• Journal of the Korean Society of Food Science and Nutrition
• /
• v.24 no.5
• /
• pp.816-828
• /
• 1995

During the industrial preparation and the storage of foods, the side chain of some protein-bound amino acids can react chemically each other or with other molecules present in the food. The following reactions have been described : destruction of amino acids, racemization, protein-protein interactions, reactions of proteins with reducing sugars, oxidizing agents, or polyphenols. Apart from total destruction, the main reacitons are the forming of Maillard reactions products(e.g. fructoselysine) and the crosslinking with other amino acids in the same or in another protein molecule(e.g. lysinoalanine). The most often involved amino acid is lysine because of its free functional ${\varepsilon}-amino$ acid group. Generally derivatives of amino acids or crosslinks in polypeptides influence the bioavailability and the overall digestibility of the protein. This work reviews the technological, analytical, nutritional, and physiological problems related to the formation of fructoselysine and lysinolalnine in human foods, and evaluates the possible health risk for humans. A summary of the available information is of help in considering whether or not the presence of fructoselysine/lysinoalanine in foods represents a danger to man. The reduction in protein quality through these reactions is not a problem for the general population, but it is extremely important in infant foods, since infants are often nourished with a limited number of food product(e.g. formular foods) which are sensitive to the Mailard reaction.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.5
• /
• pp.524-529
• /
• 2006

Chemical compounds, hydrogen peroxide and nitrite-scavenging activities of Phellinus baumii (PB) were investigated to expand the utilization of PB as functional food material. Total mineral contents of PB was 534.3 mg% and potassium was the highest content being 224 mg%. Total and reducing sugars were 56.2% and 9.8%, respectively The contents of free amino acids (FAAs) were in a range of $16.9{\sim}765.5mg%$ with the major FAAs of phenylalanine, aspartic acid, glutamic acid, leucine, serine and valine. The contents of total phenolic compounds in methanol and hot water extracts of PB were 33.3 and 20.7 mg/100 mL, respectively and were higher than those of other solvent extracts. Hydrogen peroxide-scavenging activity (80%) of methanol extract at $10{\mu}g/mL$ for 30 min was similar to tocopherol (83.1%) as control. Nitrite-scavenging activity of extracts of methanol and hot water at 500 mg/mL and pH 1.2 were 57.3% and 51.8%, respectively and then their effects were increased by lowering pH. The present results showed that the methanol and water extracts of Phellinus baumii exhibited strong hydrogen peroxide and nitrite-scavenging activities.

• Korean Journal of Food Science and Technology
• /
• v.41 no.6
• /
• pp.662-667
• /
• 2009

In this study, four Korean black raspberry wines were developed using raspberries from different regions in Korea; Gochang (G), Hoengseong (H), Jeongeup (J), Sunchang (S). Sample wines were monitored for titratable acidity, ethanol, pH, reducing sugar content, color intensity, hue, total phenolic content, and organic acids during alcoholic fermentation and aging. After fermentation was complete, the pH levels in the four wines were in a similar range (3.43-3.52), while total acidity levels ranged from 9.98 to 16.2 g/L, which were significantly different among the four wines. During 120 days of aging, the ethanol content ranged from 15.8 to 16.40% which corresponds to a good conversion rate of sugars. Among the four samples tested, the wine made with Jeongeup raspberries showed the highest levels of total phenolic content, and other color values such as hue and intensity. The predominant organic acids were citric acids (3.30-4.89 mg/mL) and succinic acids (1.92-3.48 mg/mL). Overall the wine made with Jeongeup raspberries showed differences in physico-chemical compositions compared to the other wines made with Gochang, Hoengseong, and Sunchang raspberries, respectively.

