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Atmospheric pressure is the force per unit area exerted on a surface by the weight of air above that surface in the atmosphere of earth. The gas molecules of the atmosphere are pulled towards the earth by the force of gravity and hence exert a force on earth surface. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. Atmospheric pressure influences other weather elements in a significant way. Small changes in air pressure may not be felt, but they are important for bringing a change in weather. Atmospheric pressure can be calculated as the summed weight of all gas molecules between a horizontal plane and top of the atmosphere and divided by the area of the plane. Low pressure areas have less atmospheric mass above their location, whereas high pressure areas have more atmospheric mass above their location.

Measurement of atmospheric pressure

The standard unit of pressure in the SI system is the Pascal which is the name given to one Newton per square metre (N/m²). For meteorological purposes, standard sea-level pressure is 101325 pascal (Pa). To simplify this large number, the millibar unit (mb) has been adopted, which is equal to 100 pascals. Units like kiloPascal (kPa) or hectoPascal (hPa) are also used to measure pressure. 1 kiloPascal is equal to 10 millibars and 1 hPa is 1 millibar. The standard sea-level pressure is represented as 1013.2 mb or hPa.

Soil temperature is an important environmental parameter for plant growth and development. It has direct effects on microbial growth and development, organic matter decay, seed germination, root development, and water and nutrient absorption by roots. In general, the higher the temperature the faster these processes occur. Variation in soil temperature is much more pronounced because of varying characteristics and composition of soil.

The soil gains heat by absorption of solar radiation and longwave counter radiation from the atmosphere, downward transfer of sensible heat and horizontal transfer of heat from the surroundings. On the other hand, soil loses heat by longwave radiation to the atmosphere, upward transfer of sensible heat to air when the soil surface is hotter than air and with evaporation and horizontal transfer of heat from the column to surroundings.

Temperature is the physical property of an object that quantitatively expresses the hotness or coldness. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot. When a heat transfer path between them is open, heat spontaneously flows from bodies of a higher temperature to bodies of lower temperature. If no net heat flow occurs between two objects, the objects have the same temperature which are then said to be in ‘thermal equilibrium’. Temperature plays an important role in all fields of natural and applied sciences. Most of the weather parameters are dependent on it, directly or indirectly. It has important role to play in the development and growth of all living organisms in all stages of their growth.

Atmosphere receives the heat energy from the sun and its temperature increases. Due to different amount of heat energy receipt at different places, the air temperatures at different places also vary. The variation in air temperature basically results into air motion, so as to equalise the energy content of the different regions of the earth. Thus, atmospheric temperature is one of the basic elements of weather and climate.

Sun is the prime source of energy injected into the earth’s atmosphere. The sun is the nearest star to the earth. It is a hot ball of glowing gases at the heart of the solar system. Its radiant energy is practically the only energy source to the earth. Very small and insignificant quantities of energy are available from other sources such as the interior of the earth, the moon, and other stars. Without the sun’s intense energy and heat, there would be no life on earth.

The mean distance of the sun from the earth, also known as one astronomical unit (1 AU), is approximately 1.496 × 10⁸ km, though the distance varies as the earth revolves round the sun in an elliptical orbit. At this average distance, light travels from the sun to earth in about 8 minutes and 19 seconds. The energy of the sunlight supports almost all life on earth by photosynthesis, and drives earth’s climate and weather. The minimum sun-earth distance is about 0.983 AU and the maximum is approximately 1.017 AU. The earth is at its closest point to the sun (perihelion) on around January 3 and at its farthest point (aphelion) on around July 4.

The sun makes up about 99.86% of the mass of the entire solar system. The visible disk or photosphere has a radius of 6.599 × 10⁵ km, and the solar mass is 1.989 × 10³⁰ kg. The sun is a completely gaseous body. The chemical composition (by mass) of the outer layers of sun is 71 per cent hydrogen, 26.5 per cent helium, and 2.5 per cent heavier elements like oxygen, carbon, neon, and iron among others. Since the sun is not a solid body, different parts of the sun rotate at different rates. At the equator, the sun spins once about every 25 earth days, but at its poles the sun rotates once on its axis every 36 days.

The gaseous envelope surrounding the earth is called atmosphere. Thus, atmosphere can be defined as the dynamic layer surrounding the earth above its surface containing various gases, moisture, aerosols, etc. The atmosphere is retained by earth’s gravity.

