We examined the effects of different amounts of air bubbles on the properties and preference for steamed bread made from Japanese yam with strong stickiness harvested in Fukushima prefecture, and investigated the suitability of steamed bread gruel as diet suitable for dysphagia. Although the apparent density of a pre-steamed sample continued to decrease with up to 10 min of whipping time, the degree of swelling increased. A sensory evaluation showed that steamed bread gruel with 8 min of whipping time was preferred. The ORAC values were 361 (μmol TE/100 g) for unpeeled Japanese yam, 76 for steamed Japanese yam bread, and 25 for its gruel. We consider that Japanese yam products will have desirability and antioxidant capacity when used as a secondary material.

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Samples of beef, chicken, and potato were boiled in water of differing hardness, and the resulting broths were analyzed for their mineral composition. The boiled samples were assessed for their rupture strength and microstructure, and a sensory evaluation was conducted to examine the effects of water hardness on the quality of the stewed samples. These three samples boiled in hard water absorbed Ca and Mg, while the amounts of K and Na dissolved in the broths were higher with hard than with soft water. The rupture strength of the beef sample boiled in Evian water for 120 min was significantly low, while the potato sample boiled in hard water exhibited a high value. The microstructure of beef boiled in Evian water showed marked detachment of the endomysium and perimysium from the muscle fiber bundles, and controlled gelatinization of starch, in which the cells cohered, was noted in the potatoes boiled in hard water. Boiling in Evian water imparted a tender texture to meat and a harder texture to potatoes than when cooked in soft water; this prevented such vegetables from losing firmness during cooking, suggesting that water with a relatively high level of hardness (approximately 300) would be suitable for stewing a variety of ingredients including meat and vegetables.

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Rice gruel samples were prepared by adding to rice gruel a commercial gelling agent whose main ingredients were konjak glucomannan, a kind of dietary fiber hydrocolloid, and a polysaccharide thickener. We examined the correlation between the physical properties of the samples and ease of eating by a sensory evaluation and electromyographic measurement of the musculature during mastication and swallowing. The sensory evaluation showed that adding the gelling agent to rice gruel resulted in the perception of less stickiness and better cohesion in the oral sensation. Cooling of the samples with time significantly increased the hardness and rupture load for a single grain of rice in the gruel. This cooling made mastication of the sample more difficult, and also extended the muscle activity duration of the supra-hyoid musculature that is used for conveying the food bolus from the oral cavity to the pharynx.

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We investigated the effects of soaking at high temperature on the water absorption, fracture characteristics, sensory evaluation and chemical components of boiled black soybean seeds. The seeds were soaked in water at 20°C for one hour to 20 hours and at six temperatures from 30°C to 80°C for two hours before boiling. Soaking at 20°C achieved equilibrium after 10 hours in the increasing ratio of seed weight after boiling and the fracture characteristics of the boiled seeds. Soaking for two hours increased the increasing ratio of seed weight and decreased the fracture force of the boiled seeds with increasing temperature from 20°C to 60°C, and achieved equilibrium at temperatures above 60°C. Soaking for two hours at temperatures above 70°C markedly increased the soluble solid content, and soaking above 60°C markedly inhibited the cracked seed rate. The effects of soaking at 60°C for two hours on the sensory evaluation and chemical components were comparable to those of soaking at 20°C for 10 hours. It is considered that soaking at 60°C for two hours was most effective in the cooking process to ensure the best quality of the boiled seeds.

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The effect on taste compounds was investigated in the minced meat of chicken thigh cooked by six different methods: heating by microwave (500 W for 7 min, M), heating by convection heater (210°C for 35 min, O), and heating by four other combined types (M for 3 min+O for 30 min, C1; M for 4 min+O for 25 min, C2; M for 5 min+O for 20 min, C3; and M for 6 min+O for 15 min, C4). The content of 5'-IMP was highest in the M sample and reduced with increasing convection heating. The contents of glutamic acid and other free amino acids did not vary among the differing heating conditions. The peptide with MW 18,000 decreased during convection heating, suggesting that the smaller peptides were increased by protein degradation, the taste of the cooked chicken being most affected by these smaller peptides. The effect on 5'-IMP and the smaller peptides, which most contributed to the taste, implies that combined heating by microwave and convection was the best method for cooking chicken.

