• Journal of Microbiology and Biotechnology
• /
• v.1 no.4
• /
• pp.285-287
• /
• 1991

To produce the tetramethylpyrazine (TMP) flavor compound, Lactococcuss lactis subsp. lactis biovar. diacetilactis (L. diacetilactis) FC1 was cultivated in the TMP medium containing 3% (w/v) of Na-citrate and 6% (w/v) arginine-HC1 as substrates of acetoin and $NH_3$, respectively, which are the two precursors of the TMP. After 19-day fermentation at $34^{\circ}C$, 0.57 g/l or 4.19 mmole/l of the TMP was produced. This was the first result showing that the TMP could be produced by L. diacetilactis.

• Electrical & Electronic Materials
• /
• v.8 no.1
• /
• pp.48-55
• /
• 1995

A surface acoustic wave (SAW) sensor for the detection of odorants has been constructed by depositing various phospholipids and fatty acids onto the surface of the SAW device. The characteristics of a SAW device operating at 310 MHz deposited with silicon monoxide were analyzed. Menthone, amylacetate, acetoin, and other organic gases show different affinities to the coated lipids. An explanation is given for different odorant affinities based on the monolayer properties of phospholipids. The identification of odorants depending on the tkpe of lipid used for coating is discussed in terms of the similarity of their normalized resonant frequency shift patterns. Using a number of different lipid-coated SAW devices, odorants can be identified by a computerized pattern recognition algorithm.

• Proceedings of the KIEE Conference
• /
• 1993.11a
• /
• pp.246-248
• /
• 1993

We investigated the responses of six types of lipid-coated AT-cut quartz crystal resonators to chemical vapour sensors. The responses of quartz crystal at 9 MHz coated with phosphatidylglycerol (PG), phosphatidylinositol(PI), phosphatidylethanolamine(PE), phosphatidylserine(PS), and lipid A(LA) were obtained for amyl acetate, acetoin, menthane and other organic gases which showed different affinities for each lipid. The identification of odorants depending on the species of lipid used for coating is discussed in terms of the normalized resonant frequency shift pattern.

• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1457-1459
• /
• 1994

A surface acoustic wave(SAW) sensor for the detection of odorants has been constructed by depositing various phospholipids and fatty acids onto the surface of the SAW device. Applying the Langmuir-Blodgett technique, it was possible to deposit the optimal number of layers which was found to be between 10 and 20. Menthone, amylacetate, acetoin, and other organic gases showed different affinities to the coated lipids. An explanation is given for different odorant affinities based on the monolayer properties of phospholipids.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.24 no.2
• /
• pp.261-267
• /
• 1995

Low-salted and fermented squid product, squid jeotkal was prepared with the addition of 10% salt and fermented for 50 day at 1$0^{\circ}C$. During fementation of squid, sensory evaluation and changes of volatile components were examined. Volatile flavor components in raw squid and low-salted squid jeotkal were extracted using a rotary evaporating system. The volatile concentrates were identified by GC and GC-MS. Major volatile components of raw squid were methional and 2-methyl-2-propanol. However, alcohols such as propanol, isoamyl alcohol, methionol and phenylethyl alcohol increased during the period of fermentation. The model reaction using microorganism was carried out, in order to confirm formation mechanism ofvolatile flavor compounds of the squid during fermentation. The main volatile components of Pseudomonas sp. D2 model system were isoamyl alcohol and acetoin. Those of Staphylococcus xylosus model system were isoamyl alcohol and phenylacetaldehyde.

• Korean Journal of Food Science and Technology
• /
• v.43 no.5
• /
• pp.570-576
• /
• 2011

The effect of nuruks and crude amylolytic enzyme on free amino acid and volatile components of brown rice vinegar prepared by static cultures was investigated. Five groups consisted of AV (100% nuruk without crude amylolytic enzyme), BV (75% nuruk; 25% crude amylolytic enzyme), CV (50% nuruk; 50% crude amylolytic enzyme), DV (25% nuruk; 75% crude amylolytic enzyme) and EV (100% crude amylolytic enzyme without nuruk). Free amino acid content in AV vinegar (132.06 mg%) was lower than the others (184.56-191.22 mg%). Acetic acid, 3-methyl butyl acetate, acetoin and isoamyl alcohol were major volatile components as analyzed using gas chromatography-mass spectrometry after headspace solid-phase microextraction. Acetic acid in AV and EV samples represented 67.56% and 55.53% of total GC peak area, respectively. E-nose provided different patterns in each case showing variation in sensory properties.

