Influence of selected native yeast starter cultures on the antioxidant activities, fermentation index and total soluble solids of Malaysia cocoa beans: A simulation study

Antioxidant activity of cocoa beans is often influenced by drying and roasting stages. In this study, 13 naturally-existing yeast strains were isolated and used as a starter culture and the resulted antioxidant properties of cocoa beans were determined by total polyphenols content (TPC), 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity and total flavonoids content (TFC). The isolated yeasts were identified via sequencing using universal primers ITS 1 and 4. Results revealed that the 13 naturally-existing yeast strains were Pichia kudriavzevii (MH979676, MH979680, MH979681, and MH979677), Hanseniaspora thailandica (MH979675), Hanseniaspora species (MH979678), Wickerhamomyces species (MH979679), Saccharomyces cerevisiae (MH979683), Hanseniaspora opuntiae (MH979684) and Candida quercitrusa (MH979685, MH979687, MH979686 and MH979682). Yeasts were selected based on the phylogenetic analysis, where each species of different genus (except Candida genus) was used as a starter culture. Dried cocoa beans inoculated with isolates (Hanseniaspora thailandica, Pichia kudriavzevii, Hanseniaspora opuntiae, Hanseniaspora species, Wickerhamomyces species and Saccharomyces cerevisiae) contained TPC, TFC and DPPH ranging from 21.82 to 69.81 mg/g Gallic acid (GAE), 1.68–6.33 mg/g Catechin and 113.85 to 328 ìmoles/g Trolox (TE), respectively. It is noted that there was no significant change of the antioxidant activity between isolates at 24-h to 120-h fermentation. Based on the current study, Hanseniaspora thailandica and Pichia kudriavzevii are the potential starter cultures that result in cocoa beans with higher antioxidant content (p < 0.05) compared to natural fermentation.