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Volume 19 , Issue 5
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Review
  • Yasuyuki KONISHI, Masayoshi KOBAYASHI
    Volume 19 (2013) Issue 5 Pages 717-727
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    As a new scientific method to overcome the difficulties in designing requested food products in the food engineering field, a hybrid method combining the chemical engineering-proton NMR technique was examined by using 18 different kinds of foods. The hybrid method proposed clearly distinguished water species-A1 and -A2, which were divided at the correlation time of τC = 1 × 108 s evaluated by the proton NMR technique. Water species-A1 was recognized as a weakly restricted water species, such as free water, whereas water species-A2 was recognized as a strongly restricted water species, such as bound water formed by strong adsorption. It was clearly demonstrated that the two water species were reproduced during repeated cycles of dehydration and re-hydration. All the parameters, such as effective diffusivity of water (De), activation energy of De (ED), pre-exponential factor of De (δD0) and hardness (NP) of food, were evaluated individually for the two water species.
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Food Technology and Engineering
Original papers
  • Nor Faadila M. IDRUS, Noor A. FEBRIANTO, Wahidu ZZAMAN, Tang E. CUANG, ...
    Volume 19 (2013) Issue 5 Pages 729-737
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    Virgin coconut oil is a functional food which provides health benefits. It is different from other cooking oils in that it has medium-chain fatty acids rather than long-chain fatty acids. The traditional aqueous extraction of the oil is very flexible that can be applied in a medium to large-scale industry. The study was carried out to optimize the aqueous extraction of virgin coconut oil using response surface methodology. The most influencing three factors were used for this experiment, which are the coconut milk-to-water percentage, fermentation and refrigeration time. The optimization study showed that the method can produce the best yield with quality by using coconut milk (73.8%), fermented (14.1 h) and refrigerated time (20.5 h). Coconut milk percentage and fermentation time significantly affected the response of extraction yield (p ≤ 0.01). The aqueous extraction can be used commercially for the production of virgin coconut oil as the method is environmental friendly.
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  • Azim SIMSEK, Birol KILIC
    Volume 19 (2013) Issue 5 Pages 739-747
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    The purpose of this study was to investigate the effects of marination, cooking and storage temperatures on physico-chemical and microbiological properties of salmon döner kebab. The raw meat, raw, cooked and stored döner kebabs were subjected to moisture, protein, fat, ash, color, pH, cholesterol, biogenic amines, oxidation, fatty acids profile, microbiological and sensory analysis. The major fatty acids in döner kebab were palmitic, oleic, omega-3 and omega-6 and unsaturated fatty acids were higher than saturated fatty acids (P < 0.05). It was found that 18°C of storage was more effective than 4°C for inhibition of oxidation, biogenic amine formation and microbial growth (P < 0.05). While cooking affected parameters evaluated (P < 0.05), marination did not have any significant effect. The study results indicated that salmon döner kebab could be beneficial to provide healthy meat products to consumer without posing any acceptability problems in terms of quality factors.
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  • Maryam Khakbaz HESHMATI, Nasser HAMDAMI, Mohamad SHAHEDI, Mohammad Ami ...
    Volume 19 (2013) Issue 5 Pages 749-758
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    Caviar is one of the most luxury foods in the world. In addition to the traditional method (using salt and preservative with low temperature), there are various methods to extend the shelf life of caviar. The main objectives of this study were to evaluate the capabilities of Zataria multiflora essential oil (0.03%, 0.06%(W/W)), nisin (9, 18 mg/kg), potassium sorbate (500 and 1000 mg/kg) and LDPE package containing 0.4 and 1%(W/W) nano-ZnO on the shelf life, as a new approach in caviar. Total aerobic bacteria, molds & yeasts and color of samples were evaluated immediately after packaging and after 30, 60, 90, 120 and 150 days of storage. Results showed that LDPE package containing 1%(W/W) nano-ZnO have the most capability to control total aerobic bacteria. While for molds and yeasts count, 0.06%(W/W) Zataria multiflora essential oil had the most significant effect on the caviar samples (p < 0.05). For color changes analysis, there were significant differences between all of the treatments except 500 mg/kg potassium sorbate and 18 mg/kg nisin. Minimal color changes were observed in caviar samples packaged in LDPE film containing nano-ZnO. The results also showed a considerable Zn migration from package to caviar that its rate increased after 40 days.
