eChapters

55.1. Aim

To determine dietary fibres in given samples.

55.2. Theory

Fibres can be classified into four categories like crude fibre (cellulose); acid detergent fibre (cellulose + lignin); neutral detergent fibre (cellulose + lignin + hemicelluloses) and total dietary fibre.

55.3. Procedure for estimation of dietary fibre

55.3.1. Acid detergent fibre (ADF)

Reagents: Cetyl tri-methyl ammonium bromide (CTAB) reagent and Acetone

Apparatus: Digestion apparatus vacuum pump, oven, desiccator and sintered glass crucible.

54.1. Aim

To determine crude fibre in given samples.

54.2. Theory

Fibres can be classified into four categories like crude fibre (cellulose); acid detergent fibre (cellulose + lignin); neutral detergent fibre (cellulose + lignin + hemicelluloses) and total dietary fibre (Cellulose + lignin + hemicelluloses + pectic substances). Crude fibre is the organic residue of a sample. A fat free sample is treated with boiling sulphuric acid and subsequently with sodium hydroxide. The residue after subtraction of ash is regarded as crude fibre.

54.3. Reagents/ Apparatus/Glassware

1. 0.255 N Sulphuric acid solution

2. 0.313 N Sodium hydroxide solution

3. 10% Potassium sulphate solution

4. Ethanol

53.1. Aim

To conduct practical on freezing of vegetables

53.2. Theory

Freezing is often considered the simplest and most natural way of preservation for vegetables. Frozen vegetables and potatoes form a significant proportion of the market in terms of frozen food consumption. The quality of frozen vegetables depends on the quality of fresh products, since freezing does not improve product quality. Pre-process handling, from the time vegetables are picked until ready to eat, is the important factor affecting quality of finished product. The process variables for freezing of different vegetables and flow chart are shown in Table 54.1 and Fig 54.1. Generally fruits after preliminary treatments are packed in sugar syrup and frozen in freezer.

52.1. Aim

To conduct practical on freezing of fruits.

52.2. Theory

Freezing is a method of preservation in which the food temperature is reduced below freezing point and a proportion of water changes in to ice-crystals. Immobilization of water to ice and the resulting concentration of dissolved solutes in unfrozen water cause lowering of water activity in the food. Thus, reduction in water activity and use of low temperature coupled with some pre-treatments is the basis for food preservation by freezing. The method for freezing of fruits depends upon the intended use. The process variables for freezing of different fruits and flow chart are shown in Table 52.1 and Fig 52.1. Generally fruits after preliminary treatments are packed in sugar syrup and frozen in freezer. The fruits are frozen to an internal temperature of -18oC or lower and kept at 18oC or lower throughout transport and storage.

51.1. Aim

To prepare products from tomato fruits.

51.2. Theory

Commercial products from tomatoes include ketchup, soup, cocktail, chutney, canned and dehydrated tomatoes. Processing of tomato is now practiced from home scale level to a large scale enterprise. Both puree and paste are used for preparation of different finished products like ketchup, canned and dehydrated products, soup etc. The method for preparation of these products are well standardized, however, some modification with respect to recipes are made in the processing plants owing to variation in the quality of the raw material. The method for preparation and recipe of different tomato products are as under:

51.3. Raw material, ingredients and utensils required

1. Tomatoes, sugar, salt, sodium benzoate etc.

2. Stainless steel knives, utensils, juicer, pulper, glass bottles, corking machine, crown corks, muslin cloth, boiler/gas bhatti, etc.

50.1. Aim

To prepare products from tomato fruits.

50.2. Theory

Commercial products from tomatoes include juice, puree and paste. Processing of tomato is now practiced from home scale level to a large scale enterprise. As a semi finished product, tomato puree is prepared on a small scale while at large scale tomato paste has gained commercial significance. Both puree and paste are used for preparation of different finished products like ketchup, juice, soup etc. The method for preparation of these products are well standardized, however, some modification with respect to recipes are made in the processing plants owing to variation in the quality of the raw material. The method for preparation and recipe of different tomato products are as under:

50.3. Raw material, ingredients and utensils required

1. Tomatoes.

2. Stainless steel knives, utensils, juicer, pulper, glass bottles, corking machine, crown corks, muslin cloth, boiler/gas bhatti, etc.

49.1. Aim

To perform practical on drying/dehydration of different vegetables.

