eChapters

Abstract

Drying is a widely used method of food preservation. It leads to some structural changes in the dried material resulting in poor quality and rehydration. Freeze drying, though a costly process, reduces water activity without exposing the food material to high temperatures, eventually retains the original quality to a great deal. Moisture in the foods is frozen to ice which is sublimated under low pressure. Low pressure helps to vaporise the ice without transforming it to liquid, hence leaving the food structure porous in nature. The food is claimed to preserve the nutritional, sensory and re-constitutional qualities.

1.1 INTRODUCTION

Most food materials are composed of a very high percentage of water, which can be as high as 95%, and this makes them susceptible to microbial activity. Microbial activity spoils the products, leaving them useless for human consumption. It not only changes their taste and color but it may also develop toxins, thus making them unsafe. There are various methods for preserving food but in order to make them shelf stable, removing water from foods helps keep them from spoiling for a longer period of time.

Introduction
Freezing is one of the oldest and most widely used methods of food preservation, which allows the preservation of taste, texture, and nutritional quality in foods better than any other methods. 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 the freezing point and a proportion of water undergoes a change in state to form ice crystals. Immobilization of water to ice and the resulting concentration of dissolved solutes in unfrozen water cause a lowering of water activity of the food. Thus, reduction in water activity and use of low temperatures 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 peas, green beans, sweet corn, spinach, carrots, sprouts, and potatoes are examples of commercially frozen fruits and vegetables.
The frozen food market is one of the largest and most dynamic sectors o the food industry. Despite considerable competition between the frozen food industry and other sectors, large quantities of frozen foods are being consumed all over the world. The frozen vegetable industry mostly grew after the development of scientific methods for blanching and processing in the 1940s. The commercialization history of frozen fruits is older than frozen vegetables. The commercial freezing of small fruits and berries began in the eastern part ofthe United States in about 1905.

Freezing is one of the most critical stages in ice cream manufacture because it creates the frozen structure while simultaneously incorporating air. This chapter explains the principles of dynamic freezing and the structural changes that occur as the mix is transformed into semi-frozen ice cream. It discusses ice-crystal formation, air incorporation, overrun, draw temperature, fat destabilization, and product condition at freezer draw. Different freezer systems and hardening requirements are examined, along with calculations related to output and overrun. The chapter also introduces ingredient feeders and ripple or ribbon systems. Understanding freezing technology is essential for controlling texture, body, meltdown, yield, and overall product quality.

INTRODUCTION

Preservation of food by drying or chemical means as by alcohol or acid fermentation and that by the use of ice is long recorded in history. With the advancement of science and the knowledge governing various unit operations in food processing, these food preservation techniques employing thermal, radiation, or low temperature or a combination of these have only got further refined as regards their viability and commercial applications. Process foods of different genre and cuisine, which include frozen foods too, are increasingly becoming popular the world over for reasons of quality, safety and year round supply of nutritious foods to cater to different niche segments of human society. Increasing health consciousness is buoying those processed foods which are preserved and stabilized using non-thermal technologies as these ensure retention of food nutrients to a better definition. Interest in frozen food also stems from need to deliver safe and nutritious foods with extended shelf-lives.

1. Introduction

Freezing is a method of food preservation that involves lowering the temperature below the freezing point of food generally -18 °C or below. During freezing of food the water present in them changes its state to form ice crystals. Human beings in the colder regions have used freezing as a means of preservation since they learnt hunting and gathering foods. The foundation of the modern frozen industry was laid in mid 1920 when Clarence Frank Birdseye, an American inventor used cold brine solution to chill packaged fish and extended it further for quick freezing of meat poultry fruit and vegetables. 

Freezing is one of the easiest and least time consuming methods of food preservation. The freezing process is a combination of the beneficial effects of low temperatures at which microorganisms cannot grow, chemical reactions are reduced, and cellular metabolic reactions are delayed.

