The effect of varying casein to whey protein ratio on physicochemical and structural properties of lactose and maltodextrin modified liquid and concentrated milk-tea blends

Milk tea is popular for its distinct taste and nutritional benefits. While adjusting the casein-to-whey protein ratio is commonly used to enhance milk-based formulas, its effects on milk tea quality are under-researched. This study investigates the effect of varying casein-to-whey (C: W; 80:20, 70:30, 60:40) and lactose-to-maltodextrin ratio (L:M; 90:10, 80:20, 75:25) on physicochemical and structural properties of milk-tea, including both post-pasteurized and concentrated skim milk-tea (SM-T) and fat filled milk-tea (FM-T) formulations. The primary focus is optimizing the retention of total phenolic content (TPC) to enhance the nutritional value of these formulations. The results showed that specific combinations of ratios significantly enhanced the TPC in the milk-tea such as FM-T with L:M ratios of 90:10 and 75:25, combined with C:W ratios of 70:30, and skim milk-tea formulations with L:M ratios of 90:10 and 80:20, combined with C:W ratios of 80:20 and 70:30, respectively. This enhancement was attributed to various mechanisms, including maltodextrin-phenolic interaction, enhanced protein-phenolic binding with whey proteins, the synergistic/combined effects of maltodextrin and whey proteins, fat-maltodextrin-whey protein interactions, and increased protein structural stability with higher maltodextrin and whey protein levels. Therefore, optimizing milk-tea stability and phenolic enhancement through L:M and C:W ratio adjustments provides a promising approach for enhancing final milk-tea properties.