (Malinowska et  al.,  2015; Satya et  al.,  2007).

5. Significance of Paradigm Shift

From the various dietary surveys it is evident that cereal and legume grains form a major proportion of the diet of a majority of the population of developing nations. Cereals usually lack an essential amino acid, lysine; however, they are rich in sulfur-containing amino acids, whereas legumes are a rich source of lysine but are poor in sulfur-containing amino acids. Clearly the cereals and legumes exhibit nutritionally complementary behavior toward each other. Hence, the combination diet comprising around 65% cereals and 35% legumes would be ideal with regard to nutrition. This kind of supplementation enhances the overall nutritive status and also helps in dealing with protein–energy malnutrition (PEM), which is widely prevalent in these countries. Legumes having high dietary fiber have the benefits of lowering the glycemic index in diabetics, offering prevention from cancer, and providing protection against cardiovascular diseases (Kaushik et  al.,  2010; Satya et  al.,  2010). Indiscriminate and rampant use of chemical fertilizers and pesticides—the two inseparable yet key components of the modern system of agriculture (termed the green revolution)—are mainly responsible for the contamination of the “soil–water–food” matrix. It is evident that modern agriculture clearly has proven to be unsustainable across all fronts (such as, environment, energy, health, socioeconomic aspects, etc).

In the case of India, agriculture is a way to sustain life and not just business to earn income; therefore, it solicits a holistic perspective in the search for a pragmatic but sustainable solution. The alternatives should be able to clearly explain the intrinsic interrelationships between man and nature. In view of these concerns, several alternative agriculture systems that are more sustainable, such as permaculture, organic farming, and so on (Arya, 1995), have been promoted worldwide. Pesticide residues contaminating food grains are a grave threat to food safety. Since pesticide contamination has serious consequences for both the environment and human health, it is pertinent to understand the pattern of pesticide consumption, various pathways of intake, and the adverse environmental impacts.

6. Pesticides: Types, Application, Environmental Impacts, and Human Health Effects

6.1. Pesticides: Types and Application

Chemical pesticides have increased agricultural yields by controlling pests and diseases in plants and have contributed toward better human health and longevity by checking various insectborne, diseases, such as malaria, encephalitis, filariasis, and dengue, among others (Rekha et al., 2006). It is necessary to increase food production because of the rapidly growing world population (Agoramoorthy, 2008). One key strategy to increase crop productivity is through effective pest management, as almost 25%–30% of produce is attacked by pests (Kaushik et al., 2009). In tropical countries, various pesticides are inevitably applied on crop plants for combating pests and vectorborne diseases, as severe crop losses occur due to the high temperature and humidity providing a favorable environment for rapid pest propagation (Abhilash and Singh, 2009; Kannan et  al., 1992; Malinowska et  al.,  2015).

The major classes of pesticides that are commonly used in crop production include organophosphates (such as malathion and chlorpyrifos), organochlorines (lindane, endosulfan, aldrin, and dieldrin), the synthetic pyrethroids (cypermethrin, deltamethrin, and bifenthrin), and finally the carbamates (bendiocarb and carbaryl) (Raghvani and Poshiya, 2006). For the storage of grains, mainly pyrethroids (cypermethrin, deltamethrin, and bioresmethrin) and organophosphates (malathion and chlorpyrifos) are used (Athanassiou et  al., 2004; Lal and Dikshit, 2000; Lalah and Wandiga, 2002; Mada et  al.,  2014; Malinowska et  al.,  2015).

6.2. Environmental Impacts of Pesticides

The widespread use of synthetic pesticides has resulted in significant consequences not just with regard to public health but also for food quality, leading to an impact on our environment and thus the development of pest resistance. The rampant and indiscriminate use of these pesticides not only increases the cost of crop production, but also leads to adverse environmental, as well as health, consequences. Inappropriate pesticide application affects the entire ecosystem, as the residues enter the food chain and also pollute the air, soil, groundwater, and surface water (Agnihotri, 1999; Mada and Hussein,  2013; UN/DESA, 2002).

Pesticide pollution in the local environment also adversely affects the health and survival of wildlife, birds, domestic animals, livestock, and fish. Another adverse impact of application of unprescribed pesticides often in inappropriate doses not only disturbs the soil conditions, but also destroys the healthy reservoir of natural biocontrol agents that usually coexist along with the vegetation. These agents are the best friends of agriculture and therefore need to be carefully nurtured, cared for, and also developed by minimizing reliance on the use of agrochemicals within agriculture (GoI, 2008; Malinowska et  al.,  2015).

