Multon J L, Bizot H
Ann Nutr Aliment. 1978;32(2-3):631-54.
In order to define the concept of Intermediate Moisture Foods (IMF) some ideas concerning the water bonding state in foods are reminded: water molecules properties, polar groups of hydrophilic macromolecules, activity of water (aw); sorption and desorption isothermal curves. Between dried products (solids with friable and breakable texture) anv very hydrated products (meat or fresh fruits for example), the IMF are characterized by their high aw (from 0.65 to 0.90) and their generally soft texture. Some typical examples of traditional and new IMF are then given. The IMF alterations are induced by chemical (oxydation) or biochemical (enzyme), biological (micro-organisms) or biophysical (water migration) causes, each of them being controlled by aw, temperature, pH, and other parameters. IMF technology consists generally to formulate products, the aw of which are less than 0.9, with aw depressors. Precise measurements of aw are then one of the most important mean for controlling fabrication, the direct computation being generally impossible. A manometric reference method for determination of aw is described; it consists to measure directly the equilibrium water vapor pressure. This method is preferable to a dew point determination. Some practical methods are reported, in connection with their accuracy and facilities of use.
为了定义中间水分食品（IMF）的概念，现将一些有关食品中水的结合状态的观点予以回顾：水分子特性、亲水性大分子的极性基团、水的活性（aw）；吸附和解吸等温线。在干燥产品（质地易碎的固体）和水分含量很高的产品（如肉类或新鲜水果）之间，中间水分食品的特点是其高aw值（0.65至0.90）和通常较软的质地。接着给出了一些传统和新型中间水分食品的典型例子。中间水分食品的变质是由化学（氧化）或生物化学（酶）、生物（微生物）或生物物理（水迁移）原因引起的，每一种原因都受aw、温度、pH值和其他参数的控制。中间水分食品技术通常包括使用水分活度降低剂来配制aw值小于0.9的产品。因此，精确测量aw是控制生产的最重要手段之一，一般无法直接计算。描述了一种测定aw的压力参考方法；该方法包括直接测量平衡水蒸气压。这种方法比露点测定法更可取。报告了一些实用方法，并介绍了它们的准确性和使用便利性。
