Asian Food Science Journal

Consumers are increasingly demanding nutritional quality in food products. The enrichment of yoghurt with functional ingredients, such as fruits and vegetables, has been widely explored to meet this demand. However, limited attention has been paid to the use of combined dates and beetroot as enriching ingredients in yoghurt, despite their abundance and high nutritional value. With increasing consumer demand for nutritious foods, the food industry is striving to develop formulations that offer high nutritional value and sensory quality beyond expectations. Dates (Phoenix dactylifera) are particularly interesting due to their high content of natural sugars, soluble and insoluble fibres, and phenolic compounds with antioxidant properties. Similarly, beetroot (Beta vulgaris) is an exceptional source of phytonutrients, including betalains, flavonoids, and nitrates. These compounds have health benefits, including better tissue oxygenation, reduced oxidative stress, and a supply of essential minerals such as iron and magnesium. Incorporating these ingredients into soy yoghurt could not only improve its nutritional and functional qualities but also help prevent anaemia, a common public health problem in certain vulnerable populations. This study aimed to evaluate the effect of supplementation with date powder and beetroot extract on the physicochemical, functional, sensory, and microbiological properties of soy-based yoghurt. The yoghurt was formulated using a central composite design to optimise three parameters: the soybean-to-water ratio, the quantity of date powder, and the volume of beetroot juice. The proximate composition of the date powder was determined using the AOAC methods. Sensory attributes were scored using a nine-point hedonic scale. The sensory characteristics of the yoghurt, including appearance, taste, aroma, mouthfeel, and texture, were evaluated by a panel of 30 untrained individuals. Statistical analysis of the experimental data was conducted using Analysis of Variance (ANOVA) with Statgraphics Centurion 19 (version 19.1.1). The Response Surface Methodology (RSM) was performed using Design Expert 13 (version 13.0.5.0). The responses analysed included pH, °Brix, and viscosity. Sensory and microbiological quality evaluations were performed on the optimal product and the control product. The analyses showed that the formulated yoghurts had pH values ranging from 2.49 to 5.42, °Brix values between 10.50 and 19.16 °B, and viscosities ranging from 140 to 6575 mPa.s. The optimal production conditions for the enriched yoghurt were 161.76 g/400 mL for the soybean-to-water ratio, 25 mL for beetroot juice, and 25 g for the amount of date powder. Under these conditions, the theoretical and experimental values for pH, °Brix, and viscosity were very close, with insignificant differences (pH: 4.50 and 4.47; °Brix: 14.02 and 14.67; viscosity: 1958.95 and 1973 mPa.s). Sensory evaluation revealed that the enriched yoghurt had properties comparable to the control product. Microbiologically, the enriched yoghurt contained a significantly higher concentration of viable lactic acid bacteria (8.72 ± 0.04 Log CFU/mL) compared to the control yoghurt (7.60 ± 0.02 Log CFU/mL). These results provide a solid foundation for the development of functional plant-based yoghurts, which could help reduce the prevalence of anaemia and other nutritional deficiencies in vulnerable populations. Date powder and beetroot extract can be utilised as sources of bioactive compounds, paving the way for the development of functional yoghurts. The yoghurt enriched with date powder and beetroot extract showed a positive impact on the quantity of lactic acid bacteria and on certain sensory characteristics. Furthermore, the presence of iron in beetroot extract could help reduce the prevalence of anaemia among pregnant women.