eChapters

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.

5.1. Introduction

Food processing units range from home-based businesses to large-scale processing plants. The food processing sector is a highly fragmented industry which includes fruit, vegetables, dried, preserved, canned, pulps, pickles, chutneys, milk, dairy products, ready-to-serve products, frozen desserts, meat, poultry, marine products, grain processing, beer and alcoholic beverages, consumer, convenience and packaged food, soft drinks etc.

The main objective of fruit and vegetable processing is to supply wholesome, safe, nutritious and acceptable food to consumer throughout the year. Fruit and vegetable processing also aim to replace import of products such as squashes, jams, tomato sauces, pickles, etc., besides earning foreign exchange by exporting finished or semi-processed products. The fruit and vegetable processing industries are also established in the developing countries due to following reasons:

• Reduction in fruits and vegetables post harvest losses

• Industrialization policy of the government

• Generate both rural and urban employment

• Improve farmer s nutrition by self consumption of processed fruits and vegetables during off season

4.1. Introduction

Food occupies first position among the basic needs of human beings. Food processing dates back to the prehistoric age when crude processing including various types of cooking, such as over fire, smoking, steaming, fermenting, sun drying and preserving with salt were in practice. These crude processing techniques remained essentially the same until the advent of the industrial revolution. However, the change in food habits and the quality consciousness of the consumers in the developed world raises the need of advancements in development of food processing like spray drying, juice concentrates, freeze drying and also introduces dried instant soups, reconstituted fruit juices, and self cooking meals such as ready-to-eat food rations etc., during 20th century.