• Food Science and Preservation
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• v.23 no.3
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• pp.369-377
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• 2016

This study was conducted to investigate the effects of superheated steam (SHS) on volatile compounds and the quality characteristics of onion. Onion samples were treated by SHS at various steam temperatures ($100{\sim}300^{\circ}C$) for 1 min. Thiosulfinates and pyruvic acid were reduced by SHS treatment. The absorbance values obtained for thiosulfinates, the odor-causing compounds in onions, treated by were 0.889, 0.085, 0.049, 0.049, and 0.045, while that of the untreated control sample was 1.587. The pyruvic acid contents of onions treated by SHS were 7.57, 5.85, 1.66, 0.47, and 0.26 mg/mL, while that of the untreated control sample was 8.00 mg/mL. Volatile compounds such as, dipropyl trisufide, 1,3-propanedithiol, methyl thiirane, methyl propyl trisulfide, diallyl disulfide, 1-(methylthio)-1-propene, 1,1-thiobis-1-propene, 1,1-sulfinyl bispropane, dimethyl tetrasulfide, methyl propenyl disulfide, dimethyl trisulfide, and diallyl disulfide were reduced by SHS treatment. The results showed that antioxidant activities in the of onion samples were improved by SHS treatment. The hardness and chewiness of onions treated by SHS were significantly lower than those of the untreated control onion sample. Sensory evaluation suggested that SHS could help lower off-flavors in and enhance the palatability of onions. These results suggest that the application of SHS treatment to onions can decrease their off-flavors, change their textural attributes, and promote their sensory properties.

• Korean Journal of Food Science and Technology
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• v.5 no.1
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• pp.33-35
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• 1973

If soybeans are presoaked, two minutes heating at $100^{\circ}C$ is sufficient to inhibit production of objectionable green beany flavors, with dry beans, three minutes heating at $100^{\circ}C$ accomplishes the same inhibition, These brief heat treatments are not sufficient to inactivate growth inhibition factors as determined by chick feeding trials. The inhibition of off flavor coincides with loss of lipoxygenase activity, and the inhibition is thought to be due to lipoxygenase inactivation.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.6 no.1
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• pp.19-23
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• 2000

The increasing use of plastics in food packaging materials has led to the issue of food-packaging mutual interactions from residues in the plastics. Plastic films are commonly printed by using solvent-based ink to decorate the packaged food for consumer attention. However, the residual solvents can not be completely removed and they can migrate into the contained food which lead to undesirable off-flavors. Partitioning (Kp) of printing ink solvents was studied in two types of plastic films with different chemical structure and polarity. At $25^{\circ}C$, Kp of toluene is higher than that of isopropanol in PP, but isopropanol showed higher Kp value than toluene in EVOH. This showed that polarity had a significant effect on the partitioning of printing ink solvents into the plastic films. Printing solvents had a higher affinity to the polymer with similar polarity than it did to the different one.

• Journal of Animal Science and Technology
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• v.49 no.4
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• pp.515-522
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• 2007

To develop the manufacturing method of ice cream with microbiologically safe and proper sensory quality using irradiation for sensitive consumer, 3 different flavors, which were resistant to their flavors against irradiation, were selected and used for ice cream manufacturing to reduce the irradiation-induced off-flavor problem. The general composition was not different among treatments. Total aerobic bacteria were detected as 2.38, 1.23, 1.38, and 1.15 log CFU/g level in ice cream with control(no flavor added), spearmint, mint, and citrus flavor, respectively. No viable cells were observed by irradiation at 1 kGy except for the control. Sensory evaluation indicated that the irradiated ice cream with spearmint flavor at 1 kGy and citrus flavor at 3 kGy had higher overall acceptability. Therefore, a low dose irradiation (less than 3 kGy) with mint or citrus flavors may enhance the safety of ice cream with proper sensory quality for sensitive consumer.

