Milk Gel Structure. I. Application of Scanning Electron Microscopy to Milk and Other Food Gels

Abstract

The structure of a variety of food gels was studied by scanning electron microscopy. By a stereoscopic technique, pictures of heat-induced, acid-heat, and renneted milk gels, whey gels, tofu, coagulated egg white, and gelatin gels were obtained. Because of the unique structure of gels, various modifications of fixation, mounting, and viewing were introduced. Heat-induced milk gels consisted of casein micelles linked together by short, thin fibers. Such fibers were not in acid-heat gels, which were composed of expanded protein particles closely attached to each other forming thick chains and networks. Renneted milk gels contained a high proportion of long fibers, and casein micelles were fused together. Whey gels contained particles of various sizes, and the occurrence of fiber-like material was low. Tofu and coagulated egg white had similar structures consisting of many corpuscular fibers. Warped sheets of protein were found in gelatin gels. © 1973, American Dairy Science Association. All rights reserved.