Lec.05 Fruit Processing 2024 PDF

BST 31352- Value Addition and Product Development Fruits Processing Dr. J A A C Wijesinghe  Fruits The scientific definition of a Fruit is very versatile, appropriate for puddings, pies, and jellies, salads, appetizers...

BST 31352- Value Addition and Product Development Fruits Processing Dr. J A A C Wijesinghe  Fruits The scientific definition of a Fruit is very versatile, appropriate for puddings, pies, and jellies, salads, appetizers, eaten as snacks, and served in fruit is ‘an organ that soups. Fruits can cut the richness of meats like pork and duck, develops from the ovary of a and enhances the delicate flavors of fish and veal. flowering plant and contains one or more seeds.’ The culinary definition, however, Citrus fruits are characterized by thick skins, aromatic limits fruits to those foods oils, and segmented flesh. They are abundant in vitamin C. The most common citrus fruits are oranges, grapefruits containing a high sugar (white and sweeter pink varieties), lemons, limes, content. tangelos, and tangerines. The flavor of citrus fruits range The sweetness of fruits comes from very sweet oranges to very tart, sour lemons. from a natural form of sugar called fructose.  Tropical fruits Tropical fruits are named for the climatic conditions under which they grow, and include figs, dates, kiwis (fuzzy skin with bright green-colored flesh and tiny edible seeds), mangos (thick-skinned with a light yellow flesh and spicy-sweet flavor), bananas, papayas (their vitamin C content increases as they ripen), pomegranates, passion fruit, pineapple, and coconuts (coconut milk is not the juice from the center, but a simmered mixture of water and coconut meat). Bananas are high in nutrients and are picked green and allowed to ripen during transport. Green bananas can be cooked; very overripe bananas can be used in baking. @ JAAC 3  Vegetables The parts of the vegetable plants we eat include the leaves, fruit, stems, roots, tubers, seeds, and flowers. They are eaten cooked more often than fruits are, and have a lower sugar content. These include; 1. petioles (e.g., celery, Apium grave olens Dulce group), 2. entire leaves (e.g., lettuce, Lactuca sativa), 3. immature fruits (e.g., cucumber, Cucumis sativus), 4. roots (e.g., carrot, Dacus carota), and 5. specialized structures such as bulbs (e.g., onion, Allium cepa Cepa group) and 6. tubers (e.g., white potato, Solanum tuberosum). @ JAAC 4  Principles of food preservation: A. Prevention or delay of microbial decomposition 1. by keeping out microorganisms (asepsis); 2. by removal of microorganisms, e.g., by filtration; 3. by hindering the growth and activity of microorganisms, e.g., by low temperature, drying, anaerobic conditions, chemicals or antibiotics; and 4. by killing the microorganisms, e.g., by heat or radiation. B. Prevention or delay of self-decomposition of the food 1. by destruction or inactivation of enzymes. e.g., by blanching. 2. by prevention or delay of chemical reactions. e.g., prevention of oxidation by means of an antioxidant. C. Prevention of damage by insects, animals, mechanical causes, etc. @ JAAC 5 Fruit Based Products Juices and Liquids concentrates cordial Canned and Solid nectar dehydrated products Jam Semi-Solid Products smoothies Fruit leather, Fruit Tea Jelly Chips Ice cream Other Sweet products Wine Marmalade Powder Vinegar Chutney Candies Oil Tomato Frozen fruits pulp/puree Tutti Frutti Sauces Ketchup Fruit based products.. Fruit Juice It is a natural juice obtained by pressing out the fruits. Fruit juices may be sweetened or unsweetened. RTS It is prepared from fruit juices which must have atleast 10 per cent fruit juice and 10 percent total sugar. Fruit Juice Powder The fruit juice is converted into highly hygroscopic powder. These are kept freeze dried and used for fruit juice drinks by reconstituting their composition. Fermented fruit These are prepared by alcoholic fermentation by yeast of fruit juice. The product thus contains varying amounts of alcohols e.g.; Grape wine, orange wine and berry wines from strawberry, blackberry etc. beverages Jam Jam is a concentrated fruit pulp processing a fairly heavy body form rich in natural fruit flavour. It is prepared by boiling the fruit pulp with sufficient quantity of sugar to a reasonably thick consistency to hold tissues of fruit in position