Most food materials turn into glassy state when they are dried or frozen. The characteristics of glassy state and it's transition behavior affect on significant physical properties and chemical stability of food. Our knowledge for the glassy food system, however, is too little to predict or control the properties. Among characteristics for glassy materials, glass transition temperature, the enthalpy relaxation are dominant parameters to describe glassy properties. In this article, such glass transition temperature and enthalpy relaxation for actual several food materials were reported. Particularly, new theoretical approach for enthalpy relaxation process and the reaction in glassy food system were discussed. Furthermore, ball milling for starch as an alternative method for preparing glassy state, and glass transition behavior in frozen food materials below subzero temperature were introduced.
It is now desirable to achieve HACCP-compliant hygiene control even at a food kitchen of a restaurant or home-meal replacement manufacturer for safety improvement of the foods produced there. In this study, by a field research of a food kitchen of a home-meal replacement manufacturer, we attempted to investigate expected problems caused by conducting the conventional HACCP plan at food kitchen manufacturing a wide variety of products in small quantities. The research result revealed the following three problems; (1) variety of manufactured products; (2) lack of space in the kitchen for zoning regulation and one-way process control to prevent cross contamination; (3) production procedure is often changed flexibly by cooks. From these aspects, application of the conventional HACCP plan, which supposes a single food production, to the food kitchen will not be unrealistic. As for the solutions for the problems of variety of products, we proposed a simple hygiene control plan that was based on grouping and reconstruction of the conventional HACCP plan.
A new method of analyzing the viscoelastic behavior of liquid food materials is proposed. This new analysis method is based on a non-rotational concentric cylinder (NRCC) method that simultaneously measures the static viscoelastic properties (viscosity and elastic modulus) at a constant shear rate. Mayonnaise and ketchup with or without added water were used as the liquid samples. Two-element models, i.e. a series model comprised of a Newtonian viscous element and a Hookean elastic element (Maxwell model) and a parallel model comprised of these same two elements (Voigt model), were investigated in this study to elucidate the possibility of predicting the static viscoelastic behaviors of the samples, because the dynamic viscoelasticity of liquid food materials have been discussed mostly using these two-element models. Measurements using the NRCC method yielded mainly two types of force-time curves for the liquid samples. One type was a convex force-time curve, and the other was an almost linear curve. The analytical results showed that the former curve corresponds to the Maxwell-model materials, whereas the latter curve corresponds to the Voigt-model materials. The results indicate that the liquid materials with high dispersed-phase content (volumetric ratio φ> 0.75) showed Voigt-model-like behavior, while lower-concentration liquids showed Maxwell-model-like behavior.
The freshness indices of shell eggs are storage time and Haugh unit. Haugh unit is the value derived from the weight of a shell egg and the height of thick albumen and reduces due to carbon dioxide dissipation from the inside. In the present study, Haguh unit and storage time were nondestructively measured using transmission spectroscopy from near ultra violet range to near-infrared range. Each 55 eggs were stored in 3 environments: opened, packed, and exposed to carbon dioxide. Transmission spectrums were measured with 4 combinations of light source and light path every three days. Haugh unit and storage time were predicted from absorbance spectrums in the wavelength range from 500 nm to 950 nm with PLS regression. The prediction accuracy of the PLS model for storage time was high (R=0.966, SEP=2.43 days) . On the other side, the prediction accuracy of the models for Haugh unit was (R=0.867, SEP=10.8) . In both cases, the predicted models using xenon light source which have strong spectrum in the range near 500 nm showed the best accuracy.
Slightly acidic electrolyzed water, prepared by electrolyzing dilute hydrochloric acid, has a strong anti-microbial effect, and is widely used for various washing and disinfecting purposes. To obtain the desired effect, it is important to understand quantitatively how operating parameters affect available chlorine concentrations and pH in slightly acidic electrolyzed water. In this paper, a model was developed for prediction of available chlorine concentrations and pH in slightly acidic electrolyzed water by considering dissociation equilibrium for calcium carbonate and hypochlorous acid as well as electrochemical reactions in the electrolytic cell. Calculated results were generally in agreement with experimental results, which showed a decrease in pH with an increase in either available chlorine concentrations or water flow rates for dilution. The pH of the electrolytic solution in the cell was estimated to be less than 0.5. This finding supported our assumption that gaseous chlorine generated by electrolysis did not dissolve in the strongly acidic electrolytic solution. The model also predicted available chlorine concentrations and pH of the slightly acidic electrolyzed water prepared using source water with a different hardness reasonably well.
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