The atmosphere protects life on earth by absorbing ultraviolet solar radiation, warming the earth’s surface through heat retention and reducing temperature extremes between day and night. The common name given to the atmospheric gases used in breathing and photosynthesis is air. The atmosphere has a mass of about 5.15 × 10¹⁸ kg, three quarters of which is within about 11 km from the surface. The atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. The imaginary ‘Karman line’ lies at an altitude of 100 km above the mean sea level, and commonly represents the boundary between the earth’s atmosphere and outer space. The study of earth’s atmosphere and its processes is called atmospheric science or ‘aerology’. The atmosphere serves the life-system on the earth by the following activities.

Meteorology is derived from the Greek word meteoro which means above the earth’s surface; i.e., the atmosphere. The state of the atmosphere experienced at a given time, in any location on the surface of the earth is known as weather. Thus meteorology is the scientific study of the atmosphere or the weather. It is a branch of physics dealing with atmosphere and it is often quoted as the ‘physics of the lower atmosphere’. The main focus of meteorology is to understand the weather processes and forecast the weather. Solar radiation, the air mass and moisture are the three key ingredients that make up weather. The exchange of heat, moisture and momentum between the earth’s surface and the atmosphere determines the characteristic of weather. The observable weather events are known as meteorological phenomena and are defined by a set of variables called weather elements. Atmospheric temperature, atmospheric pressure, humidity, precipitation, cloudiness, wind and visibility, etc. are examples of such weather elements. The weather elements are not separate entities. They are closely related with each other and are highly variable in nature. Meteorology explains and analyses the changes of these weather elements.

Meteorology

The major subdivisions of meteorology are dynamic meteorology (or atmospheric dynamics) and physical meteorology (or atmospheric physics). The dynamic meteorology is concerned with the analysis and interpretation of the three-dimensional, time-varying, macro scale motions and energy transformations in the atmosphere. The science of dynamic meteorology is meant to develop models based on the hydrodynamic and thermodynamic equations. The physical meteorology is concerned with the processes that alter the physical properties and the chemical composition of air parcels as they move through the atmosphere.

Genetically modified organisms (GMOs) can be defined as organisms in which the genetic material (DNA) has been altered in a way that does not occur naturally. The technology is often called “modern biotechnology” or “gene technology”, sometimes also “recombinant DNA technology” or “genetic engineering”. It allows selected individual genes to be transferred from one organism into another, also between non-related species. Genetically modified (GM) foods are foods derived from genetically modified animals and marines. Genetically modified animals and marines are those in which specific changes introduced into their DNA by genetic engineering using a process of either Cisgenesis or Transgenesis. These techniques are much more precise than mutagenesis where animals and marines are exposed to radiation or chemicals to create a non-specific but stable change. Other techniques by which food animals can be modified are selective breeding and somaclonal variation. By this means desired quality of meat, egg and other animal products can be produced. But it is a common thinking that foods derived from genetically modified animals and marines are far from safe. They are likely to be contaminated by potent vaccines, immune regulators and growth hormones, as well as nucleic acids, viruses and bacteria that have the potential to create pathogens and to trigger cancer.

Organic meat food products are choice products for health conscious people. These are the products produced mainly in most natural way without using fertilizers, pesticides and growth regulators in their feed and fodders. In addition, meat animals are also reared without growth hormones, antibiotics drugs etc. and grazing of the animals is a prerequisite in organic farming system.

The term organic farming was first time used by Lord Northbourne. The term organic farming was derived from his concept of “the farm as organism”. It is a holistic, ecologically balanced approach to farming. In 1991, the European Commission formulated the first government system to regulate organic labelling. In India, standards for organic agriculture were announced in May 2001 and the National Programme on Organic Production (NPOP) is administered under the Ministry of Commerce. The concept of organic meat food products has been emphasized now a day due to animal welfare point of view, consumer’s conscious ness, less residue level of chemicals, antibiotics and drugs, Bovine spongiform encephalopathy (BSE), Foot and mouth disease (FMD), genetically modified food etc.

Organic meat food products as a whole are dependent on the life stages of the livestock like its origin, feeding, housing, health, breeding, transportation and slaughter. The other factors accounting for organic foods are its production, harvesting, preservation and processing. Inspite of low growth rate of organic red meat globally, growth in dairy, egg and poultry is increasing day by day. At present 1.2 million hectares (0.6%) of Indian land is producing organic products (Willer and Kelcher, 2011).