Jelly Jelly is a semi solid product prepared by cooking clear fruit extract and sugar. Marmalade It is usually made from citrus fruits and consists of jelly containing shreds of peels suspended Tomato Ketchup It is prepared from tomato juice or pulp without seeds or pieces of skin. Ketchup should contain not less than 12 per cent tomato solids and 28 per cent total solids. Pickles Food preserved in common salt or in vinegar is called pickle. Spices and oil may be added to the pickle. @ JAAC 7 1.Fruit juice technologies Fruit juices are products for direct consumption and are obtained by the extraction of cellular juice from fruit, this operation can be done by pressing or by diffusion. Juices obtained by removal of a major part of their water content by vacuum evaporation or fractional freezing will be defined as "concentrated juices". @ JAAC 8 Fruit based Juices Pure fruit juice with nothing added Juices Normally contain 30% fruit solids and are drunk immediately after opening Nectars Normally contain at least 25% fruit pulp mixed with sugar syrup. They are Squashes diluted to taste with water and may contain preservatives Are crystal-clear squashes Cordials Syrups Are concentrated clear juices. They normally have a high sugar content @ JAAC 9  Categorize the Fruit Juice juices without pulp ("clarified" or "not clarified"); Based on processing method juices with pulp ("nectars"). "natural juices" from one fruit; Fruit juice Based on ingredients "mixed juices" Drink straight after opening the pack Based on method of use Further processing required with dilution @ JAAC 10  Technological steps for processing of fruit juices WASHING fruit must be thoroughly washed. Generally, fruit will be submitted to a pre-washing before sorting and a washing step just after sorting. SORTING removal of partially or completely decayed fruit is the most important operation in the preparation of fruit for production of first quality fruit juices; sorting is carried out on moving inspection belts or sorting tables. CRUSHING Crushing for grapes and berries; GRINDING Grinding for apples, pears; DISINTEGRATION Disintegration for tomatoes, peaches, mangoes, apricots. @ JAAC 11  crushed fruit mass is applied to some fruits by adding 2-8% pectolitic enzymes at about 50° C for 30 minutes. ENZYME This optional step has TREATMENT the following advantages: extraction yield will be improved, the juice colour is better fixed and finished product taste is improved. @ JAAC 12  Enzyme clarifying is based on pectic substance hydrolysis; this will decrease the juices' viscosity and facilitate their filtration. The HEATING treatment is the addition of pectolitic crushed fruit mass before juice extraction is an optional step used enzyme preparations in a quantity of for some fruit in order to facilitate pressing and colour fixing; at 0.5 to 2 g/l and will last 2 to 6 hours same time, protein coagulation takes place. at room temperature, or less than 2 hours at 50° C, a temperature that must not be exceeded. PRESSING to extract juice. Sometimes, the enzyme clarifying is completed with the step called "sticking" by DIFFUSION is an alternative step for juice extraction and can be carried out discontinuously or in batteries at water temperature of the addition of 5-8 g/hl of about 80-85 ° C. food grade gelatine which generates a flocculation of particles in suspension by the action of tannins. JUICE CLARIFYING can be performed by centrifugation or by enzyme treatment. Centrifugation achieves a separation of particles in suspension in the juice and can be considered as a pre-clarifying step. This operation is carried out in centrifugal separators with a speed of 6000 to 6500 RPM. @ JAAC 13  FILTRATION of clarified juice can be carried out with kieselgur and bentonite as filtration additive in press-filters (equipment). DE-TARTARISATION is applied only to raisin juice and is aimed to eliminate potassium bitartrate from solution. This step can be performed by the addition of 1% calcium lactate or 0.4% calcium carbonate. Pasteurization of juice can be done for temporary preservation (pre- pasteurization) and in this case this operation is carried out with continuous equipment (heat exchangers, etc.); warm juice is stored in drums or large size Rapid pasteurization receptacles (20-30 kg).Pasteurization conditions are at 75°C in continuous conditions