Microbiological Profile of ‘Ogiri’ Condiment Made from Seeds of Watermelon (Citrullus lanatus)

Abstract

Aim: This research work was conducted to evaluate the microbiological profile of ‘ogiri’ condiment made from the seeds of watermelon (Citrullus lanatus). Study Design: This work was a laboratory experimental design study. Place and Duration of Study: Dept. of Microbiology (Food and Industrial unit), Nasarawa State University, Keffi, between March and April, 2017. Methodology: Traditional method of ‘ogiri’ production was adopted to prepare the sample in replicates to facilitate the 24-hourly microbiological evaluations. Microbial isolation and identification were done using standard microbiological techniques. Also, laboratory-controlled fermentation was carried out using the isolates obtained from traditional fermentation as starter-cultures. Results: The result of the traditional fermentation of the watermelon seeds yielded an oily brownish paste that has a strong characteristic pungent aroma. The result of the microbial enumeration showed that bacteria were present throughout the period of fermentation in an increasing population that ranged from 32x101 cfu/g at the starting time (Day 0) to 288 x106 cfu/g at the end of the fermentation period (Day 5). There was no fungal growth at the beginning of the fermentation, till on Day1 (8x103 cfu/g) to the Day 5 (6x106 cfu/g). The isolation of the coliform group of bacteria showed an unusual growth pattern: no coliform isolated from the freshly boiled seeds, coliform was present at Day 1 and 2, and no isolation of coliform bacteria from Day 3 to the end of the fermentation period (Day 5). Over the 5-day period of fermentation, the organisms isolated and identified are Bacillus subtilis, Corynebacterium xerosis, Lactobacillus fermenti, Staphylococcus saprophyticus, Staphylococcus aureus, Citrobacter freundii, coliform bacteria, yeast and mould. Conclusion: Hence, it was concluded that ‘ogiri’ condiment can be made from watermelon seeds, using Lactobacillus fermenti, Corynebacterium xerosis and/or Bacillus subtilis as starter cultures.