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20192
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Subject: Food Science and Technology × End date: 2019 × Start date: 2019 × Thesis Type: M.Sc ×
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    Assessment of extrusion behaviour of white maize
    (Punjab Agricultural University, Ludhiana, 2019) Arshdeep Singh; Baljit Singh
    The present investigation was undertaken to explore the assessment of extrusion behaviour of white maize and their characterization. Response Surface Methodology (RSM) was used to optimize the extrusion process of white maize based extruded products. Central composite rotator design (CCRD) of response surface methodology was explored to evaluate the effects of independent variables, namely feed moisture content (14-18%), screw speed (400-550) and barrel temperature (125-175℃) on product responses specific mechanical energy (SME), bulk density (BD), water absorption index (WAI), water solubility index (WSI). White maize was subjected to extrusion by co-rotating twin screw extruder at varying processing conditions as per the central composite rotatable design. All the processing conditions had significant impact on product responses. Multiple regression equations were obtained to describe the effects of each variable on product responses. The product responses were most affected by change in feed moisture content, barrel temperature and to lesser extent by screw speed. The negative coefficient of moisture and temperature describes that the value of SME declined with increase of these two variables. Barrel temperature was found to elevate the expansion ratio and water solubility index. Optimization studies resulted in 12.50-16.2 % of feed moisture content, 145℃ of barrel temperature and 360-595 rpm of screw speed as optimum variables to produce acceptable white maize snacks. The products were stored for three months and were found acceptable at the end of three months.
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    Utilization of lemongrass for shelf life extension and flavor enhancement of cookies
    (Punjab Agricultural University, Ludhiana, 2019) Amandeep Kaur; Amarjeet Kaur
    Study was carried out on “Utilization of lemongrass for shelf life extension and flavor enhancement of cookies”. Lemongrass was procured from department of Agronomy, washed, sliced and dried at two temperatures i.e. 35 and 500C for 16-18 hrs. Drying temperature which was selected was 500C for 16-18 hours. Lemongrass was ground into powder and analyzed for proximate composition, total phenols and phytochemicals. It was found to contain 8.1% moisture, 9.01% ash, 1.31% fat, 8.6% protein, 7.36% fibre and 65.28% carbohydrates. Total phenol content of powder was 0.13 g/100g as GAE gallic acid equivalent and flavonoids ranged from 0.49 g/100 g powder. The powder was incorporated in cookies at 0, 2.5% and 5% levels. Cookies containing 2.5% of lemongrass powder were found best on sensory evaluation scores. Cookies were stored in high density polyethylene (HDPE) for a period of 6 months. During this period changes in free fatty acid (FFA), moisture content, water activity (aw) and peroxide value (PV) were recorded. Although there was non significant increase in these constituents but cookies were found acceptable only upto 2 months organoleptically. The estimated cost for the cookies was Rs. 211.21/kg and Rs. 211.71/kg, respectively for 2.5 and 5% level of lemongrass incorporation as compared to Rs.210.71/kg for the control.