Methods of Freezing

1. Sharp freezing (slew freezing)

In sharp freezing commodities are exposed at -15 to -29⁰C. It required 3-72 hrs. Here the thawed tissue cannot regain its original water content. The ice crystals formed are large and rupture the cells. The thawed tissue cannot regain its original H₂O content.

Introduction
Fruits and vegetables are an important part of the human diet as they provide the necessary nutrition, essential minerals, vitamins, antioxidants, dietary fiber, etc., required for maintaining proper health. India is the second largest producer of fruits and vegetables in the world after China. Comparison of area under horticultural crops during 2011-12 and 2021-22 indicate substantial improvement from 18.5 million ha to 27.6 million ha with a simultaneous increase in production from 215.04 million MT to about 333.25 million MT respectively in the country within a span of just one decade (Table 1.1). The credit for this spectacular growth in area and production goes to the sustained efforts of the central and state governments for the launch of several farmers’/ growers’ welfare schemes viz., National Horticulture Mission (NHM), Horticulture Mission for Northeast and Himalayan states (HMNEH), Mission for Integrated Development of Horticulture (MIDH); R&D support by the ICAR and State Agriculture & Horticulture Universities, extension agencies/Krishi Vigyan Kendra and proactive farmers and orchardists. However, the increase in production has still not kept pace with the improvement in infrastructure for post-harvest handling, management, processing, and value addition. Various studies still indicate that under normal conditions more than 15-20% of the produce goes to waste from production to consumption which in monetar terms accounts for huge economic losses. A recent study sponsored by the Ministry of Food Processing Industries Government of India and conducted by NABARD Consultancy Services has indicated that about 19.33 million MT worth Rs 58013.71 Crores of fruit & vegetables goes to waste annually as postharvest loss (4.87-15.05%) in various channels from harvesting to consumption (NABCONS,2022). The condition becomes even worse when there is a glut in the market, road blockades, or seasonal vagaries, and farmers are forced to leave their produce in the field itself without harvesting or dispose it at throwaway prices. Such a situation can, however, be controlled by diverting thisproduce to processing for conversion into a number of value-added products for its later use in human consumption. Thus, processing and preservation of horticultural crops have now become a necessity rather than a luxury.

4.1 Introduction

A huge amount of waste in the form of liquid and solid is produced in the fruit and vegetable processing industry which causes pollution problem if not utilized or disposed off properly. Generally solid waste is dumped in local landfills, eaten and scattered by stray animals, which has now become a major cause of environmental pollution. The waste obtained from fruit processing industry is extremely diverse due to the use of wide variety of fruits and vegetables, the broad range of processes and the multiplicity of the product [79]. The solid waste from fruits and vegetables includes peel, stone, rag, seed, core etc is of economic value and can be used for manufacturing of various by-products [21]. The extent of the waste produced from processing industries of some of the important fruits and vegetables, is given in Table 1.

In India, utilization of fruits and vegetables for processing is hardly 1.8% of the total production. There were 5166 processing units till 1^st Jan, 2009 of fruits and vegetables products throughout the country. About 90% of these units are small scale units with annual production limit of 50-250 tonnes. These units have no organized methods of waste disposal. In certain places this waste is taken away by farmers for their disposal as cattle feed or field manure.

Fruits have been one of the earliest foods of mankind. Ancient Indian texts like Charak Samhita and Sushruta Samhita, religious books and puranas are replete with mention of various kinds of fruits. The mango is believed to have been grown for more than 4000 years. Mention of apple, the forbidden fruit, in the Holy Bible is well known. The date-palm is recorded as the fruit crop grown by mankind since 7000 BC. The first book in the world on fruit culture is said to have been the one written on litchi in 1056 AD. In the earlier period of human civilization, fruits served both as food and medicine. Fruits, nuts and tubers were the staples for early wanderers and gatherers. The settled agriculture made mankind more dependent on cereals, pulses and oilseeds for staples and fruits, vegetables and nuts became more a medicine than food.

