A novel method to measure viscosity and static shear modulus of viscoelastic food fluids was developed. This method is based on the flow theory of fluid and shear deformation of elastic material in an annular channel. The method, the non-rotational concentric cylinder method, evaluated static viscoelasticity of sample in a cup easily by analyzing the force acting on a plunger immersed in the sample during the period of time of the cup movement for a very short distance at a constant speed to the axial direction. Dependence of apparent viscosity on shear rate is also evaluated by this method. A new emulsification method called the membrane emulsification method combined with preliminary emulsification was developed. The method prepares monodispersed and stable O/W or W/O emulsions easily at a high rate. Mean particle diameters prepared by this method were about two times larger than the mean pore size of the membrane used. The mean particle diameter decreased and mono-dispersibility increased with the increase of permeating flux (or pressure) of pre-emulsified emulsion. Stable and fine particle (ca. 3 μm) multi-phase emulsions such as W/O/W and O/W/O types could be prepared by using this method. The membrane phase inversion emulsification method was also developed by applying the membrane emulsification method combined with preliminary emulsification. This method prepared mono-dispersed and stable O/W or W/O emulsions with very high dispersed phase concentration up to about 80% or more. Characteristics of a newly developed superheated steam (SHS) treatment combined with far infrared heating (FIH) were investigated. Heat transfer rate under steady state condition could be estimated from empirical equations for convective and radiative heat transfer from the SHS and radiative heat transfer from the FIH heater and chamber wall. Very few degradation of edible oil was found in the SHS treatment because of almost no oxygen in the SHS. Carbonization rate of biomaterials treated in the SHS was expressed by the first order rate equation, and the rate increased with the increase of temperature and with the decrease of sample size. Combined treatment of the SHS and the FIH decreased carbonization energy significantly.
Electrical breakdown or disruption of a biological membrane by high-voltage pulsed electric field (PEF) is well understood to occur by electromechanical compression, which results in the formation of transmembrane pores. If the total area of the induced pores becomes unfavorably large, the membrane is no longer able to repair these perturbations (irreversible disruption), and that results in sterilization. A preliminary research work for PEF inactivation of microorganisms was reported about 40 years ago. Recently many reports are published on the biotechnological applications of PEF including sterilization of some kinds of microorganisms in liquid foods. We investigated effective sterilization by using fast rising high voltage pulse with changing design parameters of the reactor and operating conditions. The treatment temperature or growth temperature, and the shape of the reactor were found to have a great effect on PEF sterilization. To raise the energy efficiency for PEF sterilization to minimize consumed electrical energy, we proposed concentration of electric field by using spiral wire electrode reactor. We also proposed the textile electrode system for improvement of energy efficiency. The PEF-induced reversible disruption could be utilized for the selective release of intracellular proteins from yeast and certain gene-engineered Escherichia coli. The secretion of periplasmic protein from E. coli was achieved during cultivation. In the present paper, some biotechnological applications of high-voltage pulsed electric field are reviewed.
Food engineering plays a significant role in food production to achieve a high quality. Increasingly discriminating consumer taste has resulted in pressures to improve the flavor quality of food products at ever higher stages.These trends have created demand for food products that offer superior characteristics at the highest stages of food quality. Food production at such levels will require approaches based on new food engineering. This paper will seek to address the role of food engineering in improving quality in food production processes. The examples used to illustrate these issues will include the following: 1) a quantitative evaluation of the kneaded state of bread dough; 2) quantitative identification of factors influencing the intensity of retort sterilization; and 3) quantitative determination of flavor component dissipation during spray-drying. The importance of preventing global warming is becoming more important. The research of LCA which evaluates the environment burden from producing of food stuff, production process, consuming to dumping, become important. The Food Engineering must contribute to improve the efficiency of LCA.
