Evaluation of the Proximate and Antinutritional Properties of Juice and Concentrate Produced from Black Plum (Vitex doniana) Fruit

Abstract

Black plum (Vitex doniana) juice has received limited attention in terms of comprehensive research on their proximate and anti-nutritional compositions. This study addresses this research gap by exploring the production of dry concentrate, single strength juice and 60% diluted seven juices samples (using different treatments). The investigation of their proximate and anti-nutritional compositions were performed, using standard analytical methods. Also the Juice samples were compared with commercial black currant juice drink. The results of proximate analysis of the dried concentrate revealed a moisture content of 18.85%, ash content of 4.47%, dietary fibre content of 30.14%, fat content of 2.07%, protein content of 8.69%, and carbohydrate content of 35.78%. The single strength juice had moisture content (59.88%), Ash (1.68%), Dietary fibre (11.08%), Fat (0.70%), Protein (2.36%) and Carbohydrate (24.30%). The juices with 60% dilution had moisture content ranging from 81.26% (SSI) to 86.81% (SSC), lower than the commercial juice CEX (90.68%). An increase in the mass of the pectinase enzyme significantly reduced the moisture content, increased the ash content, but increase in the incubation time had no significant difference in the ash content. Preheating (simmering) the fruit before processing did not affect the ash content too. Neither the mass of pectinase enzyme inoculated nor the length of the incubation significantly affected the total dietary fibre of the juice samples. Both increase in the mass of enzyme inoculated and the length of incubation time did not affect the fat content of the juices. The protein content of the juice decreased significantly (p ≤ 0.05) as the mass of the pectinase and the length of incubation and aslo the heating temperature and time increased. The carbohydrate content of the diluted juices was between 8.73% (SSC) and 14.37% (SSI). Statistically, SSC, SSD, SSE, SSF, SSG, and SSI have the same carbohydrate (in quality). SSI had a significantly higher carbohydrate (14.37%). The carbohydrate content of commercial juice (CEX) (9.18%) is much less and significantly lower than that of all processed juice samples. The result of the anti-nutrients showed the concentrate (SSA) and single strength juice (SSB) contain the Oxalate (10.64 and 3.75 mg/100g), followed by Saponin (5.31 and 1.96mg/100g), Tanin (4.82 and 1.95mg/100g), Phytate (3.91 and 1.94mg/100g) while Alkaloid (1.27 and 0.39mg/100g) respectively. The increase in pectinase significantly reduced none of the anti-nutrients. Simmering the fruit before obtaining the pulp used for the juices and increasing the preheating temperature had no significant effect on most of the anti-nutrients except for saponin, which was significantly decreased by the simmering. There were no significant differences (P ≥ 0.05) in the anti-nutrients when the simmering temperature was increased from 43°C to 51°C. Almost no anti-nutrient was in the commercial juice sample (CEX).