357: Assessing the Effect of Preservatives on Properties of Nmedaa, a Traditional Fermented Corn Beverage, During Refrigerated Storage (4°C)

Introduction

A traditional functional beverage like ‘Nmedaa’ (fermented corn beverage) is popular among certain communities in Ghana. However, its susceptibility to microbial spoilage and limited shelf life prompts the exploration of preservative strategies to enhance its stability without compromising its sensory attributes. This study investigated the physicochemical, microbiological, and sensory properties of ‘Nmedaa’ during refrigerated storage (4℃) for 6 weeks.

Methods

The effect of different treatments: non-pasteurized (NPN), pasteurized (PN), and pasteurized with preservatives (lemon juice (LM), potassium sorbate (PS), and combination (PS+LM)) on the properties of the ‘Nmedaa’ were assessed using standard methods. Also, sensory evaluation was conducted to assess the sensory attributes (appearance, aroma, taste, mouthfeel, and overall acceptability) of ‘Nmedaa’. Data from triplicate experiments were statistically analyzed (p<0.05) and presented as means ± SD.

Results

Results showed a gradual decline in °Brix values for all the samples, with NPN showing the greatest reduction due to microbial fermentation. Pasteurized and preservative-treated samples exhibited slower decline. The pH for the non-pasteurized samples dropped steadily, while preservative-treated samples demonstrated greater pH stability. Titratable acidity (TA) was highest in NPN samples, while potassium sorbate-treated samples maintained lower acidity. Color analysis showed that LM-treated samples were the lightest (higher L* values), while PS-treated samples appeared darker. For redness (a*), NPN recorded highest value and yellowness (b*) was consistently low for all the samples. Total color difference (ΔE) was most pronounced in PS and PS+LM samples. Microbial analysis showed increase in total plate count (TPC), with NPN experiencing the highest microbial growth. Pasteurized samples treated with preservatives, especially PS+LM, exhibited slower microbial proliferation. Yeast and mould and E. coli counts, followed similar patterns, with preservative-treated samples showing better microbial inhibition. Sensory evaluation indicated consumer acceptance, with scores ranging between 5.5 and 7, suggesting consistent sensory quality despite the different treatments.

Significance

The findings of this study highlights the role of pasteurization and preservatives coupled with refrigeration in extending the shelf life of ‘Nmedaa’ without significantly affecting its sensory appeal, offering insights into the improvement of the shelf life of traditional fermented beverages.

Authors: Bennett Dzandu, Gifty Cromwell and Rosemary Brako Okine