Effect of Boiling Duration on Soluble Protein, Low-Molecular-Weight Peptide Fraction, and Antioxidant Activity (DPPH and ABTS) of Pensi (Corbicula moltkiana) from Lakes of West Sumatra, Indonesia

Abstract

Pensi (Corbicula moltkiana) is a small freshwater bivalve endemic to the lakes of West Sumatra principally Lake Maninjau, Lake Singkarak, and Lake Diatas where it constitutes an important component of local aquatic biodiversity and has been consumed as a traditional food and culinary ingredient in Minangkabau cuisine for centuries. Despite the well-documented nutritional value and bioactive peptide potential of marine and freshwater bivalves globally, systematic scientific characterization of pensi's nutritional composition, low-molecular-weight peptide content, and antioxidant properties under different cooking conditions remains absent from the literature. This study determined the proximate and mineral composition of fresh pensi meat, and evaluated the effects of cold-water extraction (raw control) and three boiling durations (5, 15, and 30 minutes) on soluble protein content, molecular weight distribution of the peptide fraction (< 5 kDa), and antioxidant activities assessed by both DPPH and ABTS radical scavenging assays. Fresh pensi meat was found to contain 52.6% crude protein (dry weight basis), 7.8% total fat, and notable mineral concentrations including calcium (612 µg/g), magnesium (331 µg/g), iron (48 µg/g), and zinc (21 µg/g) profiles comparable to commercially significant bivalve species. Boiling slightly increased soluble protein content (from 20.3% in raw extract to 21.8% after 30 minutes), but progressively and significantly decreased the low-molecular-weight peptide fraction (< 5 kDa, from 36.3% to 28.8%) and both antioxidant activities (DPPH from 36.0 to 23.8 µg AA/g protein; ABTS from 0.68 to 0.49 µmol TE/g protein). A strong positive Pearson correlation (r = 0.96, p < 0.001) between the < 5 kDa peptide fraction and antioxidant activity confirmed that low-molecular-weight bioactive peptides are the principal antioxidant contributors in pensi extracts. Sensory evaluation identified 15-minute boiling as the most preferred treatment (overall acceptability 4.2/5.0). Boiling for approximately 15 minutes is recommended as the optimal balance between antioxidant value retention, food safety (microbiological adequacy), and sensory acceptability.