eChapters

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.

3.1 Introduction

The subject of heat transfer is firmly grounded in the sciences of thermodynamics and fluid mechanics. It has become exceedingly important for engineers to possess a clear understanding of the principles of heat transfer and its application to a large number of problems. In view of process engineering, the knowledge of heat transfer and its application is most important, because heat transfer is one of the basic unit operations in the agricultural processing activities. The design of process equipments, refrigerators, boilers or type of heat exchangers, thermal treatment of food grains, cooling of perishables, pasteurizations, sterilizations, freezing of milk and fruit juices and a large number of similar applications involve consideration of heat transfer rates. There may be other situations where heat is being generated during a certain operation, and may be detrimental to the equipment and the food product. In such cases we are often faced with the task of removing the undesirable amount of heat as far as possible.

1.    Heat transfer by conduction is given by

(a) Boyle’s law

(b) Stefan’s law

(c) Fourier’s law

(d) Charles’ law

2.    Heat flow per hour is proportional to change in

(a) Area

(b) Vapour pressure

(c) Mass

(d) Temperature

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.

1. Herbs and Spices
       
    1.    International Standards Organization (ISO) defines spices and condiments as: Vegetable products or mixtures thereof, free from extraneous matter, used for flavouring, seasoning and imparting aroma in foods.

    2.    Rosengarten describes a spice as a product which enriches or alters the quality of a thing, for example altering the taste of a food to give it zest or pungency; a piquant or lasting flavouring; or a relish. The term ‘spice’ is thus used to cover the use of spices, herbs and certain aromatic vegetables to impart odour and flavour to foods.

    3.    Herbs may be defined as the dried leaves of aromatic plants used to impart flavour and odour to foods with, sometimes, the addition of colour. The leaves are commonly traded separately from the plant stems and leaf stalks.

This alternative pathway for glucose oxidation has enzymes in the cytosol through which glucose is degraded to carbon dioxide. It is also called a shunt because carbon atoms from glucose 6-phosphate take a long route before they proceed down the EMP or glycolytic pathway. This pathway is anabolic in nature as it produces many intermediates. In this pathway, two NADPH are generated from one glucose 6-phosphate molecule. No ATP is generated or consumed.
Overall, this pathway needs three glucose-6-phosphate molecules to complete all the reactions. Therefore, one cycle run produces 2 mol of fructose-6- phosphate, 1 mol of glyceraldehyde-3-phosphate, and 3 mol of carbon dioxide from 3 mol of glucose-6-phosphate with the reduction of 6 mol of NADP+ to NADPH.
Overall reactions of the HMP pathway are as follows:
3 Glucose-6-P + 6 NADP+→ 3 ribulose-5-P + 3 CO2 + 6 NADPH
3 Ribulose-5-P → 2 xylulose-5-P + Ribose-5-P
2 Xylulose-5-P + Ribose-5-P → 2 fructose-6-P + Glyceraldehyde-3-P

The art in producing high-boiled sweets with satisfactory shelf life is manufacturing boilings which contain the minimum amount of residual moisture and a satisfactory balance between cane or beet sugar, and glucose syrup or invert sugar syrup. The main physical change during the storage of high-boiled sweets is the formation of small crystals in the confection, usually referred to as graining, due to recrystallisation of sucrose. These spoil the appearance and cause an unpleasant roughness on the tongue.

For high-boiled sweets it is impossible, using the normal proportions of cane or beet sugar (sucrose) and glucose syrup, to obtain a product of 97% solids content, which is not supersaturated with respect to sucrose.

In practice, however, one-and-a-half parts of sugar (sucrose) to one part of forty-two DE glucose syrup will produce a high-boiled sweet stable against graining.

High Humidity Hot Air Impingement Blanching (HHAIB) is a modern blanching technology developed to overcome several limitations associated with conventional blanching. This chapter introduces HHAIB as a pretreatment used before drying, freezing, canning and frying, particularly for fruits and vegetables. It explains the underlying principle of high-humidity hot-air impingement and its effects on heat and mass transfer. The chapter discusses applications in pre-dehydration treatment, colour preservation, texture and structural integrity and enzyme inactivation. Comparative analysis with conventional blanching methods highlights its potential advantages in drying efficiency, quality retention and energy utilization, making HHAIB an important emerging technology for modern food processing.

