post harvest technology, agricultural produce, preservation, employment generation, post-harvest methods, fruits and vegetables, food technologists, post-harvest technologists, technical questions, agricultural engineers, food processors, food scientists, researchers, progressive farmers, literature gap
The book post harvest technology assumes great attention during recent years since preservation of agricultural produce is a basic necessity to sustain agricultural production. It helps to add value of produce, thus having great scope for employment generation at the production catchments. In this book, the authors have attempted to consolidate different methods of post harvest technology of fruits and vegetables focusing on recent advances. This book will benefit both practicing food technologist/post harvest technologist who are searching for answers to critical technical questions of post harvest technology. Further, it will be useful to agricultural engineers, food processors, food scientist ,researchers and progressive farmers and tom those who are working in relevant fields. it is intended to fill a gap in presently available post harvest technology literature
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
Foreword to the Series — Prof. M.S. Swaminathan
Foreword — Dr. Nawab Ali
Preface
Acknowledgement
Chapter 1. Introduction
Post harvest losses in fruits and vegetables
Definition of post harvest loss
Factors affecting post harvest losses
Primary causes
Mechanical injury
Pathological action
Environmental factors
Secondary causes
Control of post harvest losses
Cultural operations
Harvesting and field handling
Concept of packinghouse
Newer packaging
Improved transportation
Reducing moisture loss
Marketing
Chemical treatment
Creation of cold storage
Freezing injury
Chilling injury
Heat injury
Processing of fruits and vegetables
Small scale processing
Intermediate scale processing
Large scale processing
Strategies to boost horticultural processing sector
Research and development needs
Chapter 2. Structure and composition of fruits and vegetables
Structure,
Difference between fruits and vegetables
Composition and compositional changes
Carbohydrates
Proteins
Lipids
Vitamins
Minerals
Enzymes
Antinutritional and toxic factors
Colouring pigments
Organic acids
Phenolic compounds
Flavouring compounds
Water
Nutritive value of vegetables
Nutritive value of fruits
Health benefits of fruits and vegetables
Stability of nutrients
Chemical changes
Flavour changes
Changes in nutritive value
Physical changes
Biological changes
Chapter 3. Maturity and harvesting of fruits and vegetables
Classification of fruits
Climacteric fruits
Non-climacteric fruits
Classification of vegetables
Horticultural maturity
Maturity indices and its importance
Determination of harvest maturity indices
Computational methods
Physical methods
Chemical methods
Physiological methods
Harvesting of fruits and vegetables
Manual harvesting
Pole mounted cut and hold picking shears
Mechanical harvesting
Field packing
Transport to the packinghouse
Harvesting tips for high quality horticultural crops
Chapter 4. Packinghouse unit operations
Post harvest operations
Reception
Drenching
Washing/Cleaning
Precooling of fruits & vegetables
Icing
Room cooling
Forced air cooling
Hydro cooling
Vacuum cooling
Trimming
Presorting
Sorting/Grading
Sorting by size
Manual sorting
Mechanical graders
Screen grader
Diverging belt grader
Pommelo sorter
Rotary cylinder grader
Roller grader
Link grader
Iris grader
Length grader
Mass graders
Image processing
Colour sorting
Waxing
Wax types
Specifications of a desirable wax
Wax application & methods
Hot water treatment
Vapour heat treatment
Chemical treatments
Methods of application
Ionizing radiation
Labelling
Quality control
Palletization
Cooling
Cold storage
Strategies to improve efficiency of packinghouse
Chapter 5. Storage and ripening of fruits and vegetables
Factors affecting storage
Temperature
Relative humidity
Optimum temperature and relative humidity
Atmospheric composition
Ethylene synthesis and control
Light
Methods of storage
Traditional storages
On site storage
Pit storage
High altitude cooling
Clamp storage
Windbreaks
Underground storages
