Thermal processing effects on mung bean juice: Evaluating bioactive stability, viscosity, and metabolite profiles

Abstract

Mung bean juice is commonly consumed as a nutritious beverage and contains various bioactive compounds. Thermal processing is needed to ensure microbial safety, but heating may also affect physical properties and bioactive stability. In this study, mung bean juice was pasteurized at 63 °C (T1), 73 °C (T2), and 83 °C (T3) for 30 minutes. The effects of temperature were evaluated by measuring total microbial counts, reducing sugars, cooking loss, total phenolic and flavonoid contents, antioxidant activity (DPPH), viscosity behavior, and metabolite profiles using LC-HRMS. The results showed that thermal conditions reduced microbial levels in all treatments, with total plate counts ranging from 2.81 to 2.99 log cfu/mL. Increasing the processing temperature resulted in higher cooking loss, which increased from 3.51% at 63 °C to 8.85% at 83 °C, while reducing sugar content decreased from 0.358 to 0.216 mg/g. Rheological analysis showed that all samples exhibited shear-thinning behavior, with viscosity increasing with increasing processing temperature. Total phenolic and flavonoid contents did not show significant differences among treatments. However, antioxidant activity increased with temperature, from 75.22% at T1 to 87.36% at T3. LC-HRMS analysis identified 229 metabolites and showed changes related to processing temperature. Several lipid-related compounds, including L-α-palmitin, phospholipids, and citric acid, showed higher peak areas at higher temperatures, while most amino acids remained relatively stable. Overall, pasteurization up to 83 °C increased antioxidant activity and viscosity without causing significant changes in the overall metabolite profile, while microbial safety was maintained.