Many evolutionary and anthropological changes occurred in course of time with changing food habits. At every stage of major change, food habits determined the life expectancy. After completing a full cycle or helix, time has returned to focus on fruits and vegetables again as food, from a stand point of health and wellbeing. From being trees of wild and forests in earlier period, fruit crops became confined to palaces and orchards of Kings in medieval period. In modern Era, it came to stay as commercial commodities dictating the terms of trade. Due to its growing commercial importance the governments across the globe focused to expand the area under fruit crops and cross border trade in several fruits and vegetables. Horticulture research started prioritizing the traits in fruits that determine the economics of trade. In line with these developments, Indian government assigned great significance to horticultural crops since 8^th five-year plan period, and the allocation for horticultural research was increased to `110.2 crores from `31.96 crores in the previous plan. During the 10^th five-year plan period in 2005-06, the National Horticulture Mission was started. As the net outcome of these efforts, the area under fruit crops increased from 2.87 million ha in 1991-92 to 6.48 million ha in 2016-17. The production increased from 28.63 million tonnes to 92.85 million tonnes and productivity from 9.96 tonnes/ha to 14.33 tonnes/ha during the same period (Anon, 2017).

Out of the total value of output of agricultural crops, fruits and vegetables contribute the lion’s share of 23%. The major fruit crops producing states are Andhra Pradesh, Maharashtra, Uttar Pradesh, Gujarat, Madhya Pradesh, Karnataka, Tamil Nadu, Bihar, West Bengal and Chattisgarh. The major fruit crops grown are banana, mango, citrus fruits (sweet orange, mandarin, lime & lemons), peach, guava, papaya, pomegranate, sapota, apple, pineapple, ber, litchi, avocado, etc. Several minor crops like jackfruit, aonla, bael, jamun, custard apple, fig, karonda, phalsa, carambola, etc., are also grown. Some exotic fruit crops like dragon fruit, kiwi, durian, Malayan apple, rambutan, etc., are also getting imported either due to its extra ordinary taste or exotic flavor.

Fruit juices which do not undergo alcoholic fermentation are termed as unfermented beverages. They include natural and sweetened juices, RTS, nectar, cordial, squash, crush, syrup, fruit juice concentrate and fruit juice powder. Barley waters and carbonated beverages are also included in this group.

Fruit firmness is an important indicator of maturity. During ripening, fruits may soften and become too soft at the overripe stage. The changes are detected by pressing the fruit in between hands or by using devices like a pressure tester or texture analyzer to measure the texture of fruits and vegetables. Commonly used pressure testers to measure the firmness of fruits and vegetables are the Magness–Taylor Pressure Tester and Penetrometer. Principle: For the measurement of pressure, the maximum force required to rupture the sample is measured by pushing a cylindrical metal probe into the sample to a given depth. The Magness-Taylor pressure tester can be used to determine the softening of fruits during maturity. In this instrument 10 lb or 30 lb force springs are available. Each of them is provided with one or two punches of 5/16 or 7/16 inch in diameter. The plunger of larger diameter is used on softer material, while; the smaller one is used for firmer material.
Procedure
1. Select the pressure tester according to type of fruit
2. Remove a thin portion of the skin in case of waxy fruits

Fruit jelly is an important part of diet of all human being. It is easily digestible, highly refreshing, appetizing and nutritionally far superior to many foods. Today, a wide variety of fruit jellies are consumed in the home, at work place and sport stadium. There has been considerable increase in the consumption of fruit and vegetable jellies in the world during last few years. Jelly is a semi-solid product prepared by boiling a clear strained fruit extract free from pulp after the addition of required amount of sugar, citric acid and pectin. It should contain minimum 65 percent of total soluble solids and minimum 45 percent of fruit portion (Dhawan, 1998). Guava is rich source of pectin and acid content and have thick flesh is preferred for jelly making. For getting good quality jelly, mix under-ripe fruits give better pectin content and ripe fruits provide the flavor. Winter season fruits yield better quality jelly (Singh and Dhawan, 1983). It is a clear or translucent fruit spread made from sweetened fruit (or vegetable) juice and set using naturally occurring pectin. Additional pectin may be added where the original fruit does not supply enough. Jelly can be made from sweet, savory or hot ingredients. It is made by a process similar to that used for making jam, with the additional step of filtering out the fruit pulp after the initial heating.

