Abstract
Lactic acid bacteria elective habitat is food matrix, where they release encrypted metabolites from several parent proteins as a result of their proteolytic activity in the matrix. These metabolites when decrypted confer different bioactive activity thus improving public health. This study was aimed at producing peptide containing metabolites with antibacterial efficacy from defatted cowpea and peanut using Lactobacillus spp. Lactobacillus spp. isolated from spoilt yoghurt were identified using culture dependent and independent method. The isolates were screened for proteolytic ability on skimmed milk agar. The selected isolate with highest proteolytic activity was used for metabolites production through fermentation of defatted cowpea and peanut at 37 oC for 72 h. Parameters analyzed during fermentation were pH, Lactobacillus count, protease activity, peptide concentration and antibacterial activity. The crude peptides produced were assayed for antibacterial activity against bacteria isolated from spoilt meat. From the identified Lactobacillus spp., L. plantarum CAU4347 had the highest proteolytic activity with clear zone of 24.50 ± 0.707 mm. During fermentation the highest and lowest Lactobacillus counts were from cowpea and peanut media with values 294.2 ± 0.21 ×107 and 0.60 ± 0.4 ×107 cfu/ml respectively. Cowpea medium inoculated with L. plantarum CAU4347, had the highest peptide concentration of 79.92 ± 0.01 µg/ml. Consequently, peanut medium showed higher antibacterial activity of 18 mm against Escherichia coli. This result finding suggests that encrypted peptide metabolites from cowpea and peanut flour can confer antibacterial activity against meat spoilage bacteria thus could be utilized as a potential bio-preservative.
 Keywords: Metabolites, Cowpea, Peanut, Bioactive, Fermentation, Lactobacillus plantarum
Highlights
Food preservation principle is mainly concerned with preventing microbial spoilage that will result to several negative changes in integrity and loss of nutritional value of food (Rawat, 2015)
Different food varieties have been used by yeast and lactic acid bacteria, in both cases the food acts as substrate for the release of microbial metabolites which contribute to its shelf life extension (Korhonen and Philanto, 2006)
The aforementioned hydrolyzate can be formed by the hydrolytic action of lactic acid bacteria (LAB) derived protease on proteins produced by cowpea and peanuts such as globulins, albumins, arachin and coarachin (Osman et al, 2013; Abdel-Shafi et al, 2019) to increase protein content, remove antinutrients content (Adeyemo and Onilude, 2013) and release peptides of bioactive ability (Mohanty et al, 2016)
Summary
Food preservation principle is mainly concerned with preventing microbial spoilage that will result to several negative changes in integrity and loss of nutritional value of food (Rawat, 2015). These anti-nutrients can be detoxified by dehulling, soaking, boiling, steaming, roasting, sprouting and fermentation treatment (Phulia et al., 2018; Nwafor et al, 2017), leaving behind nutritional compositions for microbial protease hydrolysis These proteases endogenously or exogenously attack sited small amino or carboxyl group of parent protein (Demirci et al, 2014) to release peptides. The aforementioned hydrolyzate can be formed by the hydrolytic action of lactic acid bacteria (LAB) derived protease on proteins produced by cowpea and peanuts such as globulins, albumins, arachin and coarachin (Osman et al, 2013; Abdel-Shafi et al, 2019) to increase protein content, remove antinutrients content (Adeyemo and Onilude, 2013) and release peptides of bioactive ability (Mohanty et al, 2016) These organisms have displayed impressive attributes as starter culture in peptide assay. This study was to investigate the antibacterial activity of metabolites produced by Lactobacillus sp. during fermentation of cowpea and peanut
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