Multi-response Modelling and Quality Optimization of Plant-Based Functional Beverage

In recent times, the demand for functional foods and beverages with health benefits has been increasing. Demand for these products has risen in many parts of the world, and there has been growing recognition of the key role that functional foods and beverages play in disease prevention and treatment. Rapidly increasing knowledge of nutrition and plant biotechnology has dramatically changed concepts of food and health. Plant-based beverages are by far the most active functional drink category; they are excellent vehicles for the delivery of nutrients and bioactive compounds. They constitute the fastest-growing segment of the functional beverage market worldwide, and as consumers have become more aware of the relationship between diet and disease prevention, demand for these products has grown significantly. In this study, a powdered functional beverage developed from carrot, spinach, coconut, date fruit, garlic and beetroot was modelled and optimized using response surface methodology and the desirability function. A constrained D-optimal mixture experimental design comprising 31 randomized experimental runs was employed. The design constraints were: carrot (20–36%), spinach (20–36%), coconut (20–36%), date fruit (20–36%), garlic (0.5–2%) and beetroot (0.5–2%). The formulated samples were evaluated for selected proximate, physical, physicochemical, vitamin and mineral properties using standard procedures, and sensory evaluation was conducted by 50 consumers using a 9-point hedonic scale. Superimposition of the contour plots corresponding to each response resulted in an optimized powdered beverage with an overall desirability index of 0.599, based on the set optimization goals and the individual response desirability indices. The formulation that produced the optimal powdered beverage consisted of 21.70% carrot, 24.15% spinach, 28.32% coconut, 22.88% date fruit, 0.96% garlic and 2.00% beetroot. The quality properties of the optimal powdered beverage were: 8.58% moisture content, 9.74% protein, 43.98% carbohydrate, 6.56% fibre, 20.17% fat, 0.70 g/mL bulk density, 344.26 mL reconstitution index, 14.45 °Brix total soluble solids, pH 5.66, 5.80% reducing sugar, 0.21 mg/100 g vitamin B6, 30.01 mg/100 g vitamin C, 2.31 mg/100 g iron, 237.43 mg/100 g potassium, 40.62 mg/100 g calcium, 66.76 mg/100 g sodium and 32.08 mg/100 g magnesium, with an overall acceptability value of 6.69.