eChapters

R₁, R₂, R₃: The symbols used to designate first, second and third irradiation generation.

Race: i) A genetic subdivision of a species, with more or less distinct characteristics when grown in a particular environment. Sometimes used to denote a portion of a cline. Differences among races may or may not be adaptive; differences among ecotypes are presumed to be adaptive. Hence, ‘race’ is a more general term than ecotype. ii) A genetically and often geographically distinct mating group within a species; also a group of pathogens that infect a given set of plant varieties.

Qine: A character gradient. A gradual change in one or more characters between adjacent parts of a population. Such variation in a character is called “clinal variation.” See Ecotype; Race.

Quadrat: i) An ecological sampling unit of any kind. ii) A small field study unit or sample area, usually a square meter or a milliacre (1/1000th acre) in size, established for the purpose of detailed observation.

Quadrangle: A standard map size and scale used by the U.S. Geological Survey (TWS).

Quadrat, denuded: A quadrat from which the vegetation has been completely removed at least once.

Palatable: Having a good or at least a tolerable flavour. Some plants, although not poisonous, simply do not taste good and animals avoid them, for example, the leaves of Prosopis juliflora. Others are so highly palatable that establishing the tree can become difficult, for example, Leucaena leucocephala. Hence ‘palatability’. See also Digestibility.

Palm: Member of the aracaceae (previously palmae) family, containing over 200 genera and more than 2700 species, many of them economically important for food, fibre, canes, waxes, wood, thatch, and so forth. Typical agroforestry tree.

O horizon: A soil layer dominated by organic materials occurring at the surface of the soil. 

Oblique Aerial Photographs: An oblique photographis one which has been taken with the optical axis of the camera intentionally tilted from perpendicular position obliquely. The degree of tiltfrom the perpendicular further classifies oblique photographs into high oblique photograph and low oblique photograph. A high oblique photograph is one which is taken with the optical axis of the camera making an angle >30^° with the vertical axis and which shows the apparent horizon on the photograph.

N₂O: Nitrous Oxide.
Naphthalene Acetic Acid (NAA): Is represented which is a synthesised auxin.
Naphthalene ring/molecule: Two benzene rings condense to give the naphthalene molecule/ring.
Natality (birth-rate): i) It refers to the production of new individuals by birth or hatching. The natality rate is the number of young ones produced per female. ii) Refers to number of young individuals born or hatched per unit of time. iii) Refers to an organism or population of organisms that occurs naturally (i.e., independent of human activity) in an area.
Natural forest: A forest composed of indigenous trees and not classified as forest plantation. 

Macroclimate: The climate of a region. See also Microclimate, topoclimate.
Macronutrient: A chemical element necessary in large amounts (usually > 50 ppm in the plant) for the growth of plants. Includes c, h, o, n, p, k, ca, mg, s. ‘Macro’ refers to quantity and not to essentiality of the element. See also Micronutrient.
Maggot: Legless larva, especially of a fly.
Main effect: The response to different levels of a treatment factor, measured independently of other factors. In a balanced design such as a randomized complete block, the main effects of levels of a treatment factor are estimated by averaging the corresponding responses over all levels of every other factor.

L layer: The litter layer of the forest floor, consisting of unaltered dead remains of plants and animals.

Land : Land is a broader term than soil. In addition to soil, its attributes include other physical conditions such as mineral diposits and water supply; Location in relation centers of commerce, population, and other land; the site of the individual tracts or holdings; and existing plant cover and works of improvement.

Land capability: The suitability of land for use without damage. Land capability (as ordinarily used in the united states) is an expression of the effect of physical land conditions, including climate, on total suitability for use without damage, for crops that require regular tillage, for grazing, for woodland and for wildlife. Land capability involves consideration of the risk of land damage from erosion and from other causes and also difficulties in land use owing to physical land characteristics, including climate.

Kaolinite: An aluminosilicate mineral of the 1.1 crystal lattice group.

Ketchup: Strained concentrated extract of fruit/vegetable which is having spiced vinegar.

