Chemical Composition, Antioxidant Properties and Sensory Quality of Ogiri Produced by Fermentation of Citrullus vulgaris with Mutant and Non-Mutant Strains of Bacillus subtilis

Abstract

Ogiri is one of the naturally fermented seasonings widely applied in soup as condiment. This study investigated the chemical  composition, antioxidant and sensory qualities of ogiri fermented with mutant and non-mutant B. subtilis strains produced from Citrullus  vulgaris. Bacillus subtilis strains isolated from spontaneously fermented melon seeds (C. vulgaris) were exposed to different  Ultraviolent (UV) irradiations and Sodium Dodecyl Sulphate (SDS) at varying time intervals to obtain mutant strains. Eight (8) mutated  strains of B. subtilis that produced high D-ribose metabolites were used for ogiri production. The DPPH (83.11 %), hydroxyl radical  scavenging (49.41 %), FRAP (74.34 mgAAE/100g) and Fe²⁺ chelation abilities (86.72 %) of ogiri samples produced with B. subtilis mutant  strain was higher than that of market sample (RTE00) values 76.06 %, 41.98 %, 54.32 mgAAE/100g and 72.74 %, respectively. Sample  MIC64 had the highest fibre and protein contents (7.40 % and 26.42 %), respectively, while sample MSD51 had the highest phosphorous  (3.73 %) and copper was detected in sample 30 (0.07 %). Sample MSD99 had the highest D-ribose yield (1.00 g/kg). The protein increased from 19.82 to 26.42 %, while sample (MIC21) has most acceptable sensory quality. Ogiri produced from mutant strains of B. subtilis have improved nutrient and antioxidant capacity hence, has potential for use as functional food.