Preface   With advanced cultural and production practices coupled with improved cultivars of fruits and vegetables, India holds a unique position in production of fruits and vegetables. Though India has reached new heights in production of fruits and vegetables, the per capita availability is still far behind when compared to other major producing countries. In order to improve the nutritional status of people and also to exploit the export potential of processed products, there is need to increase production of processed food in the country. Fruit processing technology can therefore, strengthen nation’s food security, improve food safety and boost export of agricultural commodities. Less than two percent of the fruits and vegetables are processed in the country, as compared to 30 percent in Thailand, 70 per cent in Brazil, 78 per cent in Philippines and 80 per cent in Malaysia. Fruit processing industry is of enormous significance for India’s development mostly because of the vital linkages and synergies that it promotes between the two pillars of our economy, industry and agriculture. Fast growth in fruit processing sector and progressive improvement in value addition chain would be of great importance for achieving favourable terms of trade for Indian agriculture both in domestic and international markets. The time is now favourable to exploit this technology with initiative to integrate the technology with national mainstream. Post harvest technology, an integral part of agricultural system, needs to be developed at par with developments in agriculture. There is need to adopt holistic approach in selection of research and development projects and their execution to reduce losses, and to promote value addition for export and domestic consumption. Development and adoption of eco-friendly techniques for reducing post harvest losses and processes such as harvesting, cleaning, grading, transportation, packaging, preservation, processing and product development aspects need to be analysed and strategies formulated for catching up with contemporary developments in socio-economic and technical sectors. The need of the hour is to concentrate on improved technologies on post harvest handling of fruits and vegetables to make headway into global market in processed foods. With increasing realisation of the role of fruits and vegetable processing industry in value addition and its potential to improve socio- economic condition of deprived millions of people of the country, it is appropriate that the authors took up the title of the book as “Post harvest technology of horticultural crops”. We are sure that this unique venture would be helpful to solve problems in this important sector. We believe that the readers will get sufficient information connected with fruits and vegetable processing. In this book, authors have attempted to consolidate different methods of post harvest technology of fruits and vegetables, focusing on recent advances. There may, however, be still a few shortcomings in this book and the authors will be grateful to receive suggestions for incorporation in the next edition of this volume. It is hoped that the text would prove beneficial to the teachers and students of post harvest technology, food science and nutrition, food technology, agricultural engineering, home science and other personnel of food processing industries.

Fruits and vegetables are very important food commodities. India has become the largest producer of fruits and the second largest producer of vegetables. Though the production of fruits and vegetables make us believe in our strength for self-sufficiency, a significant qualitative and quantitative loss occur in the produce from harvest till consumption.  For self sufficiency and also for processing, export and to meet additional requirements, a lot of emphasis need to be given to reduce post harvest losses, besides increasing  production and productivity of horticultural produces. Processing plays an important role in  conservation and effective utilisation of these perishable commodities. However, only less than 2% of total production of fruits and vegetables are processed.  The new industrial policy has placed this sector in the list of high priority areas.

Structure Structural unit of edible portion of most fruits and vegetables is the parenchyma cells and makes up bulk of cells. A parenchyma cell is rather thin walled and may be polygonal or cubical in shape.  Walls of parenchyma cells in young plants are composed almost entirely of fibrils of cellulose. In parenchyma cells of plants actively metabolising protoplast portion represents only about 5% of total cell volume. This protoplast is rather film like and is pressed against cell wall by large water filled central vacuole.  Protoplast has inner and outer semi permeable membrane layers between which is confined cytoplasm and its nucleus. 

Maturity at harvest is the most important determinant of storage life and final fruit quality. Maturity indices are determined for many fruit, vegetable and floral crops. Harvesting crops at proper maturity allows handlers to begin their work with the best possible quality produce. Produce harvested too early may lack flavour and may not ripen properly, while produce harvested too late may be fibrous or over ripe.   Almost all fruits reach their best eating quality when allowed to ripen on the tree or plant (exceptions e.g., pears, avocados, and bananas). In general, fruits become sweeter, more colourful, and softer as they mature. A few fruits are usually picked mature but unripe so that they withstand post harvest handling system when shipped long distances.  Most of  currently used maturity evaluation is based on a compromise between those methods that would ensure the best eating quality and those that provide flexibility in transportation and marketing.  Optimum harvesting stage depends upon type of fruit or vegetable and their final use. Such a division is usually based on their classification according to physiology, environmental conditions, ripening bahaviour and nutritional aspect. Some of the classifications, important for their harvesting and storage are briefed in  subsequent sections.

Various systems were developed to take produce from field to consumer and selection of a particular method depends on several factors, including perishability and value of crop.  One method is to harvest the crop and take it to a packhouse for various unit operations like grading, cleaning, post-grading treatments, and packing for transport and marketing. When deciding upon where to locate a packinghouse, access to field and market point, adequate space for vehicles to enter and leave  packinghouse and ease of access to labor will all be considered.   In the simplest packinghouse, produce is delivered in picking containers, immediately after harvest, directly to packers.  Packers then sort, grade, size and pack the produce directly into appropriate transport containers. In this case, each worker must be aware of produce defects, grade and size requirements, and packing methods.