• Korean Journal of Food Science and Technology
• /
• v.42 no.5
• /
• pp.527-532
• /
• 2010

The properties of volatile flavor components were compared in commercial brown rice vinegars that were fermented with and without ethanol addition, for which solid phase microextraction-gas chromatography (SPME-GC), electronic nose, and sensory evaluations were performed. A total of 24 volatile compounds, mainly composed of acetic acid, ethyl acetate, benzaldehyde, iso-valeric acid, phenylethyl alcohol, 2-phenylethyl acetate, acetoin, and isobutyric acid, were identified in the brown rice vinegar fermented without ethanol, while major volatiles in the brown rice vinegar fermented with ethanol were acetic acid, ethyl acetate, 1-hexyl acetate, benzaldehyde, 2-phenylethyl acetate, and phenylethyl alcohol. The electronic nose patterns of samples indicated a significant difference in the brown rice vinegars fermented with and without ethanol. Pungent flavor and off-flavor intensity were high in the brown rice vinegar fermented without ethanol. According to the results, fermentation conditions affect the volatile properties of brown rice vinegars.

• Korean Journal of Food Science and Technology
• /
• v.28 no.2
• /
• pp.337-344
• /
• 1996

Gel-type yogurt was prepared from egg white powder (EWP), casein and glucose. The effects of EWP on acid production and growth of Lactobacillus were studied. The effect of EWP on sensory properties and volatile aroma compounds were also studied. Acid production by Lactobacillus in EWP (1-3%, W/V) was significantly lower than that by Lactobacillus in milk (control). However, the increase of EWP content from 1 to 3% increased acid production significantly, Number of viable cells of L. acidophilus at 24 hrs in milk and EWP containing samples (1-3%) was $3.1{\times}10^4/ml\;and\8.3{\times}10^7-3.6{\times}10^2/ml.$ respectively Sample containing lower amount of EWP generally showed lower number of viable cells. Sensory property of EWP samples (1-3%) was showed lower than that of milk yogurt (reference). However, sensory property of samples containing EWP 2% or 3% was significantly better than that of sample containing EWP 1%. Though the composition of volatile aroma compounds was slightly different from sample to sample, gas chromatographic analysis detected acetone, ethanol, diacetyl and acetoin in samples fermented by L. acidophilus.

• Korean Journal of Food Science and Technology
• /
• v.29 no.3
• /
• pp.546-554
• /
• 1997

Gel-type yogurt was prepared from egg white powder (3%, w/v), glucose (2%, w/v) and four kinds of milk products (4%, w/v). The effects of milk product on acid production and growth of Lactobacillus were studied. The effects of milk product on sensory property and volatile aroma compounds were also studied. Acid production by L. acidophilus at 24 hr in samples containing milk product was significantly lower than that by L. acidophilus in milk (p<0.05). The sample containing casein produced less acid than the other samples. Number of viable cells of L. acidophilus at 24 hr in milk and samples containing milk product was $2.0{\times}10^{9}/mL$ and $5.0{\times}10^{8}{\sim}8.0{\times}10^{8}/mL$, respectively. Sensory property of the samples containing milk product was lower than that of milk yogurt (reference). However, sensory property of the sample containing casein was not significantly different from that of milk yogurt (p<0.05). The sample containing whey powder showed lower sensory score than other samples. Though the composition of volatile aroma compounds was slightly different from sample to sample, gas chromatographic analysis detected acetone, ethanol, diacetyl and acetoin in samples fermented by L. acidophilus.

• Korean journal of food and cookery science
• /
• v.12 no.2
• /
• pp.153-161
• /
• 1996

A curd yogurt was prepared from egg white powder (EWP) and casein added with sugars (glucose, fructose, lactose). The effects of sugar addition on acid production and growth of Lactobacillus were studied. The effects of sugar addition on sensory property and volatile aroma compounds were also studied. Acid production by L. acidophilus in EWP 2％ (W/V), casein 3％ (w/v) and sugar 0.5,1 or 2％ W/V) was lower than that of L. acidophilus in milk (control). Acid production in sample added with glucose or fructose of 1％ or 2% (W/V) was higher than that of 0.5% (W/V), while acid production in lactose added sample was not affected with the concentration of lactose. Number of viable cells of L. acidophilus at 24 hr in milk, glucose added sample, fructose added sample and lactose added sample was 3.6${\times}$10/Sup 9/, 5.6${\times}$10$\^$8/, 6.0${\times}$10$\^$8/,and 3.2${\times}$10$\^$7/, respectively. Through 30hr fermentation, acid production and number of viable cells of L. acidophilus in milk were higher than those of sugar added samples. Sensory property of fructose added sample was slightly better than that of milk yogurt (reference), while that of lactose added sample was significantly inferior. Though the composition of volatile aroma compounds was slightly different according to sample, gas chromatographic analysis detected acetone, ethanol, diacetyl and acetoin in samples fermented by L. acidophilus.