This study investigates the impact of substituting lactose with maltodextrin in milk–tea formulations to enhance their physicochemical and structural properties. Various lactose-to-maltodextrin ratios (100:0, 90:10, 85:15, 80:20, 75:25) were evaluated in both post-pasteurized and concentrated skim milk–tea (SM-T) and whole milk–tea (WM-T) formulations. Concentration significantly improved the zeta potential, pH, and browning index in both SM-T and WM-T compared to pasteurization. L:M ratios of 90:10 and 75:25 in WM-T and 90:10 and 80:20 in SM-T showed higher phenolic preservation after concentration due to structural changes resulting from the addition of maltodextrin and water removal during prolonged heating. The preservation effect of phenolic components in both WM-T and SM-T is governed by many mechanisms including pH stabilization, zeta potential modulation, protein interactions, complex formation, and encapsulation effects. Therefore, optimizing milk–tea stability and phenolic preservation through L:M ratio adjustments provides a promising approach for enhancing milk–tea properties.

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.