49.2. Theory

Drying refers to the method of removal of moisture content from the food to a level at which the activities of food spoilage and food poisoning micro-organism are inhibited. Therefore, reduction in water activity of the food is the main principal of preservation by drying. In the dehydrator initial temperature is generally kept at 43oC which is then gradually increased to 60-66oC for vegetables. The product shall be prepared from wholesome vegetables free from blight, insect infestation and fungal discoloration. Only edible portion of the vegetables shall be used and it shall be free from stalks, peels, stems, and extraneous matter. The dried/dehydrated vegetable may contain permitted preservative. The finished product shall be of good edible quality and shall reasonably reconstitute to its original shape and quality on boiling for 15 minutes to an hour. The finished product shall be free from visible mould, insect or larvae. Kind of dry vegetable shall be declared on the label. Acid insoluble ash shall not be more than 0.5%.

48.1. Aim

To conduct practical on drying of fruits

48.2. Theory

Drying generally refers to the method of removal of moisture from the food under natural condition such as sunlight and wind for example open sun drying, shade drying etc. Dehydration refers to a process of removal of moisture by application of artificial heat under controlled conditions of temperatures humidity and air flow. It also represents drying of agricultural commodity to dry state. For drying, single thin layer of fruit and vegetables, either whole or sliced after primary pre-treatments is spread on the trays which are then placed inside the dehydrator or in the open sun for drying. In the dehydrator initial temperature is generally kept at 43oC which is then gradually increased to 66-71oC for fruits.

47.1. Aim

To conduct practical on preparation of pickle from different vegetables.

47.2. Theory

Pickles are good appetizers and add to the palatability of a meal. Pickles may be unfermented (mostly Indian pickles) and fermented (western pickles). Salt, vinegar, edible oil or acetic acid acts as preservative in pickle making. Mixed vegetable pickle from cauliflower, carrot and turnip is most common. Cucumber and olive pickles are examples of fermented pickles. The process of steeping vegetables/fruits in salt solution is also a common method used for preservation of mango and vegetable slices for longer duration storage for its later use in pickling.

46.1. Aim: To prepare pickle from different fruits.

46.2. Theory

The preservation of food in common salt (NaCl) or in vinegar or edible oil with the addition of spices and condiments is known as pickling. It is one of the most ancient /oldest methods for preservation of fruits and vegetables. Salt, vinegar, edible oil or lactic acid act as preservative in pickle making. Several kinds of pickles are sold in the Indian market. Mango pickle ranks first followed by lime, lemon, mushroom, galgal, aonla, jackfruit and karonda pickles.

Brining: For pickling, unripe fruits (like mango) after preparation (peeling, slicing) are mixed with salt or brine for its later use in pickle preparation

45.1. Aim

To conduct practical on preparation of sauce from different fruits.

45.2. Theory

Sauces are of thinner consistency as compared to ketchups and contain TSS not less than 15oBrix. Pumpkin, tomato, apple, papaya and plum pulps etc are used successfully for preparation of sauces. Mixed vegetable sauce using pumpkin, tomato, chillies, carrots are sold as continental sauces.

45.3. Raw material, ingredients and utensils required

1. Fruits like Apple, tomato, papaya, pumpkin, plum etc are used for making sauce.

2. Stainless steel knives, de-corers, ladle and utensils for cooking and mixing, glass bottles, sterilization tank, Bhatti/LPG stove etc.

44.1. Aim

To conduct practical on processing of tea and coffee.

44.2. Theory

Tea is an evergreen woody perennial grown in many Asian countries including China, Japan, Java, Sumatra and India. The plant produces dark green, small shiny leaves with white blossom. In post harvest and manufacturing practices for tea, only mechanical and physical processes are allowed with natural fermentation. It can be manufactured by orthodox, CTC (crush, tear and curl) processing.

Coffee is an important beverage used all over the world. Brazil and Columbia are the largest coffee producers in the world. Coffee is harvested in one of two ways; strip picking (entire crop is harvested at one time either by machine or by hand); selective picking (only the ripe berries are picked individually by hand) during dry season when cherries are bright red, glossy and firm. After picking, the coffee can be prepared either by dry method which produces natural coffee or by wet method which produces washed coffee.

43.1. Aim

To conduct practical on preparation of preserve and candies from fruits.

