Studies on the physico‐chemical, nutritional and microbiological changes during the traditional preparation of Marula wine in Gwanda, Zimbabwe

Abstract

PurposeThe aim of the study is to determine the microbial, physico‐chemical and nutritional changes that take place during the four‐day traditional preparation of wine from the fruits of Marula (Sclerocarya birrea subspecies Caffra) tree in Zimbabwe. It must be noted that Marula is documented as a drought‐resistant plant.Design/methodology/approachThe fruits used in the study were taken from four trees growing in different locations. The fermenting microbial populations were isolated using potato dextrose, tomato juice and nutrient agars, and then identified to genus level using simple biochemical tests. The physico‐chemical changes determined were pH, titratable acidity, sugar and alcohol content. The alcohol content was determined using the Anton Paar beer analyzer, while nutritional changes, evaluated as changes in ascorbic acid (vitamin C) levels, were determined using the 2, 6 dichlorophenolindophenol titrimetric method.FindingsDuring fermentation there was a gradual decrease in the bacterial population, and an increase in yeast counts. The pH and sugar contents decreased, while the average alcohol content increased to an average 2 per cent. The fermented Marula juice retained 72 per cent of the initial ascorbic acid content (a decrease from 133 to 96 mg/100 g) compared with orange juice subjected to similar conditions, which retained 40 per cent ascorbic acid levels (decrease from 60 to 24 mg/100 g).Originality/valueThe low pH of Marula wine could contribute to the microbiological safety of the product and relative stability of ascorbic acid. Marula wine produced after four days of fermentation is still an importance source of ascorbic acid.