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Sulphur dioxide is used as a preservative in many fruit and vegetable products. It can be added either in the form of potassium metabisulphite or by exposingthe product to sulphur fumigation by burning sulphur powder. Food safety and standards regulations have specified the maximum limit of sulphur dioxide in the finished products. Products having sulphur dioxide content exceeding the limit are considered not conforming to Indian Food Laws. Therefore, the estimation of sulphur dioxide in food products is considered an important attribute for quality evaluation.
Principle
Sulphur dioxide added to the food products may exist as undissociated sulphurous acid, as free bisulphite ions, as free sulphite ions and/or as combined SO2 in the form of hydroxy sulphonates. Sulphur dioxide is measured as free or total SO2.
Free SO2 is measured by direct titration with iodine. In the estimation of total SO2, the combined SO2 is liberated by treatment with excess alkali at room temperature, followed by subsequent acidification to prevent recombination and titration with iodine. The method used is known as the Modified Ripper Titration Method.

Preserves (Murabbas) are prepared from whole fruits and vegetables or their segments by addition of sugar followed by evaporation to a point where microbial spoilage cannot occur. The final soluble solids concentration is reached to about 70 per cent. The finished product can be stored with or without hermetic sealing and refrigeration.

The term canning refers to a process that involves heating foodstuff in hermetically sealed containers for a specific time at a specific temperature to eliminate microbial pathogens that endanger public health; and microorganisms and enzymes that deteriorate food during storage.
Principle of canning: Destruction of micro-organisms causing spoilage, within the sealed containers using heat.
Canning Process
Preparation of food commodities for canning consists of selection of commodities, washing, sorting, grading, peeling, halving, blanching, filling into cans, filling hot syrup or brine, exhausting, double seaming, Sterilization/ processing, cooling, storage, etc.
Raw material selection
Fruits should be ripe but firm, evenly matured, and free from blemishes, insect damage, and malformation. Apple, pear, peach, and banana harvested at the mature stage are preferred for canning.

Squash is a type of fruit beverage containing at least 25% fruit juice/pulp, not less than 40% total soluble solids (TSS), about 1-1.5% acid and not exceeding 350ppm sulphur dioxide or 600ppm sodium benzoate. Squash is diluted by adding cold/chilled water before serving (1:3).
Mango, orange, lemon, lime, litchi, guava, pineapple, jamun, plum, apricot, rhododendron petals etc., are used for making squash. Potassium metabisulphite (KMS) is generally used as a preservative, whereas sodium benzoate is used as a preservative in squash made from coloured fruits like plum, jamun, phalsa and rhododendron petals.
Recipe: A generalized recipe for the preparation of squashes from different
fruits as a general guideline is as under:

Previous Year Questions

1. CS 2015: Discuss the impact of rapid increase in population on food and agriculture (12.5 marks)

What is Food security?

The Food and Agricultural Organization (FAO) – “when all people at all times have physical and economic access to sufficient, safe and nutritious food to meet their dietary needs and food preferences for an active and healthy life”.

It has Following Dimensions

• Availability: It means food production within the country, food imports and the stock stored in government granaries.

Ready -to -Serve (RTS) drink is a type of fruit beverage that contains at least 10% fruit juice/pulp and 10o Brix total soluble solids with acidity ranging between 0.3-0.5%. The product is not diluted before serving like squash; hence it is called a ready-to-serve beverage. The product can be preserved by using 70 ppm SO2  or 120 ppm benzoic acid. Mango, orange, guava, lemon, lime, litchi, kiwi fruit, apricot, pineapple, etc., fruits are used for making RTS beverages. For lime & lemon drinks minimum level of juice content is 5% as per Indian Food Laws.
Recipe: As a general guideline, the following recipe is used for the preparation of ready-to-serve drinks:
Procedure
i. Select fully mature and ripe fruit like mango, guava, apricot, kiwi, etc., and wash thoroughly.
ii. Some fruits like mango, kiwi, pineapple, and litchi are peeled before heating. Apricots, guava, plums etc are not peeled. Place fruit after peeling in a pan/pressure cooker and boil till softening

Previous Year Questions

1. Discuss the reasons for food grain surplus (7.5 marks, CSE 2019)

2. What are the reasons for good grain surplus in India? Write the steps taken by the government to save the food grains. (12.5M, CSE 2015)