are as follows: stream. temperature about 80° C, over 10-60 sec., followed Pasteurization of bottled juice is by cooling; all operations then carried out just before delivery are carried out in to the market; this is performed in Preservation by freezing is carried out at about -30° C, after a preliminary de- continuous stream. water baths at 75° C until the point aeration; storage is at -15 to -20° C. where the juice reaches 68° C. In cases when the final pasteurization is done without pre-pasteurization Preservation under CO2 pressure may be done at and temporary storage, modern a concentration of 1.5% CO2 under a pressure of methods use a rapid pasteurization 7 kg/cm². At the distribution step, proceed at followed by aseptic filling in CO2 decompression and the juice is then receptacles. submitted to a sterilising filtration and aseptic filling in receptacles. @ JAAC 14 Production of concentrated juices by evaporation is performed under vacuum (less than 100 mm Hg residual pressure) up to a concentration of 65-70% total sugar which assures preservation without further pasteurization. Modern evaporation installations recover flavours from juices which are then reincorporated in concentrated juices. Additional operations for juice manufacturing are the vacuum de- aeration and mixing with other fruit juices or with sugar. Fruit which is rich in carotenoids (apricots, peaches, etc.) is only processed as juices with pulp ("nectars"). Technological steps for processing of specific fruit juices without pulp are seen. @ JAAC 15  The Pearson Square The Pearson Square is a method that processors can use to calculate the amounts of two components that should be mixed together to give a final known concentration. For example, it can be used to calculate the amounts of fruit pulp and sugar syrup to make a fruit drink. The method can only be used for blending two components. When more than two components are involved, it becomes more complex. @ JAAC 16  The Pearson Square calculation Example of how to use the Pearson Square You wish to produce a sweetened fruit juice with a final sugar content of 15%. You use orange juice (that contains 10% sugar), mixed with a 60% sugar syrup (that contains 60% sugar). 1. Draw a rectangle and label the two horizontal lines with the names of the two products to be blended (fruit juice and sugar syrup) 2. Enter the sugar composition of each product in the rectangle as shown below and put the desired final concentration of sugar in the centre of the box: 3. Mix the two components by crossing diagonally through the centre of the rectangle. Orange Juice 10 ?(60-15) 15 60 ? (15-10) Sugar Syrup @ JAAC 17  Calculation 4. Following the arrows, subtract the smaller number from the larger one to give two new numbers (45 and 5) in the opposite corners of the rectangle. These numbers (45% orange juice and 5% sugar syrup) are the amounts that need to be mixed to give a fruit drink with a final sugar concentration of 15%. Orange Juice 10 45 15 60 5 Sugar Syrup @ JAAC 18  2.Canned fruit Canning a method of preservation in which a cooked or uncooked food is sealed in tin plated and lacquered steel cans. The sealed cans are sterilized by heat treatment under high pressure in retort. The temperature required for effective sterilization varies with the pH of the product and is generally higher than boiling point of water (100°C or 212°F). Fruit pulp is prepared from selected varieties of fruits. Fully matured fruit are harvested and quickly transported to the fruit processing plant. The fruits are ripened in controlled ripening chambers or natural ripening in open yard. Fully ripened fruits are washed, pulped, deseeded, centrifuged, homogenized, thermally processed and filled hot to maintain sterility. The preparation process includes cutting, de-stoning, refining packing, processing and cooling. Fruits are also canned in slices, rings and cubes etc. along with sugar syrup of desired brix. @ JAAC 19  2.Canning of Vegetables The vegetable canning is similar to fruit canning except that the filling materials in case of vegetables is brine solution. The vegetables require thorough cleaning and slicing before passing through canning line. Since vegetables are low in acid it does not require lacquered cans. @ JAAC 20 Problems during Canning 1. Swell: In swelled can, the ends are tightly bulged due to the formation of CO2 or other gas inside the can as a result of decomposition of the contents by microorganisms. The decomposed food in the can has an offensive and sour odour and is discoloured. It is not fit for consumption and even may contain toxins produced by bacilli like Clostridium botulinum. 