eChapters

6.1 Strength of India
    ·    In India, pomegranate is cultivated over 1.31 lakh ha with a production of 13.46 lakh tonnes and a productivity of 10.27 t/ha. 
    ·    India is the largest producer of pomegranates in the world.
    ·    Pomegranate is currently ranked 10th in terms of fruit consumed annually in the world. India is the only country in the world where pomegranate is available throughout the year i.e. From January to December. It is cultivated in 3 seasons (Ambia bahar, Mrig bahar and hasth bahar) in Deccan plateau of India. 
    ·    India is endowed with wide agro climatic conditions that offer immense scope for cultivation of various kinds of fruit crops. This provides an excellent platform for the country to emerge as a leading producer of fruit crop. 

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.

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

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.

10.1    Respiration
    
10.2    Effect of Ethylene on Ripening
    
10.3    Transpiration Loss
    
10.4    Postharvest Biochemistry of Banana
    
10.5    Postharvest Pathology of Banana

11.1    Maturity Indices
    
11.2    Harvesting and Field Handling
    
11.3    Packhouse Operations
    
11.4    Packaging
    
11.5    Precooling

13.1    Biochemical Changes During Banana Ripening
    
13.2    Commercial Ripening

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

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

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

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.

2.1 Introduction

Many complicated engineering principles are to be analyzed and applied, before any food processing operations takes shape of a commercially viable enterprise. The size and type of the required equipments have to be specified and their sequences have to be arranged. Further, the process analysis consists of understanding of material and energy balances. This chapter provides the application of steady state conservation of mass and energy equations to analyze food-processing operations.

4.1 Introduction

The food preservation may be define as the state in which the food may retained over a period of time without being contaminated by pathogenic organism or chemicals and without losing its colour, texture, flavour and nutritional value. All the methods of food preservation must provide such an environment in and around the preserved food so that it produces one or more unfavourable conditions to the continued activity of the spoilage agents. The various methods used for food preservations are:

It is well known that lowering the temperature of food stuffs reduces microbiological and biochemical spoilage and thus extending the shelf life of the product. In addition, it is generally agreed upon that the reaction rate is reduced by half by lowering the temperature by 10°C. Though low temperature preservation process has been recognized as a preservation technique for several hundred years, the major developments in its utilization have occurred only in the last century.

The various unit operations of food process engineering applied to solve the problem of changing the compositions of solutions, mixture and solids. Often these operations must be conducted on large scale to meet the demands of a large manufacturing plant. In food processes engineering these operations are often referred to as separation / concentration / extraction / purification process. Usually these operations are directed towards separating substances into its component parts or concentrating a particular substance from another.

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
 
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

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

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.