Storage is one of the most important aspects of post harvest handling of fruits and vegetables. The main objective of storage is to extend storage life of fruits and vegetables and increase their period of availability. A substantial quantity of fruits go waste in India due to lack of proper storage facilities. Storage of fruits and vegetables is practiced for various reasons. Proper post harvest handling of fresh horticultural produce helps in extending  period of availability of wide range of  fruits and vegetables round the year, prevention of seasonal market gluts, orderly marketing, better return to grower and  preservation of  nutritional qualities. The   long  term  storage  of  fruits  and  vegetables is expensive and requires high level of technical  knowledge of crop. However, an orderly marketing reduces storage period considerably. 

Processing of fruits  and vegetables into various products which could be preserved for a long time and add to value of product using proper cost effective technology will be a viable tool for improving   economic status of  farmer as well as our country. Modern methods of fruit and vegetable preservation are  broadly classified as follows:

Drying is the oldest known method of preserving food. Drying or dehydration is removal of majority of water contained in fruit or vegetable. Although preservation is the primary reason for dehydration, it also lowers cost of packaging, storing and transportation by reducing both weight and volume of final product. In addition, dried foods add variety to our diets. In the process of drying, sufficient moisture is removed to protect product  from  spoilage. Processing should be done in such a way that food value, natural flavour and characteristic cooking quality of fresh material are retained after drying.

The technique of preserving fruit by the use of low temperature dates from the eighteenth century with the first use of ice house in 1750. Later in 1800s commercial cold storages have come up for the storage of perishables like meat, dairy and fruit products.  The main change took place in the cold store in recent years has been the introduction of multi temperature chambers with humidity control for specific products. Cold preservation can be either refrigeration or freezing. Household refrigerators usually run at 4-7ºC. Chilling or cold storage usually uses a slightly lower temperature on the basis of the food to be refrigerated. In freezing a temperature of -18ºC or below is used. Chilling will preserve perishable foods for days or weeks and freezing will preserve foods for months or even years.

Fruit beverages Fruit beverages are highly refreshing, thirst quenching, appetizing, easily digestible and nutritionally far superior to synthetic drinks. The fruit beverages includes natural and sweetened juices, squash, syrup, cordial, nectar, Ready to Serve (RTS) beverages, fruit juice concentrate and citrus juice barley water. Fruits most commonly used to prepare beverages are oranges, lime, pineapple, grapes, cashew fruit, mango, jack fruit, apple etc. To prepare fruit beverages select fresh, fully ripe, tart, juicy and seasonal fruits.

Fermentation was known to mankind from time immemorial. But, development of biochemical principles of  fermentation  was originated by  Lavoisier in France in 1789 by way of analysing chemical composition of  sugar and its fermentation products such as ethanol, carbon dioxide and  acetic acid. Many products are produced by fermentation process. In fermentation, controlled action of selected microorganisms is used to alter  texture of foods, preserve foods by production of acids or alcohol or to produce fine flavours and aromas which increase value of raw materials.

Minimally processed fruits and vegetables are products that have the attributes of convenience and fresh like quality. Their forms vary widely, depending on nature of unprocessed commodity and how it is normally consumed. In many cases, minimally processed product is raw and cells of tissues are alive, but these characteristics are  not regarded as essential. It is important that products have fresh-like character, regardless of   state of cells.  Minimally processed products for both retail and food service applications have increasingly appeared in market place recently.  In coming years, it is commonly perceived that this industry will have unprecedented growth.

Packaging is an integral part of fruit and vegetable processing. It has  major influence on storage life and on marketability of fresh as well as processed products. Packaging fulfills several functions including containment, facilitating transportation, protection of fruit/vegetable from further damage, protection of environment from contents of package (for example, if the contents are dirty), marketing, product advertising, and stock control.

Transportation and distribution of fruits and vegetables are important stages   of post-harvest loss. In India,  transportation of perishable commodities is in the most precarious stage. For local market, the produce is brought either by bullock cart or tractor trollies. The long distance transportation is mainly by rails and trucks, which is very costly. The basic reason for preference to road transportation is that it takes short transit period.

Quality is an increasingly important factor in the production and marketing of biological products. Consumers are becoming more discerning as their affluence increases, and would be suppliers of products must meet these demands if they are to maintain or increase market share. The term ‘quality’ is one of the most defined terms in use in food industry today. Quality may be defined as ‘The totality of features and characteristics of a product that bear on its ability to satisfy a given need’. The first part, ‘The totality of features and characteristics of a product…..’ concerns objective factors related to the product.  The second part, ‘…… to satisfy a given need’, concerns subjective factors related to user or consumer of goods.

Appendix Appendix-I. Recommended storage temperature and relative humidity for fresh fruits