6.3. Health Impacts of Pesticides

Humans are exposed to pesticides (found in environmental mediums, such as soil, water, air, and food) by different routes of exposure, such as inhalation, ingestion, and dermal contact (Rekha et al., 2006). Exposure to pesticides results in acute and chronic health problems. Pesticides used in agriculture remain in the environment and come into human contact directly or indirectly (Bhatnagar, 2001). Increasing incidences of cancer, chronic kidney diseases, suppression of the immune system, sterility among males and females, endocrine disorders, and neurological and behavioral disorders, especially among children, have been attributed to chronic pesticide poisoning. The intensity of health hazards varies with the extent of exposure. Moderate human health hazards from the nonjudicious application of pesticides include mild headache, flu, skin rashes, blurred vision, and other neurological disorders, whereas rare but severe human health hazards include paralysis, blindness, and even death (Agnihotri, 1999).

6.4. Not-to-Be-Used Pesticides

Organochlorine insecticides, such as DDT, hexachlorocyclohexane (HCH), aldrin, and dieldrin, are among the most commonly used pesticides in the developing countries of Asia because of their low cost and versatility against various pests (Gupta, 2004). Nevertheless, because of their potential for bioaccumulation and biological effects, these compounds were banned in developed nations almost 2.5 decades ago (Rotterdam Convention, 2004). Their resistance to degradation has resulted in contamination universally found in many environmental segments. Such residues may consist of many substances, which include any specified derivatives, such as degradation products, metabolites, and congeners that are considered to be of toxicological significance.

According to the Food and Agriculture Organization (FAO) inventory (FAO, 2001), more than 500,000 tons of unused and obsolete pesticides are fatal to the environment and public health in many countries. Public concern over pesticide residues has been increasing during the past decade. Recovering from the euphoria of the green revolution, India is also now battling the residual effects of extensively used chemical pesticides, such as HCH, DDT, endosulfan, and phorate, especially in the groundwater and food matrix (Abhilash and Singh, 2009; Agoramoorthy, 2008; Rekha et  al., 2006). Hence, on account of their widespread usage in crop protection and their persistence in the environment, the presence of pesticide residues in food cannot be ruled out.

6.5. Pesticide Residues in Food

As previously mentioned, pesticides are chemical substances extensively used across the world in agriculture and public health. Indiscriminate usage of pesticides, along with their high biological activity and also their persistence in some cases, might result in the presence of pesticide residues within food and feed, as well as dairy products. The widespread organochlorine contamination has been a result of the insecticides’ direct application or more on account of their industrial emissions in the environment (Abou-Arab, 2002). In India most of the tested edible grain samples revealed the presence of DDT residues even in the year 1966 at Pantnagar in Uttarakhand (Tripathi, 1966). Ever since then, several reports have confirmed extensive pesticide contamination within food (Agnihotri, 1999).

An important study carried out by the Indian Council for Agricultural Research (ICAR) found that market samples belonging to wheat grains and pulses were greatly contaminated with pesticides, such as β-hexachlorocyclohexane (BHC) (63 ppm) and DDT (83 ppm) (ICAR, 1967). In a similar manner it was reported that the seed grains of bajra, maize, sorghum, and wheat showed alarmingly high levels of the pesticides BHC, captan, and DDT (Majumdar, 1973). It may therefore be concluded that grains kept in storage may get polluted with pesticides, as they are left in stockpiles that are periodically sprayed with pesticides for controlling pest infestation. A comprehensive review concerning pesticide residues present in grains almost 91% of wheat samples investigated by the US Food and Drug Administration (FDA) revealed pesticide contamination (Haas, 1997; Ogah et  al.,  2012). Even commodities, such as wheat flour have shown the presence of residues. During the storage of contaminated grains the pesticide dissipation has been found to be low. Even after long storage duration the grains chemically treated with pesticides showed the presence of bound residues in them. Their presence might contribute toward dietary intake of the harmful pesticides (Lalah and Wandiga, 2002). Food contamination with pesticides, particularly in the legume grains, has been reported. The large-scale contamination of pulses is a result of extensive pesticide application for controlling pests, as pulses are highly vulnerable to pest attack beginning with crop production and continuing to its storage (Lozowicka et  al.,  2014; Sharma, 2006).

