SIVALA KUMARANU BABU, TAGARAM2018-08-082018-08-082017http://krishikosh.egranth.ac.in/handle/1/5810063776D5461The present work was undertaken to optimize the process parameters for spray drying of papaya leaf juice. The effects of inlet air temperatures (130, 140 and 150 oC), maltodextrin concentrations (8%, 10%, 12%) and feed flow rates (350, 475 and 600 mL/h) on the powder yield and physico-chemical characteristics of papaya leaf powder (moisture content, water activity, L* values, a* values, b* values, pH values and total flavonoid content) obtained by spray drying were studied. Response Surface Methodology (RSM) was used to investigate the optimum process conditions for spray drying of papaya leaf juice and to analyze the effects of inlet air temperatures, maltodextrin concentrations & feed flow rates on spray drying of papaya leaf juice. Response surface plots of dependent variables against process variables were studied. The different regression equations describing the process variables on the yield and physico-chemical characteristics were developed. The predicted models were adequate based on the coefficient of determination obtained. The papaya leaf juice for spray drying was prepared by adding different concentrations 8%, 10% and 12 % of maltodextrin as carrier agent to the concentrated papaya leaf juice. After adding maltodextrin, the papaya leaf juice was fed into the spray dryer under different feed flow rates such as 350, 475 and 600 mL/h and dried at different inlet air temperatures such as 130, 140 and 150 oC in a spray dryer. The storage period of papaya leaf powder was determined by measuring physico-chemical characteristics of spray dried powder for about 45 days. Spray drying of papaya leaf juice at the optimized condition of inlet air temperature 130 oC, maltodextrin concentration 8% and feed flow rate 350 mL/h has given yield, moisture content, water activity, L* values, a* values, b* values, pH values and total flavonoid content of spray dried papaya leaf powders as 20.22 g, 4.65%, 0.32, 51.12, -0.29, -73.88, 37.29, 6.43, 63.13 mg/g of powder, respectively. Moisture content, water activity, color characteristics, total flavonoid content (TFC) were significantly affected by maltodextrin concentrations, feed flow rates and the inlet air temperatures. pH of spray dried papaya leaf powders was not affected by inlet air temperatures and feed flow rates. An increase in moisture content and water activity were observed during storage period of 0 to 45 days. Slightly decrease of pH was observed with increase in storage period of 0 to 45 days. There was no loss of flavonoid content in papaya leaf powder during storage period of 0 to 45 days. Keywords: Papaya leaf powder, Physico-chemical characteristics, Shelf-life of papaya leaf powder, response surface methodology and optimizationen-USnullThesis