EFFECT OF COATING OF MODIFIED STARCH FROM WASTE POTATO ON RESPIRATION RATE AND MICRO-NUTRIENTS OF Chaenomeles japonica

Abstract

Potato starch isolated from waste potatoes of different haat-bazars, hotels and restaurants of Dharan sub-metropolitan city were modified by two techniques, viz. hydrothermal treatment (moisture adjusted to 28% and heated at 110°C for 3 h) and acid-alcohol treatment (treated with 100 ml of rectified alcohol and 20 ml of conc. HCl) to study different physicochemical properties of the extracted starch and films. The films were used to study rate of respiration and retention of micro nutrients (chlorophyll, vitamin A, retinol and β-carotene) in Chaenomeles japonica after coating with the different starch suspensions. Significant effect in functional properties of starches was found by different modifications (p<0.05). Acid alcohol treatment improved the oil absorbing capacity, solubility, and iodine affinity of starch. Hydrothermal treatment improved the water binding (WBC), dispersibility, and wettability of potato starch. Non-coated fruit had the maximum rate of respiration—2216.667 mg CO2/kg/h in day 3 compared to all coated fruits. The rate of respiration significantly (p<0.05) decreased with the starch coat in Chaenomeles japonica. The chlorophyll had maximum value (2.47521±0.02859 mg/100 g) in non-treated starch plasticized with 45% glycerol and minimum value (0.5246±0.046143 mg/100 g) HTT treated starch plasticized with 55% sorbitol. The vitamin retention was maximum (0.532193±0.05932 μg/100 g) in HTT treated starch plasticized with 55% glycerol. However, HTT treated starch plasticized with 55% glycerol and non-treated starch plasticized with 55% sorbitol were not different form each other. These treatments were however significantly different from the control sample. The treatment that had similar effects on change of both Vitamin A and retinol are HTT treated starch plasticized with 55% glycerol and non-treated starch plasticized with 55% sorbitol. The highest retention of carotene (0.721014± 0.206253 μg/100 g) was observed in HTT treated starch plasticized with 55% glycerol and non-treated starch treated with 55% sorbitol and minimum retention (0.025522±0.00287 μg/100 g) was found in HTT treated starch plasticized with 35% sorbitol. These maximum and minimum values were significantly different from the control and non coated samples of day one. Waste starch can be utilized—by coating—to increase shelf-life in fruits and vegetables.