43.2. Theory

Preserves (murraba) are made by cooking the entire fruit or its slices/pieces in sugar syrup of higher concentration (65-70°Brix). Usually for 1 kg fruit around 1.75 kg sugar is used and the cooking is continued till the TSS reaches 68%. Fruits like aonla, bael, apple, pear, karonda, pineapple and papaya etc can be used for making preserves. Aonla, bael and apple preserves are commercially available in the market.

Candies are also prepared in similar way as preserve, but the TSS maintained is slightly higher (75-80%). In preserve, the fruit is kept immersed in syrup and packed while in case of candies, the syrup is drained off and fruit pieces are further dried and packed. For candy preparation, the fruit pieces are dipped initially in 55-60% sugar solution and the TSS of the syrup is increased by 5% everyday up to 4-5 days till a TSS of 70oBrix is reached. The fruit pieces are then separated from syrup, rolled in powdered sugar, dried and packed. Karonda, apple, peels of orange, lemon, grapefruit, petha (Ash gourd) and ginger etc are used for candy preparation. Petha, ginger, papaya, aonla etc candies are commercially available in the market.

42.1. Aim

To conduct practical on preparation of chutney from different fruits.

42.2. Theory

Fruit chutney is made in the same way as jam except that the spices, salt and vinegar or acetic acid is also added. In comparison to jam, chutney contains less total soluble solids. The product shall be of good quality with palatable and appetizing taste. As per FSSAI specifications, the chutney shall contain minimum of 40% fruit (w/w) in the final product with total soluble solids not less than 50%. The acidity in the final product shall not be more than 2 percent with ash content not exceeding 5 percent. Mixed fruit chutney is commercially made by using different fruits in appropriate combinations.

42.3. Raw material, ingredients, equipments and utensils required

1. Stainless steel peeling/cutting knives, pulper for extraction of pulp.

2. Utensils for cooking and mixing, ladle, glass jars, sterilization tank, diesel or LPG stove/bhatti etc

41.1. Aim

To prepare marmalade from citrus fruits.

41.2. Theory

Marmalade is a fruit jelly in which the slices/shreds of peel are suspended. The marmalades are prepared generally from citrus fruits like orange and lemon. The pectin and acid contents of the marmalades are kept slightly higher than that for jellies. They shall contain minimum of 45% fruit and 65% total soluble solids.

41.3. Raw material, ingredients, machinery required

1. Orange and lemon like citrus fruits are used for making marmalade.

2. Stainless steel knives, utensils for cooking and mixing, muslin cloth, glass jars, sterilization tank, gas bhatti etc.

40.1. Aim

To prepare jelly from guava fruits.

40.2. Theory

Jelly is prepared by boiling the fruit with or without addition of water, straining the extract and cooking the clear extract with sugar to a stage at which it will set to a clear gel. The jelly should be transparent, well set, but not too stiff and having original flavour of the fruit. It should be attractive in colour and should keep its shape. In the preparation of jellies, pectin is the most essential constituent. As per FSSAI specifications, the quantity of fruit and soluble solids in the final product shall not be less than 45 and 65 percent (w/w) respectively. Guava jelly is the commercial product available in the market however jelly can be prepared from sour apple, karonda, jamun, loquat etc.

39.1. Aim

To prepare Jam from different fruits.

39.2. Theory

Jam is prepared by boiling the fruit pulp with a sufficient quantity of sugar to a thick consistency, firm enough to hold fruit tissues in position. For preparation of jam not less than 45 parts of fruits are used for every 55 parts of sugar. According to FSSAI specifications, minimum quantity of soluble solids in the prepared jam shall not be less than 65% (w/w). The jam prepared by using two or more fruit pulps, is called as mixed fruit jam. Approved fruit colour and flavour can also be added into the jam when declared on the label.

39.3. Raw material, ingredients and utensils required

1. Fruits like Apple, apricot, mango, plum, peach, guava, pineapple, pear and kiwifruit etc either singly or in combination (mixed jam).

38.1. Aim

To prepare nectar from different fruit pulp/juice.

38.2. Theory

Fruit nectar is also a RTS drink but it contains not less than 150Brix TSS and not less than 20% fruit juice or pulp. It is preserved only by heat processing as such no preservative is allowed in fruit nectars. Mango nectar, guava nectar etc. are the commercial products in this category.

38.3. Raw material, ingredients and utensils required

1. Mango, guava, and pineapple nectars are commercially available in the market. However the nectar can also be prepared from a number of other fruits like jamun, aonla, apricot, papaya, plum and bael etc.

37.1. Aim

To prepare ready to serve drink from fruits.

