eChapters

Aim

To design a belt conveying system

Theory

The design of belt conveying system is based on available space, horizontal conveying length, conveying lift, characteristics of the materials to be conveyed and capacity requirement.

On the basis of overall requirement and information, the belt width, belt speed, required horsepower, maximum belt tension and breaking strength of the belt, diameter of the pulleys and idlers and quantity of belt (thickness) are determined to design a belt conveyor (Fig.32.1).

Greenhouse selection

Selection of greenhouse to be constructed is important as each type has its own merits and demerits. There are two common types of commercial greenhouses namely; (i) Freestanding (single span) and (ii) Ridge and furrow (gutter connected or multi-span). Multi-span structure permits economy in construction, heating and cooling but the single span gives flexibility as far as microclimate inside the greenhouse in concerned. The freestanding Quonset type is usually accommodates many growing situations but there height restrictions near the side walls. Another freestanding type is single gable greenhouse and its many variations. The ridge and furrow or gutter connected greenhouse are joined at the eave by a common gutter.

Aim

To measure horizontal distance on the level ground using chain

Materials required

Chain

Ranging rods

Chain pins

Field note book

Theory

Area computation is an important part of surveying. The term ‘Area’ is meant the projected area on a horizontal plane. The area is computed from the following methods: (i) Graphical method (ii) Instrumental method and (iii) Use of formulae. In graphical method, the area can be computed by dividing the whole area either into triangles or squares. The area of individual triangle is computed from base and the altitude and summation of individual area gives the total area. A tracing paper is divided into number of small squares is placed over the plan. The number of complete squares within the boundary is counted. The squares more than half are counted as full squares and those less than half are neglected. The total number of squares multiplied by the area of each square gives the total area of the field. In instrumental method, the planimeter is used to measure the area of a plotted plan. In use of formulae, computation of area by formulae depends on the shape of the field.

Aim

To identify different parts of prismatic compass and to know their functions.

To practice of taking the angular measurement.

Compass survey principle

Compass surveying is a branch of surveying in which directions of survey lines are determined with a compass and the lengths of the lines are measured with a chain or tape. In practice, the compass is generally used to run a traverse. In compass surveying, a traverse consists of a series of straight lines connected together to form an open or closed polygon as shown in Fig.44.1. The points A, B, C, D and E defining the ends of the traverse lines are called traverse station or traverse points. The lengths of the traverse lines are measured with a chain or tape. At each traverse station, where the traverse lines meet, the angle is measured with a compass.

Aim

To determine the area of the field by intersection method using a prismatic compass.

To determine the included angle of the closed polygon.

Materials required

Prismatic Compass

Tripod

Measuring tape

Arrows

Ranging Rods

Aim

To determine the reduced level of various points

To find out difference of elevations of two points

Materials required

Dumpy level

Levelling staff

Aim

To determine the reduced levels on various points on the road

To plot the profile of the road

Materials required

Dumpy level

Levelling staff

Theory

Profile leveling is the process of leveling along a fixed line to determine the elevations of the ground surface along that line. The fixed line is generally the centre line of a highway, railway, canal, sewer, etc. The profile leveling is done to determine the undulations of the ground surface. Cross-sectioning is required to determine the levels across the line along which profile leveling is done. Profile leveling should be commenced from a bench mark and should end at a bench mark, as far as possible. When the ground surface does not have many undulations, the intermediate points are fixed at a uniform interval. If the ground surface is irregular and there are abrupt changes in the ground surface, the interval may be non-uniform.

Aim

To measure the irrigation water by using weirs

a) Weirs

A weir is a notch or opening of some definite shape installed on a channel or a stream through which waterfalls (Fig.59.1). Materials like wood, concrete, mild steel, rigid PVC etc. can be used for construction of a weir. Mainly a cut on a sheet metal is used for fabrication of weirs, to be installed at various locations in a channel. Advantages of weirs are (i) capable of accurately measuring a wide range of flows (ii) easy to construct, portable and adjustable (iii) tends to provide more accurate discharge rating than flumes and orifices.