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  • Jijuan CAO, Jingquan LI, Qiuyue ZHENG, Junyi XU
    Volume 19 (2013) Issue 5 Pages 759-764
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    This study was to establish the optimal real-time PCR method for specific identification of puffer fish and monkfish. In this study, we designed the specific primers and probes for fish 12s and monkfish cytochrome oxidase subunit I (COI), and used them for specific identification of fish and monkfish. Our results showed that the specific primers and probes for monkfish COI could specifically identify 3 monkfish species, respectively, from total 42 samples of aquatic products. Moreover, the primers and probes for COI were very sensitive to detect 0.01% Lophius litulon content in the mixed sample of Theragra chalcogramma and Lophius litulon. Therefore, this method is simple, practical, sensitive and specific; is helpful and useful to identify the products of fish and monkfish.
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  • Maryam E. REZAGAH, Sayaka ISHIDA, Fumihiko TANAKA, Daisuke HAMANAKA, T ...
    Volume 19 (2013) Issue 5 Pages 765-771
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    This research was conducted to study heat transfer in Japanese pears based on their exact geometry as measured by a 3D laser scanner. Some of the thermal properties of three cultivars of Japanese pear (Pyrus pyrifolia) were measured, boundary conditions were defined and heat transfer modeling was conducted using COMSOL Multiphysics 4.2a software based on the finite element method. The thermal conductivity of each examined cultivar was estimated from the model and found to be 0.66 ± 0.01, 0.56 ± 0.09 and 0.58 ± 0.06 W/m·K for Kosui, Niitaka and Oushu, respectively, which are acceptable comparing to other fruits. The thermal diffusivity of the cultivars was also calculated and was in the range of 1.37 × 10−7 to 1.76 × 10−7 m2/s. Low RMSE values of the model results compared to experimental data were observed. The model was validated with data obtained from a thermal camera and the results showed that the model is successful in predicting the temperature profile inside the fruit at any time.
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  • Leng GAO, Yang-Ping HUANG, Xiao-Chen GAO
    Volume 19 (2013) Issue 5 Pages 773-780
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    The effects of substituting pork backfat (25%, 50%, 75% and 100%) with pre-emulsified sunflower oil (using soy protein isolate) on color, proximate composition, cooking yield, texture, TBARS value and sensory evaluation of sika deer frankfurters were investigated. Increasing pre-emulsified sunflower oil from 25% to 100% increased the protein content, lightness value, cooking yield, and reduced fat content, redness and TBARS value, and enhanced oxidative stability. The treatments which contained pre-emulsified sunflower oil had better texture. However, added more than 50% pre-emulsified sunflower oil to frankfurters, due to higher moisture content, had similar texture. Added pre-emulsified sunflower oil to frankfurters decreased the energy of frankfurters from 1027.86 kJ/100 g to 816.16 kJ/100 g. According to sensory evaluation, the treatments of control, substituted 25% and 50% pork backfat had higher overall acceptance. Related to the results of proximate and physic-chemistry characters analysis, oxidative stability and panelists identified, substituted 50% pork backfat with pre-emulsified sunflower oil was the best treatment.
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  • Hasan TANGULER
    Volume 19 (2013) Issue 5 Pages 781-793
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    Up to now, this has been the first study in which the influences of fermentation temperature on the yeast growth and the production of yeast-derived volatile compounds during the fermentation of Emir grape must at various temperatures were examined. The results demonstrate that the fermentation temperature plays an important role compared to all tested variables. Fermentations were completed in 6, 8 and 14 days at 12, 18 and 24°C, respectively. Increase in temperature resulted in an increase in glycerol, total acidity, acetic and tartaric acid, 2-methyl butanol, propan-1-ol, isobutanol, acetaldehyde and acetone, but in a decrease in ethanol, malic and citric acid, isoamyl acetate, ethyl acetate, isobutyl acetate, ethyl butyrate and ethyl hexanoate. Moreover, these mixed culture fermentations formed higher amounts of isoamyl acetate in comparison with pure culture of S. cerevisiae. According to chemical composition and volatile compounds the differences between obtained wines were found generally significant.
