eChapters

Wheat Production and Consumption

Wheat, rice, maize, barley, sorghum and the millets are the main crops that provide nutrition to people worldwide. The production of grains in different countries depends on the various factors such as water availability, soil conditions, temperature, cultural and economical are most critical factors. Nutritional needs of the developing countries are more dependent on cereal grains compared to the developed ones. Approximately 60% of the calorie requirements in the developing countries are met from cereals. The International Grains Council (IGC) forecasted for total grains production in 2017-18 to 2.079 billion tonnes. There is a need to have major research to increase their productivity, reduce storage losses, enhance efficiency of processing and to ensure food safety in the entire supply chain. Among them, wheat is one of the most important crop species and is a staple food for about 35% of the world population. Wheat is unique among the grains because of its protein type, which when mixed with the water by mechanical forces yields into viscoelastic dough due to the formation of gluten. This unique property of dough is capable of retaining the gases which are produced by yeast or baking powder resulting in the production of an array of leavened products such as bread, cookie and cake.

Wheat is also an important source of dietary proteins for humans but like other cereals, it is deficient in the essential amino acid lysine. Wheat crop is adaptable to the wide range of growth conditions compared to other major cereals and hence it is cultivated widely throughout the world. Wheat cereal is the major dominating staple in the North Africa, Central and West Asia, providing the 50% of the calorie requirement in the region. The world wheat production is 740 million tonnes, with China ranking first by producing 125 million tonnes of wheat annually. Other major wheat producing countries are India, USA, Russia Australia, France and Canada. The global per capita consumption of wheat is about 66 kg, which varies widely in different regions. In Algeria, Egypt, Israel and other Middle East as well as Eastern Europe the consumption of wheat flour is high (150 kg/year). The food uses of wheat in developing countries are more than 80%, while in developed countries it is less than 50%. The consumption of the wheat in developing countries is significantly increasing due to globalization and growing economies. After rice, wheat is a major cereal crop in India and contributes to more than 50% of the total calories. It is grown in the cooler regions of India during the period of November to April. In grain production, rice ranks first with the production of about 105 million tonnes per year. In India, total grain production is 136 million tonnes for the year 2016-17 as per the International Grains Council. India ranks second in the production of wheat in the world and produce about 95 million tonnes annually. The bread wheat (astevum) contributes to approximately 94% while durum wheat is 4% and dicoccum wheat accounts to 2%.

Introduction

Food is an important contributor to human well being and is essential for sustaining life. From this point of view food is expected to contains essential nutrients, such as carbohydrates, protein fat, vitamins and other essential minerals which support life. The food production initially started for individual sustenance which slowly developed in to a community requirement necessitating the involvement of man and machinery for various activities concerned with food. The progress from famine in many parts of the world to the level of self-sufficiency and the role of science and agriculture have been absolutely significant in many parts of the world. India is no exception and the green revolution during the post 1960s and the succeeding blue and white revolution ensured the self-sufficiency in India.

Of late food acts as a vehicle for inclusion of hazard in food meant for human consumption. According to Grunert (2005), factors responsible for the alarmingly higher rate of concern by public include significantly higher number of food scares in public domain, critical understanding of production and processing of certain food products sold in the market as well as the diversified food choices of the consumers in different parts of the world. Besides, the increased awareness of the consumers on food related health issues also have its share in the increased concern on food at large.

Presently food is considered as a commodity which crosses international border concurrent with the human movement and hence quality has become a major concern. The traditional food is getting replaced with value added products, particularly ready to cook, ready to eat, partially cooked products, etc. consequent to life style changes. In order to meet the demand of the trade, the conventional processing is getting replaced by community processing or industrial processing with increased number of players in the primary production, processing, transportation and other value chain activities prompting larger product control. In the process, consumers are exposed to a variety of products produced as business ventures in modern food production systems needing efficient quality control and quality assurance to tackle the issues of quality. The increased incidence of hazards in both raw materials and final products consequent to the absence or inappropriate production schedule calls for increased food safety concerns. Besides the shelf-life of the products, addition of chemicals during the production also add to the concern.

Introduction

Meat derived from animals are subjected to various contaminations from number of sources. The animal itself is a major contributor of both pathogenic and spoilage organisms. Further contamination may be introduced from water used, equipment used for product preparation, from the meat handlers and the surrounding environment. Microbiological problems such as food poisoning or spoilage may arise when the desired effect is not achieved and is usually due to errors in the handling or processing procedures. The detection and rapid correction of such errors and their future prevention is a major objective of any quality control system.