Keystone species: i) A species that other species depend upon for survival. ii) A species whose impacts on its community or ecosystem are large, and much larger than would be expected from its abundance. iii) A keystone species is one which has a disproportionately large impact on its ecosystem, and its presence affects many other organisms by helping determine the types and numbers of other species in the community. If a keystone species is removed the delicate balance of an ecosystem would be dramatically changed, and the ecosystem itself could collapse. Important pollinators, such as hummingbirds, bats or butterflies, can be keystone species, as so many other species are reliant on them for survival. Predators such as Jaguar, are often keystone species. Jaguars are present in very small numbers in Central and South America, but they play a critical role in keeping populations of other mammals in check. Identifying and protecting keystone species is important for the long term survival of an ecosystem.

Jalshakti: It is a material (starch based polymer) which can absorb and hold 80-100 times its weight of water. It is a gel on which plant roots lock themselves and tap the water. It can be used on most soils and in all composts to promote vigorous growth and minimise plant stress. It is used by mixing with growing medium at the rate of 1-2% by weight. Plant roots attach themselves to hydrated granules of the chemical and tap their water store. Jalshakti reduces watering needs.

Jam: Concentrated fruit pulp with natural fruit flavour where pectin imparts a good set and high sugar concentration (68%) facilitates its preservation.
 
Jungle: The general Indian term for forest.

Ideotype: A conceptual model of a plant type that will be best suited to a particular set of circumstances. Ideotypes can be defined in terms of both form and function. There can be ‘isolation’, ‘competition’ and ‘crop’ ideotypes.
Illuvial horizon: i) A soil layer in which material from above has been deposited; the layer of accumulation. ii) A soil horizon that receives material in solution or suspension from some other part of the soil. See also Eluviations.
Image: Picture or graphical representation. In remote sensing and GIS as a term that describes digital representations of earth features (TWS).

H layer: The humus layer of the forest floor, consisting largely of well-decomposed, amorphous organic matter.
 
Habitat: i) The sum of effective environmental conditions under which an organism lives. ii) Often used for the natural range of distribution of a species. iii) The kind of place in which a plant or animal lives, such as forest habitat, grassland habitat etc. iv) The ecosystem in which a plant or animal lives and obtains food and water. v) It refers to a place or ecological community, or a set of ecological communities, in which an organism or population of organisms occurs. vi) The immediate environment occupied by an organism. vii) The natural environment of an organism excluding other living organisms (the biotope). See also Site. viii) The place or environment where an animal (or plant) naturally or normally lives and raises young.

Game: A species of wildlife hunted or trapped by humans, including upland birds, waterfowl, small game, forbearing, and larger mammals that are within the purview of management.

Gamete: i) A mature sex cell, such as sperm/egg used in fertilization. A reproductive cell whose nucleus and often cytoplasm fuses with that of another gamete during fertilization resulting in the formation of a zygote. Gametes are usually differentiated into male and female gametes. ii)  A male or female reproductive cell, typically the product of meiosis, capable of uniting in the process of fertilization with one of the opposite sex.

F : Symbol for a generation; F₁ the first generation of a hybrid; F₂ the second; and so on.

F1 : The first filial generation of a cross between two individuals; parental generation (P₁) from which experiment starts.

F2 : The second filial generation of a cross between two individuals; the offspring resulting from crossing the members of the F₁ among themselves.

Flayer: The fragmentation layer in the forest floor, immediately below the litter layer, composed of fragmented, partially decomposed organic materials that are sufficiently well preserved to permit identification as to origin.

E horizon: A mineral soil horizon in which the main feature is loss of silicate clay, iron, aluminum, or some combination of these, leaving a concentration of sand and silt particles of quartz or other resistant materials. 

Earth Summit: International conference held in Rio de Janeiro in 1992 to discuss issues concerning climate change, world poverty, environment and development, the worlds forest and biodiversity.

Ecocentric value: The value of ecological entities irrespective of their usefulness to humans. 

Dabbling ducks: Duck species that principally feed in shallow water by “tipping up” or dabbling on the surface.
 
