Development and enhancement of antioxidant peptides from spontaneous plaa-som fermentation co-stimulated with Chiangrai Phulae pineapple enzymatic reaction

Abstract

The present work aimed to search for a released peptide from proteolytic action on a silver barb fish muscular protein that confers health benefit through antioxidation activity. Changes in the physicochemical, microbiological, and protein characteristics of plaa-som samples during eight days of both spontaneous traditional fermentation (Batch 1; B1) and spontaneous fermentation with the addition of pineapple (Batch 2; B2) were determined. Results showed a correlation between an increase in the total acidity and bacterial counts with the length of fermentation duration, where the pH gradually decreased at the end of fermentation. Protein hydrolysis during fermentation was indicated by an increase in the amount of TCA-soluble peptide contents that peaked on day 5 (D5) in both batches (B1D5 and B2D5), which displayed their highest DPPH radical-scavenging inhibition of plaa-som protein hydrolysates (PSPHs). Twelve peptide fractions of the best PSPH were separated by ultrafiltration using molecular weight cut off (MWCO) at 3 and 10 kDa, and they were also purified by size exclusion chromatography. Results demonstrated that stronger peptides B2D5 - 3 kDa - F1 and B1D5 - 10 kDa - F1 were arranged in 12 peptides, which exhibited the highest reducing power, more than their radical-scavenging inhibition (p < 0.05). Therefore, it was concluded that both peptides obtained from PSPH have released antioxidative peptides that could be beneficial towards consumer's health, particularly the spontaneous plaa-som fermented with the addition of pineapple.