• Korean Journal of Food Science and Technology
• /
• v.26 no.6
• /
• pp.781-786
• /
• 1994

Meatlike flavors were manufactured using hydrolyzed vegetable protein (HVP) with several reactive precursors at different reaction conditions. Both pH and temperature affected significantly on brown colority of reaction product, whose velocity became fast with increasing pH and temperature. Drastic decrease in residual reducing sugars and free amino acids appeared until 1 hour, being little affected by reaction temperature. Glutamic acid and cysteine were decreased with reaction time, whereas glycine and methionine remained constant. Forty nine aroma compounds formed through Maillard reaction were isolated and identified with GC/MSD, including 3-methyl butanal, 2-methyl tetrahydrothiophen-3-one, 3,4-dimethylthiophene and 2,4-dimethyl thiazole previously known as natural meat flavors. The sensory evaluation showed that one-hour reaction product was the highest in savory taste and the lowest in nasty taste on the level of 5% significant difference among all reaction products tested in this experiment. From the results above, it could be speculated that the initial stage of Maillard reaction in this experimental system occured until one hour, thereafter, savory taste decreased accompanied by increasing nasty taste with elapsed reaction time.

• Korean Journal of Food Science and Technology
• /
• v.24 no.3
• /
• pp.266-271
• /
• 1992

The contents of capsaicinoids, free sugars and organic acids of 10 Korean varieties of red pepper power were measured and the sensory properties of their water extracts were compared in order to investigate the influence of the composition of taste components on sensory acceptability of Korean red pepper. The composition of taste components in red pepper powder varied widely depending on the varieties; total capsaicinoid content varied from 0.029 to 0.296%, free sugar $8.45{\sim}15.21%$ and organic acid $4.58{\sim}17.54%$. Capsaicinoid contents, especially dihydrocapsaicin content, were highly correlated with the pungent taste of the water extract of red pepper powder (r=0.870), but did not show significant relationship to the overall sensory acceptability. The sensory overall acceptability was highly influenced by the contents of total sugar (r=+0.815), reducing sugar (r=+0.805), glucose (r=+0.814) and fructose (r=+0.787). Multiple regression with total sugar $(X_1)$, total capsaicin $(X_2)$ and total organic acid contents $(X_3)$ increased the correlation coefficient for sensory acceptability(Y) to R=0.9008. From the result, a regression equation of $Y=0.9808X_1-10.7526X_2-0.1664X_3-4.1147$ was obtained.

• Korean Journal of Food Science and Technology
• /
• v.39 no.5
• /
• pp.515-520
• /
• 2007

To establish the roasting conditions of dandelion leaves for the manufacture of processed foods such as beverages and tea, we investigated the physicochemical and sensory characteristics of dandelion leaves and their hot water extracts by roasting treatment. As the number of roasting times increased, the free sugar content of the roasted dandelion leaves decreased, and in particular, free amino acid and total polyphenol content decreased greatly after only 1 roasting treatment. The amino nitrogen and total polyphenol contents of the roasted dandelion leaf hot water extracts also decreased greatly, and their L-, a-, and b-values showed much lower values than those of the raw leaf extracts. However, a greater amount of reducing sugars was extracted in the roasted leaves than in the raw leaves, suggesting that the roasting process allows for easier extraction of the compounds in dandelion leaves. Five sensory characteristics, including astringent taste, bitter taste, peen flavor, burnt taste, and sweet odor, were deduced through quantitative descriptive analysis of the hot water extracts. Among them, astringent taste, bitter taste, and green flavor showed significant differences between roasting treatments. The sensory evaluation results show that as the number of roasting times increased, the palatability of the hot water extracts increased greatly, in terms of color and taste.

• Korean Journal of Food Science and Technology
• /
• v.30 no.2
• /
• pp.245-252
• /
• 1998