With regard to the discussed hazards associated with chemical pesticides, it is important to assess simple but cost-effective strategies for enhancing food safety from the harmful pesticides for poor populaces. The processing of food at both the domestic level, as well as the industrial level, might offer a feasible means for tackling the present situation of unsafe food.

6.6. Sustainable Methodology for Food Safety Within the Transitional Phase

Alternative systems of agriculture, such as biodynamic agriculture, organic farming, pesticide-free farming, permaculture, and others (Satya et al., 2007), have been reported as sustainable, as well as pragmatic, solutions for tackling food safety and quality issues the world over. Hence, simple and economical solutions for satisfying the aforementioned concerns within the transitional phase are urgently warranted.

The provision of sufficient nutrients or good-quality proteins from animal sources is difficult and costly and might not be acceptable in some sociocultural scenarios. Therefore, it is imperative to provide an alternative source of proteins from plants for improving the nutritive status of the population. Food legumes are a significant part of our vegetarian diet owing to their high nutritional value. However, various antinutrients, such as phytic acid, trypsin, chymotrypsin inhibitors, and lectins, interfere with the nutrients’ availability and therefore limit legume consumption. However, processing is an effective means for enhancing the nutritional value of legumes through the reduction of antinutrient content and improvement of protein and starch digestibility (Prodanov et al., 2004). In a similar manner, domestic processing might be helpful in pesticide residue dissipation within the raw food (Abou-Arab, 1999; Kaushik et al., 2010).

6.7. Domestic Processing Techniques and Food Safety (Pesticide Residues)

Pesticides (insecticides, rodenticides, fungicides, etc.) are globally used for food protection and defense of human habitats from insect or other pest infestation. However, the overuse or misuse of these synthetic chemicals, particularly within developing countries, along with their volatile nature and transport for long distances, ultimately results in extensive environmental contamination. Further, many older, often nonpatented pesticide formulations with potentially greater toxicity and environmental persistence, being inexpensive, have more widespread use in the developing countries (Lozowicka et al., 2014). The application of such chemicals creates serious health problems along with the local, as well as worldwide environmental impacts (Ecobichon, 2001).

In addition, though noteworthy progress has been undertaken in the development of more potent pesticides, the fact is that actually a very small portion of the applied pesticides is precisely involved within the pesticidal mechanism. This means that a majority of the pesticides that are applied become “residues” in the environment and ultimately enter within the terrestrial, as well as the aquatic food chains, wherein they are accumulated, thereby exerting potentially adverse health effects over a long term (Guler et  al.,  2010; Winteringham, 1971).

6.8. Food Processing

Food processing at both the household level and the industrial level offers an effective means for tackling the present situation of unsafe food. Food-processing techniques are a set of procedures and techniques that are used for transforming raw constituents into food or for transforming food into various other forms intended for human or animal consumption either at the household level or at the industrial level (Kaushik et al., 2009). Unit operations that are usually utilized in the processing of food crops decrease or completely remove the insecticide or pesticide residues present in them. These processing operations, such as washing, peeling, juicing, blanching, parboiling, cooking, and so on, play a significant role in pesticide residue reduction (Elkins, 1989). Every operation bears a cumulative impact on the dissipation of the pesticides residues (Dos Reis et al., 2015; Geisman et al., 1975).

Washing is capable of removing loose residues that are superficial. It also removes major quantities of polar compounds, such as the pesticide carbaryl. Hot-water blanching enhances the elimination of pesticides and also might hydrolyze significant nonpersistent fractions (Farrow et al., 1969). Data have been compiled on the basis of studies reported in the literature. Table 1.2 presents a summary of the effects of chosen domestic-level processing techniques on the harmful pesticide residue dissipation in food grains.

Table 1.2

Effect of household processing on pesticide residue dissipation in grains.