In traditional approach to meat and meat product quality control system, only the samples of the final product were analyzed by laboratory test to check for compliance with specifications. However, the responsibility for control of hazards rests with individuals involved in all stages from farm to ultimate consumer. And the control of hazards at each stages of food chain may be achieved by Hazard Analysis Critical control point (HACCP). Hazard analysis critical control point is an internationally recognized system that helps to ensure the manufacture of safe food products. HACCP is not a zero risk system but rather a system designated to minimize the risk of food safety hazards. HACCP concept is a systematic and rational approach Firstly by consideration of the hazards i.e., microorganisms or their toxins, that need to be controlled in a specific operation by structured hazard analysis and secondly on the identification of the most effective means of controlling the identified hazards. This system, by focusing attention on the factor that directly affects the microbiological safety and quality of meat foods, eliminates wasteful use of resources and superfluous consideration. As a consequence, the cost/benefit relationships are more favorable. The system is applicable at all levels of meat food chain from farm production through processing, transporting, merchandising and ultimate use in the meat food service establishment or at home. Ensuring food safety and quality is the responsibility of all links in the food chain. Now a day’s food consumers are very much health conscious and they want their food to be safe and of good quality. As meat being highly perishable and high risk food product, it is very much imperative on the part of meat and meat products producers and exporters to produce safe and quality meat to stand in the competitive world and further hygienic meat processing is important not only to provide safe and wholesome meat but to provide a good public image and to increase consumer demand.

Introduction

Humans have primarily consumed "meat/meat products based on where they lived and how they evolved. According to Food Safety and Standards Act 2006, “meat means fresh meat, poultry and game meat which could be in the form of whole pieces, cuts or comminuted (minced etc.), whereas, meat products are those that have been processed by various methods so that they no longer resemble fresh meat”. These products include meat, poultry, and game products in whole pieces or cuts that are cured salted and dried, processed by non-heat treatment, fermented non-heat treated products, heat treated or frozen products. Edible casings used for sausages etc. also come in the category of meat and meat products. Through a notification dated 12^th September, 2017, the FSSAI has included domestic rabbits (Oryctolagus cuniculus) in the Food Safety and Standards (Food Products Standards and Food Additives) Regulation 2011 in the regulation under meat and meat products.

With the advent of globalisation, there has been an increase in food trade which has led to the introduction of exotic meat and meat products. Moreover, rapidly growing economies like India, now demonstrate a growing appetite for meat. As the consumer demand for high quality meat is increasing in most countries, the meat industry should consistently produce and supply quality meat that is safe and healthy for the consumer to ensure continued consumption of meat products.

Introduction

Milk, an integral component of our staple diet is nature's most ideal and complete food. There is a long history and tradition of high consumption of dairy products in India. Consumption pattern of dairy products in India is quite unique and is centred on traditional products; however, novel products are gradually gaining momentum in urban areas. Despite being the largest milk producing country in the world, India accounts for a negligible share in the worldwide dairy trade. Domestic demand for dairy products is showing an increasing trend and it is expected that demand-supply gap will further widen which might transform India being a net importer of dairy products. The domestic demand for dairy products is showing an increasing trend and it is expected that demand-supply gap will get further widened. India, world’s largest milk producer has enough scope for diversified value addition as this can definitely assure a better margin of profit. However, for this, one has to maintain reputation and competitiveness in the market. To emerge as a leader in this competitive global market, continuous improvement of quality is highly essential. Safety, just as the other side of the coin is also of utmost importance to reinforce consumer confidence. Nowadays, quality is not a matter of choice but a necessity and even a responsibility of all stake holders. In the case of food, the term, 'Quality' refers to physical, chemical, microbiological, technological, economic and aesthetic characteristics. From consumer point of view, the word, 'Quality' embraces mostly the organoleptic characteristics like body, texture and flavour than the objective properties like fat, protein, lactose and acidity as determined by science based tests.

Introduction

Over centuries, spices have been used as an important addendum for colour, flavour and preservation of foods. In addition, their medicinal and cosmetic utilities have been widely recognized (Purseglove et al., 1981; Srinivasan, 2005). All these benefits made them extremely desirable with an ever growing demand in the international market. India holds the title of the largest producer and exporter of spices with major share for pepper, capsicum, turmeric, ginger cardamom, seed spices, curry powders, spice oils and oleoresins. The other primary producers of spices includes China, Indonesia, Malaysia, Egypt, Turkey Brazil and Mexico while USA, Europe, Japan, East Asian and Middle East countries are their major importers.