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  • S. AL-RAHBI, A. MANICKAVASAGAN, R. AL-YAHYAI, L. KHRIJI, P. ALAHAKOON
    Volume 19 (2013) Issue 5 Pages 795-804
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    Surface or external qualities of fresh and dried fruits are the important factors in determining the consumer acceptability. An automated and objective method to detect the surface defects on fruits would be highly beneficial in handling and processing facilities. The objective of this study was to determine the efficiency of a computer vision system with RGB color camera to detect the surface cracks on dates. Three grades of dates (no-crack dates, low-crack dates and high-crack dates) were obtained from two commercial dates processing factories in Oman. After the confirmation of grade standards by a dates-quality-expert, the samples were imaged individually using a color camera (105 dates in each grade). Eleven features were extracted from each image and used in classification models. Red, hue and value intensities of three grades of dates were significantly different from each other. In a three classes model, the classification accuracy was 62%, 58% and 78% for high-crack, low-crack and no-crack dates, respectively using linear discriminant analysis (LDA). LDA yielded a classification accuracy of 88% and 75% for the dates with-crack and without-crack, respectively in a two classes model. In pairwise discrimination, the highest classification (96%) was achieved between high-crack and no-crack dates, and the lowest accuracy (59%) was between low-crack and high-crack dates.
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  • Chun-hua MA, Connieal TAN, Wei-lin LI, Liang-bi CHEN, Yi-ru WANG, Xi C ...
    Volume 19 (2013) Issue 5 Pages 805-811
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    Wuyi rock tea, a kind of semi-fermented Oolong tea, is produced around Wuyi Mountain. Due to its unique aroma and taste, namely the aroma of flowers and the earthy taste of rocks (hence its name as Wuyi rock tea), it has become very popular in China. Its characteristics are associated with the manufacturing processes. During which many compounds are produced. Nonvolatile compounds contribute to the taste, while volatile compounds contribute to the aroma. In this study, volatile compounds from two samples using different drying methods were extracted using headspace-solid phase microextraction (HS-SPME) approach, and then analyzed, compared and identified with gas chromatography-mass spectrometry (GC-MS). Among the volatile compounds, trans-nerolidol, farnescene, hexyl hexanoate, indole and geraniol were identified, and found to have high content in both samples. The analytical results showed that freeze drying process is an alternative drying method, which is especially suitable for the production of highly scented Wuyi rock tea.
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Note
  • En-Sheng TAI, Pao-Chuan HSIEH, Shyang-Chwen SHEU
    Volume 19 (2013) Issue 5 Pages 813-818
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    The screened strain that exhibited the highest level of polygalacturonase (PGase) activity based on coffee pectin was selected and identified as Aspergillus tubingensis. Sucrose (2%) and sodium nitrate (3%) were the best carbon and nitrogen sources, respectively, for the strain’s production of PGase. At 35°C and an initial pH of 4 as culture conditions, the strain showed the highest level of PGase production (15.9 U/mL). The highest activity of purified PGase-1 was observed at 60°C and pH 5. PGase-I activity was highly enhanced by Ca2+, Mn2+, and Ba2+. PGase-I was thermally stable at 50°C, with a half-life of 4 h. High stability was observed after 24 h incubation at pH levels from 3 to 7. The elimination of coffee mucilage was obviously improved by treating with this enzyme.
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Short Communication
  • Hongbin WANG, Saikun PAN, Shengjun WU
    Volume 19 (2013) Issue 5 Pages 819-821
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    Browning decreases the commercial value of the canned Clanis bilineata larvae meat (CCBLM), and therefore colour preservation during processing and storage is the main objective of manufacturers. In this study, the efficacy of sodium phytate as a browning inhibitor for use on the CCBLM was investigated. Browning of the CCBLM treated with sodium phytate was monitored during processing and storage. The CCBLM treated with 0.20% sodium phytate had significantly lower browning during processing and after 12 months of storage at room temperature compared with the control (P < 0.05). Results indicate that treatment with 0.20% sodium phytate is a promising way to inhibit CCBLM from browning.
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Food Science and Chemistry
Original papers
  • Aydin KILIC, Aydin OZTAN
    Volume 19 (2013) Issue 5 Pages 823-831
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    The objective of the study is to investigate the effects of ascorbic acid on the quality of cold-smoked trout (Oncorhynchus mykiss), with or without sodium nitrite (NaNO2). For this purpose, fish samples (~250 g) were treated with six forms of brine prepared with 10% salt which is the control, treated with 10% salt and 0.4%NaNO2, 10% salt and 0.2%NaNO2, only 2.5% ascorbic acid (Dry Salt Basis) and their combinations, and stored at +4°C. The groups were analyzed after 4 days interval for microbiologic quality, biochemical quality and sensory quality. According to the results, the samples treated with only ascorbic acid increased the shelf-life of smoked fish about > 8 days. TVB-N value of the control group was average 41.72 mg/100 g after 16 day; the group containing ascorbic acid was on average 30.53 mg/100 at this time. Ascorbic acid reduced the residual nitrite in all groups. The residual nitrite disappeared in the ascorbic acid including groups after 20 day.