1. Introduction

Fruit products have their unique identities having large content of micronutrients, polyphenols, vitamins, flavonoids and other nutritional compounds. Characteristic appearance and flavors distinguish among various fruit based products like juice, puree, jam, jelly, squash and other several varieties. Main concern of this fruit processing industry is the stability of the products throughout the post processing storage. Thermal treatment as mean of preservation of these products is the common process implemented so far. It ensures the safety of the product but lacks in retaining the nutritional intact that like of fresh fruit. Today’s consumer demand for minimally processed fruit products and “natural” fruit products tend to think of alternative thermal processing.

High pressure processing (HPP), a relatively new concept compared to conventional thermal processing, also sometimes known as high hydrostatic pressure (HHP), or ultra high pressure (UHP) processing, is a non-thermal food processing method that subjects liquid or solid foods, with or without packaging, to pressures ranging between 50 and 1000 MPa. HPP has already been established itself as an alternative to thermal processing. In food processing it is of great interest due to its ability to inactivate food borne microorganisms and enzymes, at low temperature, without the need for chemical preservatives and it is less detrimental than thermal processes to low molecular weight food compounds such as flavoring agents, pigments, vitamins, etc., as covalent bonds are not affected by pressure. Pressure-treated foods have sensory properties similar to fresh products, which is a major advantage in fruit processing as it matches consumer demand for healthy, nutritious and ‘‘natural’’ products. HPP of fruit products offers the chance of producing food of high quality, greater safety and increased shelf life (Hayashi 1989; Gould 1996; Butz and Tauscher 1998).

4.1 Introduction

The purpose of processing the food is to make it safe and healthy for human consumption. The term food processing refers technologically anything, which transforms raw ingredients into consumer ready products, with the aim of stabilizing food products by preventing or reducing deteriorative changes in quality. The objective of food manufacturers is to develop, modify and employ those processing technologies that retain or create desirable sensory qualities in food and eliminate or reduce undesirable changes due to processing.

The purpose of food processing is to increase the shelf life of food before spoiling (preservation); to remove, destroy or inhibit pathogens and toxins (food safety); to change flavor, texture, aroma, color or form (variety); to reduce preparation times and make food more portable (convenience); to restore and/or raise nutrient levels in food (nutrition).The various food processing methods used extensively in food industry include physical (high temperature, freezing, chilling, dehydration, packaging), chemical (control of storage gases, reduction of water activity, pH, addition of chemical additives or spices) preservation methods.

Traditionally, food preservation has been associated with thermal treatments alone or in combination with biochemical or chemical methods. For example, the thermal processing of milk is done various thermal treatments viz. at 63^oC for 30 min for low temperature long time (LTLT), 72^oC for 15 seconds for high temperature short time (HTST) pasteurisations and up to 140^oC for a few seconds for ultra high temperature (UHT) treatment. However, such thermal treatments effectively reduce level of microorganisms but in long-term preservation, it may lead to losses of desired organoleptic attributes and destruction of temperature liable nutrients and vitamins. The limitations involved with thermal processing has been overcome by employing chemical preservation, cool chain management and process hygiene in the formulation and production of food products.

Food and nutrition are necessary for all living beings to maintain good health[1]. Thermal treatment is commonly used for preservation of food. Although application of thermal treatment can ensure food safety, it may cause undesirable changes in the nutritional, sensory and functional properties of food products[2]. Due to growing awareness of connection between the diet and the health, there is an increase in demands for fresh-like, palatable, additive-free and microbiologically safe food products with high nutritional value and quality[3].

High-pressure processing (HPP) is a novel method for non-thermal preservation technique of food that inactivates harmful pathogens and vegetative spoilage microorganisms. HPP is an alternate, non-thermal food processing method, wherein the food is subjected to a very high pressure range from 100 -800 MPa (1MPa = 145.03 Psi or 10 Bar). HPP is also referred as High hydrostatic pressure processing, Ultra high-pressure processing, Hyperbaric processing and Pascalization (Rao et al., 2014).

Ice cream has evolved from simple frozen preparations into a sophisticated food industry combining dairy science, food chemistry, refrigeration, microbiology, processing technology, packaging, and cold-chain management. This chapter introduces the historical development of ice cream and explains its transformation from a luxury product into a widely consumed frozen food. It examines the characteristics of the industry, major categories of ice cream and related frozen products, flavour classifications, composition, and quality characteristics. The chapter also presents the basic manufacturing process, important quality-control parameters, common manufacturing challenges, and emerging industry trends, providing a foundation for understanding ice cream as both a technical product and a commercial business.

