Water Retention Properties of Solid Foods

Abstract

Water Retention Properties of Solid Foods "Water retention properties" is a term that is meant to represent a set of methods that have previously been collectively referred to as water holding capacity (WHC). The various water holding capacity tests used in the literature may use very different methods that lead to very different results. There are many available methods, with no standard or universally accepted methods for measuring water retention in food materials. This unit presents protocols for (1) expressible moisture by centrifugation using filter paper (see Basic Protocol 1), (2) drip loss by simple collection of moisture (see Basic Protocol 2; the same test can be used for cook loss, thaw loss, and so on), and (3) water uptake ability using the Omnimixer and centrifugation (see Basic Protocol 3). These protocols are presented as examples of rapid methods for measuring the water retention of various solid food materials, particularly flesh food material, for which they were developed. See Background Information for a discussion of these various methods. Also see UNIT B5.1 for a discussion of important considerations when choosing a protein functionality test. The expressible moisture test is a quick and simple method to measure the amount of water that might be expelled from the sample under the conditions of the test. By using a centrifuge, the actual water loss of the material is calculated rather than a relative "ring diameter" as in the classical Carver press method (Forbes et al., 1974; Lee and Patel, 1984). The water uptake ability assay is a very quick, easy, and relatively inexpensive test to determine some important properties of a solid food. It is important to choose the appropriate "solution" conditions for the added liquid. Many of the experimental parameters are somewhat arbitrary, although chosen only after preliminary experiments designed to optimize the test. This method is designed so that expressible moisture and water uptake ability can be compared using the same arbitrary experimental conditions.