eChapters

Black pepper (Piper nigrum L.), famous as “Black Gold” and also known the “King of Spices” is the most important agricultural commodities of commerce and trade in India. It is the most important, most popular and most widely used spice in the World. Of the total spices traded internationally, black pepper accounts for 34 per cent. South West India is the traditional home of this important spice, particularly the Malabar Coast. Black pepper is also grown in tropical zones such as the Asia Pacific Region, mainly India, Indonesia, Malaysia, Sri Lanka, Thailand, China, Vietnam and Cambodia. Outside the Asia Pacific region, the crop is distributed in Brazil, Mexico, Guatemala, etc., totaling about 26 countries. It is grown successfully between 20°N and 20°S latitude and from mean sea level to 1500 meters above sea level. World’s black pepper production varies in the range of 2.7 to 3.35 tonnes annually.

The natural habitat of rubber (Heavea brasiliensis) is rain forests of the Amazon basin, situated within 5° North and South at altitudes below 200m. The climate of this region is equatorial monsoon type characterized by mean monthly temperature by 25 to 28°C, well distributed rainfall and no marked dry weather. Though it is originated in the Amazon basin, it is now predominantly grown in the tropics where an equatorial monsoon type climate prevails. Regions between 8°N and 10°S which includes Indonesian archipelago, Malaysia, southern part of Sri Lanka and some other Islands, are better suited to rubber cultivation. The production of natural rubber in the country was 8.65 lakh MT in 2008–09, registering a 4.74 per cent growth compared to the previous year.

Small cardamom (Elettaria cardamomum Maton), popularly known as the “Queen of spices”, occupies an important position among the foreign exchange earning commodities. Cardamom is cultivated on a commercial scale in Sri Lanka, Guatemala, Tanzania and Papua New Guinea. Guatemala is the largest producer of cardamom in the World. In India, it is confined to the States of Kerala, Karnataka and Tamil Nadu, accounting for an area of 41588 ha, 25021 ha and 4561 ha, respectively (Spices Board, 2009). Among these States, Kerala accounts for the major portion of production (58.4 %), followed by Karnataka (35.2 %) and Tamil Nadu (6.4 %). In Kerala, Cardamom is mainly grown in the erstwhile Travancore area in the present Idukki district and it is known as the Cardamom Hill Reserve (CHR), which was specially reserved, denotified and removed from the control of forest development by the orders of the Travancore Government. By a Royal Proclamation in Medam 997(ME) 334 square miles (86,506 ha) area in Devikulam, Udumbanchola and Peermedu taluks of the present Idukki District was declared as CHR for the promotion of cardamom cultivation (Miniraj and Nybe, 2007). Cardamom is a native of the moist evergreen rain forests of the Western Ghats of South India and is grown extensively in the hilly regions at elevations of 700 to 1300 metres as an under crop in forest lands. Cardamom thrives well within certain thermal regimes. It is believed that diurnal symmetries in temperature trends, if any, have close links with the changes in cloudiness, humidity, atmospheric circulation pattern, winds and soil moisture (Kumar et al., 2002).

The global production of cocoa is around 36.49 lakh tonnes against the demand of 37.37 lakh tonnes. Ivory Coast leads in cocoa production in the world with a contribution of 38 per cent, followed by Ghana and Indonesia. Unlike in other crops, it appears that the production and demand of cocoa at the global level match each other to a large extent. However, the recent trends in the world production of cocoa beans indicated that there was a drop of nine per cent in 2006–07, declining from 3.8 million tonnes in 2005–06 to 3.4 million tonnes in 2006–07 (Table 9.1). It was attributed to unfavourable conditions in many cocoa producing areas. West Africa, the main cocoa producing region, was hit by a severe harmattan (dusty dry wind from November to March) and its inherent dry weather, which lasted from the end of 2006 to February 2007, had a strong negative impact on global cocoa production. In Asia and South America, El Nino- related weather conditions developed in September 2006 and continued until the beginning of 2007. It led to relatively low cocoa production in 2007–07. However, it was rebounced in 2007– 08 to some extent though it was low (36.49 lakh tonnes) when compared to that of 2005–06. The favourable weather which prevailed over most of the cocoa growing regions during 2002–03 and 2003–04 helped to achieve better production during the above years while dip in the global production in 2006–07 due to unfavourable weather. It reveals that the weather abnormalities like floods, droughts, cold and heat waves across the cocoa growing regions of the world adversely affect the Coca production and the cocoa industry is likely to suffer.

