Background Holding times for raw materials are relevant, since they enable us to understand the allowable time that a raw material can be kept under ideal storage conditions before the start of the manufacturing process without its quality attributes being affected. The quantification of water activity can be used as an indicator of the microbiological, physicochemical, and organoleptic stability of a specimen, since low water activity retards autohydrolysis and microbiological growth. Objective The main purpose of this investigation was to test the stability of powdered raw materials for a maximum holding time of 8 days through water activity measurements. Thus microbiological, physicochemical, and organoleptic measurements were carried out in parallel and simultaneously in order to experimentally establish a relationship between the status of the water activity of processed raw materials and the microbiological, physicochemical, and organoleptic results. Results The raw materials were stored for a maximum holding time of 8 days, in accordance with USP monographs. For all the raw materials tested, water activity measurements were performed using the dew point chilled-mirror method on days 0, 3, and 8. On days 0 and 8, microbiological, physicochemical, and organoleptic assessments were performed. It was established that under these storage conditions, the processed raw materials exhibited water activity below 0.60 during the entire holding time. However, there were statistically significant differences in water activity levels between days 0, 3, and 8 (ANOVA P < 0.05). Despite observing statistically significant differences between days, the microbiological, physicochemical, and organoleptic features were within specification at those water activity levels, below 0.60. Conclusion Water activity below 0.60 does not allow the growth of microorganisms, and the organoleptic and physicochemical features remain unperturbed. The results indicate that water activity can be used as an indicator of the microbiological load and chemical stability of the raw materials tested.

中文翻译：

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通过水活度测量进行分散粉状原料的稳定性研究

背景 原材料的保存时间是相关的，因为它们使我们能够了解在制造过程开始之前原材料可以在理想的储存条件下保存而不影响其质量属性的允许时间。水分活度的量化可用作样本的微生物学、物理化学和感官稳定性的指标，因为低水分活度会阻碍自水解和微生物生长。目的 本次调查的主要目的是通过水分活度测量来测试粉状原料在最长 8 天保存时间内的稳定性。因此，平行且同时进行微生物、物理化学和感官测量，以便通过实验建立加工原料的水活度状态与微生物、物理化学和感官结果之间的关系。结果 根据 USP 各论，原材料的最长保存时间为 8 天。对于所有测试的原材料，在第 0 天、第 3 天和第 8 天使用露点冷镜法进行水分活度测量。在第 0 天和第 8 天，进行微生物、物理化学和感官评估。已确定，在这些储存条件下，加工后的原材料在整个保存时间内表现出低于 0.60 的水分活度。然而，第 0 天、第 3 天和第 8 天之间的水分活度水平存在统计学上的显着差异（ANOVA P < 0.05）。尽管观察到几天之间存在统计学上的显着差异，但微生物、物理化学和感官特征在这些水分活度水平（低于 0.60）下均在规格范围内。结论 水分活度低于0.60不允许微生物生长，并且感官和理化特征保持不变。结果表明，水分活度可以作为测试原料的微生物负荷和化学稳定性的指标。