37.2. Theory

Ready to serve (RTS) drink is a type of fruit beverage which contains at least 10% of fruit juice and 10 degree Brix total soluble solids (TSS) with 0.3% acidity. It is not diluted before serving, hence it is known as ready to serve beverage. Mango drink, guava drink, pineapple drink are the commercial products available in the market.

Sweetened fruit juice is categorized as ready to serve beverage in which the minimum juice content shall be 85% with a minimum TSS of 10%, while unsweetened juice is a natural juice having 100% fruit juice with natural total soluble solids. These are preserved by heat processing method. Sweetened apple, pear juices are commercially manufactured.

36.1. Aim

To prepare cordial from lemon and lime.

36.2. Theory

Cordial is a sparkling, clear, sweetened fruit beverage from which pulp has been removed completely. It contains at least 25% fruit juice, 30% total soluble solids (TSS), 1.5% acid and 350 ppm sulphur dioxide. Lemon and lime juice cordials are the commercial products.

36.3. Raw material, ingredients and utensils required

1. Lemon and lime are used for making cordial.

35.1. Aim

To prepare squash from fruits or fruit pulp.

35.2. Theory

Squash is a type of fruit beverage containing at least 25% fruit juice or pulp and 40% total soluble solids (TSS). Squash is diluted before serving (1:3). According to FSSAI specifications, class II preservative in fruit squash shall not exceed 350 ppm sulphur dioxide/700 ppm KMS or 600 ppm sodium benzoate. Artificial colour and flavours can also be added when declared on the label.

35.3. Raw material, ingredients, machinery and equipments required

1. Fruits like mango, orange, lemon, lime, litchi, pear, apricot and pineapple are used for making squash.

34.1. Aim

To conduct cut out analysis of canned fruits and vegetable products.

34.2. Theory

Cut out examination of canned products is conducted to evaluate the product whether confirming to FSSAI standards or not. Canned fruit and vegetables are evaluated for presence of vacuum or pressure in the can, drained weight, total soluble solids, presence or absence of preservative, internal condition of can product contents and presence or absence of fermentation for ensuring microbiological safety.

33.1. Aim

To perform canning of fruit and vegetables.

33.2. Theory

Canning refers to a process which involves heating food stuff in hermetically sealed containers for a specific time at specific temperature to eliminate microbial pathogens that endanger public health as well as micro-organisms and enzymes that deteriorate food during storage. Broadly canning is a method of preservation of food for achieving longer shelf-life.

33.3. Principle of canning

Destruction of spoilage causing micro-organisms and enzymes within the sealed containers by means of heat.

32.1. Aim

To estimate the level of sulphur dioxide contents in fruit and vegetable products

32.2. Theory and principle

Sulphur dioxide in food product is added as class II preservative and may exists as undissociated sulphurous acid, as free bisulphate or sulphite ions or as combined SO2 in the form of hydroxy sulphonates. Sulphur dioxide is measured as free or total SO2. Estimation of SO2 in squashes, jam, RTS drinks is important as its presence beyond the prescribed FSSAI limits make the product not confirming to Indian Food Laws. Generally 2 parts of KMS (Potassium metabisulphite) releases one part of SO2 explained as under:

31.1. Aim

To estimate the sodium benzoate contents in fruit and vegetable products.

31.2. Theory and Principle

Sodium benzoate is used as a class II preservative in preservation of pickles, sauces, squashes etc. Its estimation is important as the quantity of class II preservative shall not exceed maximum limit prescribed under FSSAI. In a sample containing NaCl, the benzoic acid is converted into water soluble sodium benzoate by addition of NaOH. When the Sodium benzoate solution is acidified with excess of HCl, water insoluble benzoic acid is formed which is extracted with chloroform. The chloroform is removed by evaporation and the residue containing benzoic acid is dissolved in alcohol and then titrated with standard sodium hydroxide.

30.1. Aim

To estimate the salt contents in given samples by using Mohr method.

30.2. Theory and principle

Common salt is used during preparation of pickles, sauces, ketchup, fruit chutney and appetizers. Besides, imparting taste, the salt in appropriate concentration also acts as a preservative. In different products, it is estimated by using Mohr method. The sample is titrated with standard solution of silver nitrate for estimation of salt by using potassium chromate as an indicator. From the titre the concentration of salt is estimated by using a standard expression.

29.1. Aim

To estimate ascorbic acid in fresh and processed fruit and vegetable products.