Spices are made from diverse plant parts viz. rhizomes, barks, leaves, fruits and seeds and hence its processing methods vary depending on the raw material. However, the basic unit operations namely harvest, pre-treatment, drying, cleaning, particle size reduction, packaging and microbial decontamination in sequence remains common for the production of most of the spices. Inappropriate conduct of basic unit operations often lead to high microbial load, aflatoxin contamination, losses of valuable compounds, change in sensory characteristics, physical damages and incorporation of contaminants in spice products (Table 1). Moreover, spices being natural products, they may be fraught with a large number of microorganisms including several pathogenic species of bacteria and fungus depending on the prevailing conditions in their cultivation areas. In addition, poor food sanitation awareness and practices in spice producing countries may worsen their microbiological safety. Although spices are nonperishable in nature due to their low moisture contents after drying, they may act as a source of microbial populations upon contact with moist food products with no further thermal treatment. The outbreak of ‘salmonellosis’ in Germany (1993) due to contaminated paprika and paprika-powdered potato chips is an example. The aforesaid disadvantages related to conventional spice production may confound their international trade unless desired objectives of food safety management schemes such as International Commission on Microbiological Specifications for Foods (ICMSF) are met. Moreover, international agencies have set standard to guarantee safe spices and augment business interests of their adherents. For example, both the European Spice Association (ESA, 2015) and American Spice Trade Association have set a maximum level of 1% w/w extraneous matter in spices (ASTA, 2017). These challenges associated with the conventional production system may be effectively addressed by preventive risk management strategy by which suitable control measures are enforced at earlier phases of food chain prior to consumption. The control measures must guarantee that the level of contamination has not exceeded the maximum permissible limit at every phase of spice production from farm to table.

Introduction

As the world population continues to grow, the global market for food products is expanding, together with an increased emphasis on food safety. Consumers have become more discerning in the type of foods they buy and how these foods affect their health and well being. Food safety is generally defined as the assurance that the food will not cause any harm to the consumer when it is prepared and/or eaten according to its intended use ( To achieve food safety, a management system has been developed which aims on preventing problems before they occur, rather than trying to detect failures through end product testing. It also places more responsibility for ensuring food safety on food manufacturers, who have to develop control and traceability of their products from ‘farm to plate’. The system requires the identification of specific hazards throughout the entire process of food production, concentrates on the points in the process that are critical to the safety of the product, and highlights measures for their control (Henson and Caswell, 1999).

Introduction

Tropical tuber crops viz., cassava (Manihot esculenta Crantz), sweet potato (Ipomoea batatas), taro (Colocasia esculenta), yams (Dioscorea sp.), Elephant foot yam (Amorphophallus paeoniifolius), arrowroot (Maranta arundinacea) etc., are the important sources of starch after cereals and are used as staple or supplementary food in many of the tropical and sub tropical countries. Being the crops with adaptability to wide range of soil, climate and environment of the tropics and sub tropics and requiring minimum agronomic input and care for growth, they can be very well fitted into the prevailing cropping systems. They are the most efficient converters of solar energy and have the ability to reserve energy in the form of carbohydrate in the bulky roots and hence tuber crops are also called as calorie density crops. Tuber crops, though branded as poor man’s crops in rural areas have considerable unrealized potential for processing into high end products for food, feed and industrial uses. They are generally consumed as vegetable after boiling it in water and eaten along with some spicy curry or by extracting starch or flour. Besides serving as an insurance crop during times of food scarcity, it can also function as an industrial raw material for a wide spectrum of products

Introduction

India, with its unique agro climatic conditions is capable of producing a wide variety of fruits and vegetables. These highly perishable produce in both fresh and processed forms are of high demand in domestic as well as international market. Nowadays farming is becoming an enterprise and shifting towards consumer driven agriculture. Produce quality measurement is of utmost importance as consumers are more quality conscious and ready to pay higher for quality. Consumer preference is moving towards healthy food, minimally processed and, fresh cut fruits and vegetables, prepared salads, ready to cook, ready to eat and ready to drink health beverages. Hence health, nutrition, convenience, quality and safety of produce should be guaranteed to the consumers. Due to globalisation of production and trade, legislations and standards for markets are strict and product quality is the necessity for competitive markets.

Quality of a produce, based on subjective and objective measurement, is defined differently by consumers, wholesalers, retailers, processors or any other who is associated with it and varies with market either national or international. Quality of foods may be defined as the composite of those characteristics that differentiate individual units of a product, and have significance in determining the degree of acceptability of that unit to the user (Kramer, 1965). According to ISO (International Organisation of Standardisation), “Food quality is the totality of features and characteristics of a product that bear on its ability to satisfy stated or implied needs” and as per CAC (2003), “Food safety is the assurance that food will not cause harm to the consumer when it is prepared and/or consumed according to its intended use”. Food safety is the most important component of quality.

