An automatic measurement system was developed to determine the transport properties for food materials. Some mathematical models were developed to determine the thermal conductivity and permeability for the dried layer of food samples undergoing sublimation dehydration. The values of transport properties were presented for several food materials indicating the critical processing factors for the drying rate of each material. A micro-slicer image processing system was developed for measuring the three-dimensional structure and distribution of ice crystals formed in frozen foods. The effects of freezing conditions on the morphology and distribution of ice crystals were demonstrated quantitatively from the observations of solid foods and solution systems. A new heating program and methodologies were developed to shorten the drying time for industrial freeze-dryer to produce egg soups.
Sales of the ready-to-heat foods with cooked rice aseptically packed have increased manyfold in Japan over the past 10 years. Cooked rice aseptically packed is better taste and higher quality, as compared with retort-pouch cooked rice. KAGOME DELI that was started to sale from 1999 by KAGOME Co., Ltd., was very unique in microwave oven cooking foods. It was made up of the cooked rice aseptically packed and the retort-pouch cooking sauce (eg. for Risotto, Chicken Rice, and Doria). Consumer could cook these using a microwave oven during two minutes only, and take in the low-calorie (lower 300 kcal/menu). In this report, two technical considerations were suggested on the development process of KAGOME DELI. These were ① microorganism control, ② package development, for cooked rice aseptically packed. To improve safety of the cooked rice aseptically packed, it is preferable that cooked rice is adjusted pH 4.9 or below and 5.0% or more oxygen concentration of head space. And higher usability package for cooked rice was able to be developed by understanding the relation between the strength of sealing and peeling.
The application of microwave heating to food processing, including microwave oven, have come into wide use because of their ability to heat and cook food quickly and conveniently. However, a problem that has arisen in microwave heating is uneven heating or non-uniform temperature distribution in the foods. To control the uneven heating, it is important to know the mechanism of heating and the role of the dielectric properties of food, because they determine the heat generation when the food is irradiated by the microwaves. First of all in this manuscript, the principle of the microwave heating and the role of water in the microwave heating are explained. Next, the influence of the water and salt content on the dielectric properties of food was described. Reduction of water content primarily changes the dielectric constant, whereas the addition of salt primarily changes the dielectric loss factor. Finally, the physical properties change according to the thawing of food was described. The thermal and dielectric properties of food vary with temperature in thawing process, and the great difference in dielectric properties between frozen state and thawed one can cause a problem in uniform thawing, that is known as runaway heating.
Because it does not involve heating, “freeze-concentration” is one of the most suitable methods for concentrating thermally unstable materials, for instance, aroma components. We, therefore, tried to prepare a concentrate of the aroma components of the La France pear by progressive freeze-concentration. Condensated water containing the aroma components of La France pear was obtained by vacuum distillation of fresh juice using a rotary evaporator, and was further concentrated by progressive freeze-concentration. When the distillation-condensate was concentrated 11.5 times (volume to volume) by the progressive freeze-concentration, the major aroma components of La France pear (butyl acetate, hexyl acetate and so on) were concentrated almost to the theoretical limit, about 10-11 times. The aroma components that were incorporated in the ice phase were less than 3%, even in the worst cases (approximately 2.4% and 2.8% for 1-butanol and 1-butanol, respectively). In summary, the aroma components of La France pear were very effectively concentrated to a high degree with good yields by progressive freeze-concentration.
This study investigated the production characteristics of large soybean oil droplets dispersed in an aqueous solution containing an emulsifier using newly designed microchannel (MC) emulsification chips. The silicon MC emulsification chips consisted of numerous asymmetric through holes with a characteristic cross-sectional size of 20μm to 50μm, each consisting of a microslot and a circular MC. MC emulsification using such chips enabled the stable production of uniform large droplets with average diameters of 75μm and 179μm and a coefficient of variation below 2%. The detachment behavior of the large droplets generated from the asymmetric through holes was analyzed and discussed based on results obtained by real-time optical microscopy. The size of droplets smaller than 100μm was independent of the flow rate of the cross-flowing continuous phase (Qc) applied in this study. In contrast, the size of droplets larger than 100μm became sensitive to Qc in its range over a critical value. The results for the effect of Qc is discussed by analyzing the force balance acting on a dispersed-phase droplet that expands over the microslot. Large droplets with a very narrow size distribution were obtained at dispersed-phase fluxes (Jd) of 50 L m-2 h-1 or less, whereas their average diameter was somewhat dependent on Jd.
In cooking that there are solid foods in soup, natural convection flow in a pan may affect food quality. This study shows the visualization and quantification of the flow in the pan using developed new tracer particle during the induction heating (IH) and the gas heating. Development of the tracer particle imitated the method of making an artificial salmon roe. The density of the tracer particle could be adjusted to be the same as water. The average diameter of the tracer particle was 2.5 mm when the tracer particle was made by the diameter of the tip apex was 1 mm. Water flow in the pan was able to be visualized by using the tracer particle. In addition, at the IH and the gas heating, the position and flow velocity of the tracer particle in three dimensions were able to be measured by taking a picture using two video cameras set above and inside the pan. When the amount of energy entering into the pan is the same during the both heating, the flow velocity at initial stage of the IH was faster than that of the gas heating.
Near infrared (NIR) spectroscopy was investigated as a method for the nondestructive measurement of sugar content in intact potato tubers. The NIR spectra (400-1100 nm) of potato samples were acquired by fiber optics in the interactance mode. Calibration models for the prediction of the fructose and glucose contents were developed by a partial least squares statistical analysis method. The calibration model gave standard errors of prediction of 0.26 mg/g for fructose and 0.46 mg/g for glucose. The preliminary results showed that NIR spectroscopy gives a reasonable estimate that can be used for nondestructive sorting of potatoes according to their sugar content.
Soy sauce cake was demineralized by washing with distilled water. After freeze-drying, the demineralized soy sauce cake was treated using water or subcritical water in the temperature range of 50 to 250℃ to produce the extracts. The total saccharide, protein, and total phenolic contents, and the DPPH radical scavenging ability of each extract were measured. The protein and total phenolic contents and the radical scavenging ability were higher for the extracts obtained at higher temperatures. The total saccharide content increased with treatment temperature up to 210℃ but rapidly declined at temperatures higher than 210℃. The extracts obtained at 210℃ or higher exhibited antioxidative ability against the oxidation of linoleic acid.