Preservation of tempoyak using non-thermal process (High-pressure processing)

Abstract

Tempoyak is a Malay condiment produced from fermented durian. It is prepared by combining durian flesh with salt and lactic acid bacteria (LAB) that undergo anaerobic fermentation at ambient temperature (28 to 34°) for 3 to 8 days. Non– thermal food processing allows food to be preserved without being overheated, preserving their nutritional value and sensory qualities. To increase the shelf life of tempoyak, this research adopts high-pressure processing as a non-thermal treatment approach. Tempoyak were packed in aluminum foil vacuum packaging sachets and were treated at 600 MPa for 5 min. Results on the titratable acidity and pH were determine. Throughout the 23-days storage period, the pH, and titratable acidity of tempoyak showed a significant change for both non-treated and HPP-treated (p < 0.05). In untreated samples, the titratable acidity showed a ranged from 0.184 to 0.057%, but in HPP-treated samples, the titratable acidity values ranged from 0.1 to 0.536%. Significant changes were also shown (p < 0.05) for lightness (L* values) for untreated while for HPP-treated, it revealed no discernible changes (p > 0.05). The average lightness was 64.67 and 66.69 for untreated and HPP-treated of the tempoyak. All samples of tempoyak treated with HPP had yield and mould counts below the limit of detection by the time the storage study was complete. Yeast and mould were only detected in HPP-treated of tempoyak starting from week 2 (day 14) which were 1.0 × 103 cfu/g at week 2 and 1.363 × 103 cfu/g at week 3. No significant alterations were detected by sensory evaluation (p > 0.05) for HPP-treated samples but there was a minimal change in their taste for the untreated samples. In a nutshell, HPP successfully preserved the total amount of food and extended the shelf life for a month.