eChapters

3.1 Indian Floriculture Industry

Indian floriculture industry has been shifting from traditional flowers to cut flowers and dry flowers for export purposes. The liberalized economy has given an impetus to the Indian entrepreneurs for establishing export oriented floriculture units under controlled climatic conditions. About 60,000 ha area is under floriculture at present. During nineties, increasing demands for flowers in world market was coupled with production technology available abroad for high quality flowers. This encouraged some entrepreneurs to establish export-oriented units in Hyderabad, especially for the production of long stem rose by importing cultivars and adapting green house technology.

Preserving flowers dates back to earliest recorded history. The first evidence of use of dry flowers was when the bones of a pre historic man discovered in the Middle East were found with a mantle of delicate wild flowers. The pollen grains that remain indicated specific flowers that were used. During ancient times people used to freshen or enliven their rooms with fresh sweet smelling flowers. In the sixteenth century, when the Elizabethan Age was coming to a close, it was considered fashionable to wear silk flowers as part of one’s attire. These days flowers are dried and are versatile in their use. They supply us with food, medicines, ornaments and adornment. Flowers became essential for a fashionable appearance. Each civilization developed its own interpretation of flowers. Pressed flower art became popular in Victorian times. The Japanese use pressed plants and colorful papers to create Oshibana Art.

Flowers attract both young and old alike. They are associated with mankind from the dawn of civilization. These have become an integral part of human life in the modern era.
 
The Indian floriculture industry has been shifting from traditional flowers to cut flowers and dry flowers for export purposes. The liberalized economy has given an impetus to the Indian entrepreneurs for establishing export oriented floriculture units under controlled climatic conditions. About 60,000 hectares, area is under floriculture at present. During nineties, increasing demands for flowers in world market was coupled with production technology available abroad for high quality flowers.

Z -distribution : It is a probability density function and a normal distribution that has a mean equal to zero and a standard deviation equal to one and that is used in testing hypotheses about means or proportions of samples drawn from populations whose population standard deviations are known.

Zeatin : Zeatin is a cytokinin C₁₀H₁₃N₅O first isolated from the endosperm of Indian corn.

Yabby : It is one of the burrowing Australian crayfishes (Cherax destructor) that are used for food.

Yakitori : A bite-size marinated pieces of beef, seafood, or chicken on skewers is called yakitori.

Yam : It is edible starchy tuberous root of plants (genus Dioscorea of the family Dioscoreaceae) used as a staple food in tropical areas.

Xanthan / Xanthan gum : It is a polysaccharide that is produced by fermentation of carbohydrates by a gram-negative bacterium (Xanthomonas campestris) and is a thickening and suspending agent used in pharmaceuticals and prepared foods. It is also called xanthan. Xanthan is a stabilizer produced by Xanthomonas compestris. Xanthan is not hydrolysed or degraded by humans.

Wafer : A thin crisp cake, candy, cracker or chips is known as wafer.
 
Waffle : A crisp cake of batter baked in a waffle iron is called waffle

Warner-Bartzler Shear : It is one of the oldest but commonly used devices used to measure the tenderness of meat. It is used to test the quality in the cooked meat.

Vacreation : The pasteurization of the milk or cream under reduced pressure by direct steam is called vacreation.

Vacuum : The state of negative pressure. It is equal to atmospheric pressure minus absolute pressure.

Vacuum cooling : A technique of cooling vegetable (leafy vegetables, asparagus Brussels sprouts) having a high surface to volume ratio rapidly and uniformly by boiling off some of their water at 10C and at low pressure (5 mm of Hg) into a sealed container. The produce is cooled by evaporation of water from the tissue surface and is more rapid than hydro cooling.

U value : U value is a measure of the heat transmission through a building part (wall or window) or through a given thickness of a material (insulation). U values with lower numbers indicate better insulating properties.
 
Ubiquinone : It is one of the groups of lipid soluble quinones that are found especially in mitochondria and have a long isoprenoid side chain, and function in oxidative phosphorylation as electron carrying coenzymes in electron transport.

T A Spoilage : The spoilage of low and medium acid canned foods by Clostridium thermosacharolyticum which breaks sugars and form acid and gas (moisture of H₂ and CO₂) resulted in swelling and in severe cases even bursting of can may occur and the spoiled food usually has a sour odour.

Saccharides : A monosaccharide sugar or combination of sugars is called saccharides.

Saccharification : The process of breaking a complex carbohydrate (starch or cellulose) into its monosaccharide components is called saccharification.