This paper presents an overview of research and development of rapid analysis and nondestructive analytical techniques for the chemical and physical properties of food materials using near infrared spectroscopy. Various food materials such as raw fruit juice, raw milk and concentrated-seawater, rice flour and potato were used as the study materials. The spectrum-measuring methods suitable for the state and shape of various food materials were devised, and the analysis methods suitable for the spectral features were investigated. The rapid analytical techniques of components of liquid food materials such as raw fruit juice, raw milk and concentrated-seawater were developed, and the nondestructive analysis methods of the chemical and physical properties of solids food material such as potato were developed by utilizing the characteristics of the near infrared snectroscoov.
In this review the problems and solutions on the membrane separation of microbial cell suspensions in food and biochemical industries were discussed. The deposition of filter cakes on membranes decreases the permeation flux in the filtration. Currently filter aids such as diatomaceous earth are widely used to decrease the permeation resistance of the filter cakes although the cakes containing filter aids are discharged as industrial wastes. Crossflow filtration is a method to obtain high permeation fluxes by suppressing the formation of filter cakes on the membranes. High permeation fluxes could be obtained in the crossflow filtration of suspensions of spherical cells such as baker's yeast. However, the authors showed that the permeation flux decreases in the suspensions of rod-shaped cells or microbial suspensions containing fine particles from culture media and biopolymers. It was shown that the permeation fluxes could be recovered by the use of a modified backflushing method by the authors. The development of biodegradable polyester membranes for dead-end filtration to decrease the industrial waste was also discussed.
Coffee is a popular beverage worldwide. Recently, many epidemiological studies suggest that coffee may play a preventative role in various diseases. There has been increasing interest in the health benefits of coffee. Coffee contains several bioactive compounds, which are known to affect human body chemistry. Among them, we focused on mannooligosaccharides (MOS) extracted by thermal hydrolysis from spent coffee grounds. MOS from coffee are composed of mannose, which is known to have physiological functions such as the prevention of Salmonella infection. MOS are also expected to have various other types of physiological functions. However, no prior research is available regarding the functionality of MOS from coffee. First, we demonstrated the prebiotic effect of MOS in a human intervention study after the confirmation of this effect in vitro and in an animal feeding study. Next, we confirmed the fat reduction effect of MOS by studying the inhibition of intestinal absorption of dietary fat in animals and in a human clinical study. These findings were applied to our coffee products containing MOS. These products have been certified as Foods for Specified Health Use (FOSHU) and commercially launched.
The antiallergic properties of hop water extract (HWE) were investigated by evaluating histamine release from human basophilic KU812 cells induced by calcium ionophore A23187. HWE significantly inhibited histamine release, but boiling water extract and chloroform-methanol extract did not show any inhibitory effect on it. A 50% methanol-eluted fraction separated from HWE by XAD-4 column chromatography (MFH) had a strong inhibitory effect as compared with HWE. Quercetin glycosides and kaempherol glycosides were identified in MFH. Most quercetin and kaempherol in HWE existed in glycoside form and their aglycone content, obtained by acid hydrolysis, were approximately 200μg/g. The antiallergic properties of a hop water extract (HWE) were studied by evaluating the Evans blue leakage from ICR mice caused by compound 48/80 stimulation, and the histamine release from ovalbumin (OVA) -sensitized BALB/c mice. An oral administration of HWE significantly inhibited the vascular permeability and histamine release. HWE itself did not have any influence on the total and antigen-specific immunoglobulin E (IgE) production in OVA-sensitized mice. These results indicate that HWE exerted an antiallergic effect by inhibiting the release of chemical mediators from mast cells and basophiles.