Meat and meat products industry is a sunrise industry in India having huge potential for upliftment of agricultural economy. India is the second largest food producer in world but the contribution of meat industry is still confined to localized handlers. So to uplift industry basic infrastructure, food chains, food security and safety along with standards and laws formulation and their implementations is today’s need. Standards are carefully drawn specifications with respect to a food product. These standards are mainly of three types i.e. government, trade and research standards. Government standards are formulated by the government of India or state government and also have the power to implement these standards while trade standards are implied by the individual company. Research standards are formulated on the basis of comparative study of the products by the researchers. Laws are the legislations enforced by the organisations either government or by autonomous bodies made under the constitutional acts of the country. At present numerous standards and laws are in existence in individual country or at international level. The need is to harmonize them as per the industry and trade requirement.

Domestic Organizations Involved in Standards and Laws Formulation

For the formulation, enforcement and control of standards and legislations at domestic level various organizations are of prime value. Some of these are:

Eggs are considered as Nature’s original functional food because they are abundant source of nutrients like vitamins and minerals. It contains valuable nutrients from the high-quality protein to significant levels of beneficial vitamins, antioxidants and other healthful compounds. The protein of eggs is considered as highest quality protein as compared to other animal protein sources which is readily available and most inexpensive. Eggs are good source of all well balanced nutrients for persons of all age groups. Egg is a unique combination nutrient like it is rich in protein and low in calorie. The nutrients concentration in eggs is dependent on breed, strain, species, feed, age, season, storage and processing methods.

The nutritional value of eggs lies chiefly in their proteins of good biological value; an average-sized egg (60 g) provides approximately 7 g of proteins. These proteins are rich in essential amino acids with a very good balance between these amino acids. So the egg protein can be regarded as a reference protein. On comparison we can say that 2 eggs provide as much protein as 100 g of meat or 100 g of fish. The energy value for an average egg (60 g) is approximately 376 Kj (90 kcal). The lipid content is 7 g, most of these lipids being contained in the yolk. Among the total fatty acids 2/3^rd of these are unsaturated. Egg also contains 180 mg of cholesterol and rich in vitamins (A, D, E) and trace elements (iron and zinc).

Sensory evaluation is a scientific method of evaluating foods including meat products that applies principles of experimental design and statistical analysis through the use of human senses like sight, smell, taste, touch and hearing. It is also called organoleptic evaluation in which we measure, analyse and interpret reactions to those characteristics of materials as they are perceived by the human senses. These attributes can be perceived well by the human sense organs as compared to instruments available for this purpose. It is a fact that no single instrument is able to assess all the attributes of meat products. With the help of these instruments we can very well evaluate the single quality attribute of meat product i.e. shear force instrument or penetrometer is good for knowing the texture and refractometer is for colour interpretation.

Physico-chemical and microbiological quality of meat and aquatic food and food products gives its overall safety and quality status as a food. The physico-chemical and microbiological qualities of raw material have great importance on the product development. It also affects the shelf life of the raw material as well as final product.

Fresh meat is a type of meat which has not been subjected to any processing whereas raw meat is a fresh meat which has undergone freezing. The qualities of fresh meat are important as far as merchandiser, purchaser and consumers are concerned and it is also important for adaptability in further processing. The important quality parameters of fresh meat are:

Formulation of meat and sea food products requires various ingredients which are commonly known as food additives. Food additives are those non-meat ingredients which are used to enhance colour, flavour, aroma and texture of the meat and sea food products. These food products can fulfil the demand of modern consumers. As per the definition of Food and Drug Administration (FDA) food additives are those substance which are used to provide a technical effect in foods. The use of food additives has become more prominent in recent years, due to the increased production of prepared, processed, and convenience foods. Additives are used for flavour and appeal, food preparation and processing, freshness, and safety. These additives can be classified as curing ingredients, extenders and binders, flavour enhancers and other additives. For the formulation of different products both raw materials and ingredients should be of food grade and sound hygienic strength. In the starting of this chapter we will discuss about ingredients used then the specific formulations will be discussed for better understanding of meat and sea food processing.