Saccharimeter : A device (polarimeter) used for measuring the amount of sugar in a solution is called saccharimeter. It is also known as saccharometer. It is a hydrometer with a special scale.

R - enamel can : The acid resistant, gold coloured enamel treated can are called R enamel cans. It is used for canning of acidic food which have soluble colouring pigments.
R factor : It is a group of genes present in some bacteria that provide a basis for resistance to antibiotics and can be transferred from cell to cell by conjugation.
R value : R value is a measure of resistance to the flow of heat through a given thickness of a material (insulation) with higher numbers indicating better insulating properties.

Q fever : Q fever is caused by a rickettsia like organism (RLO), a parasitic organism falling between bacteria and viruses. It is a disease that is characterized by high fever, chills, muscular pains, headache, and sometimes pneumonia, that is caused by a rickettsia (Coxiella burnetii) of which domestic animals serve as reservoirs, and that is transmitted to humans especially by inhalation of infective airborne bacteria as in contaminated dust.

Pack inspection : It is similar to continuous inspection except that here inspector(s) may make in-process checks during different processing operations under contract but not required to be present all the times in the plant during operation.

Package : The package means a pre packed box, tin, barrel, pouch or can etc in which food article is packed.

Package store : A store that sells bottled or canned alcoholic beverages for consumption off the premises.

Obesity : A condition characterized by the excessive accumulation and storage of fat in the body. It is a physiological disorder having high body mass index (BMI), which can be expressed as a mathematical formula in which a person’s body weight in kilogram is divided by the square of his or her height in meters.

Naïve panel : It refers to the sensory evaluation panel that has not been trained specifically regarding the product evaluation being undertaken in the study.
Nano technology : It is the art of manipulating materials on an atomic or molecular scale to build microscopic devices. The word “nano’ meaning ‘dwarf” in Greek language refers to dimension / magnitude of the material / particle in the order of 10^-9. Nanotechnology is nothing but manipulating of particles into very small particles called nano-particles. These particles have dimensions in the scale of nano-meter and used to design / build materials and devices. Nanotechnology has been provisionally defined as relating to materials, systems and processes which operate at a scale of 100 nanometers (nm) or less. Nanotechnology is an anticipated manufacturing technology that allows through and inexpensive control of the structure of matter by working with atom. It will allow many things to be manufactured at low cost and with no pollution. The concept of nanotechnology was first given by Nobel Laureate physicist Richard P. Feynman in Southern California in 1959. Nanotechnology is sometimes termed as Molecular Manufacturing based nanotechnology “MNT”.

MAC : It stands for modified atmospheric coating.

Macaroni : Pasta made from semolina and shaped in the form of slender tubes.

Macaroni wheat : It is tetraploid wheat and is preferred for making macaroni, vermicelli etc.

Macaroon : A small cookie composed chiefly of egg whites, sugar, and ground almonds or coconut.

Mace : An aromatic spice consisting of the dried external fibrous covering of a nutmeg.

L - Ascorbic acid : It is a white crystalline compound with a slightly acidic taste. It is readily soluble in water, alcohol, glycerin, propylene glycol and is insoluble in oils, fats, ether, benzene, chloroform.

Lab coat : A loose white coat with deep pockets that is worn in a laboratory or medical office.

K ration : It is a lightweight packaged ration of emergency foods developed for the U.S. armed forces in World War II.
Kairomone : A chemical substance emitted by one species and especially an insect / plant that possess an adaptive benefit (stimulus for oviposition) to another species.
Kaiser rolls : A round crusty roll often used for sandwiches.
Kalamata /calamata : It is brine cured black olive grown in Greece.

Jaboticaba : It is a Brazilian tree (Myrciaria cauliflora) of the myrtle family cultivated in warm regions for its edible purplish fruit.

Jack salmon / walleye : A large vigorous American freshwater food and sport fish (Stizostedion vitreum) that has large opaque eyes and is related to the perches but resembles the true pike sometime also called walleyed pike

Jaggery : Raw brown / unrefined brown sugar in lump made from palm sap.

ICAP : It stands for International Centre for Alcohol Policies.

Ice Bank Cooler : Air forced cooler leads to desiccation of the produce. So use forced air high humidity cooler are known as Ice Bank Cooler. Ice bank Coolers are useful for strawberry.

