• Microbiology and Biotechnology Letters
• /
• v.26 no.1
• /
• pp.50-54
• /
• 1998

Ethyl caproate is one of the important flavor compounds produced during the brewing of rice wine. The rice wine yeast and koji were reported to produce the esterases which synthesize and also hydrolyze ethyl caproate. From the results of monitoring the esterase activities of rice wine yeast and koji, their roles for producing ethyl caproate during brewing were postulated. In case of rice wine yeast, the production of esterase synthesizing ethyl caproate was influenced by the substrate, caproate but that of esterase hydrolyzing ethyl caproate was promoted by ethyl caproate but inhibited by caproate. The production of esterases of koji were not influenced by the substrates for ethyl caproate production but influenced by the growth of koji. The maximum concentration of ethyl caproate produced by rice wine yeast was 0.4 ppm in this research but the production of ethyl caproate by koji was not detected under our experimental conditions. Considering the results of this research, ethyl caproate is not produced by the esterases of koji during brewing but produced by the esterases of rice wine yeast. The growth of rice wine yeast represses that of koji because of the high concentration of ethanol produced by rice wine yeast. The esterases of rice wine yeast may decide the production of ethyl caproate during brewing.

• Korean Journal of Food Science and Technology
• /
• v.31 no.2
• /
• pp.475-481
• /
• 1999

Yeast extracts were prepared using either autolysis or enzymatic digestion methods for industrial application of the Saccharomyces cerevisiae B24 strain developed previously to have high RNA content. Extraction ratio of yeast extract from yeast cell reached 65% when autolysis of yeast slurry having 10% solid content was induced at $50^{\circ}C$ and pH 5.0 by agitating with 100 rpm. However, neither 5'-IMP nor 5'-GMP was detected from the autolyzate. In another attempt to prepare a yeast extract S. cerevisiae B24 culture was treated at $90^{\circ}C$ and then treated by various enzymes including ${\beta}-1,3-glucanase$, phosphodiesterase (nuclease P1), adenylic deaminase, and a protease. The yeast extract prepared by the enzymatic digestion method contained 3.2g of 5'-IMP and 5'-GMP/100g dry yeast extract.

• Korean Journal of Food Science and Technology
• /
• v.16 no.2
• /
• pp.143-148
• /
• 1984

The effects of various nutrients added to soy protein concentrate (SPC)-yogurt on the growth of Lactobacillus acidophilus and the flavor of SPC-yogurt were investigated. Soy milk was prepared from SPC (4.2% as protein) and various nutrients. One hundred ml of the prepared soy milk was given proper heat treatment, inoculated with 2.5ml of 24 hr-old culture, and incubated for 24 hr at $37^{\circ}C$. The growth of L. acidophilus was estimated from viable cell counts, titratable acidity and pH. The growth curve obtained from the experiment suggested that the log phase ended after 6 hr and the stationary phase ended after 30 hr. Glucose and fructose greatly enhanced the acid production by L. acidophilus. The optimum concentration of these two sugars in the media was approximately 3% each. Yeast extract greatly stimulated the acid production by L. acidophilus, and the optimum concentration of this additive was approximately 0.5%. Higher concentration of SPC resulted in slightly higher acidity in soy yogurt.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.18 no.2
• /
• pp.160-166
• /
• 1989

This study was conducted to investigate whether egg-shell may be used as a mineral sourceor leavening agent in breadmaking. In Korea the waste volume of egg shell has been estimated at about 28,694 tons per year. Carbon dioxide generation maxima were established for barking powder$(153{\pm}3ml/g)$, egg-shell(205in reaction with lactic acid) and yeast$(115{\pm}3ml/sugar\;g)$. Gas release time required for each substance to reach $CO_2$ maximum was, for baking powder 7 minutes, for egg-shell 45 mins and for yeast 240 mins. Particle size of egg-shell in breadmaking was suitable more than 20 mesh (-). When egg-shell only was added to the basic formular without including lactic acid, no leavening effect was observed. However, when lactic acid and egg-shell were used together, the leavening effect was more or less equivalent to that of yeast(control). Addition of egg-shell was found to increase calcium content of bread products without noticeable altering flavor, as compared with control. Joint use of egg-shell was organic acids in breadmaking was shown to have potential in time saving, volume increase and yeast saving.

• Korean Journal of Food Science and Technology
• /
• v.20 no.5
• /
• pp.718-723
• /
• 1988

A yeast strain producing fruity-floral aroma was isolated from soil and identified as Hansenula saturnus var. saturnus. Glucose was found to be the best carbon source and sodium nitrate or phenylalanine as nitrogen source in terms of the nature and the intensity of the aroma produced by the isolated yeast. Seventeen compounds, mainly esters and alcohols, were identified in the ether-pentane extract of the culture broth by gas chromatography and/or coupled gas chromatography-mass spectrometry. Ethyl alcohol, isobutyl alcohol, isoamyl alcohol, phenethyl alcohol and their acetate esters together with ethyl caprylate were the major compounds in the aroma concentrate. Three unusual compounds, dibutyl disulfide, 3-methyl pentanoic acid and methyl pentanoate were also tentatively identified in the culture broth of the isolated yeast.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.7
• /
• pp.292-302
• /
• 2020

The purpose of this study was to investigate the sensory characteristics of 11 noodles from four countries by descriptive analysis and consumer acceptance test. Noodle types were udon, pasta, kalguksu, and plain noodles. Fourteen sensory descriptors were developed to evaluate the sensory characteristics of the noodles. The sensory characteristics of the noodles were sweetness, saltiness, springiness, hardness, chewiness, milk flavor, yeasty odor, milk powder flavor, loose particles, and so on. PCA conducted to visually summarize the sensory characteristics of noodles by consumer preference test revealed that 77.1% of the variance was positively defined by sweet, springiness, cohesiveness, chewiness, and moisture and was negatively defined by hardness, color, and floury taste. Yk_udng_KR, thin_KR showed high scores for attributes of springiness and cohesiveness. Overall consumer acceptance was surveyed. Udng_KR scored the highest for attributes such as gusu. Udng_KR showed the highest springiness and high moisture, taste acceptance, and overall acceptance. Note: Please confirm this word.