Jellies are the products used as bread spreads all over the world. These are made from fruits rich in pectin. Guava, because of its rich pectin content, is processed into jelly. Processing of guava into jelly is practiced by processors all over the world. Colouring of jams and jellies has been an age old practices colorants. Great attention is being paid now days to the usage of natural colours in view of the hazards that the synthetic colours pose to human health. Incorporation of carrot resulted in colour improvement over control. Jelly containing carrot as a colouring source was found slightly better than other vegetables. Jelly is a semi-solid product prepared by boiling a clear strained fruit extract free from pulp after the addition of required amount of sugar, citric acid and pectin. It should contain minimum 65% of total soluble solids and minimum 45% of fruit portion (Dhawan, 1998).

Introduction
Fruit juice and beverages comprise naturally extracted juices, drinks, ready to serve (RTS) beverages, carbonated juice drinks, 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 from the edible portion of the fruit. Fruit juices are generally extracted from fruits in several ways, depending on their structure and composition. Soft fruits such as berries or tomatoes can be pressed in a fruit press or pulped by using a juicer attachment to a food processor. Citrus fruits are usually reamed to extract the clear juice. Harder fruits, such as pineapple, are peeled, pulped and pressed to extract the juice. Apple and pear fruits are crushed in a fruit grater and pressed in a hydraulic/ basket press to extract a clear juice. Passion fruit juice is prepared by using a pulper-finisher that separates the skin and seeds from the pulp. The fruits like mango, guava, apricot, peach etc from which the clear juice extraction is difficult are passed through the pulper to make pulp and then the pulp is utilized for preparation of juice, fruit drinks and ready to serve beverages. 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.

10.1 Introduction

Edible oil production is a separate sector of the food processing industry. There are several species of plants in the world whose oil can be utilized for human consumption for edible and non-edible uses. Though around 40 oilseeds are known, only around a dozen oilseed crops have become commercially important including ten seed crops and three tree crops. These oil seed crops (mostly annual) of commercial importance are groundnut, rapeseed-mustard, sesame, soybean, sunflower, cottonseed, safflower, niger, castor and linseed. The three major tree oil crops are palm, olive and coconut [63]. Besides these, the kernels of some other tree crops i.e. apricot, almond, walnut, hazelnut, olive (fruits are used), peach, can also be utilized for oil extraction purposes for edible and non-edible uses. Besides oil of the oilseed crops, the oils of tree fruits and kernels are also becoming popular very fast for various food, pharmaceutical and cosmetic industries.

Large scale requirement and local shortages of oils for various edible and non-edible uses have prompted the identification of many new sources of oil during the last few decades. They are ricebran, corn, sal, mahua, jatropha, kokum, melia, rubber, mango kernel, kusum, simarouba, neem, karanj, crambe, moringa, tumba, jojoba and tobacco seed etc. Most of these oilseeds and their products have wide utility in the specialty oils sector and are mostly used for non-edible purposes. Soaps and detergents, paint and varnish, lubricants, pesticides and medicines, cosmetics, bio-diesel fuel industry are the major consumers of these non-traditional oilseeds. All the oil crops will gain greater attention in future as they are renewable and biodegradable in nature [63]. List of oil crops have been given in Table 1.

Abstract

Fruit leather is a concentrated source of nutrient, energy and minerals processed from fruits in the form of sheet or leather. It is eaten as a desert or snack since ancient time. Fruit leathers have a greater benefit than fresh fruits if equilibrium ingredients are established and seasonal surplus of fruits are utilized and contributed to minimize post-harvest losses. The process of making fruit leathers involve making fruit puree and adding additives and preservatives for the purpose of enhancing taste and shelf-life. Drying, the key unit operation in making fruit leathers, is the most energy intensive and time consuming step in the process, modern drying techniques can be implemented to overcome the limitations. By novel means of processing technologies or enrichment could lead fruit leather to introduce high quality food product in the market. Continuous research and development can lead to a new era of production and development of fruit processing and overcome the obstacles during processing. In addition study on chemical and biochemical hazards involved in overall process will guide to ensure product safety. Market research tools e.g. quality function deployment method and other market analysis methods could be applied to understand the product trend, demand, consumer expectations and the scopes of improvement.

