• Korean Journal of Food Science and Technology
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• v.19 no.4
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• pp.338-345
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• 1987

The Physicochemical properties of six varieties of domestic orange and orange juices which were grown and produced in Korea, were analyzed their qualities, including taste evaluation based on the amount and the ratio of sugar and acid The physicochemical properties of mandarin were as follows soluble solid $10{\sim}11^{\circ}$ Bx, total acidity $0.76{\sim}1.20%$ ratio of sugar and acid $7.9{\sim}13.8$. Sugars of orange are mainly composed of sucrose, glucose, fructose. The sucrose content of mandarin was a little higher than that of sweet orange. The organic acids in orange were mainly citrate and malate. The content of these two acid in oranges were 0.8-1.4%. Mandarin type oranges tastes more sour than sweet orange. Hesperdin existed 30.8-67.5mg% in oranges. Naringin, one of the bitter components. was not detected in both varieties. The optimum sweetness and acid content were determined based on the results of sensory evaluation.

• Applied Biological Chemistry
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• v.11
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• pp.49-53
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• 1969

Some properties of glucose isomerizing enzyme which produced by the strain K-17 in xylose containing nutrient broth medium were investigated. The optimal pH for enzyme reaction was indicated about 7.2 and optimal temperature was about $75^{\circ}C$. The same optimal temprature was indicated by both cell free extract and acetone dried cells using as enzyme. The glucose isomerizing enzyme from strain K-17 was not inhibited by the high concentration of substrate even in a suturated glucose solution, but most enzyme was inactivated by the heat treatment at $80^{\circ}C$. The maximum fructose forming ratio from glucose was about 50 percents.

• Korean journal of food and cookery science
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• v.29 no.5
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• pp.543-552
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• 2013

This study investigated the free sugar and free amino acids considered as the taste component in Korean Gochujang. Our goal was to search and develop the Korean traditional Gochujang taste, and to monitor the current status and characteristics of the Gochujang. For the analysis of Gochujang, it is purchased from small farms as well as major food company producing Gochujang. In the case of commercial Gochujang(COM), glucose and maltose were major free sugar, and the ratio of distribution and total amount showed very similar pattern. However, the results of the traditional Gochujang(TG) showed significant differences for each sample even they had glucose and maltose as predominant sugar. The content of glucose, maltose, fructose was reduced in order. The other hand, sucrose, rhamnose were not detected or were detected trace amounts in some samples. Even the characteristics were found at each region, it was no noticeable difference, but each sample was greater variation. Total of 17 amino acids were found from COM and the major amino acids were Pro, Glu, Asp, but His, Met were generally detected in small amounts. In the TG, they mainly contained Glu, Asp, Pro as the dominant component in addition to the Arg, Ala, Cys, respectively. TG had higher amino acid content and fairly various distribution compared to COM. It could suggest the possibility of the development for different traditional tastes because each TG had diverse characteristic taste than COM.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.4
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• pp.649-653
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• 1996

This study was carried out to quantitate the proximate composition of free sugars, amino acids, fatty acids, and minerals contents in Jehotang. The analysis of overall chemical components of Jehotang indicates that it contains 22.40% of moisture, 1.31% of crude protein, 1.24% of crude fat, 0.80% of ash and 74.25% of carbohyderate. The pH of the Jehotang was 3.2. The sugar content was relatively high. Among the identified extractable free sugars were 15.3% of fructose, 13.6% of glucose, 0.42% of sucrose, 1.18% of maltose, and a trace of isomaltose. No raffinose, maltotriose and molezitose were detected. In amino acid composition of the Jehotang, leucine was the highest with the content of 9.6mg, followed by arginine, valine, and phenylalanine. The ratio of essential/total amino acid was 40.4%. Fatty acid content, which occupies 1.24%, can be classified into 4 kinds. Major ones, in order of quantity, are oleic acid(52.7%), linoleic acid(28.5%), palmitic acid(14.6%) and stearic acid(4.2%). Among the minerals, the amount of K was the highest with the level of 2430.5ppm, followed by Ca, Na, P, Mg, Fe, Mn, Zn and Cu.

• Applied Biological Chemistry
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• v.46 no.4
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• pp.367-375
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• 2003

The puree of Rubus coreanus was fermented using lactic acid bacteria and its biological activities were examined. Lactobacillus acidophilus KCCM 32820, L. casei KCCM 12452, Lactococcus lactis subsp. lactis KCCM 40104, and Streptococcus thermophilus KCCM 40430 were used as a single or mixed starter for the lactic acid fermentation, and their cultures at the late logarithmic growth phase were inoculated to final concentration of 2% (v/v). L. casei fermented the puree of Rubus coreanus best when used as a single starter, and the culture of L. casei and L. lactis with the inoculation ratio of one to one showed the highest fermentation activity when used as a mixed starter. However, the fermented broth of the puree of Rubus coreanus using L. acidophilus and S. thermophilus showed the best results in the sensory evaluation. The optimal lactic acid fermentation conditions were as follows; the concentration of oligosaccharide added was 1% (w/v), pH of puree and fermentation temperature were 4.0 and $37^{\circ}C$, respectively, and fermentation time was $72{\sim}96$ hours. Glucose and fructose were major free sugars, and the content of lactic acid was 698.2 mg/100 g in the fermented broth. The fermented broth of the puree of Rubus coreanus showed the electron donating ability and nitrite scavenging ability with the value of 69% and 38.3% at pH 1.2, respectively. SOD-like activity and inhibitory activity on xanthine oxidase were also found in the fermented broth with the value of 60.3% and 41.8%, respectively. When the antimicrobial activities of the fermented broth were examined, it showed the highest growth inhibitory activity against Escherichia coli O-157:H7, and also contained antimicrobial activities against Salmonella typhimurium, Bacillus cereus, and Staphylococcus aureus.