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  • Vu Thu TRANG, Vu Hong SON, Lam Xuan THANH, Samira SARTER, Tomoko SHIMA ...
    Volume 19 (2013) Issue 5 Pages 833-841
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    Antimicrobial activities of aminoreductone (AR), a product formed in the initial stages of the Maillard reaction, were investigated using eight clinical isolates of antibiotic-susceptible/resistant pathogenic bacteria: four Pseudomonas aeruginosa, one multi-drug-resistant Pseudomonas aeruginosa (MDRP), one Escherichia coli, one methicillin-susceptible Staphylococcus aureus, and one methicillin-resistant Staphylococcus aureus (MRSA). AR showed advanced growth inhibition effects compared to antibiotics (amikacin, ciprofloxacin, imipenem and levofloxacin) frequently used for the treatment of infectious diseases, and worked synergistically with these antibiotics. The minimum inhibitory concentrations (MIC) of AR ranged from 13 to 20 mM. The bactericidal activity of AR was dose and time dependent. The minimum bactericidal concentration (MBC) was lower for Gram-negative bacteria (32 to 40 mM). These findings suggest that AR, a naturally formed antimicrobial agent present in thermally processed foods, has promising potential for health promotion and for use in medical practices.
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  • Kenta YAMAMOTO, Ayumi YAHADA, Kumi SASAKI, Atsuko FUNAKOSHI-YOSHIDA, C ...
    Volume 19 (2013) Issue 5 Pages 843-848
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    Sensory characteristics, colorimetric value and volatile components of shiikuwasha (Citrus depressa Hayata) juice and adulterated model juice using calamondin (Citrus madurensis LOUR.) juice were investigated. (1) A triangle test detected adulterated model juice ranging from 0% to 50%. The results of Scheffé’s paired comparison test (Ura variation) suggested that the color and flavor of juice were used to differentiate the shiikuwasha juice from the adulterated model juices. (2) Color parameters (L*, a* and b*) were detected by a tristimulus reflectance colorimeter, and significant color differences (p < 0.05) were observed between shiikuwasha juice and other model juices. The results of (1) and (2) suggested consumers are able to identify pure shiikuwasha juice personally. (3) Volatile components were measured and identified by GC/MS; γ-terpinene and linalool were new and useful chemical markers for detecting small amounts of shiikuwasha juice mixed with calamondin juice.
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  • Sadettin TURHAN, Furkan Turker SARICAOGLU, Fatih OZ
    Volume 19 (2013) Issue 5 Pages 849-853
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    In this study, the effect of ultrasonic marinating on the transport of acetic acid and salt in anchovy marinades was investigated. Anchovy fillets were immersed in marinating solution containing 4% acetic acid and 8% salt and treated with static marinating or with 20 kHz ultrasound at different ultrasonic intensity (20, 25 and 30 W/cm2) and at different times (10, 20 and 30 min). In general, the ultrasonic marinating affected moisture transport in anchovy marinades and moisture content decreased while ultrasonic intensity increased. The ultrasonic marinating accelerated acetic acid and NaCl transport depending on ultrasonic intensity and marinating time. The best results were obtained in marinated anchovies with 30 W/cm2 of ultrasonic intensity. The marinating with 30 W/cm2 of ultrasonic intensity exhibited the highest effect in decreasing the pH value. The results suggest that marinating with 30 W/cm2 of ultrasonic intensity could enhance acetic acid and salt transport and decreasing pH in anchovy marinades.
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  • Chongde WU, Chaolan LIU, Guiqiang HE, Jun HUANG, Rongqing ZHOU
    Volume 19 (2013) Issue 5 Pages 855-864
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    The aim of this study was to investigate the effect of Tetragenococcus halophilus addition on the quality of Chinese Horsebean-Chili-Paste (CHCP). T. halophilus SZ-B-2 isolated from soy sauce moromi was identified based on physiological tests, carbon substrate utilization patterns (Biolog) and the 16S rDNA sequence and deposited as T. halophilus CGMCC 3792. The strain SZ-B-2 can grow at 25% NaCl and exhibited relatively broad ranges of pH. The potential of T. halophilus as a starter culture for quality improvement in CHCP fermentation was elucidated. As a result, T. halophilus inoculated sample exhibited higher total titratable acid, formol nitrogen and reducing sugar contents compared with the control. In addition, the addition of T. halophilus decreased the content of nitrite by 39.4%. Major volatile compounds were 9,12-octadecadienoic acid, 1,2-propanediol, ethyl 9,12-octadecadienoate, ethyl 9-hexadecenoate. The inoculated sample showed higher contents of volatile compounds including acids, alcohols, esters and aromatic compounds. Thus, T. halophilus addition may promote the formation of desirable odor and improve the flavor of CHCP.
