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Theses

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2017 - 20183
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Subject: Agricultural Processing and Food Engineering × Start date: 2017 × Type: Thesis ×
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    ThesisItemOpen Access
    Optimisation of process parameters for preparation of flavoured instant green tea
    (Department of Food and Agricultural Process Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2017) Sankalpa, K B; KAU; Santhi Mary, Mathew
    Tea is the second most popular drink in the world after water. Tea can be classified into three major categories: unfermented green tea, partially fermented oolong tea, and fermented black tea. Green tea contains more catechins, than black tea and oolong tea. So it is included in the group of beverages with functional properties. Green tea consumption helps in preventing cardiovascular diseases, cancer, diabetes and obesity. Nowadays, demand is increasing for instant tea, decaffeinated tea and flavoured tea. The use of instant tea powder will reduce the preparation time to a large extent and saves energy as well. Due to these reasons efforts were under taken for optimisation of process parameters for preparation of flavoured instant green tea. Production of flavoured instant green tea mainly includes three steps, extraction, flavour addition and drying. Extraction was performed and optimised conditions were 1:47 leaf-water ratio, 30 min extraction time and 52°C extraction temperature. Extract obtained with optimised condition was subjected to spray drying and optimised condition were 174°C inlet temperature, 2.7% MD and 671 ml.h-1 feed rate to produce instant green tea. Further flavouring was carried out with two spices (ginger and cardamom) and one herb (tulsi) of different concentration and spray dried at optimised spray drying condition. The best combination selected after sensory evaluation are G2 (4% ginger extract), C6 (3 g of cardamom with 30 min of soaking) and H3 (3:10 tulsi to green tea ratio, 30 min extraction time). The best samples were packed in PET, ALF and LDPE and kept for storage studies at room temperature. Predicted shelf-life period of instant flavoured green tea powder packaged in ALF, PET and LDPE based on moisture gain was found to be 210, 152 and 92 days, respectively. Among the six tested sorption models, the GAB model described the best fit to the experimental data with higher R2 value and lowest SSE and RMSE. The HPLC analysis for catechin fraction of instant flavoured green tea indicates that, flavour addition will not affect the green tea catechins. The heat utilization efficiency of spray dryer for spray drying of green tea extract under non adiabatic condition was 18.18% and under adiabatic condition was 89.4%. The total cost of production for 310 1 kg of instant green tea was Rs. 3590/-, ginger flavoured instant green tea was Rs. 3683/-, cardamom flavoured instant green tea was 4025/- and tulsi flavoured instant green tea was Rs. 3631/- and benefit cost ratio was 1.40:1, 1.63:1, 1.49:1 and 1.65:1, respectively.
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    ThesisItemOpen Access
    Development and evaluation of process protocol for vacuum fried bitter gourd chips (momordica charantia)
    (Department of Processing and Food Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2018) Pooja, M R; KAU; Sudheer, K P
    Bitter gourd (Momordica charantia) is commonly known as bitter melon or Karela in India. The estimated post harvest loss of bitter gourd was 25%. A realistic solution to reduce the post harvest loss in bitter gourd is the adoption of the appropriate processing technologies. The vacuum frying is an excellent promising technology, in which food is fried under low pressure and temperature. Vacuum frying reduces the oil absorption, less formation of acrylamide content, and retains the colour and nutrients present in fried products. The vacuum frying system consists of two main chambers namely, frying chamber and oil storage chamber. A de-oiling system is attached to frying chamber to remove the oil content in the final vacuum fried product. This vacuum frying system used for the study was batch type and had a capacity of 3 kg/ batch with oil tank storage of 30 l. After every batch of vacuum frying, chips and oil were collected for analysing the quality. The blended oil (rice bran and palm oil at 80:20) was used as frying oil and de-oiling was done at a speed of 1000 rpm for 5 min. Different pre- treatments were done for vacuum fried bitter gourd chips. Control (Un-treated) sample had the best qualities with less oil content (4.43 %), moisture content (0.264 %), hardness (1.422 N), water activity (0.250) and green colour retention (a*(-4.13)). Quality parameters like moisture content, water activity, oil content, bulk density, true density, hardness, energy content, acrylamide content, thickness expansion, colour values and sensory evaluation of vacuum fried bitter gourd chips were analysed at different frying conditions. The treatment condition at 100oC, and 9 kPa vacuum for a duration of 10 min produced good quality parameters with less oil content (4.011%), acrylamide content (56.52 ppb), hardness value (1.411 N), high retention of green colour (a*(-5.3)) and good organoleptic properties (Hedonic score of 8.7). The laminated aluminium flexible pouches with nitrogen flushing retained the quality of bitter gourd chips during the storage period. The TPC value of blended oil increased from an initial value of 9.4 to 24.21%, due to continuous usage of oil (70 times) under the vacuum frying process, and was within the safe limit. The FFA value of blended oil was within the acceptable limit upto 50 cycles of vacuum frying process.
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    ThesisItemOpen Access
    Development and performance evaluation of a rubber tapping machine
    (Department of Food and Agricultural Process Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2018) Aswathy, M S; KAU; George Mathew
    Hevea brasiliensis, the common rubber tree, is the most important species which is the commercial source of natural rubber. The natural rubber is harvested in the form of latex, a sticky, milky colloid through the tapping process. The Hevea latex obtained from the bark of rubber tree contains natural rubber particles that can be harvested and utilised for various industrial applications. Tapping is the process of making a controlled wound in the bark of rubber tree to cut open the latex vessels, which cause the flow of latex for capturing the latex. The process of rubber tapping poses potential risk of various health problems among rubber workers. Scarcity of skilled labours for rubber tapping is one of the main challenges in the rubber industry. Mechanization of the tapping process can reduce the effort of the labour and reduces the human drudgery. Hence, the present study was undertaken to develop a rubber tapping machine and to evaluate the performance of the machine. The developed rubber tapping machine consists of a cutting blade, shaft, connecting rod, crank, gear assembly, bearing, coupling, frame, casing, motor and a battery. The rubber tapping machine is connected to a 12 V, 5 Ah battery. The battery powers the motor. 0.25 hp wiper motor was used and it delivers a rotational speed of 72 rpm. The rotary motion of the motor is transmitted to the gear assembly using a gear shaft. The gear of 48 teeth which is connected with the motor rotates at 72 rpm. The speed is increased to 288 rpm by meshing gear of 48 teeth with 12 teeth gear to obtain a speed ratio of 4. A crank is attached to the gear of 12 teeth and rotates at 288 rpm. A connecting rod linking the shaft and the crank converts this rotary motion into reciprocating motion of the shaft. The required stroke is achieved by an eccentricity of 15 mm in the connecting rod. The blade is reciprocated along with the shaft with a stroke length of 30 mm and 144 strokes per minute. The reciprocating motion of the cutting blade helps to cut the bark of the rubber tree while tapping. The field evaluation of the developed machine was conducted in two farmer’s field by three tappers and the performance of the was evaluated in terms of its capacity, depth of cut of bark, bark consumption or thickness of cut of bark, time for tapping operations and weight of the machine and compared with manual tapping. The developed machine has an average capacity of about 157 trees per hour. The machine cuts the bark with an average depth of cut of 7.2 mm and a thickness of cut of 1.8 mm. The developed machine weighs 1.6 kg without the power source and 3.6 kg with power source. The cost of operation of rubber tapping machine is estimated as Rs.1.16/tree whereas the manual tapping charges are Rs. 2/tree. The developed rubber tapping machine is more advantageous for tapping the rubber trees with less effort and human drudgery compared with the traditionally using tapping knives.