How is fruit preserved?

Answer 1

Well, if you mean preserve like "keep on Earth" then it is very important because man needs fruit to survive, but if you mean it like "keep in fridge or let it last long in your home, then, you preserve fruit to keep it fresh so you do not have to pay extra money you could be spending for other reasons.

Answer 2

Fruit Preservation

Booklet No. 315

Fruit Processing: FPR S - 1

Contents

Preface

I. Introduction

II. Forms of Fruit Preservation,

III. Principles of Fruit Preservation

A. Temporary preservation

1. Absence of infection

2. Low temperature

3. Exclusion of moisture

4. Exclusion of air

5. Mild antiseptics

6. Pasteurization

B. Permanent preservation

l . Sterilization

2. Antiseptics

3. Drying

4. Fermentation

IV. Spoilage in Preserved Fruits

A Chemical and physical spoilage

B. Microbiological spoilage

C. Enzymatic spoilage

V. Prevention of Spoilage

VI. Scope of Fruit Preservation Preface

The need of a booklet on fruit preservation has been deeply felt in the field of agricultural science. Fruits are among the most valuable foods of mankind as they are not only nutritive but also crucial for the maintenance of health. The main difficulty in the growth of fruit preservation has been the inadequacy of knowledge of the modem methods and techniques of preservation. To overcome this difficulty an attempt has been made here to deal with principles, methods and scope of fruit preservation in detail.

Dr. K. T. Chandy, Agricultural & Environmental EducationI. Introduction

The art of fruit preservation has been in practice from time immemorial and in modem times it has become a specialized branch of food technology. In the past, the most common methods of preservation were pickling with the help of salt and drying of fruits and vegetables by sun rays. Storage of fruits in a perfect consumable condition for a longer time without undergoing any spoilage is the main object of fruit and vegetable preservation.

In addition to their immense food value, fruits and vegetables constitute appreciable quantities of minerals and vitamins which are the main source of nourishment for body building. India is an ideal country in the sense that nearly all the important fruits and vegetables can be produced with ease due to varied soil and climate conditions. But many of the fruits and vegetables which are quite cheap in the season are wasted. This wastage can be minimized and these products can be consumed by a common man in off-seasons as well. There are certain periods of glut when raw materials are available in plenty and they do not fetch a good price in the market. While in other seasons they are not available at any price. Therefore, these food materials of immense economic and nutritive value must not be wasted and should be preserved when they are cheap in the market. A variety of products such as jam, jellies, marmalades, squashes, chutney, pickles, vinegars and many other products can be prepared tram fruits and vegetables.

In considering the processing of fruits, it should be remembered that the consumption of fresh fruits is preferable as preservation usually destroys some of the nutritional value as it is known that preserved fruits are not as good as fresh fruits. The extent of nutrient loss during the processing varies greatly with each individual process. For instance, the drying process destroys the fat soluble vitamins, while the boiling process breaks down the vitamins released into the water solution.

Nearly all fruits are acidic and hence called as "high acid foods". This acidity naturally controls the type of micro-or- ganisms that can grow in fruit products. In fact, the only spoilage micro-organisms likely to be found in such products are moulds and yeasts which very rarely cause illness if consumed.

However, vegetables, being low acid in nature, are more difficult to preserve than high acid fruits. Vegetables, classified as "low acid products", many harmful food poisoning organisms can grow in them when in a moist condition and expensive equipments such as boilers and pressure cookers will be required if they are to be processed through the use of heat. However, they can be safely preserved by making them acid through the process of pickling or by salting or drying them. II. Forms of Fruit Preservation

Fruits are nearly all acidic and are thus commonly called "high acid foods". This acidity naturally controls the type of micro-organism that can grow in fruit products. In fact, the only spoilage micro-organism likely to be found in such products are yeasts and moulds, which very rarely cause illness if consumed. However, it is worth describing the principles of preservation. A. Jam and jelliesThe preservation of jams, jellies, and marmalades depends on a high sugar content (between 68 and 72%) combined with the fruit acidic which prevents microbiological growth. Their setting qualities depend on the sugar content and on the formation of a pectin gel. The strength of this gel depends on the amount of pectin present and the acidity. A good jam is a complex product with a precise balance between sugar level, acidity and pectin content. Jellies are clear filtered products; marmalades, generally made from citrus fruits, contain shreds of peel; jams contain either whole fruit or fruit pulp. B. Confectionery productsAlthough, high boiled fruit preserves are manufactured in some areas. These are jam-type basic mixtures that have been further boiled so that they have been further boiled so that they reach final sugar level of between 75 and.85% and thus set as a solid block. This high sugar level combined with the natural acidity prevents spoilage. These products are normally sold as confectionery. C. Fruit in syrupFruits of various types can be packed in jars under an approximately 50% sugar syrup. After heat treatment the jars are sealed tightly while hot so that an internal vacuum forms as they cool. The preservation of products of this type depends upon adequate heat treatment and hermetically sealed containers (that is, air-tight seals). D. DrinksA wide range of fruit drinks can be produced. All contain pulped fruit or juice which has been extracted from the fruit. They are either drunk without the addition of further ingredients as a pure fruit juice, or diluted with sugar syrup. Fruit drinks can be divided into two groups: those which are drunk immediately after opening and those which are used little by little from bottles which are stored between use. The former group, if properly processed and packaged, should not need to contain any preservatives, but the latter group, if they are to have a long shelf-life after opening must contain preservatives. Un-opened bottles should have a shelf life of three-to nine months, depending on the storage conditions.