Curing Ingredients

Curing agents such as salt, phosphate, sugars, nitrite and nitrate, sodium ascorbate and erythorbate etc. have traditionally been used in various meat formulations from long back. The details of these ingredients have already been discussed in chapter-8 of this book. So we will try to discuss other ingredients which are relevant for meat and sea food products other than these ingredients. Cure accelerators such as ascorbates and erythorbates are used to speed the curing process. They also stabilize the colour of the final product. The examples are ascorbic acid, erythorbic acid, sodium erythorbate, citric acid, sodium citrate, sodium acid pyrophosphate, glucono delta lactone (GDL) etc. Glucono-delta-lactone (GDL) acts as a curing accelerator in meat and meat products. It is permissible up to 1% in sausages and up to this level it lowers the pH about 0.5 thus inhibits the growth of spoilage micro-organisms. GDL also facilitate the cured colour development.

Food packaging is an essential technique for preserving food quality and minimizing food wastage. It is a scientific technique of containing food against physical, chemical and microbiological contaminants. In addition package also display the product in most appropriate manner and provide product information to the consumers while at the same time allowing convenient handling and efficient distribution. The packaging of meat and meat products are particularly important because meat is highly nutritious food and provides good medium for the growth of micro-organisms. Meat and meat products are also susceptible to bacterial growth due to their high water activity. Exposure of meat and meat products on atmospheric temperature and sunlight leads to various types of deteriorative changes. For example when cut meat surfaces exposed to ambient air provide excellent breeding grounds for most bacteria. Minced meat is even more at risk due to the large exposed surface area. Packaging provides protection of food against external and internal factors but once food gets deteriorated it can not be controlled by packaging. For this reason rigorous hygiene in all processing and pre-packaging steps is vital for packaging of perishable food items like meat and meat products.

Meat processing is the set of methods and techniques used to bring substantial chemical and physical changes in the natural state of meat. These are the methods which are used for making meat and their products attractive, nutritious and marketable as well as for the prolongation of shelf-life. In processing techniques, grinding, chopping, addition of seasoning, alteration techniques for colour, heat treatments etc. are included but cutting, trimming and deboning are not included in processing operations.

History

Meat processing dates back to the prehistoric ages and probably the first processed meat product was sundried meat. Lator it turns to burning of meat over wood fire while salting and smoking of meat was practiced first time in the time of Homer, 850 B.C. In 63B.C.-14 A.D. at the reign of Augustus honey was tried for preservation of meat. Lator various types of cooking such as roasting, smoking, steaming and oven baking came in existance. Salt-preservation was especially common for foods including meat and meat products for warrior and sailor’s diets, until the introduction of canning methods.

Modern food processing technology in the 19th and 20th century was largely developed to serve military needs. In 1809 Nicolus Appert invented a vacuum bottling technique that would supply food for French troops and this contributed to the development of tinning and then canning by Peter Durand in 1810. Although initially expensive and somewhat hazardous due to the lead used in cans. Canned goods would later become a staple around the world. Pasturization discovered by Louis Pasteur in 1862 was a significant advance in ensuring the micro-biological safety of food. In 20^th century, food processing advances with the development of spray drying, freeze drying and the introduction of artificial sweeteners, colouring agents and preservatives such as sodium benzoate. In late 20^th century ready to eat meat food products were introduced to cater the need of consumers.

Ageing of meat is also known as conditioning or tenderising or ripening or maturing and sometime resolution of rigor. It is a process of holding unprocessed meat above freezing point under controlled conditions. By this process we can make muscle soft and pliable thus meat becomes tender. When we keep the meat above freezing point at temperature between 0-3ºC then all those changes occurs which are normally occurs at higher temperature i.e. atmospheric oxidation and enzymatic action of fat, bacterial action etc. When this temperature range becomes below freezing point then it inhibits completely the enzymatic action in the muscles. Ageing is required for marked increase in flavour, juiciness and tenderness of meat. In this process action of enzymes in meat plays key role while bacterial action is not of any importance. Meat tenderness and taste are definitely improved if carcasses or vacuum packed cuts are conditioned after slaughter but paradoxically beef is quite tender just two hours after slaughter and several days of conditioning are required to recover this degree of tenderness.

During the contraction of muscles, thick and thin filaments sliding to each other and decreases the length of sarcomeres. In turn, this decreases the length of fibrils, fibres and the whole muscle. If these muscles remain in contracted length when rigor develops, it causes massive overlap of thick and thin filaments leading to severe meat toughness. It is also necessary to avoid the cooling of meat too rapidly after slaughter, otherwise it cold-shortens and gets tough. If we avoid cold-shortening of muscles during conditioning, it will increase meat tenderness. But with too much conditioning, weight loss, surface spoilage and the cost of refrigerated storage increases.

