Quality Evaluation and Sensory Acceptability of Yoghurt Partially Supplemented with Beetroot Extract (Beta vulgaris)

Abstract:

This study aimed to evaluate the effect of partial inclusion of beetroot extract at different concentrations (0%, 10%, 20%, and 30%) on the nutritional and sensory acceptability of yoghurt. The four samples formulated were coded as YGTA, YGTB, YGTC and YGTD. The yoghurt was made from 20% reconstituted Dano powder milk (200g/1L), pasteurized at a temperature of 85 ± 0.1 °C, and cooled to 43 ± 0.1 °C. Beetroot extracted was added, and each mixture was inoculated with 3 % starter culture containing Streptococcus thermophilus and Lactobacillus bulgaricus and allowed to ferment for 9hrs. The yoghurt formed was then refrigerated 4 ± 0.1 °C and thereafter, its parameters were analyzed. The results show significant variation at p < 0.05 on proximate, total soluble solid (TSS), vitamin C, phenolic content, antioxidant activity, and sensory parameters among the samples. The YGTA sample had the highest protein (4.10%) value, and YGTD had the lowest (3.55%). Also, the energy value was highest in YGTA (82.90kcal/100g), followed by YGTB (77.65kcal/100g), and YGTD had the lowest (71.43kcal/100g). Sample YGTB had the highest vitamin C (8.20mg/100g) and total phenol (0.970mg/100g). The iron concentration of the samples ranged between 2.38mg/100g and 6.41mg/100g. Sample YGTA, which did not contain beetroot extract, had the lowest iron (Fe) content of 2.38mg/100g. The sensorial assessment, which was performed by selected staff of the institute, revealed that YGTB had the best appearance and overall acceptability of 5.2 out of a scoring scale of 7.0. All microbial counts are recorded as the number of colonies formed per 1 ml (cfu/ml) of sample. The Total Microbial Count (TMC) was between 3.7×103 cfu/ml and 6.8×104 cfu/ml, the total fungi count (TFC) was 1.0×103 cfu/ml to 4.5×104 cfu/ml, and no coliform growth was detected (NG). The microbial counts showed the samples were fit for consumption.