Ice bank cooling : Storing of fruit and vegetable in storage chamber with positive ventilation and a system countries where ice formation is allowed during night time (as electricity cost of night is less as compared to the day time). Melting of ice occurs during day time and with proper air circulation by means of ventilation process, approximately 0.5-1^ºC temperature with 90% RH in the chamber is maintained.

HACCP : The Hazard Analysis and Critical Control Points (HACCP) is a scientific, rational and systematic approach to identify, assess and control hazards during production, processing, manufacturing and use of food. It ensures safety of the food. HACCP presents a good opportunity for the food industry for upgrading quality and bringing uniformity and consistency in their supplies to international market. or It is a systematic preventive approach to food safety that addresses physical, chemical and biological hazards as a mean of prevention rather than finished product inspection. It involves identification, evaluation and control of hazards which are significant for food safety.

Galactan : It is a polysaccharide in which major monosaccharide subunit is galactose and often found among the pectic substances of cell walls.

Galactoblast : It is also called colostrums. It is female’s first milk after parturition.

Galactometer : It is an instrument used for recording the specific gravity of the milk.

Galactorrhea : A spontaneous flow of milk from the nipple is called galactorrhea.

F- distribution : A probability density function that is used in analysis of variance and is a function of the ratio of two independent random variables each of which has a chi-square distribution and is divided by its number of degrees of freedom.

F₀ value : It is used to express F-value when z =10^ºC/18^ºF and the temperature is 121.1^ºC. It is the number of minutes at a specific temperature (250^ºC) required to destroy or kill a stated number of microorganisms and has specific z-value. It is also called reference value. 

E numbers : Each food additive used in the food industry has been given a specific number code for their identification. These numbers are called as E numbers. These E numbers are used within the European Union. The word prefix “E” stands for Europe. They are commonly used on the food label through out the European Union. These are not used in Australia and New Zealand. The different food additives are given different E numbers depending upon the type of food additive like E100-E199 (food colours), E200-E299 (preservative), E300-E399 (antioxidants), E400-E499 (thickners, stabilizers, emulsifier), E500-E599 (pH regulator, anticaking agent), E600- E699 (flavour enhancers), E700-E799 (antibiotics), E900-E999 (miscellaneous like waxes, synthetic glazes, packaging gases, sweetners, foaming agents), and E1000-E1099 (additional chemicals).

Dahi : It is the product obtained from pasteurized or boiled milk by souring, natural or by harmless lactic acid or other bacterial culture. It is also called Curd.
Daidzein : These are the substance from which daidzein is derived and are isoflavone C₁₅H₁₀O₄ found chiefly in legumes and esp. soybeans.
Dairy : It is a farm building often a single room in which milk is cooled and temporarily stored prior to collection for transportation to the commercial diary. Here the milk is treated and made into cream, butter and cheese. Or

C - enamel can : The sulphur resistant lacquer is golden coloured and the can coated with it are called C-enamel can or sulphure resistant can, used for packing non acid products.

CA storage : Storage of commodities under gaseous atmosphere like gas storage, where the composition of atmosphere is controlled accurately. MA and CA differ only in degree of control and CA is more exact. These storage methods in combination with refrigeration markedly enhance storage life of fruit and vegetables.

B cell : It is one of the lymphocytes that have antigen-binding antibody molecules on the surface, that comprise the antibody-secreting plasma cells when mature, and that in mammals differentiate in the bone marrow. It is also called B lymphocyte.

B.T.U. : It stands for British thermal unit. The heat required to raise the temperature of one pond of the water through 1oF is called BTU.

Baby back ribs : Meaty pork ribs cut from the lower back rib section.

Abattoir : An establishment where animals are butchered is known as abattoir. It is also known as slaughterhouse. 
Abiotic : Abiotic means any factor which is not biological / abiological and especially there is no involvement of the organisms in synthesis of certain compounds.

Abstract

Inspired by the human eye to brain assessment process, computer vision technology has demonstrated its potential for monitoring and controlling of several operations in food industry. Computer vision technology is, therefore, applied extensively in food drying process for monitoring nutritional value and sensorial characteristics because of its promising characteristics such as reliable objectivity and repeatability. In this chapter, after providing a brief explanation of the computer vision technology and its prerequisites and principles, an example is given to elucidate how this technology is used for monitoring the visual attributes of foodstuffs during drying process. Overall, monitoring the visual properties of food products like size, shape, color, and texture in off-line mode are the most popular issues to fascinate researchers’ attention to apply the computer vision technology in food drying. Nevertheless, industrial applications of the computer vision technology for real-time monitoring and control of food drying facilities as final goals of its introduction in food drying industry seem to be limited. For future studies, it is suggested to apply this unique technology along with advanced soft computing methodologies for in-line monitoring and control of food drying process in order to achieve high quality dried products. Finally, outlooks and potential employment of this technology in food drying domain are discussed as well.