Introduction

Water is not only a vital environmental factor to all forms of life, but it has also a great role to play in socio-economic development of human population. Since antiquity humans have valued the importance of clean water and have used various techniques to improve its quality. In modern times, the safe drinking water became first a public health issue and then a human rights issue. The access to safe drinkin gwater now considered as a basic human right which is an essential component of effective policy for health protection. Improving access to safe drinking-water can result in tangible as well as intangible benefits to health. It has been shown that investments in water supply and sanitation can yield a net economic benefit, because the reductions in adverse health effects and healthcare costs outweigh the costs of undertaking the interventions (WHO, 2017). Past experiences have also proved that interventions in improving access to safe water favour the poor in particular, whether in rural or urban areas, and can be an effective part of poverty alleviation strategies. The disparity in water availability, reliability, and quality between the developed world and developing countries is enormous. Unfortunately, in many developing countries people lack access to safe water and therefore waterborne diseases are still a major cause of death, especially among children under age of 5. According to a joint report by World Health Organization (WHO) and United Nations International Children’s Emergency Fund (UNICEF) (WHO/UNICEF report 2017), around 2.1 billion people worldwide lack access to safe and readily available water at home, and around 4.5 billion, lack safely managed sanitation facilities. Moreover, many of these countries that have set drinking water standards often lack the resources to implement or enforce them.

Introduction

Food grains have been the key component of the human diet for thousands of years and have played a vital role in framing human civilization. Rice, wheat, and maize, and to a lesser extent, coarse grains are major staples, crucial to the daily endurance of billions of people around the world. Cereal grains are consumed by more than 50% of world population to meet daily calorie requirements. Most grains undergo a milling process that ideally removes the outer bran (pericarp) and germ layers; catering to consumer market requirements. To a farmer, yield is the most prominent aspect. As the grain moves along the supply chain, and as the product reaches the market, quality becomes the key determinant of its sale-ability and economic value. Grain quality is defined by a range of physical and compositional properties where threshold necessities are set according to end consumer use requirements. Most industries and consumer markets have become habituated over the years to demand grain with specific attributes. Where consumers are close to the source of grain production (e.g. in local markets), their own preferences and the laws of supply and demand control the grain quality. However, where grain is traded over large distances, particularly internationally, consumers almost have no direct influence on quality, requiring regulatory standards to be established and imposed to protect consumer rights. Therefore in the grain supply chain, all points have effects with respect to grain quality.

Introduction

The world does not function without mathematics. In our day-today life we come across many problems which are solved mathematically. The mathematical logical system follows “Yes” or “No”, “True” or “False”, “1” or “0” which are precise outputs for the precise inputs. There are several ambiguous or vague problems which cannot be given with accurate precise value with the conventional logical operators. Beyond this Boolean logic operator the logical system which mimics the human brain and gives precise solutions for the imprecise linguistic variables is the Fuzzy logic system. Fuzzy logic is a novel approach that intends to imitate human reasoning using calculations and operations with fuzzy systems and linguistic variables. The problems with vague imprecise data which we come across in our day today life cannot be solved by conventional binary logical method. The fuzzy logic solution spontaneously splits a complex problem into its component parts. This reduces the solution to its component parts. Compilers may re-assemble the code for effective execution on some target, but at the programmer level the problem is a number of simple tasks.

Fuzzy sets theory was introduced by Zadehin the year 1965, and it allows uncertain phenomena to be treated mathematically.

Introduction

The food that we consume should not only contain all essential nutrients like carbohydrate, protein, fat, vitamins, minerals, fibre etc but also should be hygienic and safe. Safety and quality of food is to be ensured not only during food production but also should be continuously monitored till it reaches the consumer (Coles and Frewer, 2013). The characteristics of food are altered during every processing operations viz., cleaning, sorting, transportation, thermal processing, packaging, storage, distribution etc which may be desirable or undesirable. Persistent physical, chemical and microbiological analyses have to be done at all levels of supply chain to ensure the quality of food. Traditional methods of food safety analysis are spectrophotometry, aerobic plate count method, microscopic plate count, titrations, chromatography etc. Though these techniques provide accurate results, the analysis demand cumbersome extraction steps, trained technical staff and are time consuming (Di-Natale et al., 2000). Hence, steady, sensitive and rapid monitoring of food analysis technique is a need of the hour in the present era. Biosensors can effectively replace the conventional techniques owing to its reliability, rapidity, economic and field applicability (Prasad et al., 2014). Biosensors are an attractive diagnostic alternative owing to their in situ detection ability and comparatively reduced detection time from several days to hours, or even minutes (Ruiz et al., 2017). Rapid food analysis can also minimise spoilage, especially in freshly harvested agricultural commodities, such as fruits and vegetables, meat, fish etc. In addition, the portable detection devices provide in-situ detection capabilities without extensive training and assist in integrating real time analysis in food processing centres.

