THE EFFECT OF COOKING DURATION ON WATER ACTIVITY, LIPID OXIDATION, AND ANTIOXIDANT ACTIVITY OF MINANGKABAU BEEF RENDANG DURING STORAGE

Abstract

Beef rendang is an iconic traditional Minangkabau meat product cooked extensively with coconut milk and mixed spices. The chemical and shelf-life stability of rendang during storage is heavily shaped by its long thermal processing matrix. This study aimed to investigate the direct effect of cooking durations (3, 4, and 5 hours) on water activity (aw), lipid oxidation (Thiobarbituric Acid Reactive Substances / TBARS value), and antioxidant activity (DPPH radical scavenging capacity) of Minangkabau beef rendang over a controlled 4-week ambient storage system (28–30 °C). The experiment followed a 3x5 factorial setup structured in a Completely Randomized Design (CRD) with three replicates. Data evaluations were executed using Analysis of Variance (ANOVA) followed by Duncan’s Multiple Range Test (DMRT) at a 5% alpha level. Results demonstrated that longer cooking significantly dropped water activity from 0.88 (3 h) to a highly stable 0.76 (5 h), which heavily suppressed microbial activity. While lipid oxidation values increased continuously across storage, the 5-hour cooking duration successfully minimized TBARS accumulation (peaking at 0.74 mg MDA/kg at week 4) compared to the 3-hour batch (1.15 mg MDA/kg). This protective feature was directly linked to higher accumulation of antioxidant-active browning melanoidins and spice lipophilic fractions generated during 5 hours of continuous simmering. In conclusion, extending the cooking duration of Minangkabau beef rendang to 5 hours maximizes oxidative and thermodynamic stability, ensuring optimal long-term functional and shelf-life security at ambient temperatures.