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food preparation,preservation and storage.pptx m

The document covers food preparation, preservation, and storage, focusing on the principles and methods of cooking that enhance food safety and nutritional value. It discusses various cooking methods, effects of cooking on different food types, safe food handling practices, and health considerations for food handlers to prevent foodborne diseases. Additionally, it addresses food preservation techniques and legislation against food adulteration to maintain food quality.

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FOOD PREPARATION PRESERVATION AND STORAGE BY : MERCIA KANAI (MSc N) LECTURER
COOKING Definition Cooking is an art itself and can be defined as the process of preparing food with any method of heat application. Cooking is done in many ways depending upon the availability of food stuffs, culture, religion and food habits. But cooking eventually fulfil the nutritional needs.
Purposes of Cooking  Cooking improves flavour and palatability of food.  It makes the food easily digestible  Cooking kills the microorganism, parasitic, ova, and eggs and making food safe for consumption  Cooking increases the availability of some nutrients.  Trypsin inhibitor present in protein food is destroyed by cooking and making trypsin freely available to the body  Cooking in different ways provide variety in the diet  Cooking eliminates indigestible material  Cooking increases appetite and acceptability of food.
Principles Of Cooking  Cooking should be done at hygienic place.  There should be sufficient light.  Cooking area should be at reasonable distance from sanitary area.  Handling and storing of food should be near the cooking area.  Always wash the vegetables and fruits before peeling and cutting to prevent the loss of water soluble vitamins.  Always cook in a minimal water to preserve the vitamins.  Cook in a covered pan except green vegetables.
 Foods must not be overcooked or undercooked to prevent the loss of vitamins and later to control the microbial count.  Do not add alkalies like sodium bicarbonate to the food while cooking as alkalies destroy vitamin B and vitamin C.  Always cook in pressure cooker. It will help retaining the vitamins.  Avoid cutting into small pieces as more surface area is exposed.  Soak pulses and rice in water before cooking. It reduces the cooking time.  Store foods in a refrigerator, covered with a lid or aluminum foil to retain nutrients.  The persons involved in cooking should maintain cooking hygiene by
Methods of Cooking  Boiling: In this method the foods are cooked in water at 100°C. Rice, grams, pulses, roots and tubers are cooked by boiling. Boiling should be done in minimum amount of water to prevent the loss of vitamin.  Simmering: This method involves cooking below the boiling point of water, i.e. at about 84°C. It helps in preserving the essential vitamins. Fish and meat are cooked by this method as the higher temperature causes hardening of fibers of such foods.  Steaming: This method is used to cook food in direct heat steaming. The temperature attained is > 100°C. Pressure cooker is used to cook foods by steam under pressure. This method is very effective as it saves fuel, time and preserves the nutrients.  Grilling: It is cooking by direct heat. Here direct flame, grill pans are used
Stewing: Stewing is the method of cooking vegetables, fruits, and other foods in small quantity of water, at lower temperature than boiling usually at 80°C. The foods to be cooked are covered with little water in a pan and then covered with lid. Cooking is done for prolonged low degree heat. The nutrients are not lost, but are present in the liquid. This stewing of fruits and vegetables are used for small children and old people with dentures. Stewing is highly nutritious Roasting: In roasting the foods are directly exposed to heat or flame after smearing with little fat. This makes the food tender. Chicken and tender meat are cooked by this method. This is also called "Barbeque". This is best method to cook as it reduces the risk of cardiovascular disorder, obesity and hypertension. Baking: In baking the foods are cooked by dry heat in hot air oven. Food is enclosed in hot air in an oven and heat from all sides is utilized for cooking. Temperature for baking is 250-500°F. Baking is expensive and slow process. Foods cooked by this method are cakes, pastry, patties, bread and biscuits
• Frying: Frying is the cooking food in oil. It is of two types: (1) Deep fry: In deep frying, foods are immersed in large amount of hot oil. This method is used for making pakoras, samosa, puri, cutlet, kachori, etc. The principle of deep frying is that, oil must be enough hot to prevent absorption of oil in the food. (2) Shallow fry: It requires less quantity of oil and suitable for making omlet, dosa, paratha, and precooked food. • Solar cooKing: This method is used in areas where direct sunlight is available. In this method solar energy is utilized for cooking foods. Solar cookers and closed containers are used, which absorbs maximum solar energy. This is very simple and economical method, but takes longer time for cooking.
