Anti-Nutritional UNIT 11 ANTI-NUTRITIONAL FACTORS, Factors, Food Contaminants and FOOD CONTAMINANTS AND Toxic Elements TOXIC ELEMENTS Structure 11.0 Objectives 11.1 Introduction 11.2 Anti-Nutritional Factors Anti-Nutritional Factors in Plant Foods Toxicants in Animal Foods 11.3 Contamination of Food by Microorganism, Pathogens 11.4 Food Intoxicants 11.5 Mycotoxins 11.6 Food Poisoning and Food Infections Food Poisoning Food Infections 11.7 Food Born Diseases 11.8 Methods of Preventing Food Contamination 11.9 Deficiency: Protein, Vitamin and Mineral – Consequences and Corrective Measures 11.10 Methods of Nutrient Retention during Processing and Storage 11.11 Food Analysis, Residue Analysis Food Analysis Residue Analysis 11.12 Let Us Sum Up 11.13 Key Words 11.14 Answer to Check Your Progress Exercises 11.15 Some Useful Books 11.0 OBJECTIVES After reading this unit, you should be able to: • describe food contamination, factors contributing contamination and methods of prevention; • list the anti-nutritional factors in food; • discuss food born illness; and • state deficiency diseases. 11.1 INTRODUCTION Foods are exceedingly complex mixtures of chemicals substances. Apart from containing nutritionally important constituents, some foods also contain substances, which are harmful. The presence of nonnutritive constituents in foods represents potential health risks of different characters and magnitudes to persons consuming them. If such food is ingested, it can cause food poisoning and infection. Food poisoning could be caused by ingestion of foods containing certain chemicals, toxic plants or animals, toxins produced by bacteria and ingestion of animal parasites. Pathogenic microorganisms may enter foods through poor handling and grow in it. When such contaminated 61 Nutrition food is ingested, it could cause food infections. Hence, food safety should be a major concern of processor for the public health. 11.2 ANTI-NUTRITIONAL FACTORS 11.2.1 Anti-Nutritional Factors in Plant Foods Plants are capable of synthesizing a multitude of chemical that cause toxic reaction when consumed. Pulses contain a number of toxic factors, such as protease inhibitors, lathyrogens and favism agents, cyanogens, haemagglutinins and saponins. Some of these toxins are also present in other foods, e.g., protease inhibitors in cereals and potatoes. Solanine, ordinarily the green parts of the potato are removed with the peel, is a toxicant in potatoes. Goitrogens (cause thyroid enlargement) are present in cabbage and related species, rapeseed and mustard. Some varieties of mushroom (e.g. Amanita) are poisonous. Oxalic acid present in spinach, beet etc may cause oxalic poisoning. Soybean contains trypsin inhibitor that affects protein metabolism. Cassava and Lima beans contain linmarin, a toxic glycoside. Lathyrism is a neurological disease caused by the ingestion of Lathyrus sativus (khesari dhal) for a period of 6 months or more. Favism agents in fava beans, gossypol in cottonseed are also potent toxic substances. The active flavoring principles present in some spices may have toxic effects if consumed habitually over long periods or in excessive amounts. Active principles in some of the foods are allyl isothiocyanate in mustard, capsaicin in chillies, myristicin in nutmeg and mace, etc. 11.2.2 Toxicants in Animal Foods The ingestion of shellfish (clams, mussels) results in paralytic shellfish poisoning. Saxitoxin, an extremely toxic metabolite, is p roduced from the plankton. The toxin resists ordinary cooking procedures. Sea food poisoning, for examples, ciguatera poisoning, moray eel poisoning, scombroid poisoning, puffer fish poisoning, cephalopod poisoning, is mostly prevalent in the areas where marine organisms constitute about 10 per cent of the diet. 11.3 CONTAMINATION OF FOOD BY MICROORGANISM, PATHOGENS A large number of careless practices cause contamination of food with potentially pathogenic microorganisms. The more common ones are unhygienic practices of food handling, personnel handling food suffer from communicable diseases, cross contamination of food, contaminated water and containers, soil adhering to foods, insects, droppings of rodents. Contamination by Bacteria Certain bacteria release poisons known as toxins. Some toxins produced by Clostridium botulinum are often cause death of persons consuming food contaminated with this organism. The bacteria such as Staphylococcus aureus and Bacillus cereus produce toxins in food during multiplication or sporulation. Although cooking may destroy these bacteria but the toxin is unaffected and can still cause the problems if food is eaten. Endotoxin are 62 generally produced by bacteria such as Salmonella in the intestines of persons Anti-Nutritional Factors, Food consuming food contaminated