The chitosanolytic capabilities of cellulases, glucosidases, proteases and commercial enzymes were evaluated, and effective chitosanolytic cellulases from T. viride, T. reesei and Celluclast, a commercial enzyme from T. reesei were characterized. The reaction of cellulase from T. viride, T. reesei and Celluclast was optimal at pH 5. 0 and $45{\sim}55^{\circ}C$. Max. chitosanolytic activities of cellulases from both T. viride and T. reesei were observed at the enzyme/chitosan ratio=0.1 and chitosan concentration=3.0%. For the possible application of commercial Celluclast to chitosan oligosaccharides production, 3%(w/v) chitosan was reacted with 1%(v/v) Celluclast at pH 5.0 and $55^{\circ}C$. The apparent viscosity decreased by 98% within 30 minutes reaction and Max. contents of 50% EtOH solubles were 70% at 15 hrs reaction. Total reducing sugars were also increased with reaction time and maintained approx. 13.5% after 2hrs reaction. In 15 hrs treated chitosan hydrolyzates, various kinds of chitosan oligosaccharides were produced and contents of chitosan hexamer, known for its antitumor activities, were about 8.0%, about 4 times higher values compared with acid hydrolysis method. The results suggested that chitosan oligosaccharides could be produced with low-cost cellulases from T. reesei.

• The Korean Journal of Mycology
• /
• v.14 no.2
• /
• pp.149-163
• /
• 1986

To determine contents of general constituents of Ganoderma lucidum in Korea, the dried carpophores were analyzed. The contents of water, ash, crude lipid, crude protein and crude cellulose were 14.6, 2.0, 3.3, 23.6, and 59.0%, respectively. Among reducing sugars, maltose was the most abundant. Seventeen free amino acids were detected, showing alanine the highest value. The pH of hot water extract was 4.1-4.2. The spores of Ganoderma lucidum was flat and ovoidal long. Their size was $6.3-7.1{\times}3.5-4.3{\times}2.0-2.5\;{\mu}m$ long. To examine effects of life span against sarcoma-180 cells, Fractions A, B and C, were obtained from the extract of Ganoderma lucidum. The survival rates of Fractions A, B and C were 131.7, 162.5, and 141.7 %, respectively. In addition, to examine effects of Fraction B on cell-mediated immunity, delayed type hypersensitivity (=DTH) test was conducted. It restored the suppressed DTH in the sarcoma-180 bearing group up to 66.7%.

• Food Science and Preservation
• /
• v.15 no.6
• /
• pp.872-877
• /
• 2008

This study was carried out to provide basic information related to improvement of flavor and consumption of cheonggukjang. Red ginseng cheonggukjang (RGC) and Rubus coreanum cheonggukjang (RCC) extracts were prepared, and their physicochemical characteristics were compared with either general cheonggukjang (GC) or non-fermented boiled soybean (BS). The moisture and crude fat contents were not significantly different among samples. RGC had the highest reducing sugar content and BS had the lowest. The free sugar content of RGC was higher than that of either GC or RCC, and the major free sugars present were glucose, fructose and sucrose. Seventeen free amino acids were detected in BS and cheonggukjang, and the content of free amino acids ranged from 1,233.8 to 2,599.6 mg/100 g. The greatest content of free amino acids was found in RGC. Color L, a and b values were highest in BS and lowest in RCC. The hardness and strength of RGC and RCC were lower than for GC.

• Korean Journal of Food Science and Technology
• /
• v.31 no.1
• /
• pp.176-182
• /
• 1999

Whole soybean cereal was fermented with four fungal strains (Mucor and Rhizopus) in pilot meju fermentation system. The pH range of the fermented soybean cereal was $7.16{\sim}8.38$, the contents of reducing sugar and amino-nitrogen were $0.54{\sim}2.64%,\;93{\sim}312mg%$, respectively, and that of free fatty acid ranged $0.06{\sim}2.00%$. The components of the amino acid, organic acid, free sugars and fatty acid showed distinctive patterns among four groups of fermented soybean cereals. Amylase activity and carbohydrate degradation rate of R. oryzae, protease and protein degadation rate of R. stolonifer was higher than other strains. But lipase and lipid degradation rates of four strains were similar. The odor concentrates of the soybean cereals fermented with Mucor strains were similar to Aspergillus strains, but Rhizopus were possessed of the flavor components of Bacillus and Aspergillus. Soysauce, made from M. hiemalis and R. stolonifer fermented soybean cereal showed excellent sensory evaluation and it was proposed that the two strains will be useful in Korean soysauce process.