Many different names are used to describe the fruit based drinks, for instance, juices, fruit nectars, squashes, cordials and syrups.

i. Juices should be exactly a pure fruit juice with nothing added.

ii. Fruit nectars would normally be expected to contain at least 30 per cent fruit solids and are drunk immediately after opening.

iii. Squashes normally contain at least25 per cent fruit pulp mixed with sugar syrup, are diluted to taste with water and contain preservatives, because they are used in small quantities over a long period of time.

iv. Ordials are simply crystal clear squashes.

v. Syrups have been filtered so as to be clear but normally have a high sugar content. They are used in small quantities for dilution.

All these products rely for preservation on their natural acidity and the fact that they have been pasteurized, that is heated to an adequate temperature (80-90°C) to destroy naturally occurring enzymes and most micro-organisms, before packaging. Some drinks such as squashes and syrups, also contain a high concentration of sugar which helps to preserve them. All products that are opened and partially used would need to contain preservatives. E. Pickles and saucesProducts of this type depend for their long shelf-life upon the presence of acetic acid which is normally introduced in the form of vinegar. Other ingredients, such as, salt, sugar and spices, have a lesser but important role in preservation as well as contributing to the flavour. III. Principles of Fruit PreservationThe two main principles which are followed in the preservation of fruits and vegetables are temporary and permanent methods. A. Temporary preservationThe principles of fruit preservation followed on a temporary basis are described here. I. Absence of infectionThe general cleanliness while picking, grading, packing and transporting of raw material increases the keeping quality of fruits and the products prepared by them are of very superior quality. The micro-organisms will also be minimized by the above precautions and there will be less chances of spoilage.

2. Low temperature

It has been established by recent researches that temperatures below 50°F check the growth, multiplication and activity of micro-organisms but do not kill them. It also retards chemical changes to a greater extent. The fruits and vegetables are either kept in refrigerators or in cold storages which depends upon the quantity of the material. The principle of maintaining the temperature for both is the same.

3. Exclusion of moisture

Moisture is one of the favourable things for the growth of micro-organisms specially moulds. Particularly, moisture plays a great role in dried products as it collects on the surface and results in growth of micro-organism. Moisture is also responsible to dilute the concentrated sugar solution which are generally without preservatives. The fruit products Should be saved from moisture and should be stored in a dry atmosphere.

4. Exclusion of -air

If the products are saved from air they prolong the keeping qualities especially fruit products. Aerobic organisms cause a great spoilage if they get external air. So, fermented products and pickles must be sealed in air tight containers to check their growth.

5. Mild antiseptics

Sugar, salt, vinegar are used in small quantities for temporary prevention of some products. Light sugar syrup is used in canning of fruits which retains the colour, flavour and shape of the fruit products. Vinegar and spices check the spoilage of tomato sauce for few weeks after opening the, bottle.

6. Pasteurization

This is a process in which the products are subjected to a temperature which kills the maximum possible micro-organisms present. There is a better method for fruit juices as & practically all the micro-organisms which can grow in liquid are killed by the heat and particularly act as a permanent method of preservation. B. Permanent preservationThis type of preservation strictly depends upon the materials to be preserved.

1. Sterilisation

By this method all the forms of life are completely destroyed due to high temperature. It is also known as processing by heat and the time and temperature varies with different products. Fruit products require high temperature to kill the spore forming organisms being non-acidic and containing

d. Chemical preservatives

Chemical preservatives are used in very little quantities to check the micro-organisms as these are more effective than sugar, salt and vinegar. Benzoic acid, sulphurous acid and their salts, e.g., potassium meta-bisulphite, sodium meta- bisulphite and sodium-benzoate are permitted by law as chemical preservatives.

3. Drying

Drying is the most popular method of preservation. Now drying by dehydration has substituted the sun drying. This is a more rapid process as artificial heat of higher temperature is provided and the fruits and vegetables are dried to such an extent that the moisture content is reduced and micro-organisms fail to survive on them and it checks the action of enzymes as well.