Abstract

By loosely inspiring the actions of neurons in the human brain, artificial neural networks (ANNs) are widely accepted as a powerful nonlinear adaptive approach to tackle complex, dynamic, highly nonlinear, and ill-defined problems in an increasing number of fields of food industry.They have been used extensively in food drying to solve problems of nonlinear function approximation, pattern recognition, data description, optimization, simulation, pattern recognition, control, data sorting, clustering, and noise reduction, due to their massively parallel structure and capability to learn from examples. In this chapter, after providing a brief description of ANN technology and its principles as well as the structure of the most commonly employed ANNs in this context, an example is given to explain how the ANN technique is used for modeling and controlling food drying process. Generally, modeling, prediction, and optimization of heat and mass transfer, thermodynamic performance indicators, and quality parameters as well as physico-chemical attributes of dried foods are the most popular subjects to attract researchers’ attention to apply the ANNs in food drying industry.

Abstract

Packaging plays an important role in the food processing Industry. It makes food more convenient as well as gives the food greater safety assurance from microorganisms, biological and chemical changes such that the packed foods can have longer shelf life. In order to meet the huge demand of processed food with longer shelf life, various methods of preservation and packaging are being used in the food processing industry. Drying and dehydration is one of the method which helps preservation of a perishable commodity against deterioration or spoilage.

Abstract

Most dryers operate at low thermal efficiency. The development of models and control systems offers an opportunity to improve dryer operation and efficiency. Dryer control is very important and with deeper understanding of the drying concept, new “smart” dryers can be made more reliable and more cost-effective than classical dryers. This chapter will provide an overview of necessity of control and safety measure in food drying system, and terminology related with drying control system. Different control strategy includes conventional and advanced techniques implemented in drying operation are reviewed  here and simple outline of intelligence control system in drying technology are briefly described in succeeding section. Various hazards in drying process and risk and safety management will also be discussed.

Abstract

Water, the most important component of common foods, is considered to be desirable as well as undesirable in the different food systems. Water-solid interaction in food systems controls various biological, biochemical and biophysical reactions affecting their acceptability. The retention or release of water from solid has been quantified in the terms of sorption isotherm. Sorption isotherm techniques have been used to characterize and identify the type of water-solid interaction in different food products. Sorption isotherm provides various information useful in designing and optimization of drying, storage, packaging, predicting quality and shelf life of the product.

Abstract

Dietary antioxidants can be found naturally in various fruits, vegetables and food products.Typically, antioxidant phytochemicals commonly found in food products are Vitamin C, Vitamin E, carotenoids, polyphenols, melanoidins and indoles. The main characteristic of an antioxidant is its ability to scavenge free radicals and form stable end product which inhibit the chain oxidative mechanisms that lead to degenerative diseases which are harmful to human health. Drying is widely used in food processing to minimize food wastage and to extend food shelf-life. Pretreatment, drying methods and storage conditions are some of the processing parameters affecting the quality of dried products. Selection of processing conditions and storage environment are therefore critical in maximizing the retention of food antioxidants. This chapter aims to compile and summarize studies carried out for antioxidants namely antioxidant contents in dried food products, effect of processing parameters and quantification methods in the analyses of antioxidants.

Abstract
 
Spray drying is used as one of the best alternatives for extracting essential constituents of fruit and vegetables. Spray drying of fruits and vegetable juice/purees, which is an excellent source of bio-functional properties into a solid phase helps to enhance their stability and controlled release in different food matrices. Spray drying along with different carrying agents helps to retain essential active compounds in fruits and vegetables. Spray drying is generally carried in three steps viz. atomization of liquid feed by suitable atomizer; drying of droplets with the help of hot air and motion of droplets. Carrier agents like maltodextrin, wax starch, Gum Arabic and microcrystalline cellulose are added to the feed to increase glass transition temperature. Chapter presents the effects of different operating parameters of spray drying as well as effects of carrier agents on the physicochemical and functional properties of spray dried fruit and vegetables powders.