Effects of Cooking on Food  Cooking softens the texture of food, thus increases its taste.  It makes the food easily digestible.  It helps in destruction of microorganism present in food.  There is a loss of some water soluble vitamins during cooking.  The fat soluble vitamins have no effect of heat, so they are not lost.  The antitrypsin substance present in pulses is destroyed to make the trypsin available for digestion.  Complex proteins are broken down into simple protein.  Over cooking destroys essential nutrients  Under cooking prevents killing of microorganisms present in the food.
Effects of cooking on different types of foods are as follows:  Effect on cereals: Cereals and millets contain starch with little protein enclosed within the cell wall of cellulose. Boiling causes gelatinization process in cereals in which starch grains swell and burst the cellulose. Rice are cooked in double quantity of water. Excessive use of water during cooking results in loss of thiamine. Sodium bicarbonate if used in cooking destroys thiamine. After gelatinization, cereals become easily digestible as the protein content on their coating coagulates. Cereals when cooked with pulses improves the quality of the nutrients and prevent the protein deficiency diseases.  Effects of cooking on pulses: An antitrypsin substance present in pulses inhibit complete digestion of proteins. On cooking this antitrypsin
Effect of cooking on green leafy vegetables: Green vegetables like-spinach if cooked in excess water the minerals and vitamins are lost. If baking soda is used, it destroys thiamine. Vitamin A is not lost during cooking in water. To preserve minerals and vitamins, vegetables should be cooked in pressure cooker using less water. Effects of cooking on roots and tubers: Roots and tubers like-potatoes and yam contain abundant starch as compared to other vegetables. These must be thoroughly cooked for complete gelatinization. These vegetables must be boiled slowly as rapid boiling breaks the mineral rich skin, less water should be used for cooking to avoid the loss of minerals.
Effect of cooking on fruits: Fruits mainly contain water, vitamins and minerals, Protein and fat content is less. Carbohydrates in the form of sugars are present in varying amount in the fruits. Citrus fruits are rich in vitamin C and potassium. Majority of fruits are eaten raw and supply good amount of nutrients. But, during preparation of fruit stews, vitamin C and little amount of sugar is lost. Fruits contain plenty of fibers and cooking reduces this level and increase the digestibility. Effects of cooking on meat fish and liver: Animal foods contain fat and protein. On cooking fat melts, the protein and fibers are lost to some extent in soup. On grilling the meat, the protein on surface coagulates and seals all juices inside the meat. During boiling or stewing, minerals are lost. Prolonged cooking makes its texture hard and indigestible. Meat soup is rich in minerals, vitamins and protein. Fish loses its flavors on cooking but digestibility improves. Liver, kidney and other organs are rich in minerals and protein but difficult to digest.
 Effect of heat on milk: On heating, a layer of fat forms on surface. Taste also changes on heating. If cream is removed from surface after boiling, it reduces casein (protein) and fat content of milk.
Effects of Cooking on Various Nutrients Effects on carbohydrates: Cereals and starch granules absorb water and swell up to burst finally. This process is known as gelatinization. Cooked starch is digested more easily than raw starch. As the carbohydrates are main source of energy they must be cooked properly for effective digestion in the gut. Effects on protein: Proteins coagulate in moist heat. Cooked proteins are digested easily, proteins are the valuable body building food and secondary source of energy in carbohydrate deficiency. Overheating of protein foods result in destruction of their nutritive values. It should be properly cooked for effective digestion. Effect on fats: Fats when cooked at normal temperature, during cooking does not undergo any change in its chemical composition. However, on overheating while deep frying, it loses some of its essential fatty acids and
Effect on vitamins: Water soluble vitamins B groups and vitamin C are lost during cooking and loss from dissolved water. Vitamins are destroyed if alkalies are used in cooking like sodium bicarbonate. But frying or roasting vegetables causes enough loss of vitamin A . Minerals: Minerals present in foods like-calcium, phosphorus, iron, sodium, potassium, magnesium and trace elements are lost when cooked in excess water for prolonged period.