• Animal Bioscience
• /
• v.36 no.9
• /
• pp.1426-1434
• /
• 2023

Objective: The objective of this study was to evaluate the effect of Debaryomyces hansenii isolated from dry-aged beef on the tenderness and flavor attributes of low-grade beef during dry aging. Methods: Five D. hansenii strains were isolated from dry-aged beef samples. The rump of low-grade beef was inoculated with individual D. hansenii isolates and subjected to dry aging for 4 weeks at 5℃ and 75% relative humidity. Microbial contamination levels, meat quality attributes, and flavor attributes in the dry-aged beef were measured. Results: Of the five isolates, the shear force of dry-aged beef inoculated with SMFM201812-3 and SMFM201905-5 was lower than that of control samples. Meanwhile, all five isolates increased the total free amino acid, glutamic acid, serine, glycine, alanine, and leucine contents in dry-aged beef. In particular, the total fatty acid, palmitic acid, and oleic acid contents in samples inoculated with D. hansenii SMFM201905-5 were higher than those in control samples. Conclusion: These results indicate that D. hansenii SMFM201905-5 might be used to improve the quality of beef during dry aging.

• The Korean Journal of Food And Nutrition
• /
• v.25 no.4
• /
• pp.974-979
• /
• 2012

This research was carried out to find herbal preservatives for Makgeolli, as Makgeolli loses its commercial value due to overproduced acidic materials. When Makgeolli was kept at $25^{\circ}C$ to find the changes in acidity, total microbial cell number, yeast cell number, and bacterial species variety, a sudden increase of acidity as well as the disappearance of yeast cells occurred at day 6, and Makgeolli was changed to complete off-flavor. Acetobacter pasteurianus is the main acidifier in Makgeolli and shows a synergy effect in acid formation when cultured in combination with Lactobacillus casei. Among 12 herbs, the ethanol extract of Sutellaria baicalensis showed antimicrobial activity against A. pasteurianus, whereas the ethanol extract of Coptidis rhizoma showed antimicrobial activity against L. casei. Makgeolli added with Sutellaria baicalensis extracts demonstrated a lower acidity than that with Coptidis rhizoma extracts, which indicates that the inhibition of an acetic acid former is more important than that of a lactic acid former in Makgeolli preservation. Sutellaria baicalensis extracts prolonged the shelf life of Makgeolli by 1~2 weeks at a minimal inhibitory concentration ($0.63mg/m{\ell}$) during storage at $10^{\circ}C$.

• Mycobiology
• /
• v.42 no.4
• /
• pp.353-360
• /
• 2014

Makgeolli is a traditional Korean alcoholic beverage. The flavor of makgeolli is primarily determined by metabolic products such as free sugars, amino acids, organic acids, and aromatic compounds, which are produced during the fermentation of raw materials by molds and yeasts present in nuruk, a Korean fermentation starter. In this study, makgeolli was brewed using the wild yeast strain Saccharomyces cerevisiae Y98-5, and temporal changes in the metabolites during fermentation were analyzed by ultra-high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry. The resultant data were analyzed by partial least squares-discriminant analysis (PLS-DA). Various metabolites, including amino acids, organic acids, sugar alcohols, small peptides, and nucleosides, were obviously altered by increasing the fermentation period. Changes in these metabolites allowed us to distinguish among makgeolli samples with different fermentation periods (1, 2, 3, 6, 7, and 8 days) on a PLS-DA score plot. In the makgeolli brewed in this study, the amounts of tyrosine ($463.13{\mu}g/mL$) and leucine ($362.77{\mu}g/mL$) were high. Therefore, our results indicate that monitoring the changes in metabolites during makgeolli fermentation might be important for brewing makgeolli with good nutritional quality.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.44 no.6
• /
• pp.928-934
• /
• 2015

The objective of this study was to reduce Nuruk flavor in Korean rice-distilled liquor using different ratios of $Sumizyme^{TM}$ and Nuruk. After 9 days of fermentation at $28^{\circ}C$, alcohol contents and pH were 16.0~17.1% and 3.82~4.16, respectively. An increased ratio of $Sumizyme^{TM}$ decreased alcohol content while increased pH of the mash. In alcohol contents, there were no significant differences up to 30% substitution of Nuruk to $Sumizyme^{TM}$. A descriptive analysis was conducted with trained panelists for determining the intensity of Nuruk flavor. The intensities of Nuruk flavor in mashes and distilled liquors brewed by traditional Nuruk, cultured Nuruk, and a mixture of 30% $Sumizyme^{TM}$ and 70% cultured Nuruk were evaluated. The mash and distilled liquor prepared using a mixture of 30% $Sumizyme^{TM}$ and 70% cultured Nuruk showed significantly lower intensities of Nuruk flavor when compared with those of mashes and distilled liquors produced by the traditional and cultured Nuruk.