Hot air drying is conventionally applied for the production of dried fruit; however, hardening and browning of the fruit pulp surface often occurs during processing. We demonstrated that microwave irradiation of Japanese pear pulp or grape, followed by hot air drying, produced high quality semi-dried fruit. Dried Japanese pear produced using this method showed uniform softness and a vivid yellow-orange color. In the case of dried grape products, microwave irradiation pretreatment improved the retention of both skin color (yellow-green and red) and original flavor (such as muscat and foxy). In addition, microwave pretreatment shortened the subsequent hot air drying period by approximately 30% for Japanese pear and 60% for grape. This method could be applied to other fruits such as apple, pear and peach. Dissemination of the method has resulted in commercialization of some dried fruit and confectionary products. However, a system capable of mass production, resulting in reduced production costs, is needed to promote the practical use of this method.
We studied the effects of food emulsifier additives, sucrose fatty acid esters (SEs) and monopalmitin (MP), on the non-isothermal crystallization of a molecular compound (MC) composed of a 1:1 ratio of two triacylglycerols (TAGs) in bulk and n-dodecane solution, using differential scanning calorimetry, X-ray diffraction and polarized light microscopy. The purpose of this study was to reveal the effects of additives on the crystallization rate, size and morphology of the MC crystals. These parameters are known to be affected by the addition of different types of additives (i.e., those containing sucrose or glycerol, and saturated or unsaturated acid moieties) as well as the concentration of the additive, cooling rate and presence of solvent. We found that MC crystallization was retarded by SEs, P-170 and POS-135, containing saturated or saturated-unsaturated mixed fatty acids. On the other hand, MC crystallization was promoted by MP, which may serve as a seed crystal to initiate heterogeneous nucleation of the MC crystals. The formation of MC crystals that produced the most stable structure of β form was not disturbed by the addition of emulsifiers. Furthermore, the addition of P-170 and POS-135 produced MC crystals of finer morphology, while MP addition produced needle shaped crystals. It appeared that the different effects of the two types of emulsifiers on the nucleation process of MC crystallization were dependent on differences in the hydrophilic-hydrophobic structure and balance.
The distribution of radioactive cesium (137Cs) from noodles to broth during noodle cooking was investigated using rice noodles differing in firmness. The firmness of rice noodles was controlled by the gluten concentration, 5%, 10%, and 20%, in rice powder. Processing factor (Pf, ratio of radioactive cesium concentration in processed materials to raw materials) and food processing retention factor (Fr, ratio of radioactive cesium amount in processed materials to raw materials) for 137Cs and nine kinds of inorganic elements were calculated. Both Pf and Fr for boiled noodles containing 20% gluten showed significantly (p<0.05) higher levels than those for noodles containing 5% gluten. A positive correlation was obtained between Pf and compressive force at 80% deformation in boiled rice noodles. Fr, likewise, also showed a positive correlation with the compressive force. The specific adsorption of radioactive cesium to gluten itself was not detected. Increase of moisture content (% DW) in boiled noodles and the compressive force were negatively correlated. Moreover, both Pf and Fr also showed a negative correlation with the increase of moisture content in boiled noodles. From these results, the increase of moisture content in boiled noodles might be involved in the difference in the transfer ratio of radioactive cesium from noodles to broth, depending on the firmness of noodles. The distribution patterns of potassium and sodium were similar to those of radioactive cesium.
We have reported that ingestion of a capsule of winter savory extract affected core body temperature (CBT) and body surface temperatures (BSTs), and alleviated cold sensitivity in humans. However, a drink of winter savory extract has an unsuitable flavor caused by carvacrol (CAR) and thymol (THY) (inducing heat-production and heat-transfer, respectively). Therefore, we aimed to determine whether a drink containing reduced amounts of CAR and THY (DK1), to improve the flavor, would affect body temperature after ingestion. DK1 affected BSTs of the wrist, finger, ankle, toe and neck. Next, we examined a capsule and a drink of winter savory extract (CP and DK2, respectively; amounts of CAR and THY in CP and DK2 are equal to those in DK1; concentrations of CAR and THY in DK2 are five times higher than those in DK1). CP only influenced BSTs of the wrist and finger, whereas DK2 affected both BSTs (the wrist, finger, ankle, toe, forehead and neck) and CBT. These results suggest that despite reduced amounts of CAR and THY, the effect of winter savory extract on body temperature was observed, and that it might be enhanced by stimulation of the oral cavity and throat after drink intake.