S. No.	Processing	Commodities	Pesticides	Residue Dissipation (%)	Reasons	References
1.	Bread making	Wheat flour	Endosulfan Deltamethrin Malathion Propiconazole Chlorpyrifos Hexaconazole	70 63 60 52 51 46	Bread making involves yeast-mediated fermentation and baking, causing pesticide degradation	Sharma et al. (2006)
2.	Milling and storage for 1 year	Wheat	Phoxim methyl	8–10	During milling, residues accumulation occurs in bran fractions and reduction in white flour	Alnaji and Kadoum (1979)
3.	Milling	Whole grain	Deltamethrin	42.39		Marei et al. (1995)
4.	Milling	Wheat	Malathion	95		Uygun et al. (2005)
5.	Parboiling	IR 20 paddy	Ekalux 25 EC 0.05% Dursban 25 EC 0.05% Lebaycid 100 EC 0.05%	49 51 68	Reduction due to inactivation or degradation of the pesticides at high temperature	Krishnamurthy and Sreeramulu (1982)
6.	Parboiling	Rough rice	Malathion	99		Cogburn et al. (1990)
7.	Storage for 6 months at 26.7°C	Wheat Maize sorghum	Malathion	85% of total residue remained on outside of grain after 24 h, residues increased inside the grain and decreased markedly on the outside during the first month, and residues disappeared more rapidly from the outside than from the inside during the remaining storage time		Kadoum and LaHue (1974)
8.	12 months of storage in an open basket	Maize grains Beans	Malathion	64 47	High losses due to volatilization and possible settling of pesticide dust formulation to the bottom and on the sides of basket during storage in the open and windy tropical laboratory	Lalah and Wandiga (2002)
9.	Milling and storage for 4 and 36 weeks, respectively	Wheat grain	Chlorpyrifos methyl Etrimfos Fenitrothion Malathion Methacrifos Pirimiphos methyl	2.7 0.08 63.33 50 50 32.35		Wilkin and Fishwick (1981)
10.	Storage around 6 months	Barley	Malathion	65–72		Uygun et al. (2007)
11.	Cooking without and with NaCl	Maize grains Beans	Malathion	56.7 and 69.7 64.2 and 75		Lalah and Wandiga (2002)
12.	Washing (twice)	Soybeans	Dichlorvos Malathion Chlorpyrifos Captan	80–90	Sprayed pesticides remain as microparticles on soybeans and are easily removed by mechanical stirring in water	Miyahara and Saito (1994)

Source: From Kaushik, G., Satya, S., Naik, S.N., 2009. Food processing a tool to pesticide residue dissipation–a review. Food Res. Int. 42 (1), 26–40.

6.9. Cooking Process: Impact on Pesticide Residues

As discussed previously, cooking is the activity by which food is prepared for consumption through heat application (either dry heat or moist heat). It involves a wide range of methods based on various customs and traditions, ease of resource availability, and affordability. Literature has numerous studies reporting the impact of cooking processes on pesticide residue dissipation within the fruits and vegetables matrix; however, there is a dearth of such studies in food grains (Ferreira et  al.,  2014; Kaushik et  al.,  2012).

Mustard samples containing initial concentrations of 0.081–1.3 ppm and 0.020–0.070 ppm of fenvalerate and dimethoate, respectively, were boiled in water for 10 min, which reduced the dimethoate concentrations by almost 50% (Watanabe et al., 1988). Maize grains and beans stored for 12 months left residues of 2.79 and 4.10 ppm, respectively. The process of cooking without and with the use of NaCl removed about 56.7 and 69.7% of residues from the maize grains and 64.2 and 75% of residues from the beans, respectively. It was noticed that although the pesticide malathion, as well as its polar metabolites (namely malathion A and malathion B monocarboxylic acids) were completely removed by boiling, malaoxon was found to be present in large concentrations within the extracts of processed beans and maize (Lalah and Wandiga, 2002). Elimination of pesticide residues from the boiled extract might be on account of degradation through heat and stronger pesticide adsorption onto the plant tissues (Abou-Arab and Abou-Donia, 2001; Ali, 1983). Therefore, the processes involving heat reduce the residue levels through enhanced hydrolysis, volatilization, or other processes of chemical degradation (Holland et al., 1994). It was found that even after 6 months following pesticide treatment about 22%–23% of deltamethrin residues existed within the grains. Culinary applications, such as washing and steaming, were able to dislodge almost 40%–60% of residues from the stored chickpea grains. Steeping grains in water followed by deskinning also reduced the residues to about 37% but was unable to reduce it to safer levels (Lal and Dikshit, 2000). In a similar study, it was revealed that the decontamination processes of washing followed by cooking made chickpea pods safe from fenpropathrin residues for edible purposes (Ferreira et  al.,  2014; Kaushik and Handa, 1993).