Ageing of carcasses with little or no fat cover is not recommended by meat specialists. Because these carcasses loose moisture rapidly, loose weight excessively and discolour the meat surface rapidly. In addition, lean meat is also susceptible to deterioration through microbial growth, slime formation by bacteria and mould growth etc. Ageing is important for beef and buffalo meat while pork and lamb do not require ageing because they are slaughtered in the age where they are young and inherently tender. Additionally, the unsaturated fats found in pork fat oxidize during ageing causes rancidity and off flavour. Veal has very little protective fat covering and is high in moisture; thus it does not lend itself to ageing.

Preservation of foods including meat and aquatic foods is a creation of conditions for the food articles in such a way to stop or greatly slow down the activities of micro-organisms, chemical and enzymatic reactions and physical forces to prevent the meat and aquatic foods from spoilage while maintaining its nutritional value and sensory attributes.

Significance of Meat Preservation

1. Meat and aquatic foods are perishable food items and are very prone to spoilage and rancidity development due to high nutrients, moisture and neutral pH.
2. Once meat and aquatic foods is exposed to microbial contamination, chemical and enzymatic reactions then it will be very difficult to attain asepsis.
3. To enhance the keeping quality of meat and aquatic foods so that it will be available for further processing.
4. It protects meat and aquatic foods from shrinkage, sweeting and other physical forces.
5. To protect human health by providing the wholesome meat and aquatic foods to the consumers.
6. By this way we can minimize utilization of energy in processing of meat and aquatic foods.

Fraudulent substitution of meat is the adulteration or mixing of the inferior or cheaper quality meat into superior quality meat. The first case of fraudulent substitution was recorded in thirteenth century A.D. at Florence in Italy. A common fraud in the meat industry in which uninspected meat is substituted for meat that has undergone inspection and been branded as satisfactory. The other frauds are the substitution of meat of another species, e.g. horse for beef especially in Britain and Ireland, beef in kangaroo meat in Australia, cat for chicken or rabbit, goat meat for mutton, mutton for venison, dog meat and cat meat for chevon in other countries including India. As per an estimate about 25-30% of meat sold in India is adulterated. These practices are more common in comminuted meat products. These illegal practices are punishable under PFA act 1955. The choice of method to be applied is depend on the need or condition of meat recovered.

Meat is an animal flesh that is used as food. Most often, this means the skeletal muscle and associated fat but it may also describe other edible tissues such as organs, livers, skin, brains, bone marrow, kidneys or lungs. Meat is highly nutritious food because it contains protein, fat and carbohydrates in relative proportion, supply energy as required by the human body, posses ability to build or replace tissues and the substances present in meat are easily absorbed by the human body. Meat is also a good source of B-complex vitamins but fat soluble vitamins are low in meat. It is a good source of phosphorous, zinc and iron but low in calcium. Meat also contains significant amount of copper, sodium, potassium and magnesium but low in carbohydrate contents. Carbohydrate is found mainly in form of glycogen which disappears completely after completion of rigor mortis. In general lean red meat is particularly good source of protein, niacin, vitamin B6, vitamin B12, phosphorus, zinc and iron. About 100g of meat can provide more than 25% RDI of these nutrients. It also provides more than 10% RDI of riboflavin, pantothenic acid and selenium. Of the four meats, mutton is particularly nutrient-dense and the richest source of thiamine.

Conversion of muscle to meat is a complex process in which several physical and chemical changes takes place over a period of several hours or even days. The major changes which take place during this process include fall in muscle pH and temperature as well as muscle shortening which further leads to proteolysis or ageing. These changes during conversion of muscles to meat are variable and have great effect on meat quality (tenderness, juiciness, flavour, colour etc.) and also on certain processing characteristics like emulsification, binding properties and yield of the products. To know this complex process it is necessary to understand the process of energy production and metabolic pathway shifting in live animals.

Pre Slaughter

In the living animal, aerobic metabolism is used to obtain energy. The source of energy at this stage is either free fatty acids or blood glucose or muscle glycogen. In this process total 38 ATP molecules are produced from single glucose or glycogen molecule by the complex processes known as glycolysis, oxidative decarboxylation and oxidative phosphorylation. However, under stressful situations, anaerobic metabolism may be used and lactic acid is produced. Lactic acid is usually transported from the muscles to the liver, where it is re-synthesized into glucose and glycogen, or to the heart, where it is metabolized to carbon dioxide and water.