The safety of the food supply suitably remains a high main concern for industry stakeholders, regulatory agencies and patrons. With the surfacing of new safety challenges and issues, companies are establishing and upgrading programs to reduce risk factors. These programs are constantly monitored for reliability, repeatability, reproducibility and effectiveness. Due to the health and safety risks posed by chemical, microbiological and environmental contaminants, analytical methods are progressively more becoming a pride and joy of food safety programs. Innovative analytical approaches are being developed in response to budding food safety issues. To monitor for known issues only the established and officially approved methods are used often. Oftentimes, new analytical methods are developed, improved or modified quickly in response to issues, such as melamine contamination, which are unforeseen. In such instances, accurate data derived from sound, validated analytical methods are required to facilitate industry stakeholders and regulators to make sound methodical decisions.

Through research, industry has improved a host of analytical methods in recent years, resulting in higher sensitivity and accuracy for difficult-to-detect contaminants, detection of contaminants in new matrix classes for grades. These advances have been made in the face of changing set of laws, more painstaking method-validation standards and end user demands for safe, quality products. Further to this, this spirit of innovation will continue to be fundamental in industry’s efforts to ensure the safety of the comprehensive food chain.

Introduction

For the year 2016-17, as per the FAO global estimate, the food grain production has crossed over 2.6 trillion metric tons, while the steadily increasing the demand is anticipated to be approximately 3.3 trillion metric tons for 2016-17. Similarly,the global production of all horticultural commodities has crossed over 1.8 trillion metric tons. The global trade of these commodities is purely based on their quality, the demand for good quality produces increases day by day. The term “quality” is a broad terminology used to explain many parameters and differs from commodity to commodity. Usually, the term ‘quality’ is classified into internal and external quality. The external quality refers the external colour, size, shape appearance, uniformity, external damage, cracks and bruishness etc. These parameters may be common for both perishables and durables.

But, in case of internal quality, each and every parameter vary from commodity to commodity, product to product. For food grains, the internal quality refers to moisture content and other nutritional parameters like carbohydrate, protein content etc. But in fruits, the internal quality refers to internal pulp colour, TSS, pH, acidity, juice content, ripeness, other biochemical and nutritional quality parameters. 

Introduction

Food safety and quality assumes paramount significance in any food industry. Globalization has driven both the food and agricultural firms to adopt systems that functions in a way to interlink food standards and international trade so as to achieve superior food quality and safety. Food industries follow several regional and international food safety procedures to procure certification from the government and other agencies in order to survive in both domestic and international markets (Ryan, 2014). The essential components in the food safety include handling, preparation and storing of the food products to ensure the food quality and to avoid food-borne diseases. The unwanted substances in a food product included by an accident is known as contaminants and the unwanted substance added to the food product to reduce the cost or to improve the other properties are known as adulterants. Contaminants and adulterants may lead to pathogens and toxins that pose serious concerns over the health of the consumer (Jha, 2016). The adulterants and contaminants are classified as physical adulterants and contaminants, chemical adulterants and residues, microbiological and pathogenic contaminants and toxins.

Hazards in food can be categorized into physical, chemical and biological.

Physical Hazards: Physical hazards are foreign organic or inorganic objects or extraneous materials in the food products. Hard and sharp physical hazards are of particular concern. Examples of physical hazards are broken glass, plastics, metal pieces, wood pieces, stones etc.

An electron impringing on a solid surface may be scattered once, several times, or never. When an incident electron beam bombard atoms of the sample, secondary electrons (SEs) and backscattered electrons (BSEs) emerge from the sample surface. Multiple scatterings occur if the dimension of the material is greater than approximately twice the mean free path of the electrons. This scattering may be elastic or inelastic. A pear shaped volume (interaction volume) is formed as shown in Fig. 1 and this volume of excitation increases with increase in the beam voltage (electron energy) and decreases with the increasing specimen density (ion atomic number).

X-ray diffraction (XRD) is an important experimental tool used in determining crustal structure of material system in bulk and nanoregimes. Therefore, it is important to understand the basic concepts of XRD.

Characterization Tools: Microscopy

Chemical Synthesis Methods

Several methods can be used for the production of these nanoparticles, namely: (i) top-down methods (Li et al., 2006) such as vacuum sputtering (Kuhn et al., 2002) or the decomposition of iron penta carbonyl (Fe(CO)5) in organic solvents (Karlsson et al., 2005); and (ii) bottom-up methods that promote the ‘growth’ of the nanostructures via chemical synthesis, for example through the reaction of iron(II) or iron(III) salts with sodium borohydride (Wang and Zhang, 1997). However, these methods present several limitations and problems; the top-down methods are generally expensive and require specific and costly equipment while the drawbacks of the bottom-up approaches are related to safety issues due to the toxicity of sodium borohydride, the production of flammable hydrogen gas during the process (Li et al., 2006), and the tendency to form large agglomerates, very fast and at a high extent, and therefore have a reduced reactivity and degradation efficiency.