Barns
Night ventilation
Evaporative cool storage
Improved storage methods
Refrigerated stores
Modified atmosphere packaging
Active packaging
Passive atmosphere modification
Silicone membrane technology
Vacuum packaging
Hypobaric storage
Controlled atmosphere storage
Storage of dried fruits and vegetables
Management of temperature and relative humidity
Strategies to improve the quality of stored produce
Ripening
Degreening
Changes during ripening
Carbohydrates
Organic acids
Pigments
Phenolic compounds
Flavouring compounds
Softening
Changes in other constituents
Chapter 6. Processing of fruits and vegetables
Peeling
Knife peeling
Abrasion peeling
Flame peeling
Flash steam peeling
Lye peeling
Slicing/Dicing
Blanching
Factors influencing blanching process
Methods of blanching
Hot water blanching
Steam blanching
Blanchers with steam and water system
Individual quick blanching
Vacuum steam blanching
In-can blanching
Microwave blanching
Hot gas blanching
Determination of blanching process
Nutritional quality of blanched product
Canning, 101
Preparation of the food
Washing
Grading
Peeling
Blanching
Filling
Exhausting
Sealing
Thermal processing
Cooling
Storage
Nutrient retention during canning
Chapter 7. Dehydration of fruits and vegetables
Use of dried fruits and vegetables
Factors influencing dehydration
Drying rate curves
Drying time Vs Drying rate
Moisture content Vs Drying rate
Drying time Vs Moisture content
Procedures for drying
Pre-drying treatments
Raw material preparation
Blanching
Sulphuring
Drying methods- principles and methodologies
Sun drying
Solar drying
Oven drying
Osmotic drying
Cabinet dryers/Tray dryers
Tunnel dryers
Conveyor dryers or Belt dryers
Foam mat drying
Fluidised bed dryers
Roller or Drum dryers
Spray dryers
Pneumatic dryers
Microwave drying
Vacuum drying
Rotary dryers
Freeze dryers
Post dehydration treatments
Packaging
Storage
Effects of drying on product quality
Nutritional quality
Texture
Flavour and Aroma
Colour
Rehydration
Chapter 8. Cold preservation: chilling and freezing
Chilling
Factors affecting chilling
Chilling injury
Equipment used for chilling
Mechanical refrigerators
Cryogenic chilling
Cook chill systems
Effect of chilling on foods
Freezing
Freezing injury
Equipment used for freezing
Chest freezers
Blast freezers
Belt freezers/ Spiral freezers
Fluidised bed freezers
Immersion freezers
Plate freezers
Scraped surface freezers
Cryogenic freezers
Effect of freezing and frozen storage on foods
Chapter 9. Processed fruit and vegetable products
Fruit beverages
Fruit juice
Squash
Syrup
Cordial
RTS beverage
Carbonated beverages
Fruit juice concentrates
Fruit juice powders
Sugar based products
Fruit jam
Fruit jelly
Marmalade
Preserves
Candied fruit/ vegetable
Glazed fruit/vegetable
Crystallised fruit/vegetable
Fruit bar/leather
Fruit toffees
Other products
Chutneys
Sauces
Soups
Tomato products
By-product utilisation of fruits & vegetables
Production of fat
Production of essential oils
Production of animal feed
Pectin production
Starch production
Production of natural colours
Biogas production
Other uses
Chapter 10. Fermentation and fermented products
Classification of fermentation
Lactic acid fermentation
Sauerkraut
Pickles
Pickling process
Preservation with salt
Preservation with vinegar
Preservation with oil
Preservation with salt, vinegar, oil and spices
Ethanolic fermentation
Wine production
Classification of wines
Process
Cider
Mixed alcoholic- acid fermentation
Vinegar production
Methods of vinegar production
Chapter 11. Minimal processing of fruits & vegetables
Physiological activity
Microbiological concerns
Techniques for minimal processing
Product preparation
Low temperature storage
Modified/Controlled atmosphere storage
High hydrostatic pressure technology
Oscillating magnetic field
Ohmic heating
Advantages of ohmic heating
Factors affecting ohmic heating
High intensity pulsed electric field
Use of pulsed light
Ozone technology
Manothermo sonication
Aseptic processing of foods
Microwave processing
Irradiation
Major benefits of irradiation
Electrolysed water treatment
Edible coatings
Multilayer coating
Osmotic membrane (OSMEMB) coatings
Membrane technology
Chlorination
Hydrogen peroxide treatment