Reason for Grain Surplus

Green Revolution

• Introduction of high yielding varieties of Rice and Wheat

• Green Revolution was made possible through the use of

Fruit nectar is a type of fruit beverage that contains not less than 20% fruit juice or pulp, not less than 15o B total soluble solids and acidity ranging between
0.3-0.5 % but not exceeding 1.5%/. For orange and pineapple nectar, the fruit juice shall not be less than 40%. The product is preserved by heat processing/ thermal processing, as such no chemical preservative is permitted in nectars. Unlike squashes, fruit nectar is served chilled as such without any dilution.
Mango, guava, pineapple, papaya, jamun etc., are the most suitable fruits for making nectar.
Recipe: As a general guideline, the following recipe is used for the preparation of fruit nectar:
Procedure
i. Select fully mature and ripe fruit and extract pulp as discussed under fruit pulp making but do not add any chemical preservative.

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 the preparation of jam, not less than 45 parts of fruits are used for every 55 parts of sugar. The jam prepared by using two or more fruit pulps is called mixed fruit jam. Apple jam, apricot jam, mango jam, guava jam, pineapple jam, and mixed fruit jam prepared by using the pulp of two or more fruits are quite common. According to Food Safety & Standards Regulations,2011 the minimum TSS in the Jam shall not be less than 65%(w/w). Earlier the minimum limit was 68% (w/w)
Raw material, ingredients and utensils required
1. Fruits like mangoes, guava, apples, apricots, plum, peaches and kiwi etc singly or in combination
2. Stainless steel knives, de-corers, ladle, utensils for cooking and mixing, glass bottles (Jars), LPG or Diesel Bhatti, bucket/tub for washing, Stainless steel sieve, Steam Jacketted Kettle, Boiler (for the commercial unit) etc. 

Bananas and plantains constitute the fourth most important global food commodity (after rice, wheat and maize). They are cultivated in over 120 countries in the tropical and subtropical regions of the world in an area of  approximately 100 million hectares, where they constitute a major staple food crop for millions of people, as well as providing a valued source of income through local and international trade.
 
Banana is one of the oldest fruit crops of India, finding its reference even in epics like Ramayana. India is  believed to be one of centres of  origin, besides southeast Asian countries like Burma, Thailand, Malaysia and Indonesia. It is a crop having multifarious uses as every part of the plant is utilized and hence aptly  called as ‘Kalpatharu’ the plant of virtues. It is important internationally from the point of view of  trade as well as livelihood security.

Jelly is prepared by boiling the fruit with or without the addition of water, straining the extract, and mixing the clear extract with sugar followed by cooking the mixture to a stage at which it will set to a clear gel. The jelly should be transparent, well set, but not too stiff, and have an original flavour of the fruit. It should be attractive in colour and should keep its shape when removed from the mould. As per FSSAI specification, the quantity of fruit and soluble solids in the final product (jelly and marmalade) shall not be less than 45 and 65 per cent (w/w) respectively. Jelly is made from fruit extract while jam is made from fruit pulp, therefore, jelly in contrast to jam is considered to be transparent and clear in appearance. Guava jelly is the most common commercial product.
Jellies: In the preparation of jellies, pectin is the most essential constituent which help in making the gel. Since, pectin is present in the cell walls of fruits as such fruit peel, whole or fruit slices along with a small quantity of water are gently boiled to extract the maximum proportion of pectin solution in the water extract. This water extract is used for the preparation of jelly.

Previous Year Questions

1. No questions were asked in past 10 years

Availability of Foodgrains

• Net availability of foodgrains = Gross Production (-) seed, feed & wastage, (-) exports imports (+/-) change in stocks.

Marmalade is a fruit jelly in which the slices of peel are suspended. The marmalades are prepared generally from citrus fruits like orange and lemon. The pectin and acid contents of the marmalades should be kept slightly higher  than that for jellies. Citrus marmalades are of two types: i) Sweet marmalade and ii) Bitter marmalade.
Procedure
Preparation of fruit extract: After washing the fruit, remove the outer yellow flavedo portion of the peel of citrus fruits thinly which contains colouring matter and volatile oils, whereas the inner white albedo portion contains pectin. The thin yellow peel is cut into fine shreds with a knife, or on a shredding machine, and the shreds are boiled and drained to remove the bitterness. The sliced or crushed fruit is boiled gently by simmering with 2 or 3 times its weight of water to extract the pectin. While it is being boiled, a teaspoonful of the clear extract is taken from the pan and tested with alcohol for its pectin content. The process usually takes 30 to 45 minutes.