Aim

To synthesize Zero valent (Fe) (nZVIs) iron using tea leaf extract.

Introduction

In this approach extracts of natural products (in most cases green tea leaves) with high antioxidant capacities are used. The compounds present in these extracts react with Fe (III) in solution to form nZVIs (Nadagouda et al., 2010).

Aim

Phytosynthesis of silver (Ag) nanoparticles using Cassia roxburghii aqueous leaf extract.

Introduction

The Ag nanoparticles constantly exhibit adverse effects on microbes such as inhibition and inactivation (Nasrollahi et al., 2011). The Ag nanoparticles synthesized by using various biological sources such as herbs, plants and biological organisms display excellent properties in various fields i.e., non-linear optics and intercalation materials for electrical batteries as optical receptors, catalysts in chemical reactions biolabelling and as antibacterials (Sanghi and Verma, 2009).

Aim

To synthesize gold (Au) nanoparticle using fungal mycelium.

Introduction

Biosynthesis of nanoparticles is a kind of bottom up approach where the main reaction occurring is reduction/oxidation. The fungal enzymes are usually responsible for reduction of metal compounds into their respective nanoparticles.

Aim

To synthesize phosphorus (P) nanoparticles from tricalcium phosphate using fungal mycelium.

Introduction

Green nanotechnology includes a range of processes that reduce or eliminate toxic substances to restore environment. Microorganisms like fungi and bacteria having naturally bestowed property of reducing and oxidizing nanoparticles, are used for synthesis.

Biological synthesis of Zinc Oxide (ZnO) nanoparticles

Aim

To synthesize nano ZnO particles using fungal isolates.

Introduction

The ZnO nanoparticle are effective anti-bacterial and antiodur agent. Biological synthesis of ZnO nanoparticle is a new approach for environmentally benign protocol in context to green nanotechnology, (Raliya and Tarafdar, 2013).

Polymer Clay Nanocomposites

Polymer clay nanocomposites has been used as to affect permeability of the maternal to gases and vapours. Majority of papers on nanocomposites have been focused on the use of smectitic type clays as nanoparticles. They are a group of swelling type of clay minerals including montmorilonite, nontronite, saponite, sauconite and hectorite.

A number of polymer-layered silicates (PLS) preparation methods has been reported in literature. The three most common methods to synthesize PLS nanocomposite are intercalation of suitable monomer and subsequent in situ polymerization, intercalation of polymer from solution and polymer melt intercalation.

In general, layered silicates have layer thickness on the order of 1 nm and a very high aspect ratio (e.g. 10–1000). A few weight percent of layered silicates that are properly dispersed throughout the polymer matrix thus create much higher surface area for polymer/filler interaction as compared to conventional composites. Depending on the strength of interfacial interactions between the polymer matrix and layered silicate (modified or not), three different types of PLS nanocomposites are thermodynamically achievable (Fig. 1 and 2 ) as outlined by Sinha Ray and Okamoto (2003). They are as follows:

Zerovalent (nZVI) Ionic Compounds

Although Ag⁺ contains a filled d¹⁰ shell, the structures of Ag compounds can in many instances be understood only if one assumes the existence of weak attractive Ag⁺ - Ag⁺ interactions. Similar attractive forces have been shown to be responsible for the formation of gold cluster compounds. In Ag⁺ solid state compounds the unoccupied 5s and 5p orbitals give rise to empty bands which may be partially occupied thus resulting in subvalent Ag compounds; examples are Ag₃O and Ag₂F. The compound Ag₅SiO₄ prepared from Ag and Si0₂ at 350 °C under a high pressure of oxygen, contains [Ag₆]⁴⁺ clusters (average oxidation state 2/3) and should be formulated at [Ag₆]⁴⁺ (Ag⁺)₄ (SiO₄ ^{4 -})₂.

Ag and Au forms numerous cluster compounds in which the metals are zero valent or subvalent. Examples are Ag₆ Fe₃ (CO)₁₂ {HC(PPh₂)₃} and paramagnetic cluster ions [Ag₁₃ Fe₈ (CO)₃ ²]^4-.

Introduction

Hydrogels are loosely cross-linked, highly hydrophilic, organic polymers. They can absorb and retain aqueous fluids up to 500 times of their own weight (Singh et al., 2011). In the field application, such absorbents exhibited a limited swelling capacity within the soil matrix.

