Use of Bitter Leaf (Vernonia amygdalina) Extract and Pasteurization Aim at Improving the Sensory Quality and Shelf-life of Mpedli, a Traditional Opaque Sorghum White Beer from Northern Cameroon

Abstract

The purpose of this study was to evaluate the sensory property and shelf life of the processed mpedli beer using aqueous leaves extract of Vernonia amygdalina (VA) and heat treatment. The white sorghum beer was made at the laboratory scale using home-made procedure (Control). Following filtration, the beer was blended with an aqueous leaf extract (1/10, v/v) of VA (BUB). Pasteurization (60 °C/30 min) was performed on a portion of the VA blended sample (BPB). The sensory parameters and shelf life of the three samples were evaluated at room temperature during a month storage. The sensory characteristics of blended and non-supplemented mpedli beer differed significantly (p < 0.05). During storage, the colour, bitterness, aroma, odour, viscosity, texture, and overall acceptability of the processed samples were improved. Bitterness (r = 0.898; p < 0.01) and odour (r = 0.930; p < 0.01) were both highly correlated with the acceptance of the processed beer. The non-supplemented samples had the highest sensory scores 48 hours after preparation, while the relevant sensory ratings in processed BUB and BPB samples were recorded from the 12th to the 21st and 27th day of storage, respectively. The findings suggest that combining pasteurization with addition of aqueous leaf extract of VA may help smallscale brewers for improving the sensory quality and extending the shelf life of mpedli. According to the findings, the use of bitter leaf could be proposed as an alternative hop in the local brewing industry and may increase incomes of producers of local sorghum beer.