Department of Food Science and Technology, College of Agriculture, Isfahan University of Technology, Isfahan, Iran.
Compr Rev Food Sci Food Saf. 2023 Nov;22(6):4190-4216. doi: 10.1111/1541-4337.13207. Epub 2023 Aug 24.
The consumption of fruit juices has been increasingly growing all over the world. The clarification process is considered as one of the most important stages in fruit juice production, which can provide the products with desired clear visual appearance. Nowadays, the tendency of consumers to use the natural-clarified fruit juices encourages the researchers to allocate much attention on utilization of natural clarifying agents to clarify different fruit juices. This review article has first introduced the most frequent causes of turbidity in fruit juices including polysaccharides (i.e., cellulose, hemicelluloses, lignin, starch, and pectic substances), proteins and polyphenols (especially tannins) as well as their removal mechanisms. After that, a comprehensive summary of research on natural fining agents, including clay minerals, polysaccharides, proteins, enzymes (free and immobilized forms), and activated carbon is provided with a focus on their application in the juice clarification process. The chemical composition of natural substances, their efficiency on reduction of turbidity-causing compounds and the changes in properties of clarified juices such as turbidity (clarity), total phenolic content, total anthocyanins, viscosity, and sensory evaluation followed by their stability during the storage have been deeply discussed.
果汁的消费在全球范围内呈增长趋势。澄清过程被认为是果汁生产中最重要的阶段之一，它可以为产品提供所需的清澈外观。如今，消费者倾向于使用天然澄清果汁，这促使研究人员更多地关注利用天然澄清剂来澄清不同的果汁。本文首先介绍了果汁中混浊的最常见原因，包括多糖（如纤维素、半纤维素、木质素、淀粉和果胶物质）、蛋白质和多酚（特别是单宁）以及它们的去除机制。然后，全面总结了天然澄清剂的研究，包括粘土矿物、多糖、蛋白质、酶（游离和固定化形式）和活性炭，重点介绍了它们在果汁澄清过程中的应用。本文深入讨论了天然物质的化学组成、它们对去除混浊物质的效率以及澄清果汁的特性变化，如混浊度（清晰度）、总酚含量、总花青素、粘度和感官评价，以及在储存过程中的稳定性。
