• Korean Journal of Food Science and Technology
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• v.25 no.5
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• pp.444-448
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• 1993

Flavor compounds of pentane, hexane, hexanal and total volatiles formed during $65^{\circ}C$ storage of ramyon fried in palm oil with ${\alpha}-tocopherol$, RHA, TRHQ, rosemary extract or defatted ricebran extract were determined by static headspace gas chromatography. The levels of the antioxidants used in the frying oil were 100 or 200 ppm, and an additional level of 300 ppm was employed in the case of ${\alpha}-tocopherol$ ${\alpha}-Tocopherol$ decelerated the formation of all the flavor compounds when used at 100 or 200 ppm, and the former was more effective than the latter. However, 300 ppm of ${\alpha}-tocopherol$ accelerated the flavor compound formation in ramyon during storage. One hundred ppm of BHA and TBHQ contributed to the reduction in flavor compound formation in the stored ramyon, whereas 200ppm level accelerated the compound formation. Rosemary extract and defatted ricebran extract lowered the flavor compound formation in ramyon when used at 100 or 200 ppm in palm oil. Their lowering effects were similar to that of ${\alpha}-tocopherol$, and superior to that of TBHQ. suggesting a possible utilization of defatted ricebran extract as a new natural antioxidant.

• Journal of Dairy Science and Biotechnology
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• v.18 no.1
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• pp.61-72
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• 2000

Consumers primarily consider flavor when they take yogurt. Recent researches on yogurt flavor productron its analytical technique have been extensively developed. These studies have provided a better understanding on the role of starter culture microorganisms on flavor formation and degradation. Yogurt volatile flavor compounds produced by the lactic cultures include acetaldehyde, diacetyl, ethanol and organic acid. Among them, acetaldehyde is recognized as a principal flavor component. since yogurt contains a delicate and low intense flavor, mild sample isolation techniques and sensitive identification means might be used. This paper attempts to discuss recent findings in yogurt flavor and to describe the application of yogurt flavor separation techniques. The section on practical aspects of culture selection based on flavor compound production and flavor analysis is also included.

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

• Korean Journal of Food Science and Technology
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• v.38 no.5
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• pp.621-627
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• 2006

To characterize aroma properties of burnt beef reaction flavor manufactured by extrusion, volatile flavor compounds and aroma-active compounds were analyzed by simultaneous steam distillation and solvent extraction (SDE)-gas chromatography-mass spectrometry-olfactometry (GC-MS-O). Hydrolyzed vegetable protein (HVP) was successfully extruded with precursors (glucose, cystine, furaneol, thiamin, methionine, garlic powder, and lecithin) at $160^{\circ}C$, screw speed of 45 rpm, and feed rate of 38 kg/hr. Sixty eight volatile flavor compounds were found in burnt beef reaction flavor. The number of volatile flavor compounds decreased significantly when HVP was extruded either with furaneol-free precursors or without precursors. Twenty seven aroma-active compounds were detected in burnt beef reaction flavor. Of these, methional and 2-methyl-3-furanthiol were the most intense aroma-active compounds. It was suggested that furaneol played an important role in the formation of burnt beef reaction flavor.

• Preventive Nutrition and Food Science
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• v.2 no.4
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• pp.360-367
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• 1997

The chemistry background of the Maillard reaction focused on pyrazines and factors affecting the reaction products were reviewed. The Maillard reaction, also called a non-enzymatic browning reaction, is quite complex and generates numerous reaction products. In processed foods, it is generally accepted as a key reaction to produce flavor components. Specially, pyrazines possess an important impact character on the roasted foods with other heterocyclic compounds. The Maillard reaction is initiated by condensation between reducing sugar and amino group, and N-glycosylamines are produced via Schiff base with dehydration of water. After the rearrangement of the N-glycosylamines, they follow transformation into deoxyhexosones which are reactive intermediates. Degradation and fragmentation are facilitated by rearranged compounds. By condensation, pyrazine, one of the final Maillard products, is generated as a relatively stable form to provide specific aromas. During the processes of the reaction, chemical or physical environmental parameters affect the formation of the products.

