Beetroot Microencapsulation with Pea Protein Using Spray Drying: Physicochemical, Structural and Functional Properties

Beetroot is a root vegetable with carotenoids, phenols, vitamins, minerals, and water-soluble betalain pigments such as betacyanins (red-violet color) and betaxanthins (yellow-orange color), which have many nutritional and health benefits. Its use in the food industry is mainly as a powdered natural dye. This study aims to investigate the effect of adding pea protein to beetroot juice as an encapsulating agent, and the spray-dried temperature on the physicochemical, structural, and functional properties of the powder. The spray drying was conducted at 125 and 150 °C with 3.5% and 7% pea protein used in the mixtures with the beetroot juice. The water content, bulk density, porosity, hygroscopicity, water solubility, water absorption index, color, and microstructure of the obtained powder were determined. In addition, betacyanin, total phenols, antioxidant capacity, and powder encapsulate efficiency were analyzed. Using pea protein in the spray drying of beetroot juice had shown high yields of spray drying and good characteristics of the powdered product. Beetroot powder with 7% of pea protein was more porous and luminous, and less hygroscopic than beetroot powder with 3.5% of pea protein. However, the use of 7% of pea protein increased the amount of water immobilized by the samples and reduced the soluble solids present in the product compared to beetroot powder with 3.5% of pea protein. The use of 7% of pea protein protected beetroot bioactive compound higher than the use of 3.5%. Higher spray-drying temperature (150 °C) significantly decreased phenols content and antioxidant capacity of the beetroot powders (p < 0.05). Results showed using 7% pea protein mixed with beetroot juice and a 125 °C spray-drying temperature gave the most content of the studied bioactive compounds and antioxidant capacity. Moreover, the proposal gives more stable powders from a functionality viewpoint because it showed the higher encapsulate efficiency.