Influence of composition and tea infusion on physicochemical properties of pasteurised and concentrated Milk-Tea: Focus on protein-carbohydrate-fat interactions

Milk-tea is popular for its flavour and health benefits, but the impact of its composition on physicochemical properties is understudied. This study examined the impact of varying tea infusion concentrations (1–5 % w/v) on pasteurised and concentrated milk-tea formulations. It explored different fat levels, casein-to-whey ratios (C:W; 80:20, 70:30, 60:40), and lactose-to-maltodextrin ratios (L:M; 90:10, 80:20, 75:25). Results showed a tea concentration-dependent increase in total polyphenolic content (TPC), with 5 % tea yielding the highest retention in both fat-filled milk-tea (FM-T) and skim milk-tea (SM-T). In FM-T, fat enhanced polyphenol stability via hydrophobic and hydrogen bonding, and allowing for greater retention of TPC after concentration despite L:M and C:W ratios. In contrast, SM-T showed a stronger polyphenol-protein binding, leading to aggregation at low L:M ratios, although maltodextrin helped preserve TPC through a hydration shell formation. Overall, tea concentration, fat, and optimal C:W and L:M ratios influence polyphenol retention and milk-tea stability.<p></p>