2. Hydrogen swell: Hydrogen formed by the action of the acids present in the fruit on the tin plate causes the can to bulge at both the ends. In such cases, the food remains free from harmful micro-organisms and is still fit for consumption. 3. Springer: A mild swell at one or both ends of a can is called a ‘Springer’. It may be an initial stage of hydrogen swell or may be caused by insufficient exhausting or by over filling of the can. Food generally remains fit for consumption. @ JAAC 21 Problems during Canning 4. Flipper: The cans appear normal, but when struck against a table top one or both ends become convex and spring or flip out, but can be pushed back to normal condition by a little pressure. Such a can is termed as ‘flipper’. It may be an initial stage of swell or hydrogen swell, but does more frequently, owe to over filling or under exhausting. 5. Flat sour: it is caused mostly in non-acid foods like vegetables by microorganisms like thermophilic bacteria (B. coagulens and B. sterothermophilus) which produce acid without formation of gas. The thermophilic bacteria thrive at a high temperature of 100OC.If cans are stored without adequate cooling, the contents remain at a temperature favourable for incubation of such bacteria for fairly long time, which results in their multiplication and spoil the product. It is therefore difficult to detect from the external appearance. It may be due to by under sterilization (processing). Therefore, the thermophilic bacteria would be of significance. The product has a sour odour, and its acidity much be higher than that of the normal product. It is not fit for consumption. @ JAAC 22 Problems during Canning 6. Leakage: A leaking can is known as leaker. A very small leak may appear in the can owing to (1) defective seaming, (2) nail holes caused by faulty nailing of cases while packing (3) excessive internal pressure due to microbial spoilage sufficient to burst the can (4) internal or external corrosion (5) mechanical damage during handling. 7. Breathing (Breather): There may be a very tiny leak in the can through which air may pass in and destroy the vacuum but not the micro-organisms. Consequently, the vacuum in the can is always nil, and the pressure inside the can is equal to that of atmosphere. The damage to food is usually owing to rusting of the can caused by oxygen in the air but still the food remains fit for consumption. 8.Bursting of the can: Cans may sometimes burst. This may be due to excess of pressure caused by the gas inside, produced by the decomposition of the food by micro-organisms, or by hydrogen gas formed by chemical action of acids of the food on the tin plate. Thus, the canned product becomes a total loss. @ JAAC 23  3.Pickle Pickling is a process of preservation by fermentation. The fruits and vegetables are immersed in 5–10 per cent salt solution (brine) leading to lactic acid fermentation. Salt prevents growth of undesirable organisms and allow lactic acid bacteria to grow. The natural sugars present in fruits and vegetables are converted to lactic acid at 25°C. The fermentation process takes a few weeks finishing at about 1 per cent acidity of final product. In India, spices and edible oils are used in pickle making. The spices and edible oil inhibit growth of undesirable micro flora in the product and also gives a desirable flavour. The process flow of pickle making is depicted in Figure 3. @ JAAC 24  4.Jam and Jelly Fresh fruits contain more than 80 per cent water and 10 to 15 per cent sugars. Therefore, fruits are good food for microorganisms. The fruits spoil very fast, if not preserved in time. One of the traditional methods of preservation is conversion of fruit pulp to jam and jelly. The preservation of fruit by addition of sugar helps in reducing water content required by spoilage microorganisms. Jam, jelly and marmalade are based on preservation by high sugar concentration. All fruits can be converted to jam by mashing or slicing it fine, adding an approximately equal amount of sugar, and simmering until it reaches