29.2. Theory and Principle

Fruit, vegetables and their products are important sources of ascorbic acid. The ascorbic acid is present in sufficient quantity in aonla, guava, grapefruit, lemon, pineapple, strawberry fruits etc. Barbados cherry is the chief source of vitamin C. The products manufactured from these fruits are also considered as rich in ascorbic acid and the contents available in the commodities can be detected by using 2, 6 dichloro-phenol - indophenol visual titration method.

28.1. Aim

Estimation of reducing sugars in fresh fruits and processed products using Lane and Eynon method.

28.2. Theory

Sugars are inherently present in different fruits and vegetables or added during preparation of different products. They are added to the fruit products to improve the taste and also to act as a preservative. Glucose and fructose in the fruits represent reducing sugars while sucrose or cane sugar added represents the non-reducing sugar. They are estimated by using Lane and Eynon method which measures sugar as reducing sugar and total sugar as invert sugar.

27.1. Aim

To estimate the titratable acidity of fresh and processed fruit and vegetable products.

27.2. Theory

Most of the fruit, vegetables and their products contain acid or mixture of acids. The acids may occur naturally in the fruit and vegetables or may be added during manufacture of different products or by lactic acid or acetic acid fermentation. Generally citric acid is added in most fruit products while in pickles, sauces and ketchup acetic acid is used. The acids are mainly responsible for the tartness or sour taste, thus estimation of acidity is used as the measure of tartness. They also help in preservation by lowering the pH of the finished products.

26.1. Aim

To determine the pH of food samples.

26.2. Theory

The hydrogen-ion concentration of a food is a controlling factor in many chemicals and microbiological reactions. Pure water has equal concentration of H+ and OH- ions, each having the value of 1×107g/litre at room temperature that is why water is regarded as neutral. The pH of pure water is 7.0, the solution having pH below 7.0 is regarded as acidic while solution with pH above 7.0 is alkaline. Most fruits and fruit products have pH below 4.0 while vegetable; milk and meat products have pH more than 4.0. The pH value of some fruits and fruit products is given in Table 6.1. Thus, with the increase in acidity in the solution, the pH value decrease and vice versa. However, presence of buffer salts helps in maintenance of pH. Estimation of pH of the food is important as the processing conditions for different food products are categorized on the basis of their pH.

25.1. Aim

To estimate the ash content in fresh and processed products.

25.2. Theory and principle

Estimation of ash contents is important as it gives an idea about the presence of minerals in the food samples. Determination of ash is also required to evaluate fruit chutneys as the maximum limit for ash in this product shall not exceed 5% as per FPO specifications.

25.3. Apparatus/instruments/equipment

1. Crucibles

2. Muffle furnace

3. Sensitive balance

4. Heating plate

5. Desiccators

24.1 Aim

To determine the moisture content in fresh and processed products

24.2 Theory

Estimation of moisture in fresh and processed fruit and vegetable products is important for evaluating their nutritive composition as well as to optimize method for their processing like drying, preparation of different products viz; jams, preserve, candies etc. Moisture is determined by drying the weighed sample to a constant weight in hot air oven and measuring the loss in weight to express the moisture content in percent. This method is used for estimation of moisture in all food products which do not decompose at 100ºC. Moisture content of some commodities (Table 4.1) is as under:

23.1. Aim

To determine the total soluble solids in fresh and processed fruit and vegetable products.

23.2. Theory and principle

Total soluble solids (TSS) are determined by means of brix which measures the specific gravity or by using hand refractometer which measures refractive index. Brix is a measure of soluble solids only in case of pure sucrose solutions. Generally, the fruit juices contain more sugar than any other soluble constituent. Hence, brix provides a useful guide of soluble solids or sugar contents. Brix hydrometer is used to determine the percentage of brix in syrup while Abbe refractometer gives refractive index as well as degree brix. The Refractive index of the test solution is measured at 20°C using a refractometer and the soluble solid content is determined by the use of tables correlating refractive index with soluble solids. Generally, hand refractometer is used for determining TSS in food samples in fruit processing units (Table 3.1).

22.1. Aim

To estimate the fruit firmness.

22.2. Apparatus/machineries/equipments required

• Magness Taylor Pressure Tester

• Penetrometer

22.3. Theory and principle

Fruit firmness is an important feature of maturity. During ripening, fruits may soften and become too soft at the overripe stage. The changes are detected by touching or by using devices like texture analyzers and pressure testers to measure texture of fruits and vegetable.