There is wastage and loss of food during its journey from production to consumption. Approximately one-third of the massive 1.3 billion tonnes of food produced annually goes to waste due to various factors such as poor
handling after harvesting, unfavorable storage conditions, insect infestations, and diseases. To combat these losses, synthetic chemicals have historically been used to control pathogens and pests, but concerns over their potential health risks have led to restrictions on their usage. In response, researchers are now focusing on developing safer and more effective physical treatments for disinfecting and protecting horticultural produce. This chapter specifically explores the advantages of using heat treatment as one such method, discussing how it helps maintain the quality of fruits and vegetables while simultaneously reducing postharvest losses.
Some of the heat processing methods are discussed below:
Fruit juices, RTS and nectars are preserved by pasteurization or by using chemical preservatives. Squashes, crushes, syrups and cordials are preserved by adding chemical preservative like potassium metabisulphite or sodium benzoate.

Importance of Fruits and Vegetables in Human Life

Fruit is the edible, and more or less juicy, product of a tree or plant and consist of the matured ovary including its seeds and adjacent parts. Usually fruits are sweet, with a wide range of flavours, colours and textures.

Composition

Fruits are very poor source of protein and fat. Avocado is the exception containing 28% fat. Fruits contain high amount of moisture hence they are highly perishable. They are also good source of fiber. Fruits are not very good sources of calories. Fruits like bananas give fairly good amount of calories. Ripe fruit contains a higher percentage of sugar than unripe fruit does and the sugar is chief in the form of sucrose, fructose and glucose. Generally fruits are poor source of iron, Mangoes are excellent source of carotenes. Oranges are fairly good source of beta carotene. Guavas are the best source of vitamin C. Citrus fruits are good source of vitamin C. Cashew fruits are inexpensive and rich in vitamin C, although there is variation of vitamin content from fruit to fruit most fruits in the raw state contain some ascorbic acid. If fruits are bruised, peeled, cooked or exposed to air, large amounts of the vitamin may be oxidized. Apples are not only expensive; they contribute little to the nutritive value. They give fiber to the diet.

1. INTRODUCTION

The Green Revolution and subsequent efforts through the application of science and technology for increasing food production in India, have brought self-reliance in food. The imputs given by the Government, State Agricultural Universities, State Departments of Agriculture and other organizations through the evolution and introduction of numerous hybrid varieties of fruits and vegetables and improved management practices have resulted in increased food production. However, the nation still faces the problem of the use of improper methods for the storage of food stuffs and their preservation leading to great wastage of the food produced. So, there is a urgent need for the application of food preservation and processing methods.

Food preservation involves all the processes used to maintain foods with the desired properties or nature for longer time. The process is has moved from an art to a highly interdisciplinary science. Food safety now the first priority of the food production and preservation industry, incorporating innovations and sustainability. The preservation and processing of food however, is not as simple or straight forward as it was in the past. A number of new preservation techniques have been developed to satisfy the current demands of economic preservation and consumer satisfaction in nutritional and sensory aspects, convenience, and safety, absence of chemical preservatives, and environmental safety. Understanding the effects of each preservation method on food has therefore, become critical in all the aspects.

    1.    Vegetables are less acidic than fruits and food poisoning bacteria are able to grow in many vegetable products

    2.    Different levels of acidity in fruits

    3.    Water for cleaning of fruits and vegetables should contain about 200 ppm of chlorine (by mixing 1 litre of bleach into 250 litres of water)

    4.    Water that is used as an ingredient in fruits and vegetable product should not contain more than 0.5 ppm chlorine (by adding 2.5 ml of bleach to 250 litres of water), to avoid contaminating products with a chlorine smell