Damping off: i) The wilting of young seedlings by certain fungi that cause decay of stem, or roots. The major diseases of germinating seeds are grouped under the single name ‘damping off’. It is caused by a number of separate fungi, mainly species of Pythium, Rhizoctonia and Phytophthora. The disease is expressed either by the failure of seedling to emerge or by the death of the seedling shortly after emergence. Protection from this is to allow the surface of the soil to dry before doing additional watering. Sphagnum moss spread thinly over the soil surface is also effective in reducing damping off. ii) A term used to describe the action of parasitic soil fungi, which cause rotting of seedlings before or soon after germination. This can sometimes be avoided by adding sand to the soil mixture to improve drainage, thus preventing the fungi from multiplying rapidly, or by using fungicides. Eucalypts and pine species are particularly susceptible to damping off.

C horizon: i) A horizon or layer, excluding hard bedrock, that is little affected by pedogenic processes and lacks properties of O, A, E, or B horizons —note the material of C horizons may be either like or unlike that from which the solum presumably formed. ii) A mineral horizon generally beneath the soil solum that is relatively unaffected by biological activity and pedogenesis and is lacking properties diagnostic of an a horizon or a b horizon. See also Soil horizon.

B horizon: i) A soil horizon that formed below an A horizon, E horizon, or O horizon, dominated by obliteration of all or much of the original rock structure and showing one or more of the following: a) illuvial concentration of silicate clay, iron, aluminium, humus, carbonates, gypsum, or silica, alone or in combination; b) evidence of removal of carbonates; c) residual concentration of sesquioxides; d) coatings of sesquioxides that make the horizon conspicuously lower in value, higher in chroma, or redder in hue than the overlying or underlying horizons without apparent illuviation of iron; e) alteration that forms silicate clay or liberates oxides, or both, that forms granular, blocky, or prismatic structure if volume changes accompany changes in moisture content; or f) brittleness. ii) A soil horizon usually beneath the a horizon that is characterized by one or more of the following: a) A concentration of silicate clays, iron and aluminium oxides, and humus, alone or in combination; b) a blocky or prismatic structure, and  c) coatings of iron and aluminium oxides that give darker, stronger or redder colour.

A horizon: i) The surface soil horizon of a mineral soil having maximum organic matter accumulation, maximum biological activity or eluviation of materials such as iron, aluminium oxides and silicate clays. ii) A mineral horizon that formed at the surface or below an O horizon, obliterating all or much of the original rock structure and (a) characterized by an accumulation of humified organic matter intimately mixed with the mineral fraction and not dominated by properties characteristic of E horizon or B horizon. See also B horizon, C horizon.

Abatement: Refers to reducing the degree or intensity of greenhouse-gas emissions.

Abstract

Forestry in India is very important for its wood, fuel and many non-wood products which were being used from ancient times by our forefathers for different personal and commercial use. Farmers face lots of problem in forestry because of its long gestation period, dependence on nature, bulkiness of outputs, season oriented production, perishable in nature, lack of processing centres for value addition at farm and intermediate levels, price fluctuation of forestry products, forced sale/distress sale of tree growers, low wage rate to workers in forestry activities and farmers in sufficient knowledge on market information. Establishment of institutional setup to promote forestry is urgent in the recent times.

Abstract

Intellectual property has increasingly assumed a vital role that we are witnessing today with the rapid pace of technological, scientific and medical innovation. Moreover, changes in the global economic environment have influenced the development of business models where intellectual property is a central element establishing value and potential growth. In India several new legislations for the protection of intellectual property rights (IPRs) have been passed to meet the international obligations under the WTO Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS). Forest seed of economic importance and the non-timber forest products (NTFPs) play a very important role in the country’s economy.

Abstract

Forests are the second largest land use after agriculture in India covers around 24% of the geographical area. The key tree species like Teak, Sal, Shisham etc are commonly used for timber purposes however the species like Eucalypts, Acacias, Poplar, Melia and Leucaena are mainly used under agroforestry system in India. The most of the genetic material (seed/planting stock material) used in forestry sector in India is obtained from unspecified sources, from stands, natural or planted, which are neither classified nor managed specifically for seed or planting stock material production.