with such organisms. Contaminants and Toxic Elements Contamination by Moulds Almost any food can be invaded by mould growth. Moulds cause various degree of visible deterioration and decomposition of foods. Moulds may produce abnormal flavours and odours due to fermentative, lipolytic, and proteolytic changes caused by enzymatic reactions with carbohydrates, fats, and proteins, respectively in foods. Contamination by Yeasts Food that is highly contaminated with yeasts will frequently have a fruity odour. Yeasts can grow in a product with low sugar concentration. Most of them do not develop in solutions containing more than 66% sugar or 0.5% acetic acid. Boiling destroys the yeasts cells and spores completely. Foods liable to be spoiled by yeasts are fruit juices, syrups, molasses, honey, jams and jellies. Contamination by Viruses Viruses are transmitted to food by workers who are carriers. An infected food handler can excrete the organism through the faeces and respiratory tract infection. The inability of host cells to perform their normal function causes illness due to viral infection. Check Your Progress Exercise 1 " Note: a) Use the space below for your answer. b) Compare your answers with those given at the end of the unit. 1. ‘Non-nutritive constituents of food can create potential health risks’, justify. ………………………………………………………………………………. ………………………………………………………………………………. ………………………………………………………………………………. ………………………………………………………………………………. ………………………………………………………………………………. ………………………………………………………………………………. 2. Write some of the important anti-nutritional substances present in vegetables. ………………………………………………………………………………. ………………………………………………………………………………. ………………………………………………………………………………. ………………………………………………………………………………. ………………………………………………………………………………. ………………………………………………………………………………. 63 Nutrition 3. Define endotoxins. List the factors responsible for food contamination. ………………………………………………………………………………. ………………………………………………………………………………. ………………………………………………………………………………. ………………………………………………………………………………. ………………………………………………………………………………. ………………………………………………………………………………. ………………………………………………………………………………. 11.4 FOOD INTOXICANTS The undesirable constituents that affect the safety of foods include toxicants naturally occurring in foods, toxins resulting from microbial growth, environmental contaminants such as processing and accidental contaminants and chemical contaminants. Naturally occurring toxicants in plant and animal foods Foods contain thousands of compounds that are potentially toxic. For example protease inhibitors, lathyrogens, favism agents, cyanogens, haemagglutinins and saponins in pulses, solanine in potatoes, goitrogens in cabbage, rapeseed, etc., trypsin inhibitor in soybean, beta oxalyl amino alanine in khesari dhal, linmarin in cassava and lima beans, Favism agents in fava beans, gossypol in cottonseed are potent toxic substances. Some spices contain active principals (e.g., allyl isothiocyanate in mustard, etc.) may have toxic effects. Paralytic shellfish poisoning from oysters, calms, mussels, and scallops has caused many fatal illness. Saxitoxin, an extremely toxic metabolite, is produced from the plankton. Microbial Toxins Microorganisms promote desirable changes in foods under controlled conditions. However, they also cause harmful effect and are involved in most cases of food poisoning. Bacterial food intoxication: Staphylococcal poisoning occurs abruptly after ingestion of food containing the enterotoxin, produced by staphylococci present in semisolid foods. Foods such as corn, peas, meat, fish are likely to be contaminated with the spore of Clostridium botulinum. They act on nervous system and are potent poisons and cause a disease known as botulism. The food infected with Bacillus cereus, if consumed is also harmful. Some species of fungi such as Aspergillus flavus, Aspaergillus parasiticus (produced aflatoxins) Claviceps purpurea, Fusarium species produce toxins in foods infected with them and make the foods unfit for consumption. Environmental Contaminants These include residues that become part of food as a result of processing, handling and distribution of food. For examples, ethylene oxide used as fumigants to sterile some food reacts with inorganic chlorides to form ethylene 64 chlorohydrin, which is toxic. During smoking of meat and fish for preservation Anti-Nutritional Factors, Food and flavouring, these foods get contaminated with polycyclic aromatic Contaminants and hydrocarbons (e.g. benzopyrine), many of which are carcinogenic. Toxic Elements Metals, find their way into foods through air, water, soil, industrial pollution and many other routes, when present beyond the permissible limit, are toxic. Mercury, cadmium, lead, tin, etc. are the toxic metals present in foods. Other contaminants from food processing