Microorganisms (or microbes) are organisms too small to be seen with the naked eye. The science of microbiology is the study of microorganisms, their properties, classification, growth requirements, method of reproduction and distribution in nature. These organisms range in size from tiny viruses to larger bacteria, protozoa, algae, fungi and some of the microscopic worms (helminthes). They are present everywhere in our environment, in our homes, on our bodies, on the things we touch and on the food we eat. They are important for human survival on Earth, playing an essential role in many processes that maintain life. In nature, microorganisms carry out a number of important functions.

1.They are responsible for the decomposition of organic matter.

2.Recycling of nutrients that help to maintain the balance of chemicals in the soil.

3.Special nitrogen-fixing bacteria live symbiotically with certain plants, absorbing nitrogen from the air and converting it into compounds which can be used by the plant for growth.

4.Some algae are capable of photosynthesis, using energy from the sun to convert carbon dioxide in air into carbohydrate.

5.Marine microorganisms form the basis of the food chain in lakes, rivers and oceans.

6.Certain microorganisms are used in the manufacture of food.

7.Pharmaceuticals and drugs.

8.Industrial processes.

9.A valuable tool for scientific research.

10.Use in laboratory experiments to understanding metabolic pathways and in the discovery of the genetic code.

Bakery Industry

Baked goods have been around for thousands of years. The art of baking was developed early during the Roman Empire. It was a highly famous art as Roman citizens loved baked goods and demanded for them frequently for important occasions such as feasts and weddings etc. Due to the fame and desire that the art of baking received, around 300 BC, baking was introduced as an occupation and respectable profession for Romans. The bakers began to prepare bread at home in an oven, using mills to grind grain into the flour for their breads. The oncoming demand for baked goods vigorously continued and the first bakers’ guild was established in 168 BC in Rome. This drastic appeal for baked goods promoted baking all throughout Europe and expanded into the eastern parts of Asia. Bakers started baking breads and goods at home and selling them out on the streets.

This trend became common and soon, baked products were getting sold in streets of Rome, Germany, London and many more. This resulted in a system of delivering the goods to households, as the demand for baked breads and goods significantly increased. This provoked the bakers to establish a place where people could purchase baked goods for themselves. Therefore, in Paris, the first open-air bakery of baked goods was developed and since then, bakeries became a common place to purchase delicious goods and get together around the world. By the colonial era, bakeries were commonly viewed as places to gather and socialize.^[2] World War II directly affected bread industries in the UK. Baking schools closed during this time so when the war did eventually end there was an absence of skilled bakers. This resulted in new methods being developed to satisfy the world’s desire for bread. Methods like: adding chemicals to dough, premixes and specialized machinery. Unfortunately these old methods of baking were almost completely eradicated when these new methods were introduced and became industrialized. The old methods were seen as unnecessary and financially unsound, during this period there were not many traditional bakeries left.

Bakery is a traditional activity and occupies an important place in food processing industry. The bakery manufacturers in India can be differentiated into the three broad segments of bread, biscuits and cake. About 1.3 million tonnes of the bakery products industry in India is in the organized sector out of 3 millions tonnes, while the balance comprises of unorganized, small-scale local manufacturers. Though, there are sufficient automatic and semi-automatic bread as well as biscuit manufacturing units in India but there are still number of people prefer fresh bread and other products from the local bakery. After entry of Pizza and Burgers’ MNCs in the country, people are changing their tastes also. Today, they are not restricted to bread, cake and biscuits but to other bakery products also. The consumers are increasingly going for newer options with respect to bakery products. With the ventures of few Companies like Britannia, Biskfarm, and Morish etc. competition has increased. Also, the Indian market is witnessing the proliferation of bakery cafe chains in the form of Baristacafe, coffee day, Café Coffee & Monginis etc.

Armed with better technology, know-how and novel ideas, these foreign companies have made rapid inroads into the lucrative market within a very short span of time. Though the demand for bakery products in India has always been on the rise, there is clearly a lack of awareness and the will to break new ground, which has helped global players to gain brownie points while exploring the market in India. The unorganized sector accounts for about half of the total biscuit production estimated at 1.5 million tonnes. It also accounts for 85 per cent of the total bread production and around 90 per cent of the other bakery products estimated at 0.6 million tonnes. The last includes pastries, cakes, buns, rusks and others.

