The thermophysical properties (effective thermal conductivity, effective thermal diffusivity, specific heat) of ground pork having a fat content range of 3-26% were measured at four different temperatures between 20°C and 50°C. The transient heat flow method using a probe was used for the simultaneous estimation of the thermophysical properties of the ground pork sample. The effects of temperature and fat content on the thermophysical properties of the sample were investigated. For the effective thermal conductivity and the effective thermal diffusivity, the observed values were compared with the values calculated from four typical structural models for thermal conductivity and thermal diffusivity, i.e., the series, parallel, random, and distribution model. The most suitable prediction models were the parallel model for the effective thermal conductivity of the sample, and the series model for the effective thermal diffusivity of the sample. An additive relationship existed between the specific heat of the sample, composition, and the specific heat of each component.

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Osmotic dehydrofreezing has been proposed as an excellent freezing technique for fresh vegetables because the texture after freezing-thawing can be kept in better condition. However, this mechanism has not yet been clearly understood. Thus we investigated in detail the osmotic dehydrofreezing mechanism through comparative measurements of water permeability using PFG-NMR (Pulsed filed gradient Nuclear magnetic resonance) spectroscopy and of texture using texture analyzer for carrot and onion tissues before and after freezing. In particular, texture was evaluated using two parameters, namely fracture stress and instantaneous elasticity, related to the strengths of the cell wall and cell membrane in the tissues, respectively. The results suggested that although the strength of the cell wall of cells in the carrot and onion tissues was maintained by osmotic dehydrofreezing, the elasticity in texture and the water permeability due to the damage of the cell membrane markedly changed. Moreover, from this study it was found that some damage was inflicted on the cell membrane by only osmotic dehydration without freezing. In conclusion, it can be said that the osmotic dehydrofreezing technique is suitable for protecting the cell “wall”, but cannot maintain the texture of the tissue the same as that of fresh tissue owing the damage to cell membrane.

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Vapor heat treatment under mild conditions (MVHT) was studied to assess its effect on anthracnose disease and assess the effect of heat on the quality of 'Irwin' mango (Mangifera indica L.). Colletotrichum gloeosporioides and C. acutatum (both, mango anthracnose fungi) did not grow when subjected to MVHT at 50°C for 10min in vitro. When the mango fruits were inoculated with C. gloeosporioides, the prevention value of MVHT for anthracnose after 5 days of MVHT was 95 (on the day of inoculation) or 76 (one day after inoculation), and the disease was controlled effectively. In addition, MVHT was effective in a proof examination using non-inoculated mango. The fruit had a yellow color after being subjected to MVHT, and the glossiness of the fruit slightly deteriorated. On the other hand, the development of the yellow color and the glossiness were restrained after 4 days storage at room temperature. Weight loss and respiration rate were decreased by MVHT, but sugar and organic acid contents were not significantly affected. The fully ripened mango subjected to MVHT was slightly inferior only in terms of hue and gloss, but palatability was good.

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The thermal conductivity and thermal diffusivity of two kinds of milk powder (skim milk powder and whole milk powder) were measured at selected moisture contents, temperatures, and bulk densities. The transient heat flow method using a probe was used for the simultaneous determination of the thermophysical properties of each sample. The effects of moisture content, temperature, and bulk density on the thermophysical properties of the sample were investigated. The thermal conductivity of each sample could be represented as a function of moisture content, temperature, and bulk density. The thermal diffusivity of each sample was related to a linear function of bulk density. In addition, the specific heat of the sample was estimated by substituting the thermal conductivity and thermal diffusivity of the sample, and the bulk density of the sample-packed bed into the definition equation of thermal diffusivity, and represented as a function of both temperature and moisture content.

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