Abstract

People dealing with forest tree seeds are very much concern with the collection and supply of pure and quality seed. Assessing genetic purity of tree seed is always a challenge. Besides, studying tree diversity and tree improvement are also the key components of forestry. With the discovery of DNA based molecular markers these tasks have been made easier and authentic. So, the basic concepts behind different molecular markers were the principal concerns of this chapter. It has been focused here about the pros and cons of the markers along with their applicability. The application may be expanded towards hybrid seed testing and even to clonal forestry.

Abstract

The forest cover has declined at an estimated rate of 3-3.5% per annum due to huge deforestation in many countries during last decades. Being the prime necessity for forest regeneration, importance of quality seed management and its handling procedures have been genuinely recognized for greater interest of the environmental stability throughout the world. Growing of new trees and forests would play a major role to save the future world particularly under the present scenario of climatic change and this implies an increased demand of quality forest reproductive materials.

Abstract

In afforestation and reforestation programs, seed has become a valuable commodity and its collection, identification, handling, processing, testing, storage and certification requires prudent planning. The research and development in seed science and technology have made significant progress in recent years. The quality of seed has been the subject of increasing interest among Forest Managers and the Scientists. Not every seed is suitable for sowing. Sometimes, the seeds do not develop into normal plants or the plants produced do not produce the expected harvest. This manuscript reviews, the progress made to-date in the forest tree seed germination and highlights future line of action.

Abstract

Seed is the most important input component for productive forestry. Large quantities of quality seed are needed every year to raise the nursery stock for propagating the desired plant species.  Commercially important species like Dalbergia sissoo, Eucalyptus tereticornis, Pinus roxburghii and Populus deltoides have become more important. Superior genetic qualities of seed have profound positive impact on growth rates and productivity of plantations and quality of the produce. To save and multiply the entire lot of valuable forest plants it is very essential to preserve and multiply those plants for which special type of nurseries are to be established. There is necessity to have special techniques and methods to meet the demand of seed and only hi-tech nurseries can satisfy this type of demand.

Abstract

Insect pests, fungi, bacteria and other injuries are found in all types of environment and affect the growth, production and survival of both plants and animal species in one way or other. Similarly a large number of insects belonging to different orders, families and genera feed on pods and seeds in natural/ during storage and cause injuries. Regeneration failure in several broad leaved and conifers in India and other countries by heavy insect attack in the natural stands at the time of inflorescence and seed formation and on the ground after seed shedding causes heavy loss to number of afforestation programmes. Several methods like chemical, cultural, natural and biological are available for reduction in loss caused to seeds by insects. Generally, earlier the control measure, the smaller the destruction. Forest seeds can be stored safely by taking some precautions before their final storage, viz. inspection of the seeds for their moisture content, visual examination of cleaning method, scanning through soft X-ray technique, thermotherapy or treatments with chemicals, etc. The present chapter has covered review regarding damage caused to seeds by different insect pests and their management options.

Abstract

On average 13 million hectares of the world’s forests disappear every year due to different reasons. Among them forest diseases is one of the prominent factor. Seeds of soft wood and hardwood trees are attacked by fungi and other microbes.  Seed-borne pathogens of wood trees affect nursery seedlings and reduce seed germination and seedling vigor. The micro-organisms that are mostly associated with tree seeds are fungi, bacteria and to a lesser extent viruses. There are many mechanisms by which tree seeds acquire pathogens. Indeed, both the occurrence and severity of many seed-borne fungi, is often traced to the mishandling of fruits, cones or seeds. The majority of pathogens associated with forest tree seeds are fungi, producing only or predominantly the asexual (anamorph) stage (Deuteromycetes).

Abstract

The drive of planting trees is increasing because the values of trees and forest are being appreciated in all over the world. In most of the countries good quality tree seed is not readily available for a number of reasons especially in forestry sector. Though providing the best conditions for crop growth and health is the foundation of seed quality, the factors that can have the most important effect on seed viability and vigor are harvesting, extraction, cleaning, transportation, and storage because it is easy for seed to become damaged at any of these stages. Ex situ conservation through long-term storage of seed is possible for a significant proportion of higher plants. Long-term seed storage serves as a safe and relatively inexpensive method of plant genetic resources conservation.