Cashew (Anacardium occidentale L.) is a very important horticultural crop which fetches considerable foreign exchange to India. The crop is a native of Brazil and was introduced in India by the Portuguese during 16^th Century. It is grown in India, Brazil, Vietnam, Tanzania, Mozambique, Indonesia, Sri Lanka and other tropical Asian and African countries. The crop is grown within the latitudinal belt of 27°N and 28°S of the equator experiencing a tropical temperature for its growth and development (Rao and Gopakumar, 1994). The trend in productivity has a phenomenal bearing to the distance from the equator. The world production of cashew is estimated to be around 20.8 lakh tonnes. The global productivity level of cashew is 690 kg/ha. Since 2000, the world raw cashewnut production registered an increase of 40 per cent. India’s share in the world raw cashewnut production accounts to about 25 per cent. In recent times, India is facing tight competition from Vietnam and Indonesia in international cashew trade. Since its introduction in the Country, cashew has well adapted to the Indian climatic conditions and is grown in the East and West Coasts of India. Now, India is the largest producer, processor, consumer and exporter of cashew in the world (Bhat, 2009 a). In India, cashew is grown mainly in Maharashtra, Goa, Karnataka and Kerala along the West Coast and Tamil Nadu, Andhra Pradesh, Orissa and West Bengal along the East Coast.

The Coconut palm, also known as the Cocos Nucifera L., is one of the most fascinating and beautiful palms in the world. Epigraphical, literary and sculptural evidence provide proof that coconut has served humanity for more than three millennia. The palm is looked upon with reverence and affection and is referred to by such eulogistic epithets as “Kalpavriksha”, tree of heaven, the tree of abundance, nature’s super market, king of palms and the tree of life. The coconut is believed to have originated in Southeast Asia (Indonesia, Malaysia, Philippines) or Micronesia (Harries, 1977; Purseglove, 1968 and 1972). Coconut has been cultivated in India since ages and plays an important role in social, economic and cultural activities of the people. The palm is amenable to both plantation and homestead management and it can be either a major crop or a minor one in a homestead garden of mixed crops. While responding favourably to scientific management, the palm also tolerates negligent farming to a certain extent. Thus, it can adapt to the divergent farming situations and management practices that are prevalent in different agro-climatic regions. The coconut palm is usually found near the sea on sandy beaches where it can tolerate salt spray and brackish soils. It is also grown under different soil types such as loamy, laterite, coastal sandy, alluvial, clayey and reclaimed soils of the marshy low lands. The ideal soil conditions for better growth and performance of the palm are proper drainage, good water-holding capacity, and presence of water table within three metres and absence of rock or any hard substratum within two meters of the surface. The coconut palm can also grow well inland, within altitudinal limit of 600 m to 1752 m in the Tropics. It requires an equatorial climate with high humidity. A year-round warm and humid climate favours the growth of coconut. The ideal mean annual temperature, which can be tolerated by coconut palm, is around 27ºC with 5–7ºC diurnal variation. The palm does not withstand prolonged spells of extreme weather/climate variations under rainfed conditions. A well-distributed rainfall of 1300–2300 mm per annum is preferred. It is known as a coastal tree since it is grown along the Coasts and Islands and does not tolerate high temperature range, that is the difference between the maximum and minimum temperatures.