4. Fermentation

Micro-organisms and enzymes are used for the decomposition of carbohydrates and the process is termed as fermentation. This is one of the oldest methods of preservation. IV. Spoilage in Preserved Fruits

Any preserved fruit or vegetable product can be classified as spoiled when for any reason the product has deteriorated during storage process. Spoilage is brought about by the activity of micro-organisms, physical factors, faulty techniques, rough handling and poor storage. The main causes of spoilage of canned and other preserved products can be classified as:

A. Chemical and physical spoilage

The spoilage caused in preserved fruits as a result of mishandling or due to chemical reactions taking place are briefly enumerated here.

1. Swelling

Generally the ends of a normal and perfect can with a good vacuum are flat or slightly concave. A can which bulges its ends by the positive internal pressure due to gas formed by microbial or chemical activity is termed as swelling.

2. Over-filling

This type of spoilage is found generally in canned products. The over-filled cans become strained due to the expansion of the contents on the other hand the absence of vacuum in such cases cause swelling of the can. If the cans are properly heat exhausted the excess material will overflow due to expansion and thus spoilage due to overfilling can be avoided.

3. Paneling

This type of spoilage is generally noticed in large sized cans due to a great vacuum, and the body of the cans is pushed in due to the atmospheric pressure. This is also caused when the tin plate is thin or the cans are pressure cooled where the air pressure is excessively high. In very severe cases it may, lead in seam leakage but normally it is not regarded as a spoilage.

4. Rust

The cans having external rust must be thoroughly examined. After removing the rust, the walls give pitted appearance. Cans affected slightly without noticeable rust should be sold or consumed immediately. Rust formation is seen due to hygroscopic substances.

5. Damage

Rough handling also causes spoilage to the cans due to damage which is the result of ignorance. If the cans show any signs of leakage or distortion they must be rejected.

6. Undesirable textures

Texture is also one of the important aspects and this should be maintained. Texture is detected easily by the consumer if there is any deviation from the standard. Periodical testing of the textures should also be undertaken. Calcium salts present in water used in canning produce a toughening effect to peas and beans, but this type of hardening proves to be useful while canning the potatoes and tomatoes. Processing is also very important so that the soft fruits may not result in the production of pulp due to over-processing.

7. Corrosion of can

The cans are corroded or perforated due to the aciditiy of products specially fruits having more acids cause a great damage and loss to canning industry. B. Microbiological spoilageThe spoilage in the preserved fruits caused as a result of micro-biological changes are briefly described here.

1. Pre-process spoilage

This type of spoilage occurs due to faulty technique. It is noticed during warm weather when micro-organisms go on multiplying if there is any delay in filling the container and heat processing. Processing may sterilize and check the growth of the organisms but the gas present in the can causes swelling and flipping. Hence, the delay between filling and processing must be avoided and particularly at all stages preparation of raw material for canning.

2. Under processing

Any pack which is spoiled due to the presence of micro- organisms even after processing may be termed as "under- processed". But in some cases contents may also be affected by a single species of organism is indicative for under processing.

The micro-organisms which are generally responsible for the spoilage of preserved foods are present everywhere in soil, water, air and even in the raw and processed materials.

These organisms include bacteria, moulds and yeasts.

3. Bacteria

These are the most harmful of all the micro-organisms. These are the microscopic organisms and are found in large numbers. Slight acidic and nitrogenous foods are best for their growth and multiplication. The bacteria are too resistant to different operations. Some bacteria cause tood poisoning.

4. Moulds

Moulds belong to that group of fungi which produce branched filaments. The common moulds consist of micro-scopic tubular filaments termed as hyphae, which are branched and intertwine to form a web-like structure known as mycelium. The mycelium is often white and cottony like and they penetrate the attacked food-stuff. After fixing itself the moulds produce viable spores which act as seeds for multiplication and resist the unfavourable conditions after dispersal and germinate when get favourable conditions.

5. Yeasts

Yeasts are also single celled microscopic organisms which multiply by means of fission, spore formation or budding and are also known as true yeasts. The bud when becomes mature separates from the mother cell and functions like an independent organisms. Yeast cells are abundantly present in atomosphere and thus found oil fruits and vegetables. Yeasts need sugar and plenty of water for their normal growth and in suitable conditions the sugar is converted into alcohol and carbon-di-oxide gas is evolved. C. Enzymatic spoilageThese are the chemical substances besides the above mentioned micro-organisms which play a remarkable role in changing the state of fruits and vegetables. Enzymes are the chemicals which make the ripening process of fruits and vegetables complete, but if their activity is not checked at proper time they spoil and cause final decay.