The quality control of frying oil and the management of cooking processes are critical to the taste of fried foods, and to the safety and economic efficiency of the commercial production of fried foods. The authors conducted research to assess the degradation of frying oil by studying its electrical properties and observed peculiar behavior of the dielectric constant believed to be caused by water present in the frying oil. An analysis of the dielectric constant suggested that water remains in high-temperature frying oil for a relatively long period of time. It is generally thought that water promptly reaches its boiling point of 100°C when added to high-temperature frying oil and is immediately discharged from the oil and into the atmosphere as steam. Verification that water indeed remains in frying oil at elevated temperature for long periods of time would indicate that there is a mechanism that hinders the discharge of water from high-temperature oil. Accordingly, in this paper we reproduce the conditions in which water remains in the frying oil and consider the factors causing this retention. We also discuss methods for extending the life of frying oils by controlling and managing the degradation of oil caused by hydrolysis when used frying oil is stored.
Soybean milk is developing as new food material beyond the conventional use in recent years. The 2015 Satellite Luncheon Meeting focusing on soybean dealt with the principle of soymilk separation technologies and its applicability of the soymilk colloid. Emeritus prof. Ono (Iwate University) has worked on explication of tofu coagulation process for many years. The heating treatment of soybean seeds before grinding is different in for tofu and soymilk drinking. He lectured the phenomenon difference causes to coagulant behavior of the protein particles and the oil body of soybean milk colloidal dispersion. Prof. Fujii (Tohoku University) presented another lecture, elucidated behavior of soymilk colloids, mainly oil droplets from a food engineering study point of view, explained the structure of the soybean milk colloidal dispersion course and behavior of aggregation process. He also showed the application of fat processing bring out creamy texture in soymilk, using papain digestion followed by heat treatment.
Soymilk specific for tofu is not used in drinks because of its bean-like flavor. Conversely, soymilk destined for drinks is not used for tofu production because it forms a soft curd. The difference in these soymilks is due to the milling temperature; room temperature is used for tofu, while high temperatures are used to inhibit the activity of oxidative enzymes in soymilk for drinks. The composition of these soymilks was discussed from the viewpoint of the previously described formation mechanism of soymilk and tofu, new data about the components, and recent soymilk composition data for drinks. The results showed that the composition of oil bodies was the same for both tofu and drinks, but the protein fraction for drinks contained a greater level of small particles compared to that for tofu. Thus, precise temperature regulation is important for soymilk processing.
In this paper, the effects of oil bodies, coagulant, pH and enzyme treatment on the aggregation behavior of soymilk were reviewed from the viewpoint of a colloidal dispersion system. The applicability of Einstein's and Krieger-Dougherty's theories of viscosity was examined using soymilk samples. The oil bodies in the soymilk behaved as suspended substances, and it was possible to predict the relative viscosity from the volume fraction of the oil bodies. The coagulation of soymilk with magnesium chloride was also investigated, and the validity of the novel viscous model with the effect of cross-linkage was discussed. The viscosity during coagulation could be predicted by the model, based on particle size as a property of the dispersion system. From the results of the effect of pH on the stability of soymilk using the centrifugal method, the state of soymilk components changed in three steps as a function of decreasing pH. The aggregation of high-fat soymilk digested by papain required heat pretreatment. It was suggested that oleosin, which stabilized the oil body emulsion, was digested by papain and the aggregation was promoted by heat pretreatment.
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