Abstract

The availability of the quality seed is the first and the most important requirement which is of great relevance in tree improvement programme. Unlike agriculture, the forestry seeds have great variation in size, shape, dormancy, viability, moisture content, etc. It needs special techniques for collection, handling, processing and storage of the seeds of the large number of forest species. A strong commitment to improving tree seed technology is required for full utilization of seed supplies with the help of recent advances in seed physiology. Substantial improvements have occurred as a result of seed technology research offering the potential for major advances in traditional seed production and distribution systems.

Abstract

Although  people have harvested seeds and fruit from trees for centuries, only after World War II, the science and theories of forest genetics begin to be seriously applied to and practiced in operational forestry around the world. The genetic improvements, or gains, need to be captured, packaged, and mass produced so that these gains could be deployed in operational forestry systems. This can be accomplished through seed orchards which is a link between tree breeding and silvicultural activities. Seed orchards are by far the most frequently used sexually reproducing forestry production populations in the world. Apart from the genetic improvement, seed orchards are also used for the production of seed that is well adapted to specific environments. Seed orchards can be categorized according to the generation of breeding or the type of plant material used.

Abstract
Better seed production technology is vital to furnish quality seed of improved varieties. Trees are generally propagated from seeds and the suitability and quality of the seeds have a big effect on the success of the plantations, afforestation and reforestation programmes raised from them. It must be stressed that good seed implies seed which is both of high viability and vigour and is genetically well suited to the site and to the purpose for which it is planted. The use of sound seed from stands of high inherent quality is widely recognized as the best means of ensuring fast-grown and healthy plantations capable of yielding high quality wood. Quantity, as well as quality, of seed production is important. Seed quality depends on factors like source, time and techniques of harvest, processing and storage practices. Unlike agriculture, the forestry seeds have great variation in size, shape, dormancy, viability, moisture content, etc.

Abstract

Knowledge of  seed biology is crucial for proper management of  seed sources as well as the handling of seeds. In broadest sense seed technology includes the development of superior crop plant varieties, their evaluation and release, seed production, seed processing, seed storage, seed testing, seed certification, seed quality  control, seed marketing and distribution and research on various aspects. Vegetative propagation has also become popular for the propagation of some tree species, but seed propagation remains the principal mode of propagation in both the temperate and the tropical region. Forest plantations are a powerful tool in the continuing efforts of foresters to increase productivity per unit area apart from mitigating the climate change and global warming issues. Hence to improve the existing stock in terms of yield, quality, disease resistant and desired traits, seed technology can play a major role in providing quality genetic material.

INTRODUCTION

Food is the basic need of human beings. It gets spoiled primarily due to microorganisms and enzymes. Energy is required for microbial growth and enzymatic reactions. At low temperature, the rate of biochemical reactions is slow resulting in prolonged storage life of food. It must have been observed long back that food could be stored for longer period without deterioration during the winter months. Since then this principle is being used to extend the storage life of foods. A sea change can be observed in development of low temperature preservation technology. It has travelled a long journey to reach this stage; however, a major break through took place in twentieth century. Low temperature technology is of two types; refrigeration and freezing. In refrigeration storage, water is in liquid phase and temperature is maintained above freezing point. In freezing technology, the food is stored below freezing point and water gets converted into ice. The former is short term preservation due to slow growth of microbes and lower enzymatic activity while the later is long time preservation due to inactivation of enzymes during blanching and inhibition of microbial activity due to unavailability of free water and much lower temperature. Low temperature preservation is widely accepted and is of commercially important in food supply chain.

