Utilization of durian seed for Monascus fermentation and its application as a functional ingredient in yogurt

Abstract As a widely consumed fermented milk product, yogurt undergoes constant development to increase its functional properties. Monascus purpureus-fermented durian seed, which has been proven to possess antioxidative properties, has the potential to improve on yogurt properties. The purpose of this study was to analyze the use of Monascus-fermented durian seed (MFDS) as a functional ingredient on yogurt and its effect on physicochemical properties, lactic acid bacteria (LAB) count, antioxidative properties, and consumer acceptability of set-type yogurt during refrigeration. Changes in physicochemical properties, including color, pH, titratable acidity, and syneresis, LAB count, total phenolic content (TPC), and antioxidant activity were evaluated at 7-day intervals during 14 days of refrigerated storage (4⁰C). Sensory evaluation were carried out for freshly made samples and after 7 days of storage. Results showed that the addition of MFDS to yogurt gave significant effects to some of the parameters measured. Yogurt with added MFDS powder produced a more red color (L = 88.55 ± 1.28, a* = 2.63 ± 0.17, b* = 11.45 ± 1.15, c = 11.75 ± 1.15, H = 77.00 ± 0.64), reached the highest TPC (2.21 ± 0.46 mg/GAE g), antioxidant activity (0.0125 ± 0.0032 mg GAE/g), and syneresis (5.24 ± 0.51%) throughout 14 days of storage. Addition of MFDS only gave a slight difference to pH and titratable acidity, while no significant difference was made for LAB count. For sensory evaluation, addition of MFDS, particularly the ethanol extract, to yogurt was well liked by panelists. Overall, addition of MFDS has a high potential of improving properties of yogurt, particularly its antioxidative properties.