Theoretical treatment of composite or reaction system of food materials requires the mathematical modelling of mixing rule for observables such as thermal, electrical and rheological ones. Typical models are of series, parallel and random type, and are generalized here to a power-law model. In the previous report, the present author developed the kinetics for a general observable ο in the first-order reaction process (R→P) where ο increases with reaction order x≡ [P] / ( [R] + [P] ) through a power-law type mixing rule ον = (1-x) ονR+xονP with οR<οP, and provided a formula for an inflection point (IP) in the observable growth curve. In this article was given a similar argument for IP in the ο-growth curve for a genaral n-th order reaction process dx/dt=Kn (1-x) n, and the following consequences were obtained. For ν≥1, the ο-t curve is convex everywhere (ο<οP) for any positive n. When n is restricted to be a positive integer, the ο-t curve can possess IP in the region -1<ν<1 with smaller values of n (=1, 2…), and so for ν≤-1 only with n=1. For ν<1, the value of observable at IP is given by the formula ο*= ( (1-ν) / (1- (1-n) ν) ) 1/νοP, and the growth rate do/dt depends on οR/οP for n≠1. The results for the power-law rule coincide in the ν→0 limit with those obtained for a logarithmic rule (a random model) . An inverse observable ο-1 decreases with a concavity property for any positive integer n.
The possibility of generating renewable bio-fuel energy through ethanol fermentation of kitchen refuse by Saccharomyces cerevisiae ATCC 26602 was established in this work. The acid-tolerant yeast S. cerevisiae ATCC 26602 was selected from among four S. cerevisiae strains as the best ethanol fermentation agent for kitchen refuse medium. The optimal kitchen refuse medium for ethanol production had a glucose concentration of only 12% (w/v) and consisted of saccharified kitchen refuse. Additional nitrogen supplementation was not necessary. A maximal ethanol concentration of 59.38 g/L with a 0.50 ethanol yield (YP/S) was obtained with the optimal medium composition in flask culture under shaking and without pH control. No significant difference was observed in ethanol production and glucose consumption between sterilized, pasteurized and non-sterilized kitchen refuse medium samples. A final ethanol concentration of 50.22 g/L, corresponding to a 0.42 ethanol yield (YP/S), was obtained using a 20-L bioreactor with a working volume of 12 L under non-sterilized conditions at an agitation rate of 100 rpm at 30°C for 18 h. Therefore, the ethanol fermentation of kitchen refuse under non-sterilized conditions by S. cerevisiae ATCC 26602 may offer an economical alternative for bio-fuel production in industrial applications.
The purpose of this study was to improve the quality of rice noodles by adjusting the gelatinized rice flour ratio in the dough. Two types of rice, Japanese Yumetoiro and Chinese Zhongzao 22 hao (Indica), were used. The color and physical properties such as maximum tensile stress, maximum tensile strain, and the time dependence of dynamic viscoelasticity of cooked rice noodles as well as the micro-structures of the cooked rice noodles were investigated. The lightness of the cooked rice noodles showed no significant differences with the different gelatinized ratios, whereas the yellowness developed with increased gelatinized ratio in the dough. On the other hand, the maximum tensile stress and maximum tensile strain of the cooked rice noodles increased significantly with increased gelatinized ratio. Storage moduli (G') and loss moduli (G'') of the cooked rice noodles also increased significantly with an increase in gelatinized ratio. The retrogradation of cooked rice noodles with higher gelatinized ratio was earlier, and the noodles hardened more easily. Finally, the cooked rice noodles with higher gelatinized ratio showed a more compact microstructure and smaller holes were observed by scanning electron microscopy (SEM) .
The ethanol production performance of the flocculating yeast S. cerevisiae ATCC26602 from non-sterilized kitchen refuse medium in repeated-batch culturing was investigated. Although no pH modification or asepsis technology was applied, no contamination occurred. Twenty cycles of repeated-batch fermentation over a period of 11 days were successfully carried out without any loss of productivity by the self-flocculating strain ATCC26602. In addition, from the third batch, the flocculent strain achieved the reduction of the fermentation time to half, which resulted in an increasing of ethanol productivity to 3.7 g/L/h. These results of ethanol fermentation from kitchen refuse under the non-sterilized condition by this acid-tolerant and self-flocculation yeast may pave the way to low-cost ethanol production in pilot applications.
