Abstract: This study developed 3D-printed lactose-whey protein isolate (WPI) composite carriers and systematically evaluated their protective effects on proanthocyanidins and vitamin B2. A lactose/WPI mass ratio of 1:1 provided the best printability and structural stability. Thermal degradation analysis showed that increasing lactose content decreased the activation energy of proanthocyanidins from 74.63 to 59.21 kJ/mol, indicating enhanced thermal sensitivity. After 8 h of storage at 65 ℃, the color difference (ΔE) increased with lactose content, and high performance liquid chromatography (HPLC) confirmed catechin as the major degradation product. The photodegradation of vitamin B2 followed first-order kinetics, with the rate constant rising from 0.054 9 to 0.099 3 h–1 as the lactose content increased. Liquid chromatography-mass spectrometry (LC-MS) identified lumichrome as the primary photoproduct. Mechanistic analysis suggested that lactose regulates molecular mobility and pore architecture within the carrier matrix, thereby influencing nutrient migration and modulating their thermal and photosensitivity. Overall, optimizing the lactose/WPI ratio in conjunction with 3D-printed structural design effectively improves the stability of water-soluble nutrients, offering a promising strategy for the development of personalized and functional foods.

Key words: 3D-printed carriers; proanthocyanidins; vitamin B2; thermal degradation and photodegradation; kinetics; nutrient protection