• Journal of Microbiology and Biotechnology
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• v.16 no.8
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• pp.1236-1239
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• 2006

Allyl alcohol (2-propen-l-ol), found in considerable amounts in heated garlic, was able to discriminate yeasts from bacteria and was approximately three orders of magnitude more inhibitory towards yeasts than bacteria. The average minimum inhibitory concentration (MIC) of allyl alcohol for bacteria and yeasts was 5.0% and 0.0056%, respectively. The unsaturated primary alcohols, including allyl alcohol and 2-buten-l-ol, seemed to work differently from all the other saturated alcohols and unsaturated secondary alcohols in inhibiting various yeasts. An alcohol dehydrogenase-negative (ADH$^-$) strain of Saccharomyces cerevisiae was as resistant to allyl alcohol as various bacteria, exhibiting an MIC of 5.0%. The unsaturated primary alcohols were apparently oxidized into the corresponding unsaturated aldehydes before they inhibited the yeasts.

• Journal of Biosystems Engineering
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• v.21 no.1
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• pp.72-83
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• 1996

This study was performed to find out drying characteristics and develop drying model for the design of an efficient dryer or drying system of garlic. The basic model which describes drying phenomenon of garlic was first established. A series of drying test were conducted with two varieties of garlic(Uiseong, Namdo) at 9-different drying conditions (drying temperatures ; $40^{\circ}C$, $50^{\circ}C$, $60^{\circ}C$, relative humidities ; 20%, 35%, 50%) and statistical analysis was made to fit the data with exponential equation, approximated diffusion equation, page equation, thompson equation and wang equation, respectively. In this test, the effects of drying air temperature and relative humidity on the drying rate were undertaken. Finally, new drying model based on these experimental results was developed to describe the drying characteristics of garlic. Also, the volatile components of garlic extracts were investigated. For experiment both Uisoeng and Namdo garlic were dried by heated-air-drying, followed by ether extraction. The extracts were analysed by Gas chromatography/Mass spectrometer.

• Food Science and Biotechnology
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• v.16 no.6
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• pp.963-966
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• 2007

The objectives of this study were to identity antioxidant substance in heated garlic juice (HGJ). We evaluated the antioxidant activities of heated garlic juice exposed to 120, 130, and $140^{\circ}C$ for 2 hr. The HGJ was partitioned using the solvents of hexane, chloroform, ethyl acetate, butanol, and water. The ethyl acetate fraction of HGJ treated at $130^{\circ}C$ for 2 hr showed strong antioxidant activity; this extract was isolated and purified using silica gel column chromatography and semi-preparative high-performance liquid chromatography. The structure of the purified compound was determined using spectroscopic methods, i.e., ultraviolet, mass spectrometry, infrared, $^1H$ NMR, $^{13}C$ NMR, DEPT, HMBC, and HMQC. The isolated compound was identified as thiacremonone (2,4-dihydroxy-2,5-dimethyl-thiophene-3-one). Thiacremonone showed strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, with a 50% inhibition concentration ($IC_{50}$) of $22.25{\pm}0.44\;{\mu}g/mL$, which is much higher than that of the antioxidants ascorbic acid ($30.06{\pm}0.42\;{\mu}g/mL$), ${\alpha}$-tocopherol ($71.30{\pm}0.97\;{\mu}g/mL$), and butylated hydroxyanisole ($50.54{\pm}0.94\;{\mu}g/mL$).

• Korean Journal of Veterinary Service
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• v.34 no.2
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• pp.167-178
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• 2011

Garlic (Allium sativum L.) has long history of reputed value and actual use for its medicinal, antimicrobial and pesticidal properties. This study was conducted to find possible developments to natural food preservatives and natural antimicrobials from garlic extracts. The antimicrobial activities of raw garlic extract, heat, pH, temperature against pathogenic bacteria were investigated. E. coli, S. Enteritidis, L. monocytogenes, and S. aureus exhibited antimicrobial activities at 20% garlic extract, but no antimicrobial activity was seen in E. faecium. Raw garlic extract and garlic extract heated for 2 min at $95^{\circ}C$ showed strong antimicrobial activities, but the antimicrobial activity of garlic extract heated for 10 min at $95^{\circ}C$ was much less. The antimicrobial activities of 50% garlic extract adjusted pH 4.0~7.0 showed much the same, but the antimicrobial activities decreased at pH 8.0 or higher. The antimicrobial activities by storage $-18^{\circ}C$ of garlic extract showed much the same. When five strains were cultured for 72 hr at $35^{\circ}C$ in the TSB containing 1~10% garlic extract, viable cell number of five strains were decreased to $10^0{\sim}10^4$ CFU/ml even at 1% or 2.5% (E. faecium) after 24 hr, but later increased to $10^4{\sim}10^9$ CFU/ml after 72 hr. When five strains were cultured for 21 day at $4^{\circ}C$ in the TSB containing 1%, 2.5%, 5%, and 10% garlic extract, viable cell number of E. coli, S. Enteritidis, and S. aureus were decreased to $10^3$, $10^0{\sim}10^2$, $10^1{\sim}10^4$ CFU/ml after 21 day, respectively, but L. monocytogenes and E. faecium increased to $10^8$ and $10^6$ CFU/ml after 21 day.

• Journal of Microbiology and Biotechnology
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• v.12 no.2
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• pp.331-335
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• 2002

Aqueous extracts of garlic (Allium sativum) preparation were prepared after the samples were exposed to various heat treatments. A quantitative assessment of antimicrobial activities was carried out by determining the minimum inhibitory and microbicidal concentrations (MICs and MMCs) of the various extracts against some selected bacteria and fungi. The antimicrobial activity of garlic decreased as the heating temperature increased. This fact implies that alliinase may be the most critical rate-determinant to produce the activity when garlic is heated.

