Effect of Nisin and Selected Essential Oils on the Physicochemical, Microbiological Properties and Storage Stability of Wara, a Local Cheese in Nigeria

Abstract

Preservation of Nigerian soft-white cheese (wara) with selected essential oils and nisin was investigated. Physicochemical and microbiological analysis was carried out periodically on the wara samples stored at 4^oC and 25^oC according to standard methods. The pH of the samples decreased overtime with a range from 4.28-6.73 while, lipid oxidation activity values ranged from 3.03 – 6.60 with higher values recorded in samples kept at 25oC. There was an increase in acidity and water activity values overtime at both storage temperatures. Untreated wara showed higher microbial loads compared to treated samples at both storage temperatures which increased marginally overtime with those stored at 25^oC having higher microbial count. Total plate count, lactic acid bacteria count and yeast-mould count ranged from 0.94×10²-13.84 × 10⁴, 0.78 × 10²-56.02 × 10³ and 0.00 x 10²-27.44 × 10², respectively. This study revealed that the application of the essential oils and nisin coupled with storage at 4^oC was able to preserve to some extent the microbiological quality of wara without affecting negatively its physicochemical properties and thus constitute a reliable alternative for the preservation of wara.

Keywords: Wara, nisin, essential oils, microbial count, physicochemical.