INTRODUCTION

Food being the basic need of all humans and other living organisms, the production and processing of food is a continuous activity with several new procedures and technologies adoption; thereby the quality of food needs an emphasis which also protects the consumers by providing safe and suitable food. The contaminated foods, food borne illness outbreaks though at times referred to poor consumer handling, commitment for provision of safe food to consumers is also a Governments concern. In the recent years, food safety measures through Food Safety programmes and increase in awareness are being followed. The food production in our country is the most promising sector which is the cause for white revolution and green revolution. India ranks first in the world in production of cereals and milk and second largest producers of fruits and vegetables. India stands second in inland fish production. It is second largest exporter of rice and so on. Food processing sector has a great potential which covers a wide spectrum of products encompassing agriculture, horticulture, plantation, animal husbandry and fisheries. But the growth of food processing industries in our country is rather slow. However, to encourage, the government is providing lot of incentives in the recent years.

INTRODUCTION

A food may have three attributes (1) Provide energy and nutrition (2) Give pleasure, i.e., enjoyable aroma, colour, and taste and (3) Health benefits. Functional food has physiological benefits and reduces the risk of chronic disease beyond basic nutrition.

Functional foods, also reported as ‘nutraceuticals’, ‘medical foods’ or ‘designer foods’ in the literature, were first described by Roberfroid (1999) as ‘Food similar in appearance to conventional food that is intended to be consumed as part of a normal diet, but has been modified to subserve physiological roles beyond the provision of simple nutrient requirements’. Examples are iodized salts, vitamin A and vitamin D fortified milk and yoghurt, folic acid enriched bread, soy products, wheat bran and oats products.

INTRODUCTION

Food processing as a technological regime is undergoing a revolutionary change in terms of conception, product and process design and energetics. The conventional approach of a food processor is to develop products with a long shelf-life in user friendly packaging systems. Food processors are usually bothered about sensory attributes and microbiological profiles without much emphasis on the fate of heat labile nutritional and nutraceutical components. The changing consumer perception is slowly but steadily leading towards emergence of novel technologies without depending upon conventional thermal processing. A few years before, non-thermal techniques have emerged for food processing and preservation, but these techniques were restricted to framing of fundamentals with regard to the inactivation of vegetative and reproductive bodies of microbes and the deteriorative enzymes.

INTRODUCTION

Packaging is an important aspect in modern life and in fact the word ‘packaging’ developed a literal value indicating presentation of an issue or material in a comprehensive and compact manner. Food packaging has become a revolutionary trend and plays a dominant role in the promotion of marketing of various fresh and processed food products. The reason could be a number of aspects inclusive of protective, legal and aesthetic elements. The industrial revolution in the late 18th century caused major impact on manufacturing process. Without appropriate packaging no food is acceptable and even in the common household food packaging is being practiced in its own way to render food safety and convenience for various culinary operations. Therefore, food packaging needs to be considered as an essential element of food processing and marketing and it is one of the key areas in food technology making rapid strides in research and development.

INTRODUCTION

For thousands of years fermentation processes were largely natural phenomena exclusively identified with food preservation throughout the world. Fermentations can play a significant role in meeting the ever growing food requirements of world population providing benefits in the form of innovative food products with improved nutritional value and food quality along side better safety. Fermentations can be used to address a large variety of food related problems and in the development of processes to meet the demand for food. In the wake of estimations made by international organizations that global food demand and population would increase by two-fold by the year 2050, much emphasis has been placed over the ways and means to increase food production and preservation.

INTRODUCTION

Fruits and vegetables are historically important constituents of human diet and the growing awareness of consumers about the beneficial effects of these commodities could result in enhancement of global trade involving fresh and processed fruits and vegetables. Emergence of postharvest handling of fresh fruits and vegetables facilitated global trade of these commodities. The developed countries started realizing the export potential of these commodities by development of adequate value addition in terms of pretreatments, shelf life extension and packaging besides grading and other associated packing house operations. However, the trade concerning fresh fruits and vegetables could never come out completely from problems related to pesticidal residues, spoilage, bulkiness of the commodities involving transportation of inedible portions and excessive packaging costs arising out of bulkiness. The other problems associated with fresh produce include mandatory requirement of specific storage temperatures with refrigeration as the primary means of regulation of metabolic rate.

