Studies on Storage Methods and Quality Attributes of Onion Stored At Farmer's Field

Abstract

Title: STUDIES ON STORAGE METHODS AND QUALITY ATTRIBUTES OF · ONION STORED AT FARMER'S FIELD. Studies were conducted on storage methods of onion being practiced by the .farmers in western l). P. and effect of storage structures on keeping quality of onion. Studies were also carried out to evaluate the physico-chemical (moisture content, TSS, pH, acidity, optical density), post harvest losses (physiological loss in weight, rotting%, sprouting %, black mold %) and microbial quality. Total plate count (TPC), Total Aerobic Count (TAC) and Total Fungal Count (TFC) of onions were determined for fresh as well as stored samples after 0, 30, 60, 90,120, 150, 180 & 210 days of storage. Analysis work was done in Food Analysis Laboratory in the Department of Agriculture Engineering & Food Technology. The experiments were conducted on tray drying characteristics of blanched and unblanched onion slices at 60, 65, 70 and 75 °C temperature. Samples were dried till 6-7 % (d.b.) moisture content, cool and ground to get onion powder for further studies. The quality of onion powder was evaluated in terms of final moisture content, drying rate, acidity, ascorbic acid, reducing and total sugar. The study revealed that the TSS, acidity, PLW, ascorbic acid, rotting, sprouting, black mold and optical density of stored onion bulbs increased with increase in the storage period. ·The moisture content, pH and amino acid decreased with increase in the storage period. The highest microbial growth value (TPC) of 8.684x1 05 cfu/ml was observed in case of Pus a white round stored in Plastic net bags (PWR+PB) after 180 days of storage. The lowest microbial growth value of 7.186 x1 05 cfu/ml was observed in case of Neelam black stored in Low cost storage structure (NB+LCSS) after 180 days of storage. The microbial growth increased with increase in storage temperature. The microbial growth was not observed up to 30 days of storage. The rotting, sprouting and black molds were not observed till 60 days of storage, but the highest sprouting % value was observed as 39.40% in case of Pusa white round stored in plastic net bags (PWR+PB).It was determined that these parameters increased with increase in storage temperature and RH. Neelam black stored in Low cost storage structure (NB+LCSS) showed lowest sprouting and black mold. Thus, it was considered better for storage of onion bulbs as compared to other. The acidity and ascorbic acid of onion powder were found to be decreased whereas total sugar, reducing sugar and non reducing sugar were found to be increased with increasing storage period in different drying temperature. The significant changes in quality were found in untreated sample in six month of storage while for storage purpose treated sample dried at 70 °C shown best result in maximum cases.