Effect of pretreatments and packaging on the growth of bacteria in value added summer onion products

Abstract

The experiment was carried out to investigate the bacteria in fresh and different processed onion. Total number of viable bacteria (cfu/g) in fresh onion and dehydrated processed onion packed in High Density Ployethylene (HDPE) and Aluminum foil (ALF) was estimated at 0, 6 and 12 month interval following storage at room temperature (RT, 20-25⁰C) and refrigerated temperature (RFT, 5⁰C). Samples tested were fresh onion (S₀), dried onion (S₁), blanched and dried (S₂), blanched + sulphited and dried (S₃), 25% salt osmosed and dried (S₄), 60% sugar osmosed and dried (S₅) and 55/15% sugar-salt osmosed dried onion (S₆). It was found that the lowest bacterial count (2X10¹ and 9X10¹ cfu/g) was given by 25% salt osmosed onion (S₄) and the total number of vialed bacteria (TVB) count in the other samples varied in the order of S₃ S₆ S₅ S₂ S₁ (45-97x10³ cfu/g) and sample S₁ having no pretreatment before drying gave the highest TVB among the samples and the preservation effect was only due to reduction of a_w during drying.

Bangladesh J. Agril. Res. 41(3): 507-519, September 2016