eChapters

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.

Synopsis

If the human being was born first, he or she needed food immediately to survive. Thereafter, human beings continued to need food and continued to eat food throughout his or her life. Hence, the relationship between human being and food is permanent and the requirement of food for the human being to be alive is everlasting. The paper provides the background, definition of right to food, and adequate food, historical events, legal perspectives, operational guidelines, and advances in its application and derives conclusion.

Note: With my personal experience, I have learnt many lessons during the course of my journey of life. The reader should ponder over it and prepare own food profile and menu for the benefit of maintaining good health. My paper does not provide any prescription but provides illustration of my experiences only, which may be of some use in knowledge and practice of food. The medical and health experts need to be consulted as appropriate.

SYNOPSIS

Human health is defined as a state of physical, mental, physiological and social well being. It is also considered as a state of body and mind, where there is a balance of body humors or secretions. The paper introduces the readers to common diseases caused through various agents like deficiency disorders, food and water, air-borne, vector, viruses, and life-styles. It also describes healthy food, health management, food management, and healthy life style.

SYNOPSIS

There have been conflicting practices, recommendations regarding a healthy diet in human beings. Unscientific food habits are limitation to good health and active life. Because of various social, cultural, religious and economic factors human beings in the same climatic conditions and living situations, have been practicing different food habits leading to many health problems. What to eat, how much to eat and when to eat are not clear with the masses. This paper attempts to throw light on these aspects.

SYNOPSIS

There is an increasing awareness about quality of food among consumers all over the world. Organically produced food is considered to be nutritionally superior, but the available information is not conclusive.

SYNOPSIS

Vegetables are essential for well-balanced diet since they supply phytonutriceuticals. About 3 billion people in the world are malnourished due to imbalanced diets. Regular consumption of a vegetable rich diet has undeniable effects on health since they have been strongly associated with improvement of gastrointestinal health, good vision, and reduced risk of heart disease, stroke, chronic diseases such as diabetes, and some forms of cancer.

SYNOPSIS

Flavor is the sensory impression of a food or other substance, and is determined mainly by the chemical senses of taste and smell. The flavor of the food, as such, can be altered with natural or artificial flavorings which affect these senses. Smell is the main determinant of a food item’s flavor. While the taste of food is limited to sweet, sour, bitter, salty, umami (savory), pungent or piquant, and metallic – the seven basic tastes – the smells of a food are potentially limitless.

SYNOPSIS

Fish has now become an important animal protein for mankind. It is a rich source of essential amino acids, vitamins and minerals. Fish meat is easily digestible compared to other animal meat and has a higher Protein Efficiency Ratio when compared to casein, the milk protein. Fish oils like body oils of fishes like sardine, mackeral, anchoviella, herring, salmon etc. are the richest source for Omega-3 long chain poly unsaturate fatty acid like Eicos- pentanoic acid (EPA) and Docosahexaenoic acid (DHA) having therapeutical applications for man. A number of fishery products and by-products like squalene, chitin, chitosan, oyster meat, mussel meat, shark bones etc.

SYNOPSIS

Animal source foods (ASF) include any food item that comes from an animal source such as meat, milk, fish, eggs, cheese and yogurt. Many individuals do not consume ASF or consume little ASF by either personal choice or necessity as ASF may not be accessible or available to these people. Animals are used as food either directly or indirectly by the products they produce. Animal source foods (ASF) include any food item that comes from an animal source such as meat, milk, fish, eggs, cheese and yogurt.

SYNOPSIS

Many plants or plant parts are eaten as food. In addition to essential vitamins, minerals, and fibers, plant foods contain phytochemicals and antioxidants, which actively provide protection against diseases. Several studies carried out all over the world have demonstrated the protective values of fruits. Fruits are the ripened ovaries of plants, including the seeds within. Many plants have evolved fruits that are attractive as a food source to animals, so that animals will eat the fruits and excrete the seeds some distance away.

SYNOPSIS

Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal or fish origin. Plant foods are the most abundant sources of nutrition on earth. Only plants contain powerful substances called phytochemicals, which protect us from cancer, heart disease, and an array of other serious illnesses.

SYNOPSIS

Nature produces plants with healing properties. Hundreds of phytochemicals and antioxidants have been identified in various food plants. Many plants or plant parts are eaten as food. There are several plant species which are cultivated for food, and many have several distinct cultivars. Seeds of plants are a good source of food for animals, including humans, because they contain the nutrients necessary for the plant’s initial growth, including many healthful fats, such as Omega fats. In fact, the majority of foods consumed by human beings are seed-based foods.

SYNOPSIS

With the change of time, and the progressive development in life-style, the menu of food has undergone significant changes in communities, countries, regions and worldwide. This is influenced by the travel, migration of the people, and enhancement of the socio-economic status among the masses.

SYNOPSIS

In all probability the ancient farmer’s market originated on the streets of villages and later on, on the streets of towns. The street food survived through decades and centuries and now it has assumed its new role in fulfilling the readymade food demand of the working people of mega cities. The street food has now more relevance to the growing urban population. With the lapse of time and migration people to the cities, the business and activities of street food got expanded in qualitative and quantitative terms worldwide.

SYNOPSIS

The availability of food is of paramount importance without which it is hard for human beings to survive. The recognized way of making food available is to produce but it is also equally important that food produced is utilized well without loss of edible food materials. The paper discusses on unused food, under- utilized food within and across countries, and puts emphasis on utilization and handling of food. In perspective, the paper highlights the steps to be taken up to save and utilize the food already produced.

SYNOPSIS

We lag in nutritional awareness. The therapeutic values of plant foods, such as vegetables, fruits, grains, legumes, nuts, seeds, herbs, spices and other foods like dairy products, fluids and meats are to be brought to light. The values of important nutrients, may lead to the basis for nutritional education lacking at present. There is need to bring awareness and add to the knowledge of the younger generation. A food is something that provides nutrients. Nutrients are substances that provide: energy for activity, growth, and all functions of the body such as breathing, digesting food, and keeping warm; materials for the growth and repair of the body, and for keeping the immune system healthy.

SYNOPSIS

Food is an essential element without which human being cannot survive. We need it for our maintenance and growth everyday and through the longevity of our life. As we understand food, it is a bunch of essential elements which is essentially needed for the engine of human body to run non-stop. The understanding of food is much required by masses who consume it every day. The present paper attempts to describe the knowledge on food, feeling on food by consumers, prevailing food, hunger and malnutrition, healthy food and studies required on consumable foods.

1.    I deem it a singular honour to deliver Dr. Sen Memorial Lecture. Dr. Sen, who was both an administrator and a visionary, was instrumental for:

It is difficult to ascertain which came first, food or human being. It is the same situation as chicken and egg where we lack evidence to indicate which came first on earth.

It does not matter which came first but we know for sure that human being needs food and he or she needs everyday and throughout his or her life. In other words, a human being cannot survive without food indicating permanent unbreakable bondage between food and human being. It supports the basics of human civilization-food, agriculture and humanity.

India

Milk legislation and regulations are designed to prevent fraud and adulteration. But they now cover many factors that affect sanitation and public health. Milk generally is classified into grades according to the care with which it is produced.