Enzymes change starch into sugar, proteins into amino acids, pectin into pectic acids and thus the constituents of the food are changed. This action can easily be controlled by regulating the temperature and exclusion of moisture and air. Some fruits when cut, change the colour of the flesh and it is due to the reaction of atmosphere with enzymes. V. Prevention of Spoilage

An attempt has been made against causes of spoilage in fruits. The following directions are kept in mind to control the spoilage.

1. The raw materials should be thoroughly examined and handled following all the hygienic principles and should be avoided from warm conditions so as to avoid possibility of microbial spoilage.

2. The equipments must be clean at every time.

3. The cans should be carefully filled and exhausted sufficiently to produce a good vacuum.

4. Processing should take place as soon as possible after closing.

5. Contaminated waters if traced should be avoided

6. The finished fruit product after canning and bottling should be stored in well ventilated houses and in cool dry place. High storage temperature should be avoided. VI. Scope of Fruit Preservation

Fruit preservation deserves a great economic importance and a wide scope. Therefore, if it is to be developed in proper prospective there are certain problems that should be dealt with. For instances, availability of raw materials, labour problems, capital, lack of interest and scientific knowledge, marketing facilities, transport facilities, availability of cans and bottles, publicity of the products and role of the government.

India produces all types of vegetables and fruits in plenty. Fruits like mango, guava, sapota, banana, cashew nut, jamun, pineapple, jack fruit are not available in every country. The fruit products have a great place in the market. These fruits are available in plenty at a quite reasonable rate in the season and a major portion of them is destroyed un-utilised. Hence, if preserved, they fetch a very good price in off seasons. A. Availability of raw materialIndia produces many varieties of vegetables and fruits in abundance. Some fruits like mango, guava, sapota, banana, cashew nut, jamun, pineapple, aonla and jack fruit are not available in every country and their products specially of mango have a great place in the foreign market. These fruits are available in plenty at a quite reasonable rate in the season and a major portion of them is destroyed unutilized. Hence, if they are preserved, they fetch a very good price in the off seasons. For maintaining the standard and quality of the products, raw material used should be of a very high merit, that is, properly ripened, free from diseases, bruises and other defects. B. Labour problemsThe labour requires proper training: domestic facilities and considerate wages, which is too low in many parts of the country. Low payment is also one of the main causes that they work proportionately according to the amount they get, capital is the main thing which is to be considered before starting any industry. In recent years, a number of preservation factories have come up and are functioning in the country due to the initiative and finance conditions but the number is still low and requires more extension. C. Lack of interest and scientific knowledgeMost of the extensive growers of fruits and vegetables have no idea of preservation. Some of them who are interested are lacking in the scientific knowledge. Hence the government is making an effort to train the private personnel on scientific and earlier lines to give proper information regarding machines, etc. and to can and preserve the food materials which are not easily possible in common Indian home conditions. D. Marketing facilitiesMarketing must be in a perfect order for any produce so that the producer may get reasonable return. In India, there is a good demand of preserved products but they are not available in every market. Therefore, there must be cooperative organizations to help in the marketing about which the government is quite particular and is making effort. E. Transport facilitiesPreviously it was a problem in India to get any fruit or vegetable from other parts of the country. It was due to less number of roads and defective transport system. Now the transport system is very much advanced and any cannery or preservation factory can get raw materials in perfect order from any part of the country by various transport agencies. By better transport facilities the raw materials as well as processed ones will be received in safe condition and also on the other hand the cost will also increase, due to less spoilage. F. Availability of cans and bottlesCans and bottles are the main containers used in preservation factories. It is very much desirable that for the proper supply of cans there must be a good number of factories in the country so that the canning process may not suffer due to the shortage of cans.

G. Publicity of the products

Publicity in the proper way is considered to be the main item which attracts the eyes of a consumer and gives him a knowledge about the Jew additions to the markets. Hence, the publicity of the preserved materials by practical demonstrations may capture good market. H. Role of governmentCentral as well as state governments are giving priority to the fruit and vegetable preservation. The remarkable functions of the department are as follows community canning centers, training courses, research commercial canning and preservation factories. Thus, the development of fruit and vegetable preservation industry, on the above lines may afford a bright future scope in India.

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Answer 3

because if you don't, then it will go mouldy and will not taste very nice.

when it is mouldy, it goes greeny black and it tastes awful and smells greasy! not very nice!

thankyou for my advice!

Answer 4

You preserve fruits and vegetables in the home to keep them from spoiling. This allows you to use them at a later date. Many people grow vegetable gardens during the summer and preserve them by canning or freezing to eat during the winter.

Foods are commercially preserved to prevent spoilage during transportation to markets and while sitting on the shelf until they are sold.

Answer 5

Fruit can be preserved in several ways, here are a few examples, bananas, grapes and plums can be dried, berries can be used to make jam or deep frozen, Oranges make marmalade, lemons can be pickled.