Aim

To synthesize chitosan/nanosilica coating solution for fruit coating aiming at increasing shelf life.

Introduction

Application of edible coatings is promising to improve the quality and extend shelf life of fruits and vegetables (Lin et al., 2011). Chitosan, a versatile biopolymer derived from deacetylation of chitin had been widely applied in the fresh-keep field owing to its good biocompatibility, biodegradability, antibacterial activity and capacities to form film (Lin et al., 2011).

Aim

To synthesize silver (Ag) nanoparticle.

Introduction

The Ag nanoparticles easily interact with other particles and increases their antibacterial efficiency. The Ag nanoparticles can be synthesized using various methods: biological, chemical electrochemical, γ-radiation, photochemical, laser ablation etc (Udapudi et al., 2012). The most popular preparation of Ag colloids is chemical reduction of Ag salts by sodium borohydride or sodium citrate (Udapudi et al., 2012).

Aim

To synthesize iron (III) oxide (Fe₂O₃) nanoparticles

Introduction

Iron oxide nanoparticles have a number of applications in catalysis, sensors and high sensitive biomolecular magnetic resonance imaging (MRI) for medical diagnosis and therapeutics. They can be synthesize by the bottom-up approaches including the sol-gel technique.

Synthesis of Zn Oxide Nanoparticle

Aim

To synthesize Zn oxide nanoparticle

Introduction

Zinc oxide nanoparticle are effective anti-bacterial and antiodur agent. They can be synthesized by number of techniques including hydrothermal methods. Their synthesis using solvothermal process is described, (Aneesh et al., 2007).

Solid state materials can exists in various forms namely:

1. Single crystals (preferred for authentic characterization of structure and physical properties)
2. Polycrystalline powders that are agglomerates of large number of crystallites and are used for characterization when single crystal cannot be easily obtained
3. Nanocrystalline or nanostructured materials that posses large surface area
4. Thin films that can be grown in the best crystalline form for many applications
5. Amorphous systems that have no long-range translational order

History and Recent Developments

Richard P. Feynman in 1959 suggested that it should be possible to build machines small enough to manufacture objects with atomic precision. His talk “There is plenty of Room at the Bottom” is widely considered to be the foreshadowing of Nanotechnology. He delivered this talk at the annual meeting of the American Physical Society at California Institute of Technology (Caltech), In 1990, a team of IBM Physicists revealed that they could write (arrange) the letter IBM using 35 individual atoms of Xenon.

In 1992 a book entitled Nanosystems: Molecular Machinery, Manufacturing and Computation was published by Eric Drexler where he outlined a way to manufacture extremely high performance machines out of molecular carbon lattice (diamondoid).

Around year 2000, federal funding for Nanotechnology in the United States began with National Nanotechnology Initiative (NNI). NNI defined nanotechnology as dealing with materials with sizes between 1 and 100 nanometers exhibiting novel properties.

The Government of India, in May 2007 launched a mission on Nano sceince and nano technology (Nano Mission) with an allocation of `1,000 crores.

Leaf Spot

Colletotrichum capsici

Economic Importance

• The disease is common in many parts of South India, and in recent years has become very severe, causing much damage to the crop.
• The yield losses occur due to leaf spot infection is through the loss of photosynthetic green surface.
• During the period of heavy infestation, yield loss could be as much as 50%.

Damping Off

Pythium aphanidermatum

Economic Importance

• The disease is reported from China, Indonesia, South Africa and the USA.
• It causes extensive damage in the tobacco tracts of Andhra Pradesh, Maharashtra and Gujarat in India.
• The damage in some areas can be hundred percent, in the absence of protective sprays.

Wilt

Fusarium oxysporum f.sp. vasinfectum

Economic Importance

• Wilt is one of the major diseases of cotton, found wherever this crop is grown like Mexico, African countries, France, Italy, Yugoslavia, India and West Indies.
• In India, the disease was first reported from Nagpur by Evans in 1908.
• It appears in almost every cotton tract of the country. However, it is more or less absent in the loamy soils of Indo Gangetic plains and sandy loams of Maharashtra, Tamil Nadu, Karnataka and other States.
• In affected susceptible varieties yield losses exceed 45-50%.

