Two prototype automatic grading systems for dried shiitakes are presented. For the first prototype, image processing algorithms utilizing neural network were developed and implemented. Image processing utilized the raw image of fed dried shiitakes without any complex processing such as feature enhancement and extraction. Performance of the network based grading was presented. Another prototype has been developed considering the efficiency of the practical usage of the system. Quantitative visual descriptors were used for grading. Grading criteria was controlled interactively. Both prototypes were composed of automatic devices for mushroom feeding and handling, a set of computer vision system with lighting chamber, one chip microprocessor based controller, and pneumatic actuators. The network based software and related interface have been developed, which can remotely control and manage an on-site operating system. Developed software modules were composed of two parts: monitoring/management modules and control/diagnosis modules. And they were designed to run on the internet and local network.
Surface plasmon resonance (SPR) sensors which belong to a family of thin film refractometry-based sensors have been concerned on the measurement of physical, chemical and biological quantities because of their high specificity and ability of real-time monitoring in molecular binding interaction. In this paper, the applications of a SPR sensor to detections of E. coli concentration, alcohol content in alcoholic beverages, and polar compounds content in frying oils were investigated. The results from the study were considered that the SPR sensors had high potentials as food quality and safety evaluators in the food industry.
Pulsed-field gradient NMR (PFG-NMR) is widely applied to probe living tissues and biological cells structure for measuring thermodynamic binding constants, membrane permeability and rates of transmembrane exchange processes. Water movements in biological systems and food matrices are important in the engineering aspect such as quality manipulation in food processing. The measurement of diffusion properties of water molecules in food systems is now possible using PFG-NMR, and the hydration properties and hydrodynamic properties of food materials can be accurately evaluated by this method. In this paper, we measured the diffusion behaviour of water in protein matrix, Tofu, and the membrane permeability in biological cell such as chlorella, yeast and human red blood cell non-invasively by PFG-NMR.
In this paper, our researches on extraction, separation, and fractionation of natural materials by using supercritical fluids such as carbon dioxide are reviewed. We measured extraction rate as a function of operating conditions for the extraction of oils, essential oils, antioxidants, and the other bioactive compounds from various natural materials. The solubility was measured and estimated for these components. Based on these results, theoretical models were developed and the extraction behavior for natural materials was analyzed and simulated. For the fraction process of liquid mixture, we have developed countercurrent extractor with supercritical carbon dioxide, where phase behavior near the critical point is effectively utilized. Deterpenation process of citrus oils was established by the experimental and theoretical study for orange, lemon, and bergamot oils. As a new process for continuous fractionation of essential oils, we have developed supercritical pressure swing adsorption process where adsorption/desorption behavior in supercritical carbon dioxide was utilized. The separation processes were successfully applied for the separation of tocopherols.
Banana leaf wax was quantified and assessed to determine the feasibility of its utilization as agricultural residue. Banana leaf wax was extracted using hexane reflux. Musa liukiuensis yielded 0.58% wax, M. acuminata 1.05%, and M. chiliocarpa 1.41% (dry basis) . The melting point of banana leaf wax was determined by differential scanning calorimetry, which indicated higher values than commercial natural waxes. Color evaluation revealed that M. acuminata leaf wax was whiter than commercial natural wax. The banana leaf wax had tolerance against organic solvent systems. Using thin-layer chromatography analysis, we identified the components of the M. chiliocarpa leaf wax as being similar to those of carnauba wax. The M. chiliocarpa leaf wax was analyzed after saponification using gas chromatography. The predominant acid was C22, and the major alcohols were C28 and C30. The results demonstrated that the banana leaf wax is a potential source of natural wax for industrial material and is expected to be used extensively.
To utilize kitchen refuse as a substrate for polylactic acid (PLA), it is essential to eliminate the L-and D-lactate initially contaminated, while preserving the glucose in it. Both the specific growth rate (μ) and the substrate consumption rate (rs) of Propionibacterium sheymanii on kitchen refuse medium (KRM) were compared at each pH 5.0, 5.5, 6.0 and 6.5 with artificial kitchen refuse medium (AKRM), lactate medium (LM) and lactate-glucose medium (LGM) which respectively contains glucose, lactate, and a mixture of these substrates. Lactate initially contaminated in KRM was assimilated prior to glucose by P. sheymanii at each pH. In KRM and LGM, enhancement and reduction of cell growth by lactate were observed at pH 6.5 and 5.0, respectively, when compared with that in AKRM. As a result, a glucose consumption rate in KRM was more than twice, but was significantly lower than that in AKRM at pH 6.5 and 5.0, respectively. Glucose could be preserved by a low glucose consumption rate when pH was changed from 6.5 to 5.0 after lactate exhaustion in KRM. Preferential substrate utilization of P. sheymanii and a pH change from 6.5 to 5.0 can increase the optical purity of lactic acid while preserving glucose.