Abstract

Drying remained at the centre stage since the initiation of the food processing due to its promise to preserve agricultural products economically and add functionality to a food product unlike other thermal as well as non-thermal food processing operations. However, many existing drying techniques have their own limitations like nutrient loss, damage of the organoleptic quality, high cost etc. Therefore, research for better drying technologies is going on. Supercritical drying (SCD) is one such technology which utilizes higher dissolving power of super critical fluids (SCFs) to dry food products. The current chapter illustrates the mechanism of SCD as well as current state-of-art and promise of the drying technology. Also, some modelling approach of SCD has been included in the discussion to facilitate new designs and optimization of SCD for various food products.

Abstract

Application of solar energy for drying of agricultural food products is one of the most attractive and cost-effective drying techniques. However, the intermittent nature of the solar energy is one of the major shortcomings of the solar drying system that can be alleviated by storing excess energy during the peak time and using it in off sun hours or when the direct availability of solar energy is inadequate. The use of sensible and latent heat storage systems in solar dryer is an effective way of storing thermal energy for drying purpose. This chapter will present information on different thermal energy storage (TES) materials, their advantages and disadvantages. The information available in the literature regarding the studies conducted on TES assisted solar drying systems is also covered in this chapter. In addition, some of the models that have been used by different researchers to test the performance of different TES materials are also reviewed.

Abstract

Food proteins are among the commonly used ingredients by food manufacturers to produce different products with desired characteristics. Due to several nutritional and functional properties, proteins have different functions in various food products in addition to their role in metabolic system of the human body. Dilute or concentrated solutions of pure proteins or unprocessed food products which are rich in protein are very sensitive to deterioration or degradation by microorganisms and thus have short shelf life at ambient temperatures due to their highly moist structure and high protein content. Drying is one of the best methods that can guarantee preservation, a longer shelf life, chemical or thermal stabilization and resistance against other stresses. A full understanding of stresses encountered during drying is needed to choose an appropriate drying process and to optimize this process for maximum product quality. A number of methods have been used by various researchers to dry protein-containing foods. Among these methods, freeze drying and spray drying are the most common techniques. Sun drying, convective hot air drying, vacuum drying, heat pump drying, radio frequency drying as well as combined or hybrid drying methods with two or more of the drying methods have also been developed.

Abstract

Medicinal herbs are economically and nutritionally important plants, which are rich in health-promoting compounds. Herbs are the backbone of both the traditional Chinese and Indian medicine, which has long history as part of their culture. Ensuring the quality of herbs is a crucial step for integrating the traditional medicine into science-based modern medicine. Drying is an essential technique in preservation of herbs as it affects directly the quality attributes of the dried products, whereas many producers lose much profit due to poor drying techniques. So, employing a suitable drying technology and selection of appropriate drying conditions are very important for producing high quality herb products. The aim of this article is to summarize the advances in drying technologies of medicinal plants, describe the current status and identify future research opportunities. The current work provides more data and information for selecting optimum technology for herb drying and would trigger innovative drying technologies to enhance drying kinetics and quality of herb drying.

Abstract

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

Abstract

Refractance Window (RW) drying is a relatively new drying technology. This method is carried out by spreading a thin film of food slurry on a conveyor belt made up of a transparent polyester material. The slurry is thermally heated as it moves along the conveyor belt, resulting in rapid drying of the product. RW drying is similar to Drum Drying, but conducted at lower temperatures (95–97^ºC) and without direct contact with the heat source. RW drying offers low operating costs with excellent retention of color, flavor and nutrients.

Abstract

Drying is an age old practice of food preservation. Removal of moisture from the food materials is usually carried out at atmospheric pressure and elevated temperature. In the presence of oxygen, drying can cause oxidation of some compounds leading to quality deterioration. Drying at higher temperature adds to the losses and can be responsible for enzymatic and non enzymatic browning, loss of aroma, nutrients, antioxidants, pigments etc. On the other hand, drying under sub atmospheric pressure helps in retaining the themosensitive compounds present in natural foods as drying can be accomplished in oxygen free environment. Under vacuum, evaporation of moisture can be possible at lower temperatures.

Abstract

It is well known that drying is an important unit operation in food processing industries, essentially used to extend the shelf life but also in making innovative processed products such as snacks with desired functionalities. Although drying of food products is carried out traditionally using several methods, the quality and energy aspects have been major focus of food drying research in the last decade or two. This is achieved by modifying and/or optimizing the existing drying systems, improving pre and post processing of the product, combination of more than one dryer type or developing altogether a new drying technique. There several dryer types which can give extremely good product quality, however, cost-effectiveness can be a major issue. It is necessary to balance both good product quality and minimum energy usage in order to sustain highly competitive market. This lecture will provide an overview of conventional drying methods used for foods, followed by some advances in these conventional methods and a discussion on some new drying techniques developed in recent years that are either commercialized or have potential of industrial use.