proper concentration or gel at 218° to 222°F (103°– 105°C). A process flow chart for jam making is given in Figure 4. The process of jelly making is also similar except that only fruit extract is used for making of jelly and pectin is added for gel formation after boiling. @ JAAC 25 Problems during Jam, jelly preparation: 1. Cloudy /foggy Jelly: It might be due to use of non-clarified extract, use of immature fruits (immature fruits contain starch which is insoluble in juice), Over cooking and cooling, non-removal of skum, faulty pouring (when jelly poured from a great height, air get trapped in bubbles form and jelly become opaque) and premature gelation is also a reason for cloudy or foggy jelly. @ JAAC 26  Problems during Jam, jelly preparation 2.Weeping /syneresis Jelly: The phenomenon of spontaneous exudation of fluid from a gel is called synersis or weeping of jelly. It is caused by following factors: Excess of acid: Addition of excess of acid results in the breakdown of jelly structure due to the hydrolysis or decomposition of pectin. Too low concentration of sugar or soluble solids: This causes the network of pectin to hold more liquid than it possibly can do under normal conditions. Insufficient pectin: This results in the formation of a pectin network which is not sufficiently dense and rigid enough to hold the sugar syrup. Premature gelation: Gelation is caused due to breakdown of pectin during pouring of jelly into the containers. The jelly becomes weak and remains broken. Fermented jellies: Fermentation usually takes place in those jellies in which synersis has taken place. @ JAAC 27  Problems during Jam, jelly preparation 3. Failure of jellies to set: Sometimes the jellies do not set due to the following reasons: Lack of acid or pectin: A jelly may fail to set due to lack of acid or pectin in the fruit from which it is made. It may also fail to set due to insufficient cooking of the fruit resulting in inadequate extraction of pectin and acid. Addition of too much sugar: If sugar is added in excess of the required quantity, a syrupy or highly soft jelly results. It can be corrected by adding fresh clarified juice rich in pectin. Cooking below the end point: If the cooking is stopped before the concentration of sugar reaches 65 percent, the jelly may fail to set and may remain syrupy and highly soft. Cooking beyond the end point: If heating is continued beyond the end point, the jelly becomes tough due to over- concentration. This occurs when the juice is rich in both acid and pectin and enough sugar has not been added. If the acid is in excess, the pectin breaks down and forms syrup like jelly. @ JAAC 28  Problems during Jam, jelly preparation 4. Formation of crystals: Crystals in the jelly may be formed due to addition of excess sugar. 5. Stiff or tough : Overcooking, Too much pectin in fruit and Too little sugar which requires excessive cooking 6.Growth of Molds @ JAAC 29  5.Squash Squashes are sweetened juice of fruits containing minimum prescribed quantity of pulp. As per Indian Standards, squash should contain at least 25 per cent (by volume) of fruit juice. The squashes are consumed after dilution by drinking water in 1:3 ratio. These beverages contain added flavours and permitted class II preservatives. Since preservatives are added in adequate quantities, the shelf life of squashes is fairly longer at room temperature. The process flow diagram is given in Figure 5. @ JAAC 30 TOMATO PRODUCTS 1) Tomato Juice 2) Tomato puree and paste 3) Tomato sauce 4) Tomato ketchup 5) Tomato chutney 6) Tomato Soup 7) Tomato chilli sauce @ JAAC 31  A) Sauces: Sauce is a product similar to ketchup, prepared from pulps of tomato or other fruits / vegetables having TSS not less than 15% and cooked to a suitable consistency with added sugar, salt, spices and vinegar (acetic acid). Sugar, salt, spices, acetic acid all act as partial preservatives. According to the FPO fruit should have a minimum of 15% TSS and 1.2% acidity. To ensure its keeping quality the sauces should contain 3% acetic acid. The sugar content may vary from 15-30% according to the kind of sauce made. Preservative and colours may also be added in sauces for increasing storability. Sauces may or may not be prepared from tomato, but ketchups are essentially prepared from tomato. Examples: Tamarind sauce, pumpkin sauce, chilli sauce, Soya sauce @ JAAC 32  B)Ketchup It is a product made by concentrating tomato juice or pulp without seeds and skin, with added spices, salt, vinegar, onion, garlic etc.so that it contains not less than 12% tomato solids and generally 28% or more total solids (not less than 25% TSS as per FPO specifications) 1. Selection of fruits: Select sound ripe tomatoes having deep red colour. Remove all green and yellow portions. Green fruits make the ketchup inferior in colour and flavour. 