• 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.

• Korean journal of food and cookery science
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• v.18 no.1
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• pp.73-80
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• 2002

The effect of sodium metabisulfite and adipic acid on the color changes of garlic juice was evaluated. The garlic(Uisung variety) juice was extracted and 1% sodium metabisulfite and 1% adipic arid were added to the garlic juice before or after concentration. Garlic juice was concentrated by heating at 90$\^{C}$, by heating using a rotary vacuum evaporator at 45$\^{C}$, or by freeze-drying at -50$\^{C}$ until the volume was reduced to 70% of the original volume. The garlic juice concentrate was kept at 4$\^{C}$ and 25$\^{C}$ for 60 days and evaluated for the color change and the relation between the additives and browning. Browning of the garlic juice concentrate containing adipic acid and sodium metabisulfite was effectively inhibited compared with the control. Inhibition effect of sodium metabisulfite on the browning of the concentrate was stronger than that of adipic acid. The addition of sodium metabisulfite afrer concentration of garlic juice was the most effective on browning inhibition in the 9$\^{C}$-heated concentrate, but the addition of sodium metabisulfite before concentration was the most effective in the 45$\^{C}$-heated concentrate and the -50$\^{C}$-freeze-dried concentrate. In the color change of the garlic juice concentrate during the storage, a and b values of the concentrate with sodium metabisulfite were lower than those of the control, which means that sodium metabisulfite inhibited the browning of the garlic juice concentrate.

• Food Science of Animal Resources
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• v.30 no.4
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• pp.641-648
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• 2010

The objective of this study was to evaluate the pre-heating treatment effects on the antioxidant properties of ethanolic garlic and onion extracts. Garlic and onion with or without heating ($100^{\circ}C$, 30 min) were extracted with ethanol, and the total phenolic content, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, iron chelating ability, reducing power, and antioxidant activity in a linoleic acid emulsion system were evaluated. Garlic (41%) had a higher drying yield than onion (11%). Regardless of pre-heating, ethanol extracts of onion resulted in an approximately 25-fold higher yield than those of garlic. Thermal treatment before extraction decreased the levels of ethanol-soluble phenolics for both garlic and onion. Regardless of pre-heating, the radical scavenging abilities of ethanol extracts from garlic were greater than the ethanol extracts from onion. The iron chelating abilities of ethanol extracts from fresh and heated garlic were 85 and 81% at 10 mg/mL, respectively, whereas those of onion extracts were 10 and 9% at the same concentration, respectively. However, no differences in reducing power between garlic and onion extracts were observed. Both garlic and onion inhibited the formation of hydroperoxide in linoleic acid emulsion systems when ethanol was used as a solvent. Overall, garlic extracts had greater antioxidant activity than onion extracts, and the antioxidant activity of garlic and onion extracts were not significantly affected by thermal treatment.

• Journal of Life Science
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• v.26 no.4
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• pp.446-452
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• 2016

Garlic (Allium sativum L.) and its extracts have been used in a wide range of applications, including as folk medicines in many Asian countries. This traditional herb has several functional properties and strong biological activities, making it useful as a functional food material. This study investigated the biological activities of solid-garlic after fermentation by lactic acid bacteria. Several solid-garlic fermentation strains of lactic acid bacteria were isolated from Korean traditional fermented food or obtained from the Korean Collection for Type Cultures. Lactic acid bacteria showed selective growth in garlic extracts on MRS media. Fermentation of solid garlic (heated 121℃, 15 min or not heated) by lactic acid bacteria gave total polyphenol and flavonoid contents of 731.0-845.2 g/g and 92.68-413.58 g/g, respectively. The DPPH scavenging activities and SOD like activities were measured as 7,584% and 9499%, respectively. These activities were relatively higher than a positive control, vitamin C. Measurement of antidiabetic activity using α-glucosidase inhibition assay showed that solid garlic fermented with lactic acid bacteria gave a higher activity than the control, acarbose. Fermentation of solid garlic with lactic acid bacteria may therefore help to alleviate adverse biological activities, as well as provide functional food materials.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.12
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• pp.1637-1642
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• 2007

The objectives of this study were to compare the aroma characteristics and antioxidant activity of raw and heated garlic ($130^{\circ}C$, 2 hr) from different cultivation areas (Danyang, Seosan, Uiseong Namhae, Namdo, Daeseo and China). The volatile compounds were extracted by simultaneous steam distillation extraction and identified with gas chromatography/mass spectrometer. The major volatile compounds of raw garlic were sulfur compounds such as diallyl disulfide, methyl-2-propenyl trisulfide, di-2-propenyl trisulfide etc. After heating, the major volatile compounds were allyl mercaptan, methyl pyrazine, 2,2-dimethyl-1,3-dithiane, 2-propenyl propyl disulfide, allyl methyl sulfide, allyl alcohol, and allyl sulfide etc. The DPPH radical scavenging activity (EDA, %) of volatile compounds from raw garlic and heated garlic was increased in a dose-dependent manner. The antioxidant activities (EDA, %) of volatile compounds from raw garlic cultivated in Danyang, Namhae and China were 20.07, 34.62, and 9.71% respectively. After heating, these values were increased to 79.90, 93.59, and 77.26% respectively. Results showed that heat treatment significantly enhanced the antioxidant activities (EDA, %) of the garlic.