eChapters

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.