In the case of sterilizing foods by heating in the industrial microwave oven, uneven heating is occurred inside heated foods. It is problem that unheated part occurs shortage of sterilization and overheated part occurs deterioration of foods. In this report, we focus attention on circular polarized wave and linear polarized wave. First, each polarized wave irradiated the food, and absorbed power distribution inside of food is calculated. We examined validity of circular polarized wave for uniform heating. Next, we used circular polarized wave generator and cylindrical chassis for actual use, absorbed power distribution inside of the food is examined. Moreover absorbed power distribution inside of the food which was arranged in cylindrical chassis with rectangular waveguide for continuous heating is examined, too. As a result, local heating is reduced, and 43% uniform heating is brought to realization by using circular polarized wave than using linear polarized wave. And, in the case of using the chassis for actual use, circular polarized wave is valid for uniform heating of foods as with basic study.
Antioxidant activities of three polyphenol compounds, teas (green tea, oolong tea, and black tea), and five commercially available bottled teas have been evaluated, because comprehensive methods to evaluate antioxidant properies have not been established yet in spite of comsumers' stong concern for the antioxidant activities of teas. The antioxidant activities against hypochlorite radical and hydroxyl radical were successfully measured by a previously reported method based on myogobin structure change. The acitivities expressed by myogrobin protective ratio increased with the sample concentration under a constant radical concentration. The antioxidant activities of the samples were also measured by the widely used DPPH method. In order to characterize the properties of the samples comprehensively, the antioxidant activities against three different radicals were compared in a radar chart. All polyphenol compounds showed relatively high activities against all three radicals. All teas showed similar patterns as the polyphenol compounds in the radar charts. The strength of the activities, however, strongly depends on the samples. Thus, the antioxidant activities of various teas have been successfully evaluated in a comprehensive way using the radar charts.
Many techniques of production have been developed to produce cooked rice packed under semi-aseptic condition (here in after called semi-aseptic cooked rice) with less spoilage by organism, better taste and higher quality. Effect of heat-resistant organisms from rice on commercial sterility of semi-aseptic cooked rice were researched and the improvement of production process were investigated in order to upgrade the stored stability involved organisms for semi-aseptic cooked rice based on philosophy of commercial sterility of retort pouch foods in this study. The necessary time for heat sterilization were estimated at 2Di to ensure commercial sterility in a production process of semi-aseptic cooked rice in this study. Di means the heating time that 90 % of heat-resistant organisms will be dead at any temperature, i. The Time of heat sterilization for present process of production were estimated at 0.43D100°C against B.subtilis strain from brown rice, and it didn't reached necessary time of heat sterilization “F= 2Di” to ensure commercial sterility. The Conditions of heat cooking was investigated to ensure commercial sterility on method of production for semi-aseptic cooked rice. We suggest that the conditions of heat cooking are 14 minutes and a temperature of 110°C as new production process to ensure equivalent eating quality to present process and commercial sterility against B.subtilis strain from brown rice for semi-aseptic cooked rice in this study.
A nanofiltration experiment on skim milk up to a volume reduction factor 2 was conducted using 2-stage continuous equipment. The results were compared with the data obtained for the batch mode. During nanofiltration, the average total solids of retentate in continuous mode were higher than those in batch mode, but the content of Na, K and Cl in dry matter of product (de-mineralized and concentrated milk) was the same for both continuous and batch modes. A continuous operation experiment was also conducted at a temperature of 2-7 degrees Celsius, initial operating pressure of 1.5 MPa, and a fixed a volume reduction factor of 2.0. When this was done, the operating pressure rose by 0.1 MPa three hours after starting. This implies the possibility of safe long-time-operation.
The optimum conditions for subcritical water treatment to produce an extract with a high phenolic content and radical scavenging activity from defatted rice bran were determined using response surface methodology. The effects of the weight ratio of bran to water from 0.05 to 0.2 and treatment time from 20 to 120 min on the total phenolic content and DPPH radical scavenging activity were evaluated using the Design-Expert program. Both the total phenolic content and DPPH radical scavenging activity increased with an increase in the bran/water ratio, but decreased with the treatment time. The optimum bran/water ratio and treatment time were 0.2 and 20 min, respectively, to attain a relatively highest total phenolic content and DPPH radical scavenging activity.
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