Aim

To measure the irrigation water flowing through a pipe by using Venturimeter

Theory

A venturimeter is a device used to measure the rate of flow of a fluid through a pipe and is often fixed permanently at different sections of the pipeline to know the discharge there. Venturimeter consists of three parts: (i) a short converging part (ii) a throat (iii) a diverging part (Fig.62.1). In the venturimeter, the fluid is accelerated through a converging cone of angle 15-20° and the pressure difference between the upstream side of the cone and the throat is measured, and provides the signal for the rate of flow. Due to the constriction there is an increase in the flow velocity and hence an increase in the kinetic energy. The fluid slows down in a cone with smaller angle (5-7°) where most of the kinetic energy is converted back to pressure energy. Because of the cone and the gradual reduction in the area there is no “vena contracta”. The flow area is at minimum at the throat.

Loquat (Eriobotrya japonica) is a subtropical evergreen fruit tree belongs to family Rosaceae and subfamily Pomoideae (Lindley, 1982). It flowers in early winter and fruits ripen in mid march and may where there is scarcity of fruits. It is native to southeast China and has been cultivated in China for over 2000 years and many species occur there in wild state (Lin et al. 1999). Loquat is introduced in India under the name of Japanese medlar or Java plum. In India, it is commercially cultivated in Uttarakhand, Uttar Pradesh, Delhi, Punjab, Himachal Pradesh and hills of southern states. Among different states Uttar Pradesh occupies the first position under loquat production.

Loquat is delicious fruit known for their mild, subacid and sweet taste. It contains 60 to 70 per cent pulp depending upon the cultivar and 15–20 per cent seed. In addition to 88% water pulp is composed of 55% vitamins and 0.5% minerals, 0.6% proteins, 9.6% carbohydrates and 1.0% fibre. Loquat fruit is also rich in phenolics and carotenoids.

The 20^th century had seen unprecedented increase in fishing capacity; in terms of the vessel number, increase in size of the vessels and advances in the electronic and navigational equipment coupled with easily manufactured and durable fishing nets. The effect of these innovations sequentially, was the burgeoning in the fish production, plateauing of catches and the myth of inexhaustibility of fishery resources in the sea was proven wrong. A large number of stocks world over have declined and the stock status of many are now alarming, but still the trend towards larger, more powerful and faster vessels continues.

Global fisheries production has reached a plateau and is now hovering around 80 million tonnes during the last decade. It is also noted that the status of world’s marine fish stocks have not improved overall. About 31.4% of assessed fish stocks are fished at a biologically unsustainable level and therefore overfished. Fully fished stocks accounted for 58.1% and underfished stocks 10.5%. It is evident that most of the stocks are fully fished with no further potential for increase in production.

The importance of reducing bycatch and minimizing ecological impacts of fishing operations has been emphasized by scientists and fishery managers and recognized by fishermen. Trawl fisheries in different parts of the world are now being required to use bycatch reduction devices as result of pressure from conservation groups and legal regimes introduced by the governments. The Code of Conduct for Responsible Fisheries (FAO, 1995), which gives guidelines for sustainable development of fisheries, stresses the need for developing selective fishing gears in order to conserve resources, protect non-targeted resources and endangered species. Although the problems of using non-legal gears and designs often with smaller mesh sizes are reported. Most of the problems due to generation of bycatch and damage to the ecosystem function, has been implicated due to trawling.

Quality of fish raw material plays an important role for the quality of the end-product. Once the fish raw material freshness and nutrition value is lost, it cannot be recovered in the processing stages. Products that are processed from low quality raw material are not always a safety risk, but the quality (nutrition value) and shelf life is significantly decreased. The quality deterioration can start right away during fishing and it continues all the way to the final user. Time-temperature abuse should be avoided at all stages of handling till landed fish reaches the consumer or the processor. In tropical countries more care in handling is necessary as fishes thrive in high ambient temperature has high body temperature and hastens spoilage.

