A starch ingredient with antioxidative activity, as measured by the DPPH method, was produced by baking corn starch with an organic acid; it has been named ANOX sugar (antioxidative sugar). The baking temperature and time were fixed at 170°C and 60 min, and the organic acid used was selected from preliminary trials of various kinds of acid. The phytic acid ANOX sugar preparation showed the highest antioxidative activity, but the color of the preparation was almost black; we therefore selected L-tartaric acid which had the second highest antioxidative activity. The antioxidative activity of the L-tartaric acid ANOX sugar preparation was stable against tem-perature, light, and enzyme treatments (α-amylase and glucoamylase). However, the activity was not stable against variations in water content and pH value. The antioxidative activity of ANOX sugar was stabilized by treating with boiled water or nitrogen gas, or by pH adjustment.
We detected pesticides by nano-particle assisted laser desorption/ionization mass spectrometry (Nano-PALDI MS). Several nanoparticles (NPs) by mixing aqueous solutions of 3d transition metal chlorides (MCl2·nH2O) and (3-aminopropyl) triethoxysilane were synthesized to explore the optimum NPs for detection of pesticides by Nano-PALDI MS. The prepared NPs were examined by X-ray diffraction, transmission electron microscope, and Fourier transform infrared spectroscopy. The synthesized NPs were surrounded by amorphous SiO2 and possessed amino and hydroxyl groups on NPs surface. The number-average diameter of the NPs was determined to be about 3 to 5 nm. The NPs could assist ionization of pesticides in MS. We selected the suitable NPs to detect pesticide by statistical method. The copper oxide-based Nano-PALDI MS could be time lapse analysis of the pesticides as environmental pollutant from paddy field.
In order to ascertain the quality and microbiological risk of meat cooked with the vacuum-pack cooking method (sous-vide), we simulated the thermal denaturation of meat protein and the bacterial survival changes (Escherichia coli O157:H7) and performed unsteady-state 3D heat transfer analysis using the finite element method during sous-vide cooking. To simulate the denaturation processes, we used the kinetics parameters for the thermal denaturation of intact beef using the differential scanning calorimetry (DSC) dynamic method. The results of the simulation showed the characteristics of the sous-vide cooking of roast beef to be as follows. The denaturation of myosin was completed throughout the meat sample. Actin was hardly denatured inside the meat, although denaturation was completed at the surface region. This characteristic denaturation profile formed in the cooked meat has produced a high-quality meat product and various benefits using the sous-vide method. In contrast, the prediction of the bacterial survival changes revealed that there was little sterilizing effect at the meat core because of the low temperature heat treatment of the sous-vide cooking. That is, it is important that fresh food material be used, and maintaining the optimal cooking temperature and strict sanitary control in the sous-vide cooking was highly recommended.
In order to utilize low-utilized fish species as a raw material for kamaboko, we investigated the gelation properties of frozen blue mackerel. Blue mackerel was caught from Kumano-nada region and immediately frozen-stored at −20°C for three months. After thawing the mackerel, surimi was prepared by washing in fresh water or alkaline solution. Unlike the processing of unfrozen blue mackerel, little or no effect of washing in alkaline solution on the gel forming ability of frozen blue mackerel was observed. The addition of alkaline salt (Na2CO3) into the salt-ground meat, however, resulted in increases in both breaking strength and breaking deformation of the heated gel of the salt-ground meat. Furthermore, we clearly observed effect of setting at 30°C on the gel strength of the salt-ground meat with Na2CO3. These results showed that frozen blue mackerel would be a new raw material for kamaboko, which was less expensive and could be supplied stably.
We studied the hydration properties and enzymatic hydrolysis of micro-sized rice flour obtained by dry jet-pulverization to find new applications for the flour in the food industry. Ultra-fine rice flour (both white and brown) with a mean size of <5 μm was far more dispersible than coarser flours (15–120 μm). Dispersibility increased with finer mean particle size and higher starch damage. The ultra-fine flour also had the highest solubility, swelling power, water absorption index, and glucose release. Dry jet-pulverization to <5 μm mean size and consequent starch damage to (>30%) decreased enthalpy and gave very different hydration properties and enzymatic hydrolysis than in coarser flours.
Mechanical properties of tofu were investigated in order to control tofu processing. Several kinds of the elastic parameters were determined from the stress-strain curve of tofu, and the effect of lipid concentration on the elastic parameters in the small and large deformation conditions was analyzed from the viewpoint of emulsion gel. The tofu sample in which lipid or protein concentration was different was prepared from the same breed of soybean for the purpose of discussing the influence of lipid and protein significantly. The initial elastic modulus of high MgCl2 concentration tofu increased with increasing MgCl2 concentration, while its rupture stress decreased with increasing MgCl2 concentration. Therefore, the contribution of continuous phase would be large in initial elastic modulus, and disperse phase would be dominant in rupture stress. The rupture stress of tofu was shown to tend to harden in low lipid concentration when lipid concentration increased. On the other hand, when the lipid concentration condition was high, rupture stress of tofu decreased with increasing lipid concentration. Furthermore, we examined the applicability of the numerical model for the rupture stress of tofu. The model could be described the behavior of rupture stress depending on lipid and protein concentrations.
Six types of pulverized rice were prepared by ultracentrifuge cryomilling. In this method, the sample being pulverized is immersed in liquid nitrogen. The moisture content and protein content of pulverized rice obtained were determined, and their characteristics were compared with those of rice flours pulverized with three types of mill (disk mill, hammer mill, and jet mill) and a purified non-waxy rice starch. The particle size distributions of rice pulverized by ultracentrifuge cryomilling showed two peaks at 14.3–17.8 μm and 52.1–92.1 μm. The most finely pulverized rice showed a major peak at 17 μm. The pulverized rice particles (average particle size of 40 μm) were composed of spherical shapes. Rice flour pulverized to a micro-scale point (average particle size of 6.5 μm) was characterized by the enhancement of whiteness, which is one of the most important indices for bulk flours.