21.1. Aim

To familiarize the students with the machineries and equipments used in fruit and vegetable processing.

21.2. Theory

The students will visit the processing unit/pilot plant and familiarize with different machineries and equipment used in fruit processing units. The students will observe the layout and the details of the machinery for different unit operations viz; raw material receiving, washing, sorting/grading, peeling, slicing, pulping, heating, filling, exhausting, sealing, sterilization/processing, labelling and storage for different products. The list of the machineries and equipments and important chemicals used in fruit preservation is as under:

21.3. Apparatus/machineries/equipments used in food industries

21.3.1. Basic equipment/ accessories

20.1. Introduction

Food laws and regulations are the legal standards of quality which regulate the manufacture and marketing of food products. The major objectives of enacting the food laws and regulations are:

1. To maintain quality of food produced

2. To prevent exploitation of the consumer by the sellers

3. To safeguard the health of the consumers and

4. To establish a standard of quality for different food products.

19.1. Introduction

Quality is a measure of the degree of excellence or degree of acceptability by the consumer. It is also defined as the combination of attributes or characteristics of the products that has significance in determining the degree of acceptability of the product to a user. Industry defines quality as the measure of purity, strength, flavour, colour, size, maturity, workmanship or any other distinctive attribute or characteristics of the product. According to USDA Marketing Workshop Report (1951) quality is the combination of attributes or characteristics of a product that have significance in determining the degree of acceptability of the product to the user . The quality standards of fresh and processed fruit or vegetable products vary with their intended use. For marketing purposes; size, attractiveness, maturity, organoleptic quality and freedom from defects are to be kept in mind. While for processing, physico chemical attributes of raw material such as presence of soluble solids, development of uniform colour, flavour, juiciness, uniform maturity, tenderness in some vegetables etc are taken into consideration. During processing of fruit or vegetables into value added products; colour, flavour and texture etc also become important.

18.1. Introduction

Spoiled food is defined as the food that has been damaged or has undergone changes so as to render it undesirable/unacceptable/unfit for human consumption. Spoilage of processed products is mainly caused by the action of micro-organisms and due to the physical or chemical changes. The reasons for microbial spoilage include under- processing, inadequate cooling, contamination from leakage through can seams and pre-process spoilage. In under-processed cans (receiving low heat treatment) large number of micro-organisms is expected to be involved in spoilage.

18.2. Causes of food spoilage

Food spoilage or deterioration may be described as loss of weight, softening, souring, rotting, wilting, moulding or a combination of one or more forms. The major causes of food deterioration are: biotic and abiotic factors.

17.1. Introduction

Tea (Camellia sinensis L), coffee (Coffea arabica L.) and rubber (Hevea brasiliensis) are known as estate crops or conventional plantation crops. These plantation crops are perennial in nature and cultivation of these crops generates considerable employment opportunities during on farm and off farm processing activities. The plantation crops are high value industrial crops contributing about 25% of AGDP. India is a largest consumer of tea accounts for 22% global tea consumption and also accounts for one-fifth of global tea area. Indian coffee industry also have prime place among plantation crops and also contributing 4% coffee to global market. Similarly, rubber plantations also provides basic raw material to toys, balloon, tyres, seed oil cake and rubber wood factory. The plantation crops along with main processed products also produce large quantity of biomass like husk, coir dust, coffee husk, tea waste, shedding etc which can effectively used to reduce nutrient requirements of crops. Parchment coffee prepared by using the wet method is generally favoured by the market. Cherry coffee, due to its very nature of preparation and longer contact with the mucilage and fruit skin, is usually associated with a characteristic fermenting flavour.

16.1. Introduction

Plantation crops are high value industrial crops grown in the tropics play a vital role in agricultural economy and export trade of developing countries. Plantation crops have great potential for utilization of waste land like rainfed dry land, hilly, arid and coastal areas to provide nutritional security, earn foreign exchange and to ensure livelihood security. The major plantation crops grown in India are tea (Camellia sinensis L), coffee (Coffea arabica L.), rubber (Hevea brasiliensis), coconut (Cocos nucifera), arecanut (Areca catechu L.), oilpalm (Elaeis guinensis), cashewnut (Anacardium occidentale L.), cocoa (Theobroma cacao L.) and cardamom (Elettaria cardamomum). India is the leading producer of most of these plantation crops. Among all fruit crops, the processing plays an important role in plantation crops as they are generally consumed only after processing. In addition to primary products which are exported largely, some by-products from these crops also have industrial as well as commercial uses. Coconut, arecanut, cashewnut, black pepper and cardamom are known as small holder plantations whereas, crops like rubber, tea and coffee are known as estate crops or conventional plantation crop. Coir, wood and shell from coconut, leaf sheath in arecanut, cashew nut shell liquid (CNSL) and feni from cashew are some of by-products with a great impact and demand in the market.

