食品.水分活度测定

[中文适用范围]： 本文件确立了在 0 至 1 测量范围内测定人类食用食品和动物饲料水分活度 (aw) 的方法的基本原则并规定了要求。 测量原理基于露点测量或基于测定电解质电导率或聚合物介电常数的变化。 该方法不适用于低于冰点（相当于产品中出现冰晶的温度）储存的产品，也不适用于与脂肪包水乳液相对应的产品，也不适用于糖、盐或糖等晶体产品。 矿物质。 对于含有挥发性化合物（例如酒精）的产品，可能需要对特定设备进行改造才能应用该方法。 进行的实验室间研究的结果见附件 B。 [外文原描述]： ISO 18787:2017 establishes basic principles and specifies requirements for the methods of determining water activity ( a w ) of food products for human consumption and animal feed within a measurement range of 0 to 1. The measurement principles are based on the dew-point measurement or on the determination of the change in electrical conductivity of an electrolyte or in the permittivity of a polymer. The method does not apply to products stored below their freezing point (equivalent to the temperature at which ice crystals appear in the product), neither to products corresponding to a water-in-fat emulsion, nor to crystal products such as sugars, salt or minerals. For products containing volatile compounds, such as alcohols, specific equipment adaptations may be necessary to apply the method. The results of the interlaboratory studies that were carried out are given in Annex B.