Effects of Hurdle Technology on Microbial Stability and Sensory Characteristics of Durian Paste (Durio zibethinus cv. D24)

Chan, Yuan Mi (2017) Effects of Hurdle Technology on Microbial Stability and Sensory Characteristics of Durian Paste (Durio zibethinus cv. D24). Final Year Project (Bachelor), Tunku Abdul Rahman University College.

Text Chan Yuan Mi_FULL TEXT.pdf Restricted to Registered users only Download (1MB)

Abstract

Mild heat treatment in combination with pH reduction and the usage of potassium sorbate was applied as hurdles to reduce the microbial load of frozen durian paste. Optimization of pH, processing time and temperature, and potassium sorbate dosage to obtain desired microbial and organoleptic qualities was done via Center Composite Rotatable Design. The validation test proved that the optimized parameters (Solution 1: pH 5.99, 60 oC for 32 sec, 300 ppm potassium sorbate) have achieved a higher microbial reduction in 0 day (5.44 log) and 6 days (3.14 log) than the predicted results (4.02 log and 2.40 log). In 28 days of storage study, the durian pastes treated via solution 1 and solution 3 without addition of preservative (pH 5.86, 60 oC for 24 seconds) showed 0 counts of microbial load. Based on quantitative descriptive analysis (QDA), no significant changes (p< 0.05) in aroma (sweet note, caramel note, fruity note, sulphur note, alcohol note) and taste (sweetness, bitterness, sourness) attributes between the processed and fresh durian paste, except colour attribute. Furthermore, solution 1 treated durian paste received higher likeness compared to the fresh one in the preference ranking test. Thus, the combination parameters of solution 1 (pH 5.99, 60 oC for 32 seconds and 300 ppm potassium sorbate) was the most capable to improve the microbial and sensory quality of durian paste.