INTRODUCTION

Now-a-days, food products with maximum health benefits and ease in preparation are gaining popularity globally, the reason being changing awareness level about food and dietary habits. Since ages, a number of methods like cooking, baking, drying etc. have been used to thermally process the food materials. Electrical sources of electromagnetic waves are very promising because of advances in nuclear and hydroelectric power as well as ongoing cost rises in traditional forms of fuel, of which there are only restricted reserves. The heating aids include use of wooden fuel, gaseous fuel, electric energy etc.; but the new era of electromagnetic rays had introduced new horizons of food processing by utilizing it in various unit operations (Sakai and Hanzawa 1994). Though, these radiations are gaining popularity in various walks of life; their destructive impact is much dominating. Hence, one should handle these radiations with utmost care as well as comprehensive understanding of the know-how and control over the process.

INTRODUCTION

Radiation processing is a promising technology for improving hygiene and increasing storage and distribution life of food products. Ionizing radiation can be used to bring about beneficial changes in food stuffs (Urbain 1995) and it has been suggested as a method of ensuring safety of meat products (Patterson and Stevenson 1995). Ionizing radiation interacts with an irradiated material by transferring energy to electrons and ionizing molecules by creating positive and negativities (Moseley 1989).

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.

INTRODUCTION

Drying or dehydration is defined as the removal of moisture from its initial level to a level which renders food materials safe for subsequent storage. It is a simultaneous heat and mass transfer operation in which heat is supplied externally to evaporate moisture and air is forced through the bed to carry away the moisture. Drying is the oldest technique to preserve food materials. Advantages of drying include reduction in water activity, enhancement of shelf life, maintenance of flavor and nutritive value, and reduction in packaging and transportation costs. When the water activity of the dried product is reduced to below 0.6, most microorganisms do not grow and the rates of other deteriorative reactions are substantially reduced.

INTRODUCTION

A mixture is a combination of two or more elements or compounds in any proportion so that the components do not lose their identity. Most materials in our world are mixtures and very few materials are pure substances. Foods are complex mixtures of compounds and the extraction or separation of food components is fundamental for the preparation of ingredients to be used in other processes. Separations usually aim to remove specific components in order to increase the added value of the products, which may be the extracted component, the residue or both. Purposes include cleaning, sorting and grading operations, extraction and purification of fractions such as sugar solutions or vegetable oils, recovery of valuable components such as enzymes or flavour compounds, or removal of undesirable components such as microorganisms, agricultural residues or radionuclides. For example, cooking oils from oilseeds or gelatin from connective tissue; or for retrieval of high value compounds, such as enzymes (e.g. papain from papaya for meat tenderisation or rennet from calf stomachs for cheese making). Other types of separation methods are used to sort foods by separating them into classes based on size, colour or shape and to clean them by separating contaminating materials.

INTRODUCTION

The concept of hurdle technology has been developed as a new way to realize safe, stable, nutritious and economical foods. It employs combination of different preservation techniques to achieve a multi-target, mild but reliable preservation of foods. The application of hurdle technology in food preservation is increasing rapidly worldwide. Over the years, insight into the hurdle effect has been broadened and the application of hurdle technology has been extended. A better understanding of the occurrence and interaction of food preservative factors (hurdles) in foods is the basis for improvements in food preservation. If the hurdles for the microbes are known, the microbiological stability and safety of this food might be optimized by changing the intensity or quality of these hurdles. Using the proper combination of hurdles, it is possible to improve not only the microbial stability and safety but also the sensory and nutritive quality as well as the economical aspects of food. The hurdle concept is also referred to as food preservation by combined methods, combined process, combination preservation or combination processing techniques. The hurdle effect is of fundamental importance for the preservation of foods. The illustration of hurdle effect was first introduced by Leistner in 1978. Based on the understanding of hurdle effects, the concept of hurdle technology was derived (Leistner 1985).

