Abstract Red onion microcapsules were produced by spray freezing into liquid cryogenic (SFLC) and spray drying (SD) and their anthocyanin contents were evaluated kinetically at different water activities ( a w ) at 35 °C. The spreading pressure-area isotherms were determined at 35 °C. These isotherms provide important information about the different phases of adsorbed water present in SD and SFLC capsules, which can be related to minimal integral entropy and to chemical stability during storage. The porosity of the microcapsules was examined using low-temperature adsorption of nitrogen. The maximum anthocyanin stability occurred at a w from 0.108 to 0.318, and 0.108 to 0.515, for SD and SFLC, respectively. SD products were nonporous whereas SFLC were mesoporous. The tendency to contraction of the adsorbed water film was compared with the minimum integral entropy and was proposed as a new stability criterion to predict suitable storage conditions of dehydrated foods.

中文翻译：

---

多孔结构和铺展压力对喷雾冷冻成液低温喷雾干燥红洋葱微胶囊贮藏稳定性的影响

摘要 采用喷雾冷冻成液体低温（SFLC）和喷雾干燥（SD）制备红洋葱微胶囊，并在35℃、不同水分活度（aw）下对其花青素含量进行动力学评价。铺展压力-面积等温线在 35 °C 下确定。这些等温线提供了关于 SD 和 SFLC 胶囊中吸附水不同相的重要信息，这可能与最小积分熵和储存过程中的化学稳定性有关。使用氮气的低温吸附来检查微胶囊的孔隙率。对于 SD 和 SFLC，最大花青素稳定性分别发生在 aw 为 0.108 至 0.318 和 0.108 至 0.515 时。SD 产品是无孔的，而 SFLC 是中孔的。