• Journal of Life Science
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• v.25 no.2
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• pp.174-179
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• 2015

The presence of psychrotrophic bacteria downgrades the quality of dairy products. This study evaluated the effect of lipolytic psychrotrophic bacteria on the chemical properties of Gouda cheese made from raw milk experimentally inoculated with a psychrotrophic bacterium (Acinetobacter genomospecies 10). Raw milk experimentally inoculated with Acinetobacter genomospecies 10 and refrigerated at $4^{\circ}C$ for 3 or 6 days produced a 6-week ripened Gouda cheese with a significant decrease in total solids (p<0.05) or an increased fat content (p<0.05), respectively. Raw milk inoculated with Acinetobacter genomospecies 10 and refrigerated for 3 days had higher (p<0.05) SCFFA (1.35 times), MCFFA (1.42 times), and LCFFA (1.44 times) than the control 6-week ripened Gouda cheese. The cheese manufactured from the inoculated and refrigerated raw milk had higher (p<0.05) total free fatty acids (1.68 times) compared with the control. Raw milk inoculated with Acinetobacter genomospecies 10 and refrigerated for 6 days had increased SCFFA (1.45 times), MCFFA (1.28 times), and LCFFA (1.38 times) compared with the control 6-weeks ripened Gouda cheese. The 6-week ripened Gouda cheese manufactured from this inoculated milk had higher (p<0.05) total free fatty acids (1.34 times) compared with the control. The results indicated that the production of excessive free fatty acids in dairy products by psychrotrophic bacteria can be critical in predisposing dairy products to off-flavors and in turn degrading their quality.

• KSBB Journal
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• v.20 no.1 s.90
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• pp.12-17
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• 2005

Despite a wide range of fatty acids in fish oil, its the usage are very limited owing to off-flavors and volatile compounds in the oil. A way to extract and remove volatile compounds was performed at a semi-flow extractor by using supercritical carbon dioxide $(SC-CO_2)$. Samples of the oil were treated at the conditions which ranged from $30\;to\;80^{\circ}C$ and from 80 to 200 bar with 10 mL/min flow rate of carbon dioxide. In the oil the volatile compounds were analyzed by gas chromatography. Before extraction with $SC-CO_2$ the oil sample was detected over 129 peaks but 99 compounds were identified. The results demonstrated that at $40^{\circ}C$ and 200 bar extraction condition the volatile compounds in the tuna fish oil were removed, except for 14 compounds identified after extraction and other $SC-CO_2$ extraction conditions reached to high reduction of the volatile compounds.

• Korean Journal of Food Science and Technology
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• v.42 no.5
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• pp.533-540
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• 2010

Effects of pH (1.8-10.2) and time (56 sec-15 min 4 sec) at high hydrostatic pressure (500 MPa) on the reduction of volatile compounds in garlic were studied. Volatile components of garlic were obtained from the headspace, analyzed, and identified by gas chromatography (GC)-mass spectrometry and an electronic nose. Nineteen sulfur compounds were identified as major compounds in garlic, and furan, aldehydes, alcohols, and ketones were also detected. Off-flavor compounds were more effectively reduced under strong acidic conditions. As the residence time at 500 MPa increased from 56 sec to 15 min 4 sec, the total amount of volatile compounds decreased significantly. The total amount of sulfur compounds decreased about 70% compared to those of raw garlic when the garlic was soaked in buffer (pH 6.0) and treated at 500 MPa for 15 min 4 sec. A principal component analysis showed that the off-flavors of garlic were reduced by the operating time of high hydrostatic pressure as well as pH treatment. The correlation coefficient of the results between GC and the electronic nose analysis was 0.9620. Therefore, pH and high hydrostatic pressure treatment could be used as an efficient method for reducing of garlic off-flavor.

• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.767-774
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• 2010

In this study, the problems of high caloric content, increased maturation time, and off-flavors in commercial beer manufacture arising from residual sugar, diacetyl, and acetaldehyde levels were addressed. A recombinant industrial brewing yeast strain (TQ1) was generated from T1 [Lipomyces starkeyi dextranase gene (LSD1) introduced, ${\alpha}$-acetohydroxyacid synthase gene (ILV2) disrupted] by introducing Saccharomyces cerevisiae glucoamylase (SGA1) and a strong promoter (PGK1), while disrupting the gene coding alcohol dehydrogenase (ADH2). The highest glucoamylase activity for TQ1 was 93.26 U/ml compared with host strain T1 (12.36 U/ml) and wild-type industrial yeast strain YSF5 (10.39 U/ml), respectively. European Brewery Convention (EBC) tube fermentation tests comparing the fermentation broths of TQ1 with T1 and YSF5 showed that the real extracts were reduced by 15.79% and 22.47%; the main residual maltotriose concentrations were reduced by 13.75% and 18.82%; the caloric contents were reduced by 27.18 and 35.39 calories per 12 oz. Owing to the disruption of the ADH2 gene in TQ1, the off-flavor acetaldehyde concentrations in the fermentation broth were 9.43% and 13.28%, respectively, lower than that of T1 and YSF5. No heterologous DNA sequences or drug resistance genes were introduced into TQ1. Hence, the gene manipulations in this work properly solved the addressed problems in commercial beer manufacture.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.2
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• pp.97-104
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• 1988

Condensed phosphates have been used in various meat products to enhance the water holding capacity, to improve texture and to prevent the development of off flavors and off odors. This study was intended to observe the effects of poly - and pyrophosphate on the growth of sanitary indicative bacteria and food poisoning bacteria. The bacteriostatic effect of poly - and pyrophosphates against Gram positive bacteria was much stronger than that of against Gram negative organisms. The effective inhibitory concentration of sodium polyphosphate on the growth of bacteria was varied by species such as $0.3\%$ to Staphylococcus aureus, $0.9\%$ to Salmonella, and more than $1.0\%$ to Escherichia coli in nutrient broth. When Staphylococcus aureus suspension was treated with $0.5\%$ sodium polyphosphate at $35^{\circ}C$ for 1 hour, the release of UV-absorbing substances from the organism was confirmed. However no significant effect was observed in Escherichia coli under the similar condition. When alaska pollack fillets were dipped in $ 3.5\%$ sodium polyphospahate at $2^{\circ}C$ for 1 min. prior to freezing, the viable cell count and coliform MPN's of the frozen product were decreased with the range of 30 to $50\%$ in comparison with those of control.

• Korean journal of food and cookery science
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• v.4 no.2
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• pp.57-64
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• 1988

The present study was conducted to characterize lipoxygenase isoenzymes isolated from germinating soybean seeds to obstain pH profiles, carbonyl Production, carotene bleaching abilities, and stability to heat. The roles of these lipoxygenase isoenzymes in the generation of volatile carbonyl compounds were investigated to associate with off-flavor and odor of soybean sprouts cooked to different temperatures. Lipoxygenase isoenzymes were isolated from soybean sprouts using ammonium sulfate fractionation, gel filtration and ionexchange chromatography. Two main lipoxygenases exhibited maximum activity at pH 6.5 (lipoxygenase 2) and at pH 9.5 (lipoxygenase 1), respectively. Both lipoxygenase 1 and 2 produced 280 nm absorbing carbonlys and bleached carotene. The abilities of hydroperoxide formation, 280 nm absorbing carbonyl production and carotene bleaching of lipoxygenase isoenzymes were decreased significantly as the cooking temperature raised. Sensory evaluation data presented that raw and $50^{\circ}C$ cooked soybean sprouts showed significantly higher grassy odor than $80^{\circ}C$and $100^{\circ}C$ cooked soybean sprouts. On the other hand beany odor was significantly higher in $50^{\circ}C$ and $80^{\circ}C$ cooked soybean sprouts than in raw and $100^{\circ}C$ cooked soybean sprouts. These results indicate that lipoxygenase plays a role in the development of off-odor and flavors in soybean sprouts under the condition of chewing and inadequate heating.