Powdered yoghurt produced by spray drying and freeze drying: a review

Abstract Yoghurt is one of the dairy products most consumed worldwide but dehydrated yoghurt is still uncommon. Considered a nutritious food, yoghurt powder could be used as an ingredient or supplement in juices, cookies, ice cream and dairy beverages. Spray drying and freeze drying are the methods most widely used to dehydrate dairy products, and the process conditions are directly associated with the production costs and value of the final product. Due to osmotic and thermal stress during dehydration, it is often necessary to incorporate agents such as carriers, thermal protectants, cryo-protectants and stabilizers in order to improve the process yield, preserve nutrients and even facilitate rehydration of the product. Thus the present review presents the technologies available to obtain yoghurt powder, including the processes, drying agents, drying rates, rehydration conditions and survival of the lactic acid bacteria.

摘要 酸奶是全球消费量最高的乳制品之一，但脱水酸奶仍较为少见。作为一种营养丰富的食品，酸奶粉可作为配料或添加剂应用于果汁、曲奇、冰淇淋及乳饮料中。喷雾干燥（spray drying）与冷冻干燥（freeze drying）是乳制品脱水最常用的两类工艺，其工艺参数直接与生产成本及最终产品的价值挂钩。由于脱水过程中会受到渗透胁迫与热胁迫的影响，通常需要添加载体、热保护剂、低温保护剂及稳定剂等助剂，以提升工艺得率、保留营养成分，甚至改善产品的复水性能。因此，本综述对可用于制备酸奶粉的相关技术进行了系统梳理，涵盖制备工艺、干燥助剂、干燥速率、复水条件以及乳酸菌存活率等核心内容。