Lactic acid fermentation from kitchen refuse by Rhizopus oryzae KPS 106 was studied in this work as a biological method of converting food waste into value added-products. Our aim was to achieve high-concentration and high-purity L (+) -lactic acid production. Several pretreatment methods to modify kitchen refuse as a medium were adopted: saccharification, natural precipitation, freezing and thawing technique, centrifugation and chromatography. The main component of sugar in saccharified kitchen refuse (SKR) was glucose (98.5% of total sugar) . The most efficient technique for removing suspended solids (SS) in SKR was a freezing and thawing technique, by which approximately 55% of SS was eliminated. Kitchen refuse syrup (KRS) as a separated sugar from SKR by ion-exclusion chromatography could be used as a substrate for lactic acid fermentation by R. oryzae KPS 106 in a submerged culture. Addition of some inorganic minerals to KRS was effective in enhancing sugar consumption and lactic acid production. The sugar in KRS medium was assimilated almost as well as glucose in synthetic medium. The lactic acid yield from the KRS and glucose media were 63.9±1.8% and 73.3±2.9% (w/w) (based on initial total sugar concentration), respectively after 72 h of rotary shaking at 35°C and a rate of 100 rpm. L (+) -lactic acid produced from KRS medium was 98.7±0.3% in purity. From these results, kitchen refuse was demonstrated to be a promising renewable substrate for lactic acid fermentation, a use that would be new strategy for converting food waste into value-added products.
Lipase catalyzed hydrolysis reaction of fatty acid bonding with triglyceride docosahexaenoic acid (DHA) was attained with the aid of soybean lecithin based W/O microemulsion. This reaction was fruitful as a pretreatment of enrichment of DHA in triglyceride from marine bioresources. Ester-bonded DHA was hardly hydrolyzed by Candida rugosa lipases due to their steric hindrance. On the other hands, mono unsaturated fatty acid in triglyceride was easily hydrolyzed by lipase specificity. Phosphate buffer (6.0≤pH≤7.5) was used as an aqueous phase and 2, 2, 4-trimethylpentane was employed as an organic solvent. Molar ratio of water to lecithin presented by W0 was used as a measure of water content. Initial reaction rate was strongly depended on the W0 value and appeared a maximum at ca. W0=10. The optimal lecithin concentration was found to be 12 mM, which was almost same as the critical micelle concentration. Soybean lecithin was superior to AOT to obtain higher initial reaction rate due to moderate electrostatic interaction. Temperature dependency obviously appeared under the suitable water content and the lecithin concentration.
Maillard reaction rates of model freeze-dried foods which consist of lysine and various reducing sugars (i.e. ribose, arabinose, xylose, galactose, glucose, and maltose) embedded in glassy trehalose matrix were examined at various temperatures below the glass transition temperature (Tg), and the effect of reducing sugar on the Maillard reaction rate was studied. The extent of Maillard reaction was examined spectrophotometrically from the absorbance at 280 nm (ABS280), and the reaction rate (k280) was evaluated as a pseudo zero order reaction rate from the time course of ABS280. The Tg of each sample was almost same value, however, the k280 showed a considerable different value depending on the kind of reducing sugar. From the comparison of the k280, it was found that the k280 became lower as Tg of the reducing sugar itself which was contained in the sample became high. From this result and our previous result, it was suggested that the reducing sugar and lysine embedded in glassy matrix can react partially independently of the molecular mobility of the matrix, and the contribution of the molecular mobility of Maillard reaction reactants itself to the reaction rate in the glassy matrix should be considered.
From ancient times, konjac has been recognized as a food rich in dietary fiber, and its use is still prevalent in a variety of food preparation applications. Konjac gel is prepared by adding an alkaline gelling agent to konjac flour that has been swelled with water. The effects of this method are rather unfavorable: the konjac becomes alkaline and emits a distinct alkali smell; it has an acrid taste; and it can change the taste and/or texture of other food ingredients. For this reason we searched for methods to prepare neutral konjac using microcapsules with an acid coated with hydrogenated oil. To keep the microcapsules from floating as a result of swelling, we selected konjac flour with a viscosity that would increase rapidly at temperatures 40°C. Our efforts to produce an agreeable flavor led to our selection of calcium hydroxide for the alkali coagulant and fumaric acid for the neutralizing agent. We prepared the content of a microcapsule by mixing fumaric acid with hydrogenated rapeseed oil with a melting point of 67.5°C at a ratio 7: 3. We found that neutral konjac can be prepared when the ratio of a microcapsule to calcium hydroxide is within the range of 0.7 to1.3. Our study of storage methods indicated that the quality can be maintained for a long time when neutral konjac has been subjected to retorting. Thus, a preparation method for industrial neutral konjac has been established.
We prepared neutral konjac using microcapsules where fumaric acid is coated with hydrogenated rapeseed oil with a melting point of 67.5°C. The resulting texture differs from traditional konjac. While the microstructure of traditional konjac has a complex structure with a network of thin walls within a network of thick walls, that of neutral konjac has mainly a network of thick walls. It has been confirmed that the rate of permeation of seasoning to neutral konjac is faster than that of traditional konjac, and it is conjectured that this difference in permeation rate is a result of the difference in structure between the two types. Cooking water becomes alkaline when traditional konjac is cooked. On the other hand, the water is unaffected when cooking with neutral konjac. Furthermore, when cooked with beef, neutral konjac hardens the meat at a lower rate than that of traditional konjac.
Banana cultivation in tropical plantation generates a large amount of waste such as leaves and stems. The importance of an effective banana waste utilization has been increasingly recognized. In order to approach this issue, we focused on the banana leaf extract, which has not been studied. The objectives of this study were to collect information of banana leaf and to propose an effective extraction procedure. Lipid, basic, acidic, neutral and phenolic fractions were extracted from fresh and dry banana leaves. The lipid fraction had a high concentration of wax. The wax yield from fresh banana leaves in the fruits-harvesting stage was high (approximately 3% on a dry basis) . There were antibacterial and antioxidative activities in the acidic and phenolic fractions of banana leaf extract. An effective extraction procedure was proposed as follows; i) to extract wax from the fresh banana leaves, ii) to dry the leaf materials, iii) to extract functional components.
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