Of the various weather elements affecting crops, temperature and rainfall are perhaps the most important. It is the reason for the development of special flora and fauna in different climatic zones of the world as seen in the tropical, temperate and frigid zones. The tropical regions get abundant solar heat and the vegetation is high while it is low in the temperate regions. The vegetation is very little in the frigid zones. Similarly, natural vegetation is at its poor growth in the Arid Climates and better in the Humid Tropics. Xerophytes are confined to the Arid Climates where low rainfall is seen, while hydrophytes are confined to the Humid Tropics. Mesophytes are intermediate in their water requirement. Most of the crops are included in this group. If the crops are selected for cultivation on the basis of the optimum climatic requirements, it is likely that crop production can be maximised under rainfed as well as irrigated conditions. For example, coconut is grown in vast areas across the East and West Coasts of the Country in different agroclimatic zones and known as a coastal tree. It gives reasonably better yield in terms of quantity and quality in the Humid Tropics under rainfed conditions. However, the coconut yield scenario is totally different when the crop is cultivated in Semi-arid Tropics under irrigation. Therefore, it is a complex phenomenon to understand the influence of weather and climate on crops under rainfed and irrigated conditions in various climatic zones. The production potential of crops under field conditions could be explained through crop-wise agroclimatic zonation, whether the crop is well-suited with minimum inputs for maximising yields under rainfed conditions, but not under irrigated conditions due to crop manipulation. Many attempts were made to explain the climatic boundaries for various crops based on agroclimatic indices under rainfed conditions.

Rice is one of the major staple food of the world’s population. About 114 countries grow rice and more than 50 have an annual production of 100,000 tonnes or more. Asian farmers produce about 90 per cent of the total, with two countries, China and India, growing more than half of the total crop. For most rice producing countries where annual production exceeds one million tonne, rice is the staple food. In Bangaldesh, Cambodia, Indonesia, Lao PDR, Myanmer, Thailand and Vietnam, rice provides 50–80 per cent of the total calories consumed.

Kerala, popularly known as the God’s own country, is situated at the southern tip of India between latitude range 8°15‘ N to 12°50’ N and 74°50’ E to 77°30’ E longitude. The State is graced with 44 rivers and numbers of streams and has rich biodiversity and tropical rain forests spread in 13 agro-ecological zones under humid tropics. Kerala is the Gateway of monsoon in India. Though Kerala is identified as Plantation State, the major staple food is rice. The annual rainfall in Kerala is about 2.7 times the national average. More or less assured amount of rainfall is being received in almost every year over the State, though inter-annual variability is felt more in recent decades. Uncertainties in rainfall are also felt much in the recent decades. Droughts during summer and floods during rainy season are frequent. Natural disasters like landslides/mud slips during rainy season are common across the mid and high lands of Kerala as the intensity of rainfall is high. Atmospheric temperature across the State is increasing. 1983 was a disastrous drought year in Kerala. The severe summer affected the State’s plantation crops economy to a considerable extent. Insignificant rainfall led to the severe summer drought during 1982–83.

Food security is one of the most important issues during this century under the projected climate change scenario. The world is facing severe food crisis due to weather vagaries as a part of global warming and climate change. One sixth of world’s population is under starvation. It is estimated that 300 million people in the world do not get food three times a day. About 18,000 children die every day due to malnutrition. Many Asian-African countries are under severe food crisis. It is also estimated that out of the World’s most hungry people, 29 per cent is in India. 47 per cent of children below three years of age are suffering from malnutrition problem. 75 per cent of world’s population is dependant on agricultural activities for their livelihood. Therefore, there is an urgent need to produce more and more foodgrains at the global as well as national levels to meet the food requirement of growing population under the projected climate change scenario. There has been a major decline in world rice production since late 2007 due to various reasons including global warming and climate change in top rice producing countries. Deficit monsoon over India during 2009 resulted to poor foodgrains production including rice as the area under rice cultivation was less. There were also devastating floods in southern States of India viz., Andhra Pradesh and Karnataka. Andhra Pradesh, one of the major rice producing states of India, was affected first by drought and then by floods. Thus rice production decline in India was a real set back in 2009. Similar was the case in 2010 due to excess rain during monsoon and floods during NE monsoon across the rice growing regions. At the same time, Philippines got hit by two major typhoons in September-October, 2009 causing damage to rice crop on ground. Approximately one million tonnes of rice in storage also got damaged. These events resulted to low world rice production over the country in 2009. The immediate impacts of global warming and climate change on rice production systems and food security will be felt in the form of adverse effects of extreme weather events such as floods, droughts, heat and cold waves, hailstorms and cyclones on rice production. Less immediate but significant impacts are anticipated due to changes in mean temperatures, increasing weather extremes and sea level rising.

