Evaluation of Acetic Acid Concentration Effects on Microbial Quality and Proximate Composition of Cabbage (Brassica oleracea var. capitata)
Omorodion, Nnenna J.P *
Department of Microbiology, University of Port Harcourt, PMB 5323, Rivers State, Nigeria.
Barido, Lenu. J
Department of Microbiology, University of Port Harcourt, PMB 5323, Rivers State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Vegetables are an exceptional source of nutrients, trace elements, vitamins, and dietary fiber, and are therefore essential for human health and well-being. This study investigates the effects of varying concentrations of acetic acid on the microbial quality and proximate composition of cabbage (Brassica oleracea var. capitata). Standard microbiological methods were employed to determine total heterotrophic bacterial count, total fungal count, Staphylococcus count, and Escherichia count. Results showed that cabbage treated with acetic acid concentrations of 0.5%, 1.5%, 2.5%, 3.5%, 4.5%, and 5.5% exhibited microbial loads ranging from 2.75 × 10⁵ cfu/g to 1.05 × 10⁵ cfu/g for total heterotrophic bacteria. Staphylococcus counts ranged from 2.08 × 10⁴ cfu/g to 1.15 × 10³ cfu/g, while Escherichia counts decreased from 4 × 10³ cfu/g to 2.5 × 10² cfu/g. The control (untreated sample) had Staphylococcus and Escherichia counts of 1.55 × 10⁴ cfu/g and 4.5 × 10⁵ cfu/g, respectively. Fungal counts in treated samples ranged from 4.4 × 10³ cfu/g to 5.4 × 10³ cfu/g, compared to 6.45 × 10³ cfu/g in the control. Microbial growth decreased progressively with increasing acetic acid concentration, confirming the concentration-dependent antimicrobial effect of acetic acid. Organisms isolated included Staphylococcus (22%), Escherichia coli (24.3%), Bacillus (17%), Proteus (10%), Micrococcus (10%), Pseudomonas (12%), Klebsiella (5%), Mucor (11.8%), Aspergillus spp. (41.2%), Saccharomyces (29.4%), Fusarium (11.8%), and Rhizopus (6%). Escherichia coli and Aspergillus spp. were the most predominant bacterial and fungal genera, respectively. The proximate composition (moisture, ash, protein, fiber, fat, and carbohydrate) of treated and untreated cabbage showed no significant differences, indicating that nutritional integrity was maintained. The findings suggest that acetic acid treatment is an effective, low-cost method to reduce microbial contamination on cabbage while preserving its nutritional quality. This study provides useful insight for the food industry and consumers aiming to enhance cabbage shelf life and food safety using natural preservation methods.
Keywords: Cabbage, acetic acid, microbial quality, proximate composition, food safety