Chemical Content and Color of Dried Organic Beetroot Powder Affected by Different Drying Methods

Abstract

Preserving vegetable products through drying, which reduces the water concentration to levels inhibiting the growth of microorganisms, is a method to extend their shelf life. Consequently, dried products can be stored for extended periods, mitigating seasonality in some regions. Beetroot roots are a good source of minerals, vitamins, and bioactive compounds, as well as valuable betalain pigments, which consist of red-purple betacyanins and yellow-orange betaxanthins. During processing, the content of betalains decreases because they have insufficient resistance to high temperatures; therefore, color changes occur. Different drying methods were used for beetroot dehydration: conventional drying, vacuum freeze-drying, and spray-drying. The chemical content and physical properties were analyzed. The total phenolic content, as well as betalains, depended not only on the drying method applied but also on the cultivar of beetroots. The phenol content ranged from 2.30 mg GAE g−1 DM in vacuum freeze-dried ‘Scarlet’ beetroot powder to 1.85 mg GAE g−1 DM in conventionally dried ‘Jolie’, as well as ‘Scarlet’, beetroot powder. The predominant betalains in beetroot powder were betacyanins, with the highest content in spray-dried ‘Scarlet’ beetroot powder and the lowest in conventionally dried ‘Kestrel’ beetroot powder. The most significant color changes were observed in spray-dried beetroot powders.