India is the seventh largest country in the world with 17 per cent of the world’s population and with a total geographical area of 329 Mha, extending from 8°4’ to 37°6’ in the North and 68°7’ to 97°25’ in the East. It is bounded by the World’s highest mountains- the Himalayas in the North and surrounded by the Arabian Sea, the Indian Ocean and the Bay of Bengal in the South. The Indian Coastline along the southern part of the Country is over 7500 km long. The Country includes vast plains like the Indo-Gangetic Plains, and the Central Deccan Plateau, bordered by the Western Ghats on either side in the West and the South. The biodiversity in the terrain leads to a wide variety of climatic conditions, ranging from tropical to temperate climates across the Western Ghats. These range from permanent snowfields to tropical coastlands; areas of virtual desert in the northwest to fertile intensively cultivated rice fields in the northeast. A large proportion of India’s population continues to live in rural areas and depends heavily on climate-sensitive sectors such as agriculture, fisheries, animal agriculture and forestry for its livelihood. Agriculture is the mainstay of Indian economy. The Indian climate is dominated by the great wind system called the Monsoons, on which the Indian agriculture is dependant. The southwest monsoon is critical to the kharif crop (first crop), which accounts for more than 50% of the foodgrains production and 65% of the oilseeds production in the Country. The inter-annual monsoon rainfall variability in India leads to large-scale droughts and floods, resulting in a major effect on Indian foodgrain production (Parthasarathy and Pant, 1985; Parthasarathy et al., 1992; Selvaraju, 2003; Kumar et al., 2004) and on the economy of the Country (Gadgil et al., 1999a; Kumar and Parikh, 2001). Climatic variability and occurrence of extreme events are major concerns for the Indian subcontinent as they are inbuilt features under the projected climate change scenario. All the projections on climate change are based up on the General Circulation Models (GCMs). All the models project increase in temperature over the Country under different GHG emission scenarios. Rainfall variability is felt in different sub-meteorological divisions across the Country. Though the GCMs have been successful in depicting the gross features of the observed large scale climatological features, there is large uncertainty associated with these projections on regional scale, since the GCMs are yet to realistically reproduce the observed features at regional scale, particularly over the monsoon region (Kumar, et al., 2002). Several downscaling approaches are being used to derive the regional features from large scale model simulations. Under the projected climate change scenario, India will be one of the Countries facing the adverse impacts of climate change as agriculture is the mainstay of people of India. Hence, understanding of rainfall and temperature variability across the Country deserves attention in the projected climate change scenario.

Climate Change has emerged as one of the most serious environmental concerns of recent times. The most imminent climate change is increase in atmospheric temperature due to increased levels of greenhouse gases such as carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O) and hydrochlorofluoro carbons (HCFCs). Because of increasing concentrations of the greenhouse gases in atmosphere, there is much concern about future changes in the climate system viz., Atmosphere, Lithosphere, Biosphere, Hydrosphere and Cryosphere. Direct or indirect effects on the society linked sectors like water, forestry, agriculture, animal agriculture, fisheries, land and marine biodiversity and health due to climate change/variability are many-fold and economic impact of climate change is enormous. The recurrent drought and desertification threaten seriously the livelihood of over 1.2 billion people who depend on land for most of their needs.

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.

Abstract

The objective of this chapter is to provide an overview of heat pump dryer (HPD) and recent developments in its applications for drying of agricultural and food products. The basics of heat pump dryer, classification, operating principle, configuration and control system have been presented for better understanding. Many researchers have concluded that HPDs use energy more efficiently than electrical dryers. The heat pump dryer is best suited for drying high value commodities such as fruits, vegetables, spices, condiments, herbs, medicinal and aromatic plants at near ambient temperature for producing better quality dehydrated product.

