文摘

This study describes novel formulations and approaches to produce reconstitutable (in water) spray dried kiwifruit milk powders that possess the intrinsic fruit colour and antioxidants of kiwifruits. Novel feed formulations, containing the aqueous fraction of green or gold kiwifruit puree, skim milk, fortifying zinc (in the form of zinc citrate) and a minimal amount of maltodextrin (3?% w/w), were spray dried at a relatively low inlet temperature (150?°C) to produce kiwifruit juice–milk powders with good dissolution efficiency (complete dissolution in 21-8?s), low water activity (0.22-.28) and high retention of vitamin C, phenolics and carotenoid antioxidants. Both the green and gold kiwifruit juice–milk powders were pseudoplastic-like materials. Their reconstituted aqueous solutions had viscosity of 2-3?mPa?·?s and exhibited a shear rate dependence. Adding kiwifruit pulp residue to the feed solution at a mass ratio of 25:75 significantly enhanced the dissolution efficiency and the natural kiwifruit colour of the product powders without affecting the total phenolic and vitamin C contents. Preheating the feed solution to 50?°C for 1?min had a positive impact on the physicochemical attributes and bioactive profile of kiwifruit juice–milk powders, including a greater retention of initial kiwifruit juice colour, lower water activity, better dissolution efficiency and a higher total phenolic content. The powders obtained in this study contain multiple health-promoting nutrients and bioactives including kiwifruit antioxidants and milk proteins, and can be used in beverages or as functional ingredients for nutraceutical applications.