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  • Hai-Ning YU, Zun-Chen WANG, Sheng-Rong SHEN, Wei-Guang SHAN
    Volume 19 (2013) Issue 5 Pages 865-873
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    Capsaicin is an organic compound in chili peppers which are consumed by over one quarter of the world’s population daily. Studies have shown that capsaicin can prohibit proliferation in some cancer cells. In the present study, both gastric cancer and normal epithelial cell lines were employed and treated with capsaicin and its analogs and examined for the structure-activity relationship as well. 3-(4, 5-di-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide yellow tetrazole (MTT) assay results showed the order of effectiveness of capsaicin analogs in the used cell culture system was as follows: dihydrocapsaicin > capsaicin > 6-gingerol > vanillin ≥ vanillylamine, and, reactive oxygen species (ROS) and malondialdehyde (MDA) contents were markedly increased; the biological activity pathway of Superoxide dismutase (SOD) and Glutathione Peroxidase (GSH-Px) was up-regulated, whereas, the catalase (CAT) activity was down-regulated by dihydrocapsaicin, capsaicin and 6-gingerol. In conclusion, the results implied that B and C region are indispensable for the anti-cancer activity of capsaicin and CAT activity down-regulation was responsible for apoptosis of gastric cancer cells induced by capsaicin and its analogs.
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  • Emiko TAKEYAMA, Masako FUKUSHIMA
    Volume 19 (2013) Issue 5 Pages 875-882
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    Cold-pressed oil from the seeds of Plukenetia volubilis L. (green nut oil, GNO) has been shown to be rich in n-3 fatty acid content, similar to flaxseed and perilla oils. These fatty acids are readily oxidized at high temperatures and under UV irradiation, limiting their potential applications. We therefore set out to clarify the physicochemical properties of green nuts. In addition, to explore means of the degradation process, we investigated the oxidation characteristics of GNO and the effects of oxidation on fatty acids. Results showed that GNO was stable up to 140°C and exhibited greater UV resistance than the other oils. This may be related to the 10% lower α-linolenic acid content of GNO, compared to the other oils, as well as the presence of γ- and δ-tocopherols. GNO was capable of tolerating a certain degree of heat processing.
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  • Nobuya SHIRAI, Yumiko YAMASHITA, Michiaki YAMASHITA
    Volume 19 (2013) Issue 5 Pages 883-891
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    Male mice (4 months old) were fed green tea extract- (GTE; 0.25% w/w) and/or fish oil- (FO; 5% w/w) containing diets with 8 ppm methylmercury (MeHg) chloride for 4 months to investigate the effects of simultaneous intakes on brain functions, antioxidant defenses against MeHg, and MeHg accumulation in tissues. In mouse maze tests, intake of GTE or FO significantly improved the learning ability of MeHg-exposed mice. GTE and FO also significantly decreased liver and brain catalase activities in MeHg-exposed mice. Total Hg concentrations in muscle were significantly lowered by dietary GTE and FO in the MeHg-exposed group, though no remarkable differences were observed in the brain. These data indicate that simultaneous intake of GTE and FO effectively prevents MeHg-mediated oxidative stress and reduces the effects of Hg exposure with fish consumption.