SAFE FOOD HANDLING, AND HEALTH OF FOOD HANDLERS Safe food handling is the basic step to prevent food borne diseases in the food industry as well as at household level. Food can get contaminated at any stage right from storage, cooking, preservation and distribution. The contaminated food can cause various food borne diseases and food poisoning. The following points has to the observed in safe food handling: Clean storage place: The place for storage food should be clean and away from sanitation. Food hygiene: The perishable foods start deteriorating immediately if not properly preserved. Fruits, vegetables, milk, meat should be kept at low temperature in refrigerator. The food handlers suffering from any infectious disease should be excluded
Control of rats, rodents and insects:They should not have access to food storage or preparation places. Sanitation of all work surfaces, utensils and equipment should be ensured. All raw vegetables and fruits should be thoroughly washed before use. Periodical medical examination of the food handlers should be conducted to exclude the carries of the disease.
Health Education to Food Handlers  They should be educated regarding personal hygiene, clean habits and about the food hygiene.  They should be emphasized and made to practice.  Hand washing: Hands should be scrubbed and washed with soap and water immediately after going to toilet.  Finger nails should be trimmed and free from dirt.  Hair should be covered with cap.  Use of apron and gloves while preparing food and serving. Smoking, coughing, and sneezing in the food premises should be forbidden.
After cooking food, it should be covered and kept in safe place. Safe water should be used for cooking the food. Milk, milk product and eggs should be pasteurized. Food must be thoroughly cooked. Most of the food poisoning organisms are killed at 60°C. Foods not eaten immediately should be kept in cold storage to prevent bacterial contamination. Cook and eat on the same day is a golden rule.
Health of Food Handlers Health of the food handler is of paramount importance as the diseases such as typhoid, and paratyphoid fever, viral, hepatitis, diarrhoea, dysentery and worm infestations and tuberculosis are spread through them if they are carriers of the diseases or suffering from these diseases. The following points are to be carried out to prevent the spread of diseases through them: At the time of employment, complete medical examination has to be carried out including blood. urine and stool test and X-rays chest to exclude the respiratory tract diseases. Any person with a previous history of typhoid, fever, chronic dysentery should not be employed in eating establishment. Persons suffering from skin diseases, ear discharge or infected wound should not be permitted to handle food or utensils . Health education regarding personal hygiene should be frequently reinforced.
Every three months, their medical examination has to be carried out including urine, stool and blood test to rule out any infection. Coughing, sneezing and cigarette smoking should be prohibited in the premises of area where food is prepared and distributed. Any person suffering from diseases transmitted through food and coughing, sneezing should be treated immediately and excluded from place of work till he/she is clear of infection. Periodical immunization during the outbreak of cholera, viral hepatitis, typhoid and paratyphoid to be done of all the workers engaged in food preparation and distribution. Special attention to hand washing after toilet, covering hair with cap and use of apron and gloves should be strictly implemented
FOOD PRESERVATION Food preservation is the technique to prevent food spoilage, food poisoning, and microbial contamination in food. Purposes of Food Preservation To have all types of foods available throughout the year, i.e. to make non- seasonal foods also available. Readymade canned foods save time and energy. Variety of foods are available for consumption. To prevent wastage of food, due to spoilage or destruction. To preserve foods for future use. To make commercial profit. To preserve the taste, odor and flavor of food.
Household Methods of Food Preservation • Cooking: Cooking is done by various methods like boiling frying stewing, simmering, roasting and baking. The cooked foods can be stored for prolonged time than uncooked ones. Cooking at different temperature kill microbes and destroy toxins in the food. • Sun drying: Sun drying is used to dry many foods for long-term preservation, for example, vegetables such as spinach, cauliflower, carrots, ginger. This method is simple and economical where there is an abundant sunlight as by drying in sun moisture is removed and the microorganism cannot grow. • Refrigeration: Temperature 1-4°C prevents foods from spoiling for a short time. Fruits, vegetables and cooked foods are preserved in the refrigerator for few days. The frozen foods kept at -18°C are preserved for a year.