2. Preparation of pulp: Take the selected tomatoes in an aluminum or stainless steel vessel and crush thoroughly with a wooden handle. Cook the crushed mass for 5 minutes and mash it well while cooking. While it is sufficiently soft. Strain through the fine mosquito net cloth or 1mm mesh stainless steel sieve. Discard the sheds and skins. 3. Cooking: To the pulp add about 1/3rd of sugar given in the receipe. Place the spices (onion, garlic, cloves, cardamom, black pepper, jeera, mace, cinnamon and chili powder) in a muslin cloth bag (Jelly bag) and immerse it into the pulp. Heat the pulp till it thickens and is reduced to about 1/3rd of its volume. Remove the bag and squeeze it well to extract the aroma and flavour of the spices. @ JAAC 33  B)Ketchup contd; Add vinegar, salt and the remaining sugar. Heat the mass for a few minutes so that the volume of the finished product is about 1/3rd of the original pulp. 1. Addition of preservatives: To a small quantity of finished product, add the preservative sodium benzoate, at the rate of 295mg/kg of finished product and mix thoroughly. This can be increased up to 885 mg/kg as per specifications of FPO, 1955.Transfer the dissolved preservatives to the rest of the product and mix thoroughly. 2. Cooling and Mixing: Pour the finished product into a medium size sterilized bottles, seal them air tight with crown cork and pasteurize in boiling water for 30 minutes. Cool the bottle in air and store in a cool dry place. Judging end point: End point is determined by hand refractometer.when TSS reaches desired level (28-30%) sauce or ketchup is considered ready. Judging end point by volume is very simple and common in practice. The volume is measured by stick. If the volume of the produce remains 1/3rd of its original volume sauce/ketchup is considered ready. Note:  Chilly powder, spices, onion, ginger and garlic should be tied loosely in a muslin cloth bag.  Vinegar and colour may be added towards the end of boiling.  1/3rd of sugar may be added in the beginning to preserve the red colour of pulp.  Instead of clove, cinnamon and cardamom, their essences may be added more conveniently. Garlic may or may not be added, depending upon consumer’s acceptance. @ JAAC 34 C) Tomato Puree Tomato pulp without skin and seeds, containing not less than 8.37% of salt free from tomato solids is called as “medium tomato puree”. It is further concentrated to 12% solids to form heavy tomato puree. Pulp is extracted and concentrated in open cookers or vacuum pans and packing is done in glass bottles or cans. @ JAAC 35  CHEMICAL/PRESERVATIVES (A) Preservation by use of chemical preservatives-- Chemical or preservatives are substances which are added to food just to retard, inhibit or arrest the activity of micro organisms such as fermentation, pacification and decomposition of the food. Two types of chemical preservatives: Class-1 preservatives common salt sugar dextrose spices vinegar, Ascorbic acid Class-2 preservatives Benzoic acid and SO2 and the salts ascorbic acid and propeonic acid lactic acid and its nitrates, its salt, of sulphuric acid, its salts, and its salts, salts @ JAAC 36 Among the class-2 preservatives, only two chemical preservatives are used in fruits and vegetables preservation: (i) KMS (Potassium Meta bisulphate) : It releases the SO2 and it is unstable. It is used for the fruit which have non water solvent pigment (colourless). It cannot be used in naturally coloured juices such as phalsa, jamun because they have the Anthocynin pigment. It cannot be used in the product which is packed in container because it acts on the tin containers and oil, Hydrogen sulphide (H2S) which has an unpleasant smell and also form a black compound with the base plate of containers. Best to control moulds than bacteria. 