Pasteurization or sterilization is one of the essential processes carried out in the food industry for ensuring quality and for designing new products. At the sterilization process, new subjects arise one after another and we have been working on these issues consistently. In this article, we describe our approaches for improving continuous direct steam heating. The mixing length of steam in a steam injection system should be known to calculate the holding time required for precisely evaluating sterilization effect. We developed two methods for measuring this length and performed CFD analyses in order to fabricate practical sterilizers. For steam infusion system, we proposed a new method to determine the pasteurize conditions which have the same effect as plate systems which includes heating and cooling periods. We also approached for high-viscosity, adherent, and solid final products such as cheese. To produce cheese with stable physical properties, we measured the viscosity inline and developed a new direct steam heating system for heating and melting raw materials. Thus, by conducting research on sterilization technologies, which are fundamental in food manufacturing, we developed and improved the direct steam heating systems used in producing a large variety of products in the food industries.
Acyl ascorbates were synthesized through the condensation of various fatty acids with L-ascorbic acid using immobilized lipase in a water-soluble organic solvent, and their antioxidative properties against food conponents were examined by kinetic analysis. The continuous production of acyl ascorbate was carried out using a continuous stirred tank reactor and plug flow reactor, and high productivity was achieved for at least 11 days. The oxidative degradation of linoleic acid and catechin with acyl ascorbate were depended on the type of the system, and the amount and acyl chain length of the added ascorbate. Therefore, the state of food material and the additional amount of antioxidants would be important factors for improvement of food stability by use of such components.
We have investigated techniques for extracting aroma components from fruits for the purpose of utilizing them as flavors. Since many aroma components are unstable to heat, we have researched concentration techniques that do not involve a heat-treatment, such as progressive freeze-concentration and membrane-separation. Aqueous solutions of aroma components were obtained by distillation from various fruits (European pear (La France), peach and apple), and were further concentrated by progressive freeze-concentration or membrane-separation. When the aqueous solutions of aroma components were concentrated about 11 times (volume / volume) by progressive freeze-concentration, the recoveries of many aroma components were about 90%. When the same samples were concentrated 10 times (volume / volume) by reverse membrane osmosis, the solute rejections were about 80-90%. By either method, the aroma components were condensed efficiently. The osmotic pressure of the aqueous solutions, vacuum distillation condensates of fruits juice, were considerably smaller than that of fruit juice. In the case of the La France pear, the osmotic pressure of the aqueous solution was about 1/43 of that of juice, and for peach it was about 1/18. Since the osmotic pressures of the aqueous solutions were low, we considered that the solutions were condensed efficiently. These technologies were applied to produce a new flavor which used La France aroma components. The response of food producers and consumers to the flavor is positive, and some foods and a drink which uses it, have already been commercialized.
The food markets of Islamic countries are becoming attractive because of their large populations and rapid economic growth. Food companies from non-Islamic countries experience difficulties entering markets in Islamic countries due to the Halal system, which controls trade, distribution and production of nonstandard foods according to the religious principles. From careful observation of the Halal system, the author argues that the system is considerably technical, as it can be considered as an industrial standard that factory staff can easily observe. The author also shows that the best way for Japanese food companies to enter and develop these markets is to invest in establishing their factories in an Islamic country as a base from which export their products to other Islamic markets. The author believes that Japanese food companies with high levels of technology can cope with the system.
Defatted rice bran was treated with subcritical water between 120 and 240℃. The extraction temperature affected the total carbohydrate and protein contents of the extracts. In the tested temperature range, the total carbohydrate and protein contents were the highest at 180℃ and 210℃. The DPPH radical scavenging activity of the extracts increased with increasing extraction temperature up to 240℃ and showed a linear correlation with the total phenolic content. The antioxidative ability of the extracts was evaluated in both the bulk oil and aqueous dispersion systems of linoleic acid. The antioxidative ability differed in the two systems. The extract obtained at any temperature elongated the induction period for the oxidation of linoleic acid in the aqueous dispersion system. However, only the extract obtained at 240℃ showed significant antioxidative ability in the bulk linoleic acid system.
Hardening process in the manufacture of rice cakes is the most important process, because it is time-consuming process. We aimed to develop a new cultivar of waxy rice characterized by both high yield and excellent processing properties. For this purpose, the urea dissolution and X-ray diffraction (XRD) methods were employed in order to quantitatively assess the factors associated with rice cake hardness. In this study, rice starch dissolution rate and measurement of relative starch crystallinity (RSC) are discussed. Four waxy rice cultivars with different hardening properties were selected as test samples, and pasting properties, hardness, urea dissolution of starch and XRD properties were assessed. It is supposed that dissolution rate and RSC are closely related to rice cake hardening, are suitable parameters for quantifying rice cake hardening, and are useful for predicting the hardness of new novel cultivars. To assess rice cake hardness in novel cultivars, it is important that tests focusing on the determination of different parameters, such as pasting properties, urea dissolution and XRD, be designed.
Retention factors of galactose, glucose, trehalose, and maltotriose for a column packed with hydrophobic resins were measured using water as the eluent in the temperature range of 0.5 to 150℃. The van’t Hoff plots of the retention factors were nonlinear, indicating that hydrophobic interactions between the resin and solutes occurred. The temperature dependence of the retention factor could be analyzed based on Kirfhoff’s law and the enthalpy change for distribution was calculated.