History

Pineapple was discovered a little later in time than expected. It had been a staple of the American diet for years before Christopher Columbus, an Italian explorer, discovered it on November 4, 1493. (www.library.ucf.edu; www. levins.com). That’s when the Guadeloupe Island natives served him and his colleagues this delectable fruit, pineapple. The varieties cultivated at the time were all seedless, and many typical wild cultivars were missing (Collins, 1948), demonstrating the area’s early vegetation. He brought the fruit to Europe. The European travellers were so fascinated by this fruit that they frequently mentioned it in their accounts (Morrison, 1963; Collins, 1960).

It was known as ‘nanas’ or ‘ananas’ by the people of South America (‘ananas’ meant ‘excellent fruit’ in Guarani). People in the area literally cultivated it according to a strict protocol, and they were especially keen to select superior varieties in order to increase fruit yield and quality. They gained a thorough understanding of crop agronomy and production. They also put into practise some of the processing standards that are still in use today around the world (holidayandtraveleurope.blogspot.in). Pineapple wine was made, fibre was extracted, and pharmacological needs such as emmenagogue, abortifacient, antiamoebic, vermifuge, stomach disorders, and poisoning arrow heads were met (Leal and Coppens d’Eeckenbrugge, 1996). In 1980, Antoni and Leal proposed that the pineapple originated in an area further north, between 10° N and S latitudes and 55–75° W longitude, which included parts of north western and eastern Brazil, Columbia, Guyana, and Venezuela. During colonisation, Spanish and Portuguese navigators were instrumental in the distribution and spread of pineapple to all corners of the globe (www.daf.qld.gov.au 2015).

11.1 Introduction
“Homogenization” is the method of mechanical treatment producing a stable emulsion of milk fat and milk serum. Homogenizer is the name given to the equipment employed for this aim. The fat globules in milk range in size from 1 to 20 microns; the average is 4 to 6 microns. The homogenizer reduces the size of the fat globules in milk or cream passing through it. The most of them are less than two microns. After homogenization, no cream line develops on milk; churning homogenized cream cannot generate butter grains. Moreover, milk like cream’s viscosity is changing, which increases the resistance the smaller fat globules face. The increase in viscosity is ascribed to the fact that more milk protein will be deposited on the surfaces of more fat lobules. Homogenizing milk changes its clotting characteristics, so the curd made with rennet or pepsin is supposed to be softer. Because lipolytic enzymes adsorbed on the extra surfaces provided by the more numerous tiny fat globules hydroly fat, homogenized milk or cream may become rancid more quickly than untreated goods. The milk or cream must be pasteurized either right before or right after homogenization to prevent these changes. Usually, the milk is homogenized after main heating and then pasteurized. Driven via a small valve against hard surfaces, heated milk is under pressure of 2500 psi and in a second stage under 500 psi. With a 1/10000 inch diameter, the aperture the liquid is driven through is quite small. Mechanical force milk through a narrow passage at high speed produces homogenized milk. This produces a stabile fat emulsion and breaks down the fat globules in milk into considerably smaller ones. Homogenization reduces the inclination of the fat globules to cluster and merge into cream. Milk is an emulsion whereby fat globules are distributed across a constant skim milk phase. Raw milk left to sit will finally cause the fat to climb to the top and form a cream layer. By means of a small opening under high pressure, homogenization mechanically breaks down the fat globules. While increasing their number and surface area, this lowers the average size of the fat globules. Practically speaking, the net effect is a substantially decreased inclination for creaming of fat globules. Three elements contribute to this increased stability of homogenized milk: a decrease in the mean diameter of the fat globules (a factor in Stokes Law), a decrease in the size distribution of the fat globules (causing the speed of rise to be similar for most globules such that they do not tend to cluster during creaming), and an increase in density of the globules (bring them closer to the continuous phase) owing to the adsorption of a protein membrane. < Heat pasteurization also breaks down the cryo-globulin complex, which often clusters fat globules causing them to increase. The homogenizer consists of a high-pressure pump with an adjustable opening based on a minute orifice. High pressure force of fluids through the orifice causes a notable change in the physical characteristics of the treated product and generates a very intimate combination of the fluid components. Annexure- II has a Homogenizer schematic.

1. Introduction

Raw milk is an emulsion. It is a mixture of milkfat globules, Solid Not Fat (SNF) and water. Over time, milkfat globule separate out from milk serum and comes to the surface of milk as a layer of cream due to the low density of milkfat or due to heating of milk. When milk is heated rapidly and continuously, some of the water in it evaporates from the surface. This exposes proteins and fat molecules, which bind and dry out and forms a skin like film on the surface.