Using Rheology of Weak Gels to Improve Fluid Foods

摘要

The rheology of solid or semi-solid food gives the food scientist insights into the relationships between physical properties and product performance. The instrumental measurement of the rheology of low-viscosity liquids has been a difficult task, but with the advent of controlled stress rheometers, it is now possible to characterize the rheology of fluids with viscosities as low as 1 mPa sec. This sensitivity is especially useful in applications in the food and beverage industry, allowing investigation of the properties of liquid systems that were previously seen only in more-structured materials. Food ingredients such as proteins and stabilizers impart rheological properties to liquids and produce effects which can be classified as "gel-like." The presence of these "weak" gels in liquids provide an opportunity for the food scientist to use rheological properties to improve texture and stability. The rheological properties of thin liquids have been explored and compared to the rheology of more-concentrated, and thus gelling, systems (Morris, 1989). There are many similarities between solutions of polysaccharide stabilizers and concentrated "true gels". Furthermore, these dilute solutions exhibit some of the rheological character of gels, and are designated as "weak gels".