Red Rot

Colletotrichum falcatum (Perfect stage: Physalospora tucumanensis)

Economic Importance

• The disease is so devastating in nature that it has been referred to as cancer of sugarcane.
• Red rot occurs in all sugarcane growing tracts of India and several epiphytotics have been recorded in the past from states like U.P., Bihar, Haryana, Punjab, Andhra Pradesh and Kerala.
• In U.P and Bihar, the two popular varieties, namely, CO 213 and CO 312 were badly hit by the epidemics of 1938-40 and 1946-47.
• There have been reports of red rot epidemics in many other countries viz., USA, Mauritius, Australia, Hawaii and Myanmar.
• Red rot also causes appreciable damage to canes in Bangladesh, Taiwan and Pakistan.
• The loss in cane yield has been estimated 12 to 44.5% and 35 to 86 % in cane yield of ratoon over preceding plant crops have different levels of disease.

Root Rot or Stem Rot or Charcoal Rot

Macrophomina phaseolina (Sclerotial stage: Rhizoctonia bataticola)

Economic Importance

• Root rot is an important disease of sesame as infection occurs from seed germination and emergence to adult plant stage.
• The losses incurred are even up to 100 per cent, if conditions are favorable.

Wilt

Fusarium oxysporum f.sp. carthami

Economic Importance

• The disease was reported for the first time from America in 1950.
• Wilt is a devastating disease infecting the crop right from seedling to maturity resulting in crop losses to varied degrees depending on the severity of infection.
• The disease incidence has been reported in India to the tune of 80 percent under favorable condition.

Wilt

Fusarium oxysporum f.sp. carthami

Economic Importance

• The disease was reported for the first time from America in 1950.
• Wilt is a devastating disease infecting the crop right from seedling to maturity resulting in crop losses to varied degrees depending on the severity of infection.
• The disease incidence has been reported in India to the tune of 80 percent under favorable condition.

Ozonium Wilt

Ozonium texanum var. parasiticum Thirum / Guizotia abyssinica

Economic Importance

• The disease was reported around Varanasi.
• Heavy losses are incurred as the diseased plants dry.

Wilt

Fusarium oxysporun lini

Economic Importance

• The wilt is very serious disease and occurs in almost all the countries where linseed is grown.
• Continuous cropping in the infected field makes the soil sick.
• Yield losses upto 80 percent has been reported due to this disease. However, in severe cases crop is destroyed completely.

Seedling Blight

Phytophthora parasitica

Economic Importance

• Seedling blight is wide spread in Africa, India and other Asian countries.
• The average economic loss due to the disease has been 10%.

White Rust

Albugo candida

Economic Importance

• White rust is an important disease affecting mustard crop in world.
• Countries where the disease occurs include the Brazil, Canada, Fiji, Germany, India, Japan, New Zealand, Pakistan, Turkey and UK.
• Up to 60 per cent or more yield losses on B. rapa and B. juncea from this disease have been reported in India.

Root Rot or Charcoal Rot

Rhizoctonia bataticola

(Pycnidial stage: Macrophomina phaseolina)

Economic Importance

• Charcoal rot is of great economic importance in the World and has been found to reduce head weight and diameter, stem height and weight and in particular, the stem girth and root weight of sunflower plants.
• The first report of the occurrence of charcoal rot on sunflower was from Sri Lanka by Small (1927).
• Under favourable condition, losses can reach 60-90%.
• Infected plants generally die before seed set is finished.

Tikka or Leaf Spot

Cercospora arachidicola/ Phaeoisariopsis personatum

Economic Importance

• Tikka disease of ground nut is regarded as the most important fungal disease of this crop.
• The infection appears when the plants are one to two month old; one can see this disease in the month of September in the plains of our country.
• Losses due to this disease may go up to 15-50%.

Dry Root Rot / Charcoal Rot

Macrophomina phaseolina

Economic Importance

• Dry root rot has been found in most of the soybean-growing areas of the India.
• The disease has been increasing in importance and can result in substantial yield losses.
• In most fields, stand losses range from less than 5% to over 50% in severe cases.
• It is most prevalent on seedling and young plants, causing a root and stem rot.

Anthracnose

Colletotrichum lindemuthianum, Glomerella lindemuthiana Shear [teleomorph]

Economic Importance

• Anthracnose is an important disease in Kenya, Uganda, Brazil, Argentina, Mexico, Guatemala, Costa Rica, Nicaragua, India, Peru, Ecuador, and Colombia .
• The disease causes huge losses in temperate and subtropical zones.
• Yield losses of 95% have been recorded in Colombia and over 92% in Malawi.
• Anthracnose also affects seed quality and marketability of the crop.

Anthracnose

Colletotrichum lindemuthianum (Sacc. & Magnus)

Glomerella lindemuthianum Shear

Economic Importance

• Anthracnose warrants a serious attention as it inflicts heavy economic losses to the crop, which may reach up to 100%, under conducive conditions.
• In India disease incidence has been reported to vary between 24.59 to 51.72 per cent.
• In Jammu region of Jammu and Kashmir state disease incidence of 63.46% was recorded.