15.1. Introduction

Freezing is one of the oldest and most widely used methods of food preservation, which allows preservation of taste, texture, and nutritional quality in foods better than any other method. It is a process of bringing down the temperature of food below its freezing point and the frozen storage generally refers at temperature below -18oC.

15.2. Theory of freezing

The freezing process is a combination of the beneficial effects of low temperatures at which micro-organisms cannot grow, chemical reactions are reduced, and cellular metabolic reactions are delayed. Freezing is generally referred to as a unit operation in which the temperature of food is reduced below freezing point and a proportion of water undergoes a change in state to form ice-crystals. Immobilisation of water to ice and the resulting concentration of dissolved solutes in unfrozen water cause lowering of water activity of the food. Thus reduction in water activity and use of low temperature coupled with some pre- treatments like blanching is the basis for food preservation by freezing. Fruits such as strawberries, oranges, raspberries, black currants and vegetables like green pea, green beans, sweet corn, spinach, sprouts and potatoes are examples of commercially frozen products.

14.1. Introduction

Tomato is grown in India in abundance both in summer and winters. Tomato though botanically a fruit is generally considered as vegetable because of the way in which it is consumed. Fresh tomatoes are very refreshing and appetizing but can not be stored for a long period. During peak season, about 25% of the produce is spoiled due to mishandling and such losses can be avoided by converting tomatoes into different value added products. Tomato can be processed into pulp, paste, puree, juice, ketchup and sauce. In India, tomato sauce and ketchup are very popular. High quality products can be prepared from tomatoes by:

1. Using uniformly ripened, red coloured tomatoes.

2. Avoid prolonged heating and cool the product immediately after cooking.

3. Avoid using iron and copper equipments and utensils at any stage of processing.

13.1. Introduction

The preservation by using common salt, spices and vinegar is a common method for preparation of pickles, sauce and chutneys. Salt is mostly used as preservative in pickles in combination with acid. Minimum concentration of salt to act as preservative is about 12%. It inhibits enzymatic browning/discoloration by acting as an anti-oxidant. It exerts its preservative action by:

• Causing high osmotic pressure and thus suppress the microbial cells.

• Dehydrating food by tying up the moisture thus making it unavailable for the growth of microorganisms.

• Salt in the food affects the solubility of oxygen and thus growth of aerobic microorganisms is inhibited

• Chlorine in sodium chloride being good oxidizing agent is toxic to microorganisms

• Salt increases the permeability of the cell wall and thus cause changes in the permeability. Only the haloduric microorganisms can tolerate these effects while others are unable to survive.

• Similarly addition of acid to the food lowers the pH of the food which inhibits the growth of spoilage causing microorganisms.

• Addition of spices and edible oil in these products besides improving flavour and taste also help in preservation.

12.1. Introduction

Drying refers to the method of removal of moisture content from the food to a level at which the activities of food spoilage and food poisoning micro-organism are inhibited. Drying under open sun is probably the oldest method of food preservation used for agricultural crops including food grains, oilseeds as well as fruits and vegetables. Most of the fruits and vegetables contain enough moisture to permit the activity of enzymes and micro-organisms for spoilage and drying is necessary to reduce the water activity. Therefore, reduction in water activity of the food is the main principle of preservation by drying. Two commonly used terms for dried foods are low moisture foods and intermediate moisture foods (IMF). During drying, a single layer of fruit and vegetables, either whole or sliced after primary pretreatments is spread on trays which are placed inside the dehydrator or in the open sun for drying. In mechanical dehydrator, the initial temperature is generally kept at 43oC which is then gradually increased to 60-66oC for vegetables and 66-71oC for fruits.