• Applied Biological Chemistry
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• v.40 no.4
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• pp.313-317
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• 1997

To assess the physiochemical characteristics of greenhouse Satsuma mandarin (Citrus unshiu Marc. var, miyakawa) produced in Cheju, were analyzed chemical compositions for fruits, external and internal factors influencing the edible quality. Changes in organoleptic value according to brix and acid content were also evaluated. The ratios of sucrose : glucose : fructose in citrus juice were 2 : 2 : 1.5. Citric acid as the main acid in the juice represented about 70% of total organic acid. Most of the amino acids were found to be nonessential amino acids. Deep yellow color of the citrus peel showed a significant relationship(r=0.563) with brix/acid ratio of the citrus juice, indicating the ripeness of the fruit. Since the acid content showed highly negative statistical relationship(r= -0.882) with the pH value of the juice, the pH value appears to be a simple indicator for the sourness of the fruit in the field test. The fruits were divided into 9 groups based on the brix/acid contents for sensory evaluation. The palatability patterns of each group changed depending on the acid content. The optimal ranges of brix/acid content for acceptable taste were 11 and $0.5{\sim}1.0$, respectively.

• Food Science and Preservation
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• v.17 no.1
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• pp.23-29
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• 2010

The effects of vinegar, alcohol, and vitamin C on the color, microorganism count, volatile flavor components, free sugar level, free amino acid concentration, and free fatty acid level of minced ginger were investigated during storage for 17 weeks at $10^{\circ}C,\;20^{\circ}C\;or\;30^{\circ}C$. Bacterial levels remained unchanged during storage and mold was not initially detected. Yeast levels in minced ginger were $5{\times}10^1$ CFU/g initially, and yeast was not detected after 2 weeks. The color values increased during storage at high temperature. The volatile flavor component levels decreased during high-temperature storage. The free sugars of minced ginger were glucose, sucrose, and fructose. Sugar levels did not vary greatly with storage temperature. Free amino acid content decreased during high-temperature storage, and glutamine, valine, alanine, asparagine, tyrosine, and leucine were detected. Free fatty acid content increased during storage and the ratio of unsaturated to saturated fatty acids was 3:7.

• Food Science and Preservation
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• v.12 no.2
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• pp.156-160
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• 2005

To obtain basic data utilizing chestnuts as a raw food material, proximate analysis was conducted. Chemical component of chestnut flesh were $63.60\%$ moisture, $118\%$ ash, $3.02\%$ crude protein, $0.615\%$ crude fat, $1.21\%$ crude fiber, and $30.37\%$ nitrogen free extract, respectively. The weight ratio of tegmen, seed coat and flesh of chestnut sample were 17.05, 14.9, and $68.05\%$, respectively. The total amino acid contents of flesh and seed coat were $2,994\;mg\%$ and $1,450\;mg\%$, respectively. The total amount of free amino acids was less than that of total amino acids. As results of mineral analysis, the content of K was higher than that of any other minerals. The contents of maltose and sucrose were higher than those of fructose and glucose. The total polyphenol contents of tegmen, seed coat, fresh, leaf and bark were $9.56\;mg\%$, $0.047\;mg\%$, $0.23\;mg\%$, $15.44\;mg\%$ and $17.85\;mg\%$, respectively.

• Applied Biological Chemistry
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• v.34 no.2
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• pp.102-109
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• 1991

Quality of three kinds of honey from acacia, chestnut and polyflower sources, was evaluated by physicochemical and GC-MS analysis in respect to some chemical composition. The average contents of moisture, ash, HMF(hydroxy methyl furfurol) and free acidity were 19.7% , 0.028% , 18.28mg/kg and 8.85meq/kg , respectively, in acacia honey, 19.1% , 0.05% , 18.47mg/kg and 10.24 meq/kg , respectively, in polyflower honey, and 18.9% , 0.050% , 20.21mg/kg, 12.28meq/kg respectively, in chestnut honey. The average contents of glucose and fructose ranged from 31.0 to 32.0% and from 35.0 to 36.0% , respectively, in all three kinds of honey. The average ratio of fructose to glucose was 1.14 in all three kinds of honey. Fatty acid composition in honey identified by GC-MS analysis was dodecanoic acid, 10-hydroxy-2-decanoic acid, 6,9-undecadienoic acid, tetradecanoic acid, 12-(acetyl oxy) -9-octadecenoic acid and 14-octadecenoic acid. The content of 10-hydroxy-2-decenoic acid was about 10% in three kinds of honey.

• Korean Journal of Food Science and Technology
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• v.39 no.6
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• pp.676-680
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• 2007

This research was conducted to investigate the changes in quality characteristics of cheonggukjang made with 24-hr germinated soybeans during fermentation. Our study confirmed that the pH of the 24-hr germinated soybeans was 6.7, and the value increased as fermentation progressed. The amount of viscous substances in the cheonggukjang produced with the 24-hr germinated soybeans constantly increased to 5.89% at 36 hr of fermentation, and then remained unchanged. Free sugars (raffinose, sucrose, glucose, and fructose) rapidly decreased with the fermentation process. The levels of free amino acids in the 24-hr germinated agakong and the 48-hr fermented cheonggukjang were 391.0 and 10,994.8 mg%, respectively. Glutamic acid content was highest, followed by aspartic acid, lysine, leucine, and proline. The ratio of glutamic acid to total free amino acids at 48-hr of fermentation was 18.0%. Finally, it was confirmed that the sensory evaluation score of the 24-36 hr fermented cheonggukjang, made with the 24-hr germinated soybeans, was superior to that of the 24 and 48-hr fermented cheonggukjang.