Development of Starter Culture for the Improvement in the Quality of Ogiri, a Food Condiment

Abstract

The objective of the present study was to isolate Lactic Acid Bacteria (LAB) from ogiri, a Nigerian fermented vegetable product, with the primary focus of selecting suitable isolates as candidates for starter cultures for use in possible improvements in the quality of the product. LAB was isolated from ogiri using phenotypic methods and then subjected to technological tests to evaluate suitability as starter cultures. Based on their considerable technological properties, two isolates of LAB were selected as candidates for starter cultures. The starter cultures were inoculated at 103 CFU/g during the production of ogiri, while un-inoculated samples served as a control. The ogiri samples were stored over nine days, within which samples were taken for microbial and proximate analyses. Four LAB isolates were isolated and identified phenotypically from ogiri procured from a commercial market, including Lactobacillus acidophilus, Lactobacillus fermentum, Enterococcus sp. and Lactobacillus plantarum. The species of Lactobacillus displayed the usual cell shapes of rods when examined under the microscope, which is typical of most members of the genus. The cells of the Enterococcus sp. were, however, cocci in shape, and this is also typical of members of the genus. The basis of the identification of the LAB isolates was their ability to utilize a wide range of carbon sources in their physiological and biochemical activities. Among the LAB isolates, L. acidophilus, L. fermentum produced less than 0.35 and 0.024 mg/l of acetic acid and hydrogen peroxide respectively, and were therefore chosen as starter cultures for production of ogiri. Inoculated ogiri samples showed reduced counts of coliforms, yeast, and moulds in comparison with their un-inoculated counterparts during storage. Coliform counts increased beyond 105 CFU/g in the un-inoculated control samples, whereas counts were lower in samples inoculated with L. acidophilus and L. fermentum. Yeast and mould count of 8.1 106 CFU/g was recorded as the highest value in the un-inoculated control samples, but count was generally below 106 CFU/g in the starter culture inoculated samples. Inoculation with LAB did not have significant difference (p > 0.05) in the proximate compositions of the fermented product. The LAB cultures L. acidophilus and L. fermentum demonstrated considerable control of coliforms and fungi in ogiri. Storage of the fermented product should not exceed 5 days for safety concerns, as increase in counts of coliforms was recorded beyond this period. No significant difference (p > 0.05) was recorded in the proximate compositions of starter culture inoculated ogiri and un-inoculated samples. Doi: 10.28991/HIJ-2022-03-01-04 Full Text: PDF

Keywords

• technological properties
• ogiri
• lactic acid bacteria
• lactobacillus
• enterococcus
• phenotypically
• food technology.