Study of Drying Conditions for dried Wolffia arrhiza powder Used in Buckwheat Milk Beverage

Abstract

This research investigated 2 different drying technologies (hot air drying and microwave-vacuum drying) in combined with blanching as a pre-treatment. The objective was to identify suitable drying conditions for Wolffia powder intended to use in buckwheat-based milk beverage. Dried Wolffia was required to have less than 10% moisture content and particle sizes ranging from 850 to 1,180 micrometers. Results indicated that blanching Wolffia for 0.5 minute prior to microwave-vacuum drying at 460 watts for 25 min provided the highest yield (7.50±0.88%). Physical quality was determined as water activity of 0.29±0.01 and color values (L* 41.68±0.28, a* -0.28±0.16 and b* 10.08±0.47). This drying condition provided Wolffia powder with the highest water solubility (37.99±2.05%) and protein content (29.23±0.65%, dry basis). Incorporating 0.09% of the dried Wolffia powder into the buckwheat-based milk beverage along with 0.84% matcha flavor resulted in liking scores from sensory evaluation on appearance & color, matcha flavor, taste, viscosity and overall liking between 6.46±0.73 and 7.51±1.0. Nutritional composition per 100 ml of the beverage was 56 kcal of energy, 0.63 g of fat, 1.06 g of protein, and 5.63 g of total sugar. Wolffia powder obtained from this study could be applied in plant-based milk products. It possessed the high protein content and good water solubility. Distinctive aroma of Wolffia powder could enhance matcha flavor in the beverage.