6.10. Other Processing Methods Resulting in Pesticide Residue Dissipation

Other processing methods, such as bread making, infusion, milling, and washing, have also been investigated as causing significant dissipation of pesticide residues. Commercially manufactured bread forms an important part of the daily diet in various countries. Bread is manufactured from wheat flour spiked with different types of pesticides, such as chlorpyrifos, deltamethrin, endosulfan, hexaconazole, malathion, and propiconazole (spiked at concentrations in the range of 1–4 ppm). It was reported in one of the studies that at the highest level of spiking at 4 ppm, the pesticide is degraded as a result of yeast-mediated fermentation and high-temperature baking. The degradation of pesticides was chlorpyrifos (51%), deltamethrin (63%), endosulfan (70%), hexaconazole (46%), malathion (60%), and propiconazole (52%) (Sharma et al., 2006).

Milling of grains is a processing step commonly done to make flour and has also been found to substantially remove the residues. Usually the major portions of residues accumulate within the outer layers of the grains; consequently, often the residue levels in bran are significantly higher than in wheat (almost 2–6 times). Even for those pesticides that enter the grain by translocation, residues are found to be greater in the bran portion than within the flour (Holland et al., 1994). In laboratory experiments, the application of pirimiphos methyl to wheat grains was done at concentrations of 7.3 and 14.6 ppm, respectively. At the lower level, residues within the milling fractions (after 24 h and 12 months of treatment) accounted for more than 83.46 and 81.8%, respectively, of the level of residues that were initially found on the whole grain. For the higher spiking level at 14.6 ppm, the residues accounted for almost 82.7 and 79.01%, respectively, of the initial levels present on the grains (Kadoum et al., 1978). In contrast, a study found almost 95% reduction in the malathion residues (initial level was 8.89 ppm) within the wheat through the process of milling to flour (Uygun et al., 2005).

Parboiling is a process that involves the precooking of rice right within its husk. This process first includes hydrating of paddy, which is followed by heating for cooking the rice, and then the rice is dried. In a study, rough rice was treated with chlorpyrifos methyl (technically Reldan at 6 ppm) and malathion (14 ppm). Malathion residues within the nonparboiled rice averaged 0.016 ppm whereas the concentration was 0.013 ppm in parboiled rice. The concentration of Reldan residues in nonparboiled rice averaged 0.05 ppm, and the levels were 0.065 ppm within parboiled rice (Cogburn et al., 1990).

The most simple and preliminary step within both domestic and commercial processing involves washing with water. Different forms of washing processes effectively dislodge the loosely held pesticide residues (Street, 1969). Rice grains were spiked at 456 and 3.4 ppb, respectively, with the pesticide chlorpyrifos and its metabolite [chemically 3,5,6-trichloro-2-pyridinol (TCP)]. Washing of the grains helped in removing almost 60% of chlorpyrifos residues (Lee et al., 1991). Washing with water removed almost the entire permethrin content present in rice, which was initially at 19 ppm (Fukuhara et al., 1994). In another study, when soybeans containing pesticides captan (2.87 ppm), chlorpyrifos (11.2 ppm), dichlorvos (5.01 ppm), and malathion (7.9 ppm) were washed twice with water, pesticides content was reduced by almost 80%–90% of their initial levels, suggesting that the pesticides exist as microparticles over the soybean surface and can be easily eliminated by mechanically stirring in the water (Miyahara and Saito, 1994).