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Four kinds of rice gruel with different amylose content (high-amylose rice, middle-amylose rice, low-amylose rice and non-glutinous rice) were studied to examine the relationship between the physical properties of the cooked rice samples and their ease of eating. The physical properties were measured, a sensory evaluation was conducted, and the electromyographic activities (EMGs) were recorded from the masseter muscle. The high-amylose rice gruel sample, whose textural properties were hard and low in cohesiveness and whose single grain of rice gruel demonstrated a significantly high load in the low-strain region of the strain-load curve, was significantly harder, less sticky in the mouth, and less cohesive than the other three samples in the sensory evaluation. The EMG measurements during mastication of the high-amylose rice gruel sample, whose textural properties were harder than the other samples, indicated a higher frequency of mastication and greater total masseter muscle activity than with the glutinous rice gruel sample, whose textural properties were softer than the other samples. However, the average masseter muscle activity and muscle amplitude per masticating motion for the glutinous rice gruel sample, whose total muscle activity was small, were greater than those for the high-amylose rice gruel sample.

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We investigated the changes in the properties of the bolus while chewing mashed potato with added oil and fats to elucidate the swallowing characteristics. The hardness, yield stress and horizontal resistance force of the bolus for the samples with added liquid (BPW and BPO) were significantly lower than those for the samples with added solid (BPF and BPS). The samples with added liquid (PW and PO) and mixed with saliva after 5 times chewing gave close to a swallowable bolus, while the samples with added solid (PF and PS) needed chewing 10 times or more. Microscopic observation of the dispersion of the oil in the bolus of those samples with added oil (BPO) showed fine oil droplets between the potato cells after 5 times chewing, while the bolus of the samples with added solid fat (BPF and BPS) had a separate aqueous layer (potato cell) and fat layer (solid fat) after 10 times or more chewing. These results indicate the importance of ease of mixing with saliva in the process of chewing and of the state of oil and fats dispersed in the bolus to produce suitable swallowing characteristics for mashed potato.

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In the present study, the cooking quality of the major sake rice variety Yamadanishiki was compared with that of the table-rice variety Koshihikari. (1) Yamadanishiki characteristically contains a certain percentage of white-core grains (grains having a white opaque structure in the center) apart from ordinary non white-core grains. The water absorption rate of white-core grains was higher than that of their ordinary non white-core counterparts. This difference in the water absorption rates could be associated with uneven cooking, particularly if the soaking periods were insufficient. (2) When compared to Koshihikari, Yamadanishiki yielded a larger volume of cooked rice from a smaller amount of raw rice. Sensory texture evaluation showed that cooked Yamadanishiki rice had a good eating quality that was comparable to Koshihikari. (3) Cooked Yamadanishiki rice showed unique texture properties (hard, elastic, and less sticky) that were not found in Koshihikari. From the above results, the application of the unique texture of Yamadanishiki rice in cooking is expected in the future. (4) These texture properties and the cooking quality of Yamadanishiki appear to be related to the high amylose content and unique characteristics of sake rice (i.e., white-core structure and large-sized kernels).

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The heating rate and energy consumption of a steam convection oven, and the physical properties of baked bread were measured in seven heating modes with samples of water, batter and bread. The rate of temperature increase for water, the coagulation rate for batter and the browning speed for bread in the combination mode were faster than those in the hot-air mode. The energy consumption per unit time based on hot-air at 180°C was 1.87 times in hot-air at 280°C, and it became 3.62 and 3.95 times in combination mode at 180°Cand 280°C with steam set at 100％. The energy consumption for water or batter heating based on hot-air at 180°C was 1.37-1.44 times in hot-air mode and 2.41-3.01 times in combination mode. Raising the temperature from 180°C to 280°C, increased the browning speed of the bread by 6 or more times, and the amount of energy consumed for the same color based on hot-air at 180°C was 1/2 or less. Long cooking time in the hot-air mode tended to make the bread b dry and hard in combination mode, however, although there was a rapid initial change in the physical properties of the bread, there was little change in hardness with long cooking time.

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We examined the effect of cooking conditions on bread and sauce made with wheat flour for patients with wheat allergy to eat safely. The amount of the wheat antigen, which was measured by a FASPEK kit, was used as an index for the allergenicity. Bread samples were prepared with dry yeast and various kinds of fermenting liquid made from raisins, koji and yoghurt. The preparation conditions for the sauce were unheated, and heating the roux at 120°C, 160°C and 210°C. The amount of the wheat antigen was significantly lower in the bread made with yogurt [the sponge dough method] than in the bread made with dry yeast. The sauce samples prepared at various heating temperatures showed a significantly lower amount of the wheat antigen in brown sauce (210°C) than in beurre manie sauce (unheated). Brown sauce made with spelt wheat flour had a particularly low antigen content.

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