• Food Science and Biotechnology
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• v.15 no.6
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• pp.838-843
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• 2006

The chemical processes involved in the formation of green pigment in crushed garlic cloves were investigated based on the principle of pink pigmentation in macerated onions. Intact greening and non-greening garlic cloves were either left untreated or heated at $90^{\circ}C$ for 3 min to inactivate enzyme activities. First, a colorless ether soluble compound referred to as color developer reacted with glycine (among all free amino acids) in garlic to form a second compound insoluble in ether. The latter compound then reacted with formaldehyde to yield the green colored pigment. Alliinase activity was necessary for the production of color developer and for the development of green pigment. In greening garlic that had been heat treated, green pigmentation did not proceed due to the heat-inactivation of alliinase, but the addition of alliinase solution into the garlic homogenates restored the pigmentation. However, this phenomenon was not observed in non-greening garlic with or without heat treatment. Finally, the mechanism of green pigment formation in crushed garlicis similar to that of pink pigment formation in macerated onions.

• Journal of Microbiology and Biotechnology
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• v.1 no.3
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• pp.202-206
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• 1991

To produce acetoin as a precursor of the tetramethylpyrazine flavor compound from citrate by Lactococcus lactis ssp. lactis biovar. diacetilactis FC1, fermentation factors such as inital pH of culture media, temperature, concentration of Na-citrate, thiamin-HC1 and sugars were examined. The best acetoin production was achieved with initial pH in the culture media of 5.5, fermentation temperature of $34^{\circ}C$, Na-citrate concentration of 3%, addition of thiamin-HC1 at 2 mg/l and galactose as a carbon source. When fermentation was carried out under the optimum conditions, the exhaustion of Na-citrate and the production of acetoin took simultaneously and acetoin reached the maximum content, 80 mmole/l after 20 hours.

• Journal of Microbiology and Biotechnology
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• v.1 no.4
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• pp.281-284
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• 1991

To investigate the optimum conditions for the production of ammonia as a precursor of tetramethylpyrazine flavor compound from arginine by Lactococcus lactis ssp. lactis biovar. diacetilactis FC1, fermentation factors such as initial pH of culture media, fermentation temperature, concentration of arginine-HC1, and sugars were examined. The optimum conditions were initial pH 5.5 of the culture media, fermentation temperature of $34^{\circ}C$, 6% (w/v) of arginine-HC1, and 1% (w/v) of galactose as a carbon source. Under the optimum fermentation conditions, 40 mmole/l of ammonia was produced after 40 h.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.5
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• pp.655-660
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• 2003

Flavor components of dry shrimp, roasted-dry shrimp and roasted-dry shrimp with corn oil (w/w: 10%, 25%) were investigated to evaluate the effects of added corn oil on the formation of volatile components in dry shrimp during roasting process. The identified volatile included 20 nitrogen-containing compounds (7 pyrazines, 7 pyridines 3 pyrroles, others) 14 aldehydes, 5 alcohols, 4 ketones and 11 others. The largest quantities of lipid-derived products hexanal, nonanal, 2-pentylfuran, 1-octen-3-ol, trans-2-decenal, trans, cis-2,4-decadienal, trans, trans-2,4-decadienal were detected in the roasted-dry shrimp samples with corn oil. The lipid-derived aldehydes might be involved in the formation of 3- ethyl-2,5-dimethylpyrazine, 2,3,5-trimethyl-6- ethylpyrazine, 2-ethyl-5,6-dimethylpyrazine, 2,3,5- trimethylpyrazine, 3- ethyl-2,6-dimethylpyridine, 2-propylpyridine, ben-zopyrrole and the others. The nitrogen-containing compounds seem to be a major flavor component and responsible for characteristic flavor in roasted-dry shrimp with corn oil.

• KSBB Journal
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• v.31 no.2
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• pp.91-99
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• 2016

Tea is an aqueous infusion of dried leaves of the plant Camellia sinensis L. and is the second most widely consumed beverage around the world after water. Aroma compounds of tea differ largely depending on the manufacturing process, even from the same categories of different origins. The flavor of tea can be divided into two categories: taste (non-volatile compounds) and aroma (volatile compounds). In the present study, we review the formation mechanism of main aromas generated from carotenoids, lipids, glycosides as precursors, and Maillard reaction during the tea manufacturing process, with biological and chemical mechanisms.