The effects of homogenization treatment of raw milk on the physical properties of the produced Gouda-type cheeses were determined using rheological techniques. In this study, cheese samples were produced using well-controlled raw milk and production methods with and without the homogenization of raw milk. The fracture strength and frequency dependence of the dynamic modulus of the cheese samples were measured immediately after production until eight weeks of ripening. Both the fracture strength and modulus were lower immediately after production in samples homogenized than in samples with no homogenization. The rheological properties of the cheese samples varied throughout the ripening period, but especially around the 10th day of ripening, they showed irregular changes, suggesting that some changes occurred in the microstructure of the cheese during this period. These results suggests that the homogenization treatment of raw milk caused some changes in the structure of casein micelles and their network structures.

Tempura coating that is fried with wheat flour batter should have crispy texture; however, the gluten present in wheat prevents the development of a favorable texture. Thus, we prepared tempura using barley flour, buckwheat flour, or Job's tears flour, which do not form gluten structure. Their quality and palatability were compared to that of normal rice and waxy rice, which are gluten-free grains, in addition to wheat flour. We focused on the changes over time of texture which was an issue with tempura. We hypothesized that the changes in the texture involved moisture absorption from the ingredients, and aimed to reveal the difference in the changes over time by using grain flours. Changes in crispiness and moisture content were different based on the grain flour. Wheat, normal rice, and buckwheat tempura coating absorbed moisture from ingredients and lose crispiness over time. Waxy rice and barley tempura absorbed ingredients moisture only in the tempura coating near ingredients, and there was no change in the crispiness of that surface. Alternatively, Job's tears tempura coating did not change crispiness and moisture content even after 30 min of frying. Therefore, it would be beneficial to use appropriate tempura coating material based on the occasion.

The acoustic emission (AE) technique was used to develop a method for the objective evaluation of the crispness of porous foods. The crispness of six types of commercial porous foods was changed by controlling their moisture contents at six levels by varying the humidity (i.e., dry, 22, 43, 56, 68, and 81 % relative humidity) of the storage environment at 25 °C. As the crispness of a sample with high water activity (a_w) was expected to deteriorate, the physicochemical, mechanical, and acoustic characteristics of a_w-controlled food samples were evaluated. The a_w had no influence on the shape and porous structure of the foods. However, the number of force peaks in the uniaxial compression test appeared to be related to their a_w. Moreover, the breaking characteristics of a sample at different a_w values changed depending on the porous food type classified according to the degree of starch gelatinization. Among the AE characteristics, the number of AE events and AE count corresponded well with the a_w of the porous food. Therefore, for an objective evaluation of the crispness of porous foods, the AE events and AE count, which are highly sensitive, can be suitable indicators, rather than the number of force peaks.

The viscosity of liquid care foods is adjusted with a thickener, because suitable thickness prevents aspiration for the patient with dysphagia. Videofluoroscopy is used for detailed investigation of swallowing disorder, where the test liquid of an X-ray contrast medium is thickened to become comparable to the mealtime liquid. The effect of thickeners is influenced by the original viscosity of the contrast medium. Considering this influence, it is important to adjust the thickener concentration for the X-ray test liquid corresponding to the target viscosity. In this study, the effect of thickener concentration on viscosity thickening was investigated for xanthan gum-based thickeners. The viscosity/shear rate curve measured for the aqueous solution was fitted to a Carreau model, and the model constants were formulated as functions of the thickener concentration. Next the modelling method was extended to include the influence of contrast medium viscosity on the thickener concentration effect through the relative viscosity and apparent shear stress. The proposed method made it possible to easily determine the thickener concentration corresponding to the target viscosity for an X-ray test liquid. In addition, the influence of solution density on the syringe flow test was discussed.

Masticatory devices are expected to elucidate the relationship between changes in physical properties of food during mastication and masticatory parameters. This study analyzed the relationship between the progression of gummy candy fracture and some parameters that can be controlled by a novel mastication process simulator named “ORAL-MAPS”. Three commercial gummy candies were selected as test materials. The gummy candies were processed under the following 18 conditions: compression force (200, 400, and 600 N), compression frequency (30 and 60 cycles/min), and number of compressions (20, 40, and 60 cycles). Thereafter, the mean volume of the bolus particles was calculated utilizing a 3-dimensional shape measuring machine and used as an indicator of fracture progression. The result of multiple regression analysis with the logarithm of mean particle volume as the objective variable and device parameters as the explanatory variables showed that the number and frequency of compressions markedly affected the fracture of all gummy candies, whereas compression force exerted a smaller effect than these. Therefore, the standardized partial regression coefficient could be used to evaluate the characteristics of the gummy candies.

Mucociliary clearance (MCC) is the first line of defense in the respiratory tract, where beating cilia and viscous mucus play a pivotal role in eliminating inhaled harmful substances. Homeostasis of mucus rheological properties is a crucial factor in maintaining the functionality of MCC. However, rheological properties of the mucus is poorly understood because of the challenges associated with collecting intact mucus samples. In this report, in vitro three-dimensionally cultured human bronchial epithelial cells were used as a source of mucus to investigate mucus rheological properties. The mucus exhibited rheopectic and shear-thinning behavior, and mucus viscosity increased over time under constant shear when the mucus concentration was high. In addition, intermittent interruption of shear forces caused further increases in mucus viscosity. The experimental conditions mimic disease-state-MCC (i.e., mucus hypersecretion and impaired ciliary function). Thus, the results match the high mucus viscosity found in respiratory disease patients. Inhibiting disulfide bonding and hydrophobic interactions between mucin molecules, which are authorized therapies for chest congestion, reduced the rheological behavior. The rheopectic behavior of respiratory mucus and its importance in MCC has been presented herein, and our experimental approach should facilitate drug discovery against respiratory diseases.