饮料中的油溶性香料通常以油包水(O/W)乳化形式提供。香料成分——精油、树脂油、油溶性芳香化学品——溶解在食品级油相中,然后作为微小的油滴分散在水相连续相中。每个油滴由乳化剂(常用阿拉伯胶、变性淀粉或两者结合)稳定,防止油滴聚合。As noted in the Encyclopedia of Food Sciences and Nutrition entry on "Microscience of the Beverage Industry" (encyclopedia.pub, 2023),饮料乳液非常稀,成品中分散油相含量低至 20 mg/L。工程挑战是在饮料的保质期内(可能为 6 至 18 个月)保持这些微小油滴的稳定分散,抵抗驱使它们分离的力(乳化、絮凝、聚结和奥斯特瓦尔德熟化)。MDPI期刊的全面综述 Beverages (2018)探讨了饮料乳化剂配方及胶体稳定性在加入复杂食品基质后所面临的关键问题。该综述强调,饮料乳化剂不仅在浓缩香味中须保持稳定,稀释至成品饮料后,pH值、离子强度、甜味剂浓度及其他溶解固体均可能影响其稳定性。
发表于某学术期刊的研究 Journal of Food Science (2010)对比不同阿拉伯胶和淀粉基乳化剂制成的饮料云乳化体系的稳定性,发现阿拉伯胶乳化剂在模型饮料系统中的长效稳定性普遍优于改性淀粉;然而,改性淀粉在较短保质期的应用中表现尚可,并具有成本优势。
3.2 加重剂与密度匹配
Most flavor oils have a density lower than water (typically 0.8–0.9 g/mL for citrus oils), which means that unstabilized oil droplets will rise to the surface over time, producing the familiar "ring at the neck" of a beverage bottle. To prevent this, beverage emulsions commonly incorporate weighting agents—food-grade materials with density higher than water—to bring the overall oil-phase density closer to that of the aqueous phase.常用的增重剂包括酯胶(木质松香甘油酯)、蔗糖醋酸异丁酯(SAIB)和溴化植物油(BVO),但由于法规与消费者担忧,BVO在许多市场逐渐被淘汰。增重剂在乳化前溶解于油相中,配比以使最终油相密度尽可能接近成品饮料的密度,糖饮料的典型值为1.02至1.04克/毫升。
Oil-soluble systems are necessary or advantageous when: the flavor profile relies on citrus oils, spice oleoresins or other strongly hydrophobic materials; the brand wants a natural "juice-like" turbidity that emulsions can provide (many citrus-flavored soft drinks use emulsions for both flavor delivery and visual appearance); the product requires extended shelf-life protection against flavor degradation, because the oil phase can protect sensitive compounds from hydrolysis and oxidation; or the product is carbonated, because CO₂-driven acidity and bubble nucleation can destabilize some water-soluble systems but typically have less impact on well-formulated emulsions.CUIGUAI's work on floral notes in beverages using lavender and elderflower阐明了某些细腻植物风味在乳化传递体系的保护下得以展现。同样,早前文章中探讨的热加工饮料的开发亦展现了此优势。 pasteurization and fruit flavor volatiles此段强调热处理方式对可溶与乳化香精系统的相互作用,必须在实际生产过程中进行测试验证。
"Microscience of the Beverage Industry." Encyclopedia of Food Sciences and Nutrition, 2023. Encyclopedia.pub.
Piorkowski, D. T. and McClements, D. J. "Beverage Emulsions: Key Aspects of Their Formulation and Physicochemical Stability." Beverages (MDPI), 2018. MDPI饮料.
Chanamai, R. and McClements, D. J. "Depletion Flocculation of Beverage Emulsions by Gum Arabic and Modified Starch." Journal of Food Science, 2001.
CUIGUAI Flavoring. "Floral Notes in Beverages: Using Lavender and Elderflower Effectively." 翠桂技术博客.
CUIGUAI Flavoring. "The Impact of Pasteurization on Fruit Flavor Volatiles in Juices." 翠桂技术博客.