Use of additives
Biopreservation
Hurdle technology
Quality of minimally processed products
Quality of raw fruit
Firmness and texture
Colour at cut surface
Sensory aspects
Aroma & flavour
Microbiology
Chilling injury of minimally processed product
Fruit size and yield
Chapter 12. Packaging and packaging materials
Packaging
Requirements and functions of packaging materials
Moisture and gases
Microorganisms
Mechanical strength
Light
Heat
Primary and secondary containers
Packaging materials
Wooden containers
Bags/Textiles
Metal
Three-piece cans
Two-piece cans
Tin plate cans
Tin free steel cans
Double reduced tin plate cans
Lightly tin coated steel sheet cans
Aluminium containers
Aluminium foil
Aerosol cans
Glass containers
Plastics in packaging
Flexible films
Single films
Cellulose
Polyethylene
Low density polyethylene (LDPE)
Linear low density polyethylene (LLDPE)
High density polyethylene (HDPE)
Polypropelene (PP)
Polystyrene (PS)
Nylone
Polyester films
Polycarbonate films
A-Pet films
Ethylene vinyl acetate (EVA)
Polyvinyl chloride (PVC)
Polyvinylidene chloride
PVC shrink sleeves
Polymethylpentene (PMP)
Iridescent films
Stretch, cling and twist-wrap films
Laminates
Retortable pouch
Coated film
Coextruded film
Rigid and semi-rigid containers
Biodegradable plastics
Paper
Glassine paper
Paperboard
Laminated paperboard cartons
Fibreboard containers
Chapter 13. Transportation of fruits and vegetables
Tips for efficient transportation
Road Transportation
Unrefrigerated road transport
Refrigerated road transport
Rail transportation
Unrefrigerated rail transport
Refrigerated rail transport
Sea transportation
Unrefrigerated sea transport
Refrigerated sea transport
Refrigerated containers
Shipping of mixed loads
Air transportation
Container for air transportation
Chapter 14. Quality of fresh and processed products
Importance of quality
Factors influencing product quality
Natural contaminants
Microbial contamination
Synthetic toxicants
Measurement of product quality
Instrumental
Destructive tests
Mechanical destructive measurements
Penetrometer
Universal testing machine
Texture analysers
Tenderometer
Denture tenderometer
Twist tester
Warner bratzler
Succolumeter
Visual destructive tests
Physiological changes
Colour
Refractometer
Chemical tests
General chemical assessment
Starch test
Chemical residues
Moisture content measurement
Biological destructive testers
Nondestructive testing methods
Mechanical nondestructive tests
Mass and bulk density
Quasistatic low-pressure indentersm
Dynamic low-pressure indenters
Nondestructive use of texture analysers
Acoustic methods
Visual nondestructive measurements
Size and shape
Colour
Near infrared spectroscopy
Delayed light emission and transmittance
Immunoassay
Sensory evaluation
Quality control measures
Good Agricultural Practices (GAP)
Basic principles of GAP
Requirements and implementation of GAP
Good Manufacturing Practices requirements
Personnel hygiene
Plant hygiene
Sanitary operations
Sanitary facilities and controls
Equipment and utensils
Material and process controls
Hazard Analysis Critical Control Point (HACCP)
Principles HACCP
Application of principles of HACCP
Implementation of HACCP
Description of the product and its use
Preparation of process flow diagram
Identification of all hazards
Identification of the Critical Control Points (CCP’s)
Establishment and monitoring of critical limits
Corrective actions and verification procedures
Record keeping and documentation
Labelling
Appendix
I. Recommended storage temperature and relative humidity for fresh fruits
II. Recommended storage temperature and relative humidity for fresh vegetables
III. Recommended storage gas composition for fruits
IV. Recommended storage gas composition for vegetables
V. Nutritive value of leaf vegetables
VI. Nutritive value of roots and tubers
VII. Nutritive value of other vegetables
VIII. Nutritive value of fruits
IX. Optimal ripening conditions for few fruits
X. Symptoms of chilling injury in some fruits and vegetables
XI. Characteristics of sacks made from different packaging materials
Glossary
References
Index
About the Chief Editor
About the Volume Authors
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