11.1. Introduction

A fruit preserve is a product made from properly matured fruit by cooking it whole or in the form of large pieces in heavy sugar syrup, till it becomes tender and transparent. A fruit impregnated with cane sugar and glucose, followed by subsequent draining and drying is called a candied fruit e.g. petha candy, ginger candy. Further, candied fruit covered or coated with a thin transparent coating of sugar, which imparts a glossy appearance is referred to as a glaced fruit. When candied fruit is coated with sugar crystals either by rolling it in powdered sugar or by allowing the sugar crystals from glucose syrup to deposit on it, it becomes a crystallized fruit. The use of high concentration of sugar in these products acts as the preservative. The products like Petha candy, aonla preserve, apple rings; candied citrus peels, ginger candy, ginger in syrup; bael, pineapple and carrot preserve are the commercial products in this category.

10.1. Introduction

Sugar acts as a preservative by osmosis and sugar is not a true poison fo micro organisms. It absorbs most of the available water and restricts the availability of water/moisture required for growth of micro-organism. The concentration of 68 70% sugar is used for preparation of jam and jellies. Sugar adds value to these products as it imparts sweetness as well as body to these products. When sugar is boiled with acid and fruits it is hydrolyzed into dextrose and fructose, the degree of inversion depending on the pH and duration of boiling. Because of inversion of sucrose, a mixture of sucrose, glucose and fructose are found in jams and jellies.

Jams, jellies and marmalades constitute an important class of preserved fruit products. Apple jam, pineapple jam, strawberry jam and mixed fruit jam prepared by using pulp of two or more fruits are quite common. Similarly, guava jelly and orange marmalade are also examples of such products.

9.1. Introduction

Fruit juice and beverages generally comprise of naturally extracted juices, drinks, ready to serve (RTS) beverages, nectars, squashes, cordials and appetizers etc. These products are highly refreshing, thirst quenching, appetizing and nutritionally superior to many synthetic and aerated drinks. Fruit juice is the natural liquid expressed by pressure or other mechanical means from the edible portion of the fruit. Fruit juices are generally extracted from fruits in a number of ways, depending on their structure and composition.

The composition of juice is unaltered during preparation and preservation while for fruit beverages like drinks, squashes, cordial etc the fruit juice or pulp, sugar, acid, colour, flavour etc are mixed in appropriate proportions to a desirable taste. Apple juice, orange juice, mango squash, guava drink, pineapple juice and squash, mixed fruit drink, mango nectar etc are the commercial products available in the market.

8.1. Introduction

The term canning refers to a process which involves heating food stuff in hermetically sealed containers for a specific time at specific temperature to eliminate microbial pathogens that endanger public health and micro-organisms as well as enzymes that deteriorate food during storage. The canning of fruits and vegetables is canned out in the season when they are available in plenty. The canned products are then sold in the off season for getting better returns and to assure availability of fruits and vegetables throughout the year at reasonable prices.

8.2. History of canning

Important historical developments in canning are as under:

• The credit for invention of canning goes to Nicholas Appert, a French confectioner who was awarded a prize in 1809 by the French government for developing new method of heat preservation of food in sealed container and after whose name the process of canning is known as Appertization.

• In year 1810, Appert published the first book on canning entitled The Art of Preserving Animal and vegetable substances for many years which is the first known work on canning.

• The work of Appert consists of packing food in glass bottles, closing with corks and heating the container in boiling water for several minutes depending upon type of food.

7.1. Introduction

Preservation of fruit and vegetables by application of heat is one of the important methods of food preservation as it not only imparts desirable effect in the eating quality of the food but also exerts a preservative effect on the foods by destruction of micro-organisms, enzymes, insects and parasites. Other advantages of heat processing include destruction of anti nutritional factors (e.g. trypsin inhibitor in some legumes), improvement in availability of some nutrients (eg improved digestibility of proteins, gelatinization of starches, and release of bound niacin), production of shelf-stable foods that do not require refrigeration and above all it offers a relatively simple control of processing conditions. The disadvantages of heat processing include alteration or destruction of sensory quality of foods like flavor, colour, taste and texture as a result the heat processed foods are perceived to have different quality as compared to fresh produce.

6.1. Introduction

Chemical preservatives are those substances which minute organoleptic and physico-chemical properties . Preservation of food products with chemical preservatives is usually based on the combined or synergistic activity of several additives, intrinsic product parameters (e.g. composition, acidity, water activity) and extrinsic factors (e.g. processing and storage temperature).

Many chemical substances are added to the food for functional purposes and are called as additives and in many cases these are found to occur naturally in some foods. An additive is defined as a substance or mixture of substances other than basic food ingredient present in a food as a result of any aspect of production, processing or packaging.