350 ppm KMS is mostly used in fruit juice products. (ii) Sodium Benzoate: It is a salt of benzoic acid and soluble in water. It delays the fermentation in the juices. It is commonly used in the product which are having natural colour such as anthocynin pigment. It is more effective against the yeast. 750 ppm Sodium benzoate is mostly used in fruit juices, squashes and cordials. Ionizing to yield the chloride ion which is harmful to micro organisms, and Reducing the solubility of oxygen in water, sensitizing, and the cells against CO2. @ JAAC 37 Preservation by use of food additives (Sugar, Salt, acids and vinegar): Food additives are substances or mixture of substances other than basic foodstuffs, which are present in the foods as reagent of any aspects of production, processing, storage, packaging etc. sugar salt Food additives Acid spices and condiments @ JAAC 38  Food additives cntd; (a) Sugar: The concentration of 68-70% is used for preparation of jam, jelly, marmalades etc. Sugar act as a preservative by osmosis and not as a true poison for micro organisms. It absorbs most of the available water, so little water available for the growth of micro organisms. (b) Salt: The concentration of 15-20% is used for the preparation such as pickles. Salt inhibits enzymatic browning and discolouration and also acts as an anti-oxidant. It exerts its preservative action by:  Causing high osmotic pressure resulting in the plasmolysis of microbial cells.  Dehydrating food and micro organisms by tyeing up the moisture. Ionizing to yield the chloride ion which is harmful to micro organisms, and Reducing the solubility of oxygen in water, sensitizing, and the cells against CO2. @ JAAC 39  Food additives cntd; (c) Acids: Many processed foods and beverages need the addition of acids to impart their characteristic flavor and taste in the final product because acids provide desired flavor and taste. They adjust the sugar and acid ratio in the food.proper balance of flavor of the food. They are also playing the role for controlling the pectin- gel formation. Example - Acetic acid (Vinegar), Citric acid (Lime juice) and lactic acid. Acetic acid: It is commonly used for pickles, chutney, sauce and ketchup, just to inhibit the growth of micro organisms. Citric acid: It is used for the preparation of jam, jelly, squash, nectar etc. just to increase the acidity. Lactic acid: It is used for the formation of curd from milk @ JAAC 40  Other preservation Methods (A) Preservation by oil- A layer of oil on the surface of any food produces anaerobic conditions which prevent the growth of moulds and yeasts. Eg., pickles (B) Preservation by fermentation- Decomposition of carbohydrates by microorganisms or enzymes is called fermentation. Foods are preserved by the alcohol or organic acid formed by microbial action. The keeping quality of alcoholic beverages, vinegars, and fermented pickles depends upon the presence of alcohol, acetic acid and lactic acid respectively. Wines, beers, vinegar, fermented drinks, fermented pickles etc., are prepared by these processes. In wines – 14% alcohol acts as a preservative. About 2% acetic acid prevents spoilage in many products. @ JAAC 41  Other preservation Methods C. Preservation by Carbonation - Carbonation is the process of dissolving sufficient CO2 in water or beverage so that the product when served gives off the gas as fine bubbles and has a characteristic taste. Fruit juice beverages are generally bottled with CO2 content varying from 1 to 8 g/ l, it is sufficient for supplementing that effect of acidity on pathogenic bacteria. The keeping quality of carbonated fruit beverages is enhanced by adding about 0.005% sodium benzoate. The level of carbonation required varies according to the type of fruit juice and type of flavor. D. Preservation by Antibiotics- Certain metabolic products of microorganisms have been found to have germicidal effect and are termed as antibiotics. Nisin is an antibiotic produced by Streptococcus lactis. Commonly found in milk, curd, cheese and other fermented milk products. It is non-toxic. @ JAAC 42 Home Assignment List all value added products available in the makert from following fruits. Draw processing flow chart for those products. a. Mango b. Banana c. Pine apple d. Guava e. Avocado f. Durian g. Strawberry h. Orange i. Cherry j. Passion fruit k. Apple l. Grapes m. Wood apple n. Papaya @ JAAC 43 Thanks https://www.youtube.com/watch?v=5rYukViwiUk @ JAAC 44