Etsuko Maruyama

Effects of sugars on stability of egg foam and their rheological properties

Publisher Summary This chapter studies the rheological property of foams and describes the effects of saccharides on the stability of foam systems. The linear viscoelastic region for foam systems under uniaxial compression is very narrow. The creep behavior for foam systems can be divided into three parts: elastic, viscoelastic, and steady flow part. The creep compliance and steady flow part of the foam systems decreases with increases in sugar concentration. The amounts of draining from the foam systems increase and the protein contents in drainage liquid decrease with standing time. The rate of draining is impeded when sucrose is added to albumen. Furthermore, the density of the foam systems becomes larger on addition of saccharides because the particle size of the gas cells becomes smaller and more homogeneous in the presence of sugar. The spin-spin relaxation times of foam systems, obtained by the Carr-Purcell-Meiboom-Gill (CPMG) method, becomes shorter on addition of sugar. It might be considered that saccharides prevent the mobility of water between the films of foam, therefore foam systems might be stabilized.

Studies on the Browning of Foods (Part 1)

This study was carried out to obtain the lead which clarified the mechanism of the browning phenomenon. In this report, polyphenolic substances and intermediates of browning reaction in Tsukune-imo were investigated by paper chromatography, color test and absorption spectrum. The results are summarized as follows: 1. At the least, six polyphenolic substances were detected in the extract of Tsukune-imo by Amberlite column chromatography and there were identified as pyrocathecol, catechin, Dopamine, tyrosine, Dopa, and other flavanol tannin. 2. The spectrum changes of Tsukune-imo juice were observed during the incubation period. At first, in a visible range of wavelength, two small peaks were observed at 450•`455 mp, 480•`490 mƒÊ and the increase of the optical density in ultraviolet spectrum was estimated at around 260 mƒÊ. 3. In model system, four polyphenols were respectively incubated with phenol oxidase which was extracted from acetone powder of Tsukune-imo, and the changes in the absorption spectrum of model system were estimated. It was found that the spectrum changes of model system with catechin was resemble with those of Tsukune-imo juice. 4. Paper chromatogram of the browned Tsukune-imo juice was resemble with that of intermediates which occurred in model system with catechin.