Abstract

Food dehydration is an oldest method to increase the shelf life of food by reducing the water activity. A dried food product provides advantages of increased shelf life and reduced cost due to decreased weight as well as transportation. However, there is a decrease in product quality due to inadequate control on drying process parameters such as drying temperature and moisture removal together with change in thermo-physical properties of food. Computational modeling and simulations can provide a unique insight on the drying parameters that influences the product quality, and optimize the process conditions which are difficult by experimental analysis. Moreover, the computational techniques are advantageous over experimental optimization methods by minimizing the time and cost. This chapter reviews different computational modeling techniques such as, finite element modeling, finite volume and finite difference methods for modeling of food dehydration process. Also, this chapter describes the application of modeling techniques for determining the influence of shrinkage and porosity during dehydration.

Abstract

There are several empirical models to describe deep bed drying dividing the domain into many thin layers. Empirical equations are seen as a resource that only serves to describe the thin layer drying kinetics of an agricultural product. Normally an empirical model is used to determine drying rate. The validity of following thin-layer drying models are accounted by coefficient of correlation (R2), standard error of estimated (SEE), root mean square error (RMSE). The properties of dried foods vary substantially depending upon the type of product, moisture content, drying type and ultimately drying conditions. To take care all above variables, a promising approach is to use Artificial Neural Network (ANN). In process control, the main objectives are food safety, high quality and yield at minimal costs. To obtain high quality products, on-line control techniques are required. Most food processes are highly nonlinear, with time varying dynamics, which complicates food automation. However, the recent developments in artificial intelligence based advanced control tools such as ANN to food processing have opened up novel possibilities for processing industries.

Abstract
 
Drying is one of the most popular methods used for preserving products and extending their shelf lives by reducing moisture content to a low level to prevent microbial spoilage and moisture-mediated deteriorative reactions. As an efficient technology with high heat and mass transfer rates, impingement drying has been commonly used in various industrial drying such as tissue paper, textiles, photographic films, coated paper, nonwovens, carpets, lumber etc. In the past two decades, air impingement technology has got more and more attention in the field of food and agricultural products processing.

Abstract

The primary commercial energy sources such as coal, oil and natural gas poses an enormous challenge to our development goals including environmental degradation, as India is not well endowed with these exhaustible natural resources. Further, these conventional sources are also not available in right quantity and producing environmental pollution manifold in land, air and water. There are number of unit operations in food processing and value addition consuming bulk of conventional energy sources where renewable energy sources can easily be integrated for energy conservation and environment protection. There is significant potential for application of Renewable Energy Sources in different unit operation of food processing including drying of food products for energy conservation and for reducing hydrocarbon emissions.

Abstract

Recently, the reduction of post harvest food losses around the globe is a critical issue for ensuring future food security. Drying techniques is important option to prevent losses and preserve food for long time. The solar thermal energy required to remove moisture from the food during the drying process can be optimized by designing suitable solar dryers. Moreover, the application of solar energy in drying of agricultural products has tremendous potential, since it can easily provide the low temperature heating required for drying and helps in reduction of CO2 emissions. Hence, the present chapter deals with descriptions of different types of solar dryers used to dry various types of agricultural food products and design of solar dryers. Also, the heat and mass transfer parameters with respect to various process variables to estimate the performance of the food dryer system were analyzed. The advantages of solar dryers in terms of net CO2 emissions mitigation potential and the quality attributes of dried food products are also discussed. It is suggested that properly designed solar dryers having low operational cost compared to electrically heated dryers may prove to be an energy saving device for drying of agricultural products. However, the techno-economical and environmental aspects of various efficient solar dryers are needed to be further studied for applications in various irregular shaped food products.

Abstract
 
Grains are usually harvested above 20% (wb) moisture level and they are prone to microbial attack at high moisture level. In order to avoid both qualitative and quantitative losses that arise from microbial growth, grains are usually dried to safe moisture level. The safe storage moisture content may vary from 8-16% (wb), depending upon the grain and climate type. Therefore, drying is a necessary step in preventing these losses. Drying also reduces the bulk weight of the materials, thus easing transportation and storage. Drying can occur in thin layer or in deep bed. Different drying theories are proposed to characterize these drying processes. Theoretical as well empirical drying equations have been developed.