In-vitro antibacterial potential of bran extracts of selected Philippine rice (Oryza sativa) cultivars

Issue Date

7-2018

Abstract

This study determined the in-vitro antibacterial activity of bran Philippine rice varieties with varying pericarp colors. Rice samples were first screened for free, bound and total phenolic content. Six samples, namely one white (non-pigmented), two red, and three black/purple varieties were then selected and evaluated for in vitro antibacterial property. Crude bran extracts were tested against six common Foodborne pathogens, namely Salmonella enteric, Escherichia coli, Listeria monocytogenes, Clostridium perfringens, Enterococcus faecalis, and Staphylococcus aureus using agar well diffusion, bacterial growth curve, and minimum inhibitory concentration (MIC) assays. Results showed that pigmented rice generally had higher free, bound and total phenolic content than non-pigmented varieties. Agar well diffusion assay revealed that except for the extract of Black Rice 3, all selected pigmented rice brans at 100, 500 or 700 mg/mL concentrations displayed inhibitory property against S. aureus and C. perfringens only. Ethanolic extracts of the bran samples exhibited higher zones of inhibition than methanolic extracts, with the highest values observed in Black Rice 2. Growth curve assay test showed that viable cells of S. aureus decreased by 4 to 6 log using 5 to 100mg/mL ethanol extracts of pigmented rice starting at 5 hr incubation. Black Rice 2 was the most effective in preventing the growth of S. aureus and 2.5-3.125 mg/ml for C. perfringens, indicating mild antibacterial activities against the two Foodborne pathogens. In conclusion, pigmented rice bran can therefore be natural antimicrobial agents for potential use in food and/or pharmaceutical industries or other applications.

Source or Periodical Title

Philippine Journal of Crop Science

ISSN

0115-463X

Volume

43

Issue

Supplement no. 1

Page

111

Document Type

Article

College

College of Agriculture and Food Science (CAFS)

Language

English

Subject

Oryza sativa L.; Rice varieties

En – AGROVOC descriptors

ORYZA SATIVA; RICE; VARIETIES; BRAN; EXTRACTS; PHENOLIC CONTENT; ANTIMICROBIAL PROPERTIES; CONTAMINATION; FOODS; PATHOGENS

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