Fruit chutney is a product made in the same way as jam except that spices, salt, and acid (vinegar) in addition are added. The total soluble solids in chutney are] also less than that of jam. The product shall be of good quality with a palatable and appetizing taste. As per Food Safety and Standards Regulations, chutney\ shall contain a 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% with ash content not exceeding 5%. However, for vegetablebased chutney as well as hot & sour (spicy) chutney, the TSS shall not be less than 25%.
Recipe: The generalized recipe for the preparation of chutney from different fruits is as under:

Fruit syrup is a beverage that contains at least 25% fruit juice/pulp, 65% total  soluble solids and acidity ranging between 1.2 -1.5%. It is preserved by using
350 ppm SO2 or 600 ppm benzoic acid. Fruit syrup is diluted before serving. Syrup can be made from the juice/pulp of jamun, ginger, lemon, phalsa, rose extract, bael, pomegranate, and brahmi (Bacopa monnieri) leaves/root extract, etc. Besides, a syrup/sharbat containing a minimum of 10 per cent of dry fruits is also regarded as fruit syrup.
Recipe: The generalized recipe for the preparation of syrups from different fruits is as under:

Most banana producers in Africa, Latin America and Asia are small-scale farmers who grow bananas either for home consumption or local markets. Because bananas and plantains produce fruit year-round, they provide an extremely valuable food source during the hunger season (when the food from one annual/semi-annual harvest has been consumed, and the next is still to come). Bananas and plantains are therefore critical to global food security. However, the export trade of banana depends mainly on commercial plantations in Latin America, East Asia and Africa. These plantations are owned by multinational corporations.

Preserve (Murabba) is made by cooking the fruit either whole or in slices/ pieces in sugar syrup of heavy concentration (65-70oBrix). Usually for 1 kg fruit around 1.75 kg sugar is used and the cooking is continued till the TSS reaches 68oB. Fruits like petha (ash gourd), aonla, bael, apple, pear, karonda, pineapple and papaya etc., are used for making preserve/murabba.
Candies are also prepared similarly but the TSS is maintained up to 75-80%. 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 and then the fruit slices are drained free of syrup and dried in driers. Fruits like aonla, karonda, cherry, apple, ginger peels of orange, lemon, and grapefruit etc., and petha (ash gourd), are used for candy preparation.
Selection and preparation of fruits: Wash the fruits in water to remove dirt and residues. Peel, core and cut the fruits into pieces. Pricking should be done with stainless steel forks. In case of petha (ash gourd), after pricking place them in lime water

Tomato, apple, plum, mushroom, etc., are used successfully for the preparation of sauces. Sauces are of two kinds 1) thin sauces consisting of vinegar extracts of flavoring material like herbs or spices and 2) thick sauces which are highly viscous.
Sauces are prepared by maceration of spices, herbs, fruits, and vegetables in cold vinegar or by boiling. Thickening agents like pectin, carboxymethylcellulose,n etc., are also added to sauces to prevent the sedimentation of solid particles. The sauce is generally cooked to such a consistency that it can be freely poured without fruit tissues.
Procedure
Tomato fruits are washed, cut into pieces, and heated/boiled for about 10 minutes in their own juice in SS pan to soften the tissue. The heated fruit mass is passed through a pulper to separate skin and seeds. Half of the sugar and spices are placed in a muslin cloth bag which is then immersed in the pulp during cooking. Cooking is continued till the pulp is reduced to half of the original volume.

Drying and dehydration are interrelated terms. Drying generally refers to the method of removal of moisture from the food under natural conditions such as sunlight and wind for example open sun drying, shade drying etc. Whereas, dehydration refers to a process of removal of moisture by application of artificial heat under controlled conditions of temperature and airflow. In this case 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 the dehydrator, the initial temperature is generally kept at 43oC which is then gradually increased to 66-71oC for fruits and 60- 66oC for vegetables. Dried grapes (raisins and monucca), apricots, dates, apple rings/cubes, Morchella (Guchhi), bael, aonla, fig, green peas, cauliflower, cabbage, onion, garlic etc are commercial products prepared by using drying.
Procedure for drying: Drying generally involves three stages: pre-drying treatments or pre-treatments, drying of commodity and post-drying operations such as handling, packaging and storage. The flow sheet for drying of fruit and vegetables is shown in Figure 1 and details of pretreatments for drying fruits and vegetables are shown in Table 1&2 respectively.

9.1    Temperature
    
9.2    Relative Humidity
    
9.3    Physical Damage
    
9.4    Microbial Load
    
9.5    Packaging
    
9.6    Transportation