Physico-chemical properties and sensory evaluation of jam made from black-plum fruit (vitex doniana)

Abstract

The potential of some wild-growing indigenous fruits such as black-plum (Vitex doniana) has remained largely untapped. Most tropical fruits can be processed and preserved in small-scale operations using simple techniques. Various uses have been reported for black-plum ranging from medicinal to dietary utilization. This study was carried out to investigate the possibility of producing jam from black-plum and to evaluate the physico-chemical properties, nutritional properties and consumer acceptability of the product. Black-plum jam was produced using traditional openkettle method. The physico-chemical analyses of black-plum fruit and jam were determined. Physico-chemical analyses of black-plum fruit showed that it had soluble solids of 18.83 + 0.11 oBrix, pH 3.85 + 0.07 and ascorbic acid was 33.35 + 0.21 mg/100g. Na, K and Ca contents were (0.1 mg/100g); (1.33 mg/100g); and (0.765 mg/100g), respectively. Physico-chemical analyses of the jam showed that it had soluble solids of 68.0 + 0.71oBrix, 24.22 + 0.08% reducing sugar, pH of 3.42 + 0.03 and total acidity of 0.34 + 0.01%. Proximate analysis of the jam showed nutrient values of crude protein 4.23 + 0.03%, crude fibre 1.0 + 0.03%, ash 4.30 + 0.02%, crude lipid 2.43 + 0.03%, carbohydrate 68.1 + 0.28%, sodium (Na) 0.28 + 0.01 mg/100g, potassium (K) 1.42 + 0.01 mg/100g, calcium (Ca) 0.97 + 0.01 mg/100g, moisture 21.65 + 0.33%, dry matter 78.36+ 0.33%. Physico-chemical and proximate analyses of the fruit on wet and dry basis were also carried out. Sensory evaluation by untrained panelists indicated consumer acceptability. Statistical evaluation using simple-paired comparison between black-plum jam and commercial black currant jam on a nine-point hedonic scale showed a preference for the commercial jam, particularly in terms of colour. The differences in flavour and spreadability were not significant (P > 0.05) 5% level; while the differences in colour, taste and overall acceptability were significant (P < 0.05) 5% level. Some assessors, however, scored black-plum jam high for flavour and spreadability.

Keywords: indigenous, Vitex doniana, black-plum jam, evaluation