Physicochemical and Retrogradation Properties of Fermented Melinjo (Gnetum gnemon) Seed Flour

Abstract

The fermentation effects of melinjo (Gnetum gnemon) seed flour on the physicochemical and retrogradation properties were investigated. Fermented melinjo seed flour (FMF) was prepared using a Lactobacillus fermentum. The DSC and RVA were used to evaluate the properties of the samples. The results indicated that FMF had a higher significant (P<0.05) value for gelatinization temperature and enthalpy but lower values in the starch-lipid temperature, enthalpy, and viscosity peak than the unfermented sample (UMF). X-ray diffraction demonstrated that fermentation resulted had little effect and the crystalline pattern cannot be changed (type A), but it was shown that a crystalline region ratio to region amorphous increased from 30.9 to 36.66%. The FTIR spectra showed that FMF and UMF were identical. Furthermore, the observation of the FMF using a SEM showed that starch granules had slight superficial corrosion, but UMF has a smooth outer surface. The retrogradation rate (k) of UMF was slowed (0.63 day-1) when compared with the FMF (0.68 day-1). Thus, fermentation may alter starch amorphous region and chemical components, eventually transforming the physicochemical and retrogradation characteristics of melinjo seed flour.

Keywords

• fermentation
• gelatinization
• lactobacillus fermentum
• starch-lipid