INTRODUCTION

By the turn of the century, consumers have been more demanding, sophisticated and discretionary. They want much safer, higher quality, and more convenient to foods. The food processor need to get the best from their existing processing technology in addition to looking for newer ones. New and alternative food processing methods and/or novel combinations of existing methods are continually being investigated by the industry in pursuit of producing better quality foods more economically. Thermal processing is one of the most important food preservation techniques that was first introduced at the beginning of 1800 and has evolved itself in to one of the most scientific mature food processing techniques of recent times. Both science and technology have gone through tremendous transformation in the last two centuries and today it is the most reliable method to assure food safety and stability. Developments in thermal processing and evolution of non-thermal processing technologies like high pressure processing, pulsed electric field, pulsed light etc. have enhanced the utility of thermal processing principles and increased the awareness of possible alternative processing technologies.

INTRODUCTION

Food processing is necessary for the conversion of raw food products in to finished products with desired textural, sensory and nutritional attributes. This is required to be done mainly due to seasonal production and facilitating non-seasonal availability of different commodities. Stages of processing are primary and secondary. In primary processing raw material is converted into food commodities, while in secondary processing commodities are converted into edible products. Processing is mainly done to convert the products into edible forms, to extend shelf life, availability, accessibility and also to provide variety into the form of value added products. Processing of products destroys inhibitors, microorganisms, retards physico-chemical and biochemical deterioration, maintains good sensory properties, preserves and enhances the nutritive value. Unit operations involve phase changes and sometimes chemical reactions also, which are undesirable as they cause inferior quality of the product (Gekas 1992). Different processes like separation, assembly, preservation and packaging are broader classification for unit operations in food processing (Saravacos and Kostaropoulos 2002).

Food Science is one of the ancient sciences and the genesis originates to the very beginning of human civilization. The advent of food science was associated with practice and observation by humans before establishment of scientific concepts. The ancient man knew that roasting or smoking of meat improves the edible quality and digestibility. As a consequence, he started practicing the same much before the reasons for the same could be established. Many of the modern preservation concepts had their origin in prehistoric period itself as humans could use techniques such as dehydration, fermentation and pickling to their advantage to improve the sensory attributes of the products and also to enhance their shelf life. Humans during the Pre-Neolithic period about 2,50,000 years before used fire for cooking meat. During the Paleolithic period humans not only roasted food but also developed grinding, pounding and drying. During the Mesolithic era, humans were desperate for food and got involved in extensive hunting and fishing. During the same time domestication of animals took place and animal husbandry became a reality (Stewart and Amerine 1982). The Neolithic period made qualitative changes in the food habits of humans and they changed from a food gathering and hunting society to one of food production (Heizer and Elsasser 1980).

11.1 Introduction

The laws governing the flow of water in wells are referred to as the hydraulics of wells. Just like surface water flows from a higher elevation to a lower elevation by gravity, groundwater also flows from a region of higher water table to a region of lower water table. This difference of water table measured by any two piezometers divided by the longitudinal distance between them is called as hydraulic gradient. Hydraulic gradient plays a dominant role in deciding the flow of groundwater. This hydraulic gradient together with the hydraulic conductivity of the aquifer material forms the main law of well hydraulics called as Darcy’s law. An understanding of Darcy’s law together with some other laws as discussed subsequently in this chapter is essential in order to know the discharge of a well in a particular formation. Darcy’s law is valid for studying groundwater flow in alluvial formations. However, it is not valid for aquifers having hard rock areas.

10.1 Introduction

During rain or heavy irrigation, a part of the rainfall or irrigated water moves below the effective root zone of the crop which moves further below and adds to the water table lying above the impermeable bed or hard rock which is called as  ground  water  reservoir. At  times  the  accumulated  surface  water  is  also recharged to the soil reservoir both naturally as well as artificially that add to the underlying ground water reservoir. This groundwater is an important source of water for irrigation as well as domestic uses. It is the most abundant fresh water resource of the earth. Underground water reservoirs contain large stock of fresh water resources. Total quantity of groundwater within 800 m distance below  the  ground  surface  is  more than  30  times  the  total  water  in  all fresh water lakes, more than 60 times the total water in soil and other unsaturated rock materials, more than 300 times the water vapour in the atmosphere and 3000 times the average volume of all rivers and rivulets in the world (Lenka, 2001). But the distribution of groundwater is not uniform.