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Notes
  • Shyuichiro INAGAKI, Takahiro KATO, Shizuka MORI, Tomoyuki FUJITA
    Volume 19 (2013) Issue 5 Pages 893-899
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    In recent years, more effective use of rice has become important because of an annual increase in surplus rice. We fermented rice in pure cultures of eight organisms (Aspergillus oryzae, Monascus pilosus, Absidia corymbifera, Mucor circinelloides, Mucor racemosus, Rhizopus oligosporus, Rhizopus oryzae, and Saccharomycopsis fibuligera), which were isolated from molded rice and soybean products in Asian countries, and evaluated the composition and antioxidant activity of the products. Rice fermented with the two Rhizopus species had a high methanol extract yield, implying good fermentation properties. High saccharification and increased levels of total amino acids and total polyphenols were also found in Rhizopus-fermented rice samples. Ethyl acetate extracts of rice fermented with Ab. corymbifera and Mu. circinelloides had enhanced antioxidant activity compared to unfermented rice, and some fractions obtained from the extracts by high performance liquid chromatography exhibited high antioxidant activity. Based on these results, Ab. corymbifera, Mu. circinelloides, R. oligosporus, and R. oryzae are promising starter organisms for the development of new fermented rice products.
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  • Xiu-Lian CHANG, Han XU, Jiao-Jiao WANG, Wen-Hua WANG, Yong-Mei FENG
    Volume 19 (2013) Issue 5 Pages 901-907
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    Crude water-soluble polysaccharides were isolated from gel juice, skin juice and flowers of Aloe ferox Miller. Result indicated that skin juice contained 15 fold the level of polysaccharides in gel juice from one plant, strongly suggesting the potential industrial application of A. ferox skin as the resource of polysaccharides, rather than discarded. The amount of polysaccharides in the flower of A. ferox was about 2 fold compared with those of A. arborescens and A. vera. After fractionation by anion-exchange chromatography and gel permeation chromatography, gel juice polysaccharide was separated into three neutral (GN1, 1.7%; GN2, 17.6% and GN3, 0.4%) and one acid (GA1, 19.7%) fractions. Skin juice polysaccharide consisted of one neutral (SN1, 25.2%) and two acid (SA1, 7.2%; SA2, 18.0%) fractions. Flower polysaccharide consisted of one neutral (FN1, 1.6%) and one acid (FA1, 26.4%) fractions. All the subfractions have relatively high polydispersity indices (1.0 to 2.5). Sugar analysis shows that the subfractions are constituted predominantly by galactose, glucose and mannose with different mole percentages, except that acidic flower polysaccharide was composed of two more monosaccharides, rhamnose and xylose, and neutral skin juice polysaccharide yielded glucose as the sole monosaccharide. Galacturonic acid was identified as the sole uronic acid in all acidic polysaccharides from different tissues.
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  • Yoichiro SHIMIZU, Masashi IMAOKA, Shigekazu YANO, Yosuke SAWARAGI, Kaz ...
    Volume 19 (2013) Issue 5 Pages 909-913
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    Theanine (γ-glutamylethylamide) is the major “umami” component in tea and exhibits various favorable physiological effects in mammals. To quantify theanine contained in commercial tea beverages, a coupled reaction of γ-glutamyltranspeptidase from Pseudomonas nitroreducens NBRC 12694 and amine dehydrogenase from Paracoccus denitrificans NBRC 12442 was investigated. This method measures changes in the absorbance of 2, 6-dichloroindophenol at 600 nm and is fast (less than 10 min, including the time required for sample pretreatment). The calibration curve was linear between theanine concentrations of 0 − 200 μM, with R2 = 0.998. Theanine concentrations in samples of commercial tea beverages (black tea, green tea, and oolong tea) obtained using this method were similar to those obtained using the pre-column derivatization HPLC method. The proposed colorimetric assay for theanine determination is a reliable and timesaving method and can be used in food quality control and biological research.
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Short Communication
  • Zaixiang LOU, Yijun LIU, Ying HONG, Xinyi SONG, Hongxin WANG, Lianzhon ...
    Volume 19 (2013) Issue 5 Pages 915-921
    Released: November 20, 2013
    JOURNALS FREE ACCESS
    The antibacterial and anti-biofilm activities of essential oil (EO) from burdock leaf have been first investigated. The results indicated EO greatly potential for inhibition the growth of all the bacteria tested. The MIC values for bacteria strains were in the range of 250 − 1000 μg/mL. The EO significantly inhibited the formation of biofilm by E. coli and S. aureus. The lowest concentrations of EO to completely inhibit biofilm formation were 500 and 250 μg/mL. It could be inferred that the biofilm formation inhibition effect of burdock leaf EO was mainly due to its inhibition effect on the viability of bacteria. Then the composition of EO was analyzed by GC-MS. Sixty three compounds were identified. The EO was dominated by beta-Eudesmol (13.67%). The EO of burdock leaf based on its antibacterial efficiency and its significant inhibition on biofilm formation, could be highly useful in control of foodborne bacterial biofilms.
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