Fish is highly perishable because of their chemical composition. It has high content of soluble substances in the flesh (many of which contain nitrogen and triglycerides characterized by polyunsaturated fatty acids) and high level of autolytic enzyme. After the death of the fish, spoilage starts due to the action of microbes, enzyme and oxidation. It is therefore, necessary to preserve fish after harvest if not consumed or disposed immediately.

Thermal processing also known as heat processing is commonly used processing method which helps in extending the shelf life of the food productswith high safety level, convenience and a healthy product.Seafood as a whole food is highly nutritious. Benefits to human health associated with the consumption of seafood is well recognized for multiple bodily organs and physiological functions but their high perishable nature is a concern. Seafoodundergoes spoilage due to autolytic, microbial action as well as oxidation of lipid. Proper handling and preservation is essential to maintain quality of fish. Heat processing is an age old preservation method practiced in many countries to extend the shelf life of food products. Heat treatment causes the destruction of microbes which increases the shelf life. There are number of thermal processing operations like- baking, blanching, canning, dehydration, extrusion, frying, pasteurization, sterilization, etc. All these operation serves various purposes and helps in manufacture of different food products.

Thermal processing is of utmost importance to low acid high water activity foods, where there are no hindrances to microbial growth. The proper delivery of heat is essential to cause the destruction of microbes to avoid food spoilage. In seafood’s processing, thermal processing through canning (retort pouch processing) is a common approach. In canning, the food is preserved by application of heat in hermetically sealed cans (pouches). Hermetic sealing means- complete airtight sealing. This prevents contamination from outside. Heating at very high temperature ranging from 110 to 135⁰C for a desirable time helps in killing all the vegetative forms of microorganisms as well as most heat resistant microbial spores. The amount of time needed for processing is different for each food type depends on hurdles present in the food and heat transfer characteristics. In thermal processing of seafood products, heat processing is aimed for the destruction of spores of Clostridium botulinum. A number of thermally processed ready-to-eat (RTE) products are available on market shelf.

Pre-processing of fish

Fish is a highly perishable food which requires proper handling and preservation to increase its self life and retain its quality and nutritional aspects. Therefore, fish pre-processing and preservation are become a very important part of commercial fisheries. Preservation means keeping the fish after landing in a condition of wholesome and fit for human consumption for a particular period. This preservation should cover the entire period from the time of capture of fish to its sale at retailer’s counter. The main aim of processing and preservation of fish is to prevent fish from deterioration. Methods which are commonly used to preserve fish and fishery products include the control of temperature using ice, refrigeration or freezing and control of water activity by drying, salting, smoking or freeze-drying etc (FAO, 2011). Fish has to be pre-processed in such a manner that it remains fresh for a long time with a minimum loss of flavour, colour, taste, odour, nutritive value and digestibility. Fish processing can be subdivided into fish handling which is the preliminary processing of raw fish and the manufacture of fish products.

Drying

Drying is one of the age-old techniques for preservation and value addition of food products. Generally, it means removal of moisture from the food products by evaporation. It is aimed at lowering the water content of food stuff, thereby arresting the growth of microbes, action of enzymes and other autolytic chemical reactions (Naidu et al., 2016). This preservation technique is predominately used for food materials which are regarded as “highly perishable”. The benefits of drying includes extended shelf-life, lower storage space, reduced packaging requirements, lower handling and transportation costs, off-seasonal availability and importantly diversified product for the ultimate consumers (Bonaui et al., 1996).

Fish drying

Open sun drying as a method of fish preservation is recorded in history by the primitive societies. However, open sun drying of fish has few draw backs which includes poor product quality, higher microbial contamination and complete dependence of weather conditions for drying (Bala & Mondol, 2001). In the later stages, drying developed into completely a controlled process in which drying air temperature, relative humidity and air velocity were precisely maintained at optimum level. The fish drying process is slightly different from other food materials mainly due to its gel like behaviour until considerable reduction of moisture. Moreover, significant amount of shrinkage takes place in fish during drying in addition to the other irreversible changes.