Microbiological Profile of ‘Ogiri’ Condiment Made from Seeds of Watermelon (Citrullus lanatus) | Chapter 03 | Current Trends in Food Science Vol. 1
Introduction:
Condiments are essential part of the diet of various cultures in different
parts of the world. Its consumption continues to increase due to some factors
that include population growth and increased consumer preferences. A condiment
refers to a substance that is added to food to impact a particular desired
flavour or texture to the dish. ‘Ogiri’ refers to a fermented oily paste that
is used as soup condiments for its strong smell. It is a product prepared by
traditional method of uncontrolled solid state fermentation of castor bean
(Ricinus communis) and/or melon seeds (Citrullus vulgaris), involving the use
of natural inoculation or chance fermentation.
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.
The results obtained from the study have shown the prevalence of bacteria
throughout the period of fermentation in an increasing population. Fungi and
coliform group of bacteria were not isolated at the beginning of the experiment
till after 24 hour of commencing the fermentation process. Filamentous fungi
(mould) growth was obtained only after the fifth day of fermentation, thereby suggesting
it to be spoilage growth. Bacillus spp. was isolated throughout the
fermentation period, thereby proving to be major fermentative organisms. The
result of the laboratory-controlled fermentation confirmed that ‘ogiri’
condiment could be obtained with Lactobacillus fermenti, Corynebacterium
xerosis and/or Bacillus subtilis starter cultures. However, it is recommended
that the products of this study should be further assessed for any possible
toxicology study before it can be wholly acceptable for human consumption.
Author(s) Details
F. O. Adebayo
Department of Microbiology
(Food and Industrial Unit), Nasarawa State University, Keffi, Nigeria
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