• Salting and pickling: Salt is a good preservative. By adding certain spices along with lot of salt, certain foods are preserved, e.g. mango pickle, lime and vegetable pickles, chutney, and fish can be stored for a long time as microorganism cannot grow in high concentration of salt. Same way sugar with certain spices are used to preserve fruits, e.g various fruits like, apple, amla and jams are also prepared on the same
Commercial Methods of Foods Preservation • Canning: Some foods such as fruit juices, milk, baby foods, soups and soft drinks are preserved by canning. The food is sterilized first at a temperature of 135-175°C for a short time, i.e. only few seconds and then cooked and filled in presterilized containers in a sterile atmosphere • Creating a vacuum: This process is just like canning, only difference is that oxygen is removed from the top, Oxygen removal can stop the growth of microorganisms. Packing of prepared food in vacuum packs is an excellent means of preserving food.. Packs should be stored at room temperature and well labeled.
• Freezing: A number of fruits and vegetables, meat and fish are preserved by freezing techniques Vegetables can be preserved for 8-10 months and meat for 3 months. • Irradiation: Gamma rays of various frequencies ranging from low to high frequency are being used to preserve various foods. Ultraviolet radiation is the most widely used in food industry. These are invisible form of light and used to control mold growth on surface of bakery products and to prevent spoilage of meat. Treating water for beverages is another use of ultraviolet rays. These are also used to inhibit sprouting of potatoes and onions, garlic. • Drying • By adding preservatives: Preservatives are used for long-term storage of foods as the preservatives retard the deterioration of food.
• Sugar: A high concentration of sugar prevents molds, yeast and bacterial growth. High concentration of sugar is used to preserve jams, jellies and candied fruits. • Pasteurization is used to control microorganism in milk, fruit juices and wines. Foods are pasteurized by any of the 3 methods 1. Low temperature holding method at 62°C for 30 minutes 2. High temperature short time at 92°C for 15 minutes 3. Extra high temperature above 135°C for 2 seconds. This method makes food commercially sterile.
FOOD-BORNE DISEASES • Food-borne infections • Bacterial infections: Typhoid fever, paratyphoid fever caused salmonella typhi and typhoid bacillus. • Fungal infection: • Liver diseases • Viral infection:Viral hepatitis due to hepatitis A virus. • Parasitic infections: • some of the food borne diseases cause mild symptoms whereas others may cause severe symptoms resulting in emergency hospitalizations due to food poisoning.
Signs and symptoms of food poisoning  Vomiting and nausea  Severe diarrhea resulting into severe dehydration  Rapid pulse  Low BP  Sunken eyes and dry coated tongue  Low urinary output  Cold and clammy skin  Shock may be present. Management • Replacement of fluids and electrolyte by intravenous therapy. • Anti-emetic drugs to stop vomiting • Antibiotic to treat infection
FOOD ADULTERATION AND RELATED ACTS Food adulteration: Food adulteration is the addition or subtraction of anything from the food which affects its nutritional value for unfair economic gains. Methods of Adulteration  Mixing up food products with edible or nonedible substances.  Substitution of the quality nutrients with substandard adulterants.  Abstraction of nutrients, i.e. removing something from the original food article.  Misbranding  Concealing the quality  Mislabeling  Adding toxic substances
Acts Related to Food Adulteration To prevent the adulteration of food, the government of India passed an Act. "Prevention of Food Adulteration Act" in 1954 and it was implemented in June 1955. To rectify its drawbacks, some amendments were made in 1964, 1976, 1986, 2001 and 2002. Advantages of PFA Act 1955: Maintaining the quality of food stuffs. Preventing adulteration. Punishing the defaulters and organizations responsible for adulteration. Giving special rights to the consumer and voluntary organization so that they can play active role in checking adulteration. Checking the quality of imported edible stuffs.
Fruit product order standard (1961): This order specifies the standards for qualities of fruits and vegetables products. The manufacturer is required to obtain licence to meet the required standard. The main aim of FPO is to maintain minimum level of quality during farming, manufacturing and retailing. Agmark standard The directorate of marketing and inspection gives this standards. The foods under this standard are vegetable oils, ghee, butter, rice, jaggery, eggs, ground nut, spices, potatoes and pulses. It also specifies various foods according to quality.
Indian standard institution ISI : The ISI mark symbolizes its quality. Foods covered under this are vegetable and fruit products, spices, condiments, meat products, processed foods such as biscuits, sweets, flour, soya products, tea, coffee, beverages, etc. Vegetarian and nonvegetarian standard: According to this standard, on each packet of food stuff or edible product, if it is vegetarian, a green mark should be there and brown mark on foods containing nonvegetarian products.