6.11. Grain Storage and Pesticide Residue Dissipation

To reduce the losses resulting from pests, various pesticides and insecticides are applied on food grains when they are stored for long periods (in the range of 3–36 months) at ambient temperatures within bulk silos (Holland et al., 1994). On account of this, the grains and foods based on them potentially serve as major sources of pesticide residues in the human diet. Studies concerning the postharvest treatment of food grains with pesticides have revealed that the concentrations of residues decline over a period of time (Holland et  al., 1994; Snelson, 1987). Residues belonging to greater lipophilic materials remain confined to the seed coat, though a small portion may reach through to bran, as well as germ that contain high triglyceride content (Anderegg and Madisen, 1983; Holland et  al., 1994). In a study during a storage period of 32 weeks at ambient temperature 20°C and relative humidity in the range of 50%–70%, the residues showed little decline, whereas at 30°C temperature residues of malathion declined by around 30%–40% while the pirimiphos methyl residues stayed constant. The residues of organochlorines and synthetic pyrethroid were also quite stable under the conditions prevalent within the silo (Holland et  al., 1994; Rowlands, 1975). With the assistance of radiotracer techniques various countries have studied insecticide persistence in stored beans and grains (Holland et al., 1994; International Atomic Energy Agency, 1990). Even after storage periods of 3–9 months the residues of parent pesticide maldison were extracted from the matrix within the range of 16%–65% of the initially applied doses. Significant concentrations of the hydrolysis products were also found, and the bound residues (which were unextractable by the solvent used) also made up almost 52% of the initially applied dose. In terms of persistence, the pesticides chlorpyrifos methyl, pirimiphos methyl, and fenvalerate were observed to be more persistent than malathion (Holland et al., 1994). The degradation, as well as penetration kinetics, of the pesticide malathion (10 ppm) applied to maize, sorghum, and wheat grains under storage conditions for a period of 6 months at the ambient temperature of 26.7°C was investigated. The results revealed a similar trend for all the grain types; it was found that greater than 85% of the total residues were superficially present on the outer side of the grain even after 24 hours. In the first month of grain storage, the residues penetrated and increased in concentration within the grain and there was a marked decrease in the residues on the outer side. In the storage duration that remained, the decline of residues was quicker from the outer surface than from within the grain (Kadoum and LaHue, 1974). Wheat grains were treated with a variety of pesticides, namely chlorpyrifos methyl, etrimfos, fenitrothion, malathion, methacrifos, pirimiphos methyl (treatment at 3.7, 5.0, 6.8, 8.2, 2.6, and 3.4 ppm, respectively) and were stored for a duration of 4–36 weeks. Flour showed residue levels of 3.6, 4.6, 3.0, 4.1, 1.3, and 2.3 ppm, respectively (Wilkin and Fishwick, 1981). A storage period of 12 months within an open basket resulted in respective declines of 64% and 47% within the malathion residues from maize grains and beans from the initial concentrations of 7.73 and 7.52 ppm, respectively. The high losses in malathion were supposed to be due to the process of volatilization and the probable settling of the pesticide formulation dust to the lower portion and the side of the basket during storage in an open, as well as windy, laboratory in the tropics (Lalah and Wandiga, 2002). The impact of storage was investigated on malathion degradation (initial level 10.2 ppm) in the 5.5-month period of storage. Significant malathion and isomalathion degradation was observed in barley (65%–72%), and the metabolite malaoxon was extensively (85%) degraded within the storage duration (Uygun et al., 2007).

7. Conclusions

Legume seeds have made a significant contribution to the human diet, as they are inexpensive sources of dietary proteins, carbohydrates, vitamins, and minerals. However, they also contain large amounts of ANFs (e.g., trypsin inhibitors, phytic acid, and α-galactosides) at the same time that need to be eliminated or reduced by processing, such as soaking, germination, cooking, fermentation, and extrusion, so as to enhance digestibility and nutritive value. Food contamination can occur inadvertently as a result of direct or indirect exposure to toxic chemicals. Widespread contamination of food commodities with harmful chemical compounds has shown negative impacts on human health and degraded the environment, and thus has reaffirmed the significance of safe and high-quality food products. Hence, a sustainable solution to this scenario of unsafe and poor-quality food warrants a paradigm shift in the current mind-set.

In view of these concerns, several alternative agriculture systems, such as organic farming, permaculture, and biodynamic farming, have been proven to tackle existing agricultural problems the world over. However, for several inherent sociotechnical and sociocultural reasons, especially in some developing countries, diffusion and acceptance of these alternatives may be quite difficult and slow. Domestic processing may help in the dissipation of pesticide residues in raw food during this transitional phase. Unit operations normally employed in processing food crops reduce or remove residues of insecticides and other pesticides that are present in the crops. These operations, such as washing, peeling, blanching, and cooking, play a vital role in the reduction of residues. Each operation has a cumulative effect on the reduction of the pesticides present. Therefore, a combination of processing techniques would render food grains safe for human consumption. In addition, it is necessary to optimize the cooking process to maximize nutrient content and minimize antinutrients, so that it can be recommended to the masses for good health.

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Further Reading

Mahdavian SE, Somashekar RK. Dietary intake of insecticides from food in Karnataka, India. Adv. Res. Biol. Sci.. 2013;1(2):24–30.

Podbielska M, Szpyrka E, Matyaszek A, Kurdziel A, Rupar J, Słowik-Borowiec M. Estimation of the dietary exposure associated with pesticide residues in vegetables grown under covers in 2010–2012. Prog. Plant Protect.. 2013;53(2):391–396: (in Polish).

Tiwari U, Cummins E. Factors influencing levels of phytochemicals in selected fruit and vegetables during pre- and post-harvest food processing operations. Food Res. Int.. 2013;50(2):497–506.