Abstract

Drying is a very important unit operation in food processing. Being an energy intensive unit operation, drying process demands improvement to make it energy efficient. Beside this operating conditions used in drying affect product quality substantially; however, traditional dryers do not allow enough flexibility to meet quality requirements for several products. This has resulted in development of number of new drying techniques, to cope with both energy efficiency and product quality.

Abstract

In recent years microwave processing have attained increasing recognition in food industries particularly in drying and dehydration. During microwave processing, electromagnetic energy is supplied directly to the food material for volumetric heating. This provides rapid temperature rise throughout the material with reduced thermal gradients. This unique heating mechanism reduces processing time and saves energy. In-spite of advantages of microwave heating it leads to overheating in food material and formation of cold and hot spots if applied improperly during drying. To overcome these challenges different microwave assisted hybrid drying technologies have been developed by many researchers. These techniques are microwave assisted hot air drying, microwave assisted osmotic dehydration, microwave assisted vacuum drying, microwave- infrared assisted hot air drying, microwave assisted rotary drying. This chapter comprises the fundamentals of microwave and provides comprehensive update of microwave assisted hybrid drying processes for food and agricultural materials.

Abstract

Hot air circulation is the most common industrial method of drying foods which has its own inherited disadvantages. Microwave drying can be an alternative method for removing moisture from foods and there has been a surge of interest in the application of microwave to process the foods, in past few years. The reason being that there is worldwide energy crisis and the growing acceptance and familiarity with domestic microwave ovens. It is well known that conventional means of heat processing irreversibly alter the flavor, colour, and texture of many foods. From the point of flavor alone, it is desirable to improve our present methods of processing foods. Some improvements have been made in this direction with a number of food products by use of high-temperature short- time processing.

Abstract

Spray drying is one of the most preferred methods of converting food and pharmaceutical solutions into powder form. Very high product throughput, hygienic and highly automated process and relatively benign thermal and dehydration stress on products associated with this process has made it ubiquitous in powder manufacture. Compared to freeze drying, spray drying is significantly less expensive both in terms of operation and capital costs. In this chapter, key features of spray drying such as underlying operational principle, types of spray nozzles used, the flow pattern of droplets/particles and drying medium within the drying chamber, the particle formation process of individual droplet are discussed in considerable detail. The modelling aspect of a single droplet subjected to spray drying environment has also been included. Finally, the most commonly considered characteristics of spray dried powders including morphology, crystalline/amorphous nature and solubility are highlighted and discussed.  The content presented in this chapter will be very useful for practising engineers, technologists, researchers as well as postgraduate and undergraduate students.

Abstract

Osmotic dehydration is gaining popularity due to several energy and product quality related advantages it offers. It has huge potential as a complementary process step prior to operations such as air-drying, microwave drying, freezing, frying etc, if not an alternative one, in the food process chain. It can be easily integrated with other processing steps in order to improve the overall efficiency of a given food process. Application of additional driving force either prior to or during osmotic dehydration can enhance the mass transfer rates in the osmotic dehydration. Role of mathematical modelling both in osmotic dehydration and rehydration have been discussed. Current limitations for the adaptation of osmotic dehydration in the food processing industry and possible solutions are also discussed in detail.

Abstract

Classification of the hundreds of possible dryers is essential to the logical selection of appropriate dryer for a given application. Diverse criteria for classification as well as selection of dryers are presented and discussed briefly. The advantages and limitations of different dryer types must be taken into consideration. Initial capital cost is often the key deciding criterion in industrial dryer selection. This is not a good strategy as the user must pay for the operating costs over a long period of life of the dryer. In general several different dryer types are suitable for a given product. Careful selection is essential for cost-effective operation of the dryer.

Abstract
 
Food products can have moisture content as high as 90% which needs to be lowered to acceptable limits to prevent microbial growth and deteriorative reactions. Drying is one of the most common and cost effective techniques for removal of excess moisture from the food by application of heat. In addition to its role of extending the product shelf life and providing stability, drying also helps to produce variety of products from agricultural, horticultural and industrial products. But to obtain the desired quality product, adequate drying is essential which depends on type of dryer and drying technique employed which further requires proper understanding of drying process. Despite being important unit operation in food processing industry, appropriate scientific knowledge of the drying process is still limited. So, the fundamental principles and associated terminologies with drying has been discussed in detail in this chapter to have thorough understanding of the drying process. In addition, different models and calculation procedures for drying of different types of commodities has also been reviewed.

The present publication has highlighted the issues on different aspects of food sector expressed by very distinguished authors. The issues have been discussed and illustrated how we conceive food as an item, what and how much food is known to consumers, what are common food sources, the relationship between food and health, food and nutrition security programmes in different regions of the world and how do we perceive food and nutrition policy challenges?

SYNOPSIS

After the break-up of the Soviet Union in 1992, the countries of Central Asia and the Caucasus (CAC) began making the transition from controlled to market economies. All of the countries have programs for economic and social development as well as food security. Over the last decade, the regional population increased 11%, from 72 million in 2002 to 79 million in 2012. Agricultural production has increased throughout the region. For example, vegetable production per decade has nearly doubled due to an increase in the area of the crops grown and to increased yields, and was more than 19 million t in 2011.

SYNOPSIS

Food and nutritional challenges continue to be tackled in East and Southern African countries. Prevailing rates of high malnutrition among children and often in adults in vulnerable geographical locations do suggest the need for appropriate interventions. Of several global nutrition interventions during the 1980s, successful implementation of nutrition programmes in Tanzania, Uganda, Malawi and Ethiopia have established strategies / approaches that are promising.  In Tanzania, the Iringa nutrition programme (WHO/UNICEF Joint Nutrition Support Programme) was implemented during 1983-1988.

SYNOPSIS

India has been conspicuous as one of the most malnourished nations, as every child out of two is malnourished. Moreover, the levels of under nourishment is substantially high among tribal communities. The present investigation has been made to examine the levels of food insecurity at the micro level in four regions identified in the tribal dominated areas of Maharashtra on the basis of macro level indicators. A comparison of food insecurity between the two communities reveals a high incidence of food insecurity among the tribal as compared to that of non-tribal. The nutritional status of tribal children is much lower than that of their non-tribal counterparts.

SYNOPSIS

Food security is a complex issue, linked to availability and access to food, malnutrition in the population, economic development, environment, and local and global trade. Malnutrition hinders healthy growth and proper development of the human immune system affecting neurological and cognitive development especially in children.

Synopsis

Food safety has become increasingly important with globalization due to various factors such as increased volume and diversity of trade in foods, greater public demand for health protection, changing hazards e.g., resistant microbes, more sophisticated methods for detection of hazards, changes in production and consumption pattern, etc. Food safety contributes significantly to food security as unsafe and poor quality food leads to illnesses as well as food wastage. This leads to a strong need to emphasize not only on availability of food but also ensure that the same is safe.

SYNOPSIS

Urban and rural agriculture are different entities in terms of stakeholder involvement and enabling environment for farming but they are dialectically interlinked in providing food and nutrition security of any country. Urban agriculture is more suitable on the production of nutritious crops, while rural agriculture’s first priority is to produce more food from staple. Attaining nutrition security is more complex than it is previously thought. However, while existing systems of production should continue at field levels by developing more nutritionally rich cropping patterns, its integration with farmers’ farming systems remains more important.

On different occasions I have expressed my views on hunger and food security. Here are some of the views published earlier.

1. Food Security bill: Why it is an opportunity lost

Several years ago I and Dr M S Swaminathan were speaking at a conference on hunger at Rome. Also speaking at one of the sessions was the Brazilian Minister for Zero Hunger Programme, the dream programme of ex-President LuizInácio Lula da Silva. After he had listened to us, he sat down with us to know of how India was battling hunger, specially the way India was managing its food self-sufficiency and the massive food procurement programme.

SYNOPSIS

Inspite of the fact that governments in various food summits and conferences have made commitments on food and nutrition security, presently more than a billion people are suffering from hunger and malnutrition worldwide. The food and nutrition policies need to be revisited and updated to address both man-made food scarcities and natural disasters of present and future to mitigate hunger and malnutrition.