• Nutrition Research and Practice
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• v.11 no.3
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• pp.206-213
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• 2017

BACKGROUN/OBJECTIVES: Although studies have revealed that black garlic is a potent antioxidant, its antioxidant mechanism remains unclear. The objective of this study was to determine black garlic's antioxidant activities and possible antioxidant mechanisms related to nuclear factor erythroid 2-like factor 2 (Nrf2)-Keap1 complex. METHODS/MATERIALS: After four weeks of feeding rats with a normal fat diet (NF), a high-fat diet (HF), a high-fat diet with 0.5% black garlic extract (HF+BGE 0.5), a high-fat diet with 1.0% black garlic extract (HF+BGE 1.0), or a high-fat diet with 1.5% black garlic extract (HF+BGE 1.5), plasma concentrations of glucose, insulin,homeostatic model assessment of insulin resistance (HOMA-IR) were determined. As oxidative stress indices, plasma concentrations of thiobarbituric acid reactive substances (TBARS) and 8-isoprostaglandin $F2{\alpha}$ (8-iso-PGF) were determined. To measure antioxidant capacities, plasma total antioxidant capacity (TAC) and activities of antioxidant enzymes in plasma and liver were determined. The mRNA expression levels of antioxidant related proteins such as Nrf2, NAD(P)H: quinone-oxidoreductase-1 (NQO1), heme oxygenase-1 (HO-1), glutathione reductase (GR), and glutathione S-transferase alpha 2 (GSTA2) were examined. RESULTS: Plasma glucose level, plasma insulin level, and HOMA-IR in black garlic supplemented groups were significantly (P < 0.05) lower than those in the HF group without dose-dependent effect. Plasma TBARS concentration and TAC in the HF+BGE 1.5 group were significantly decreased compared to those of the HF group. The activities of catalase and glutathione peroxidase were significantly (P < 0.05) increased in the HF+BGE 1.0 and HF+BGE 1.5 groups compared to those of the HF group. The mRNA expression levels of hepatic Nrf2, NQO1, HO-1, and GSTA2 were significantly (P < 0.05) increased in the HF with BGE groups compared to those in the HF group. CONCLUSIONS: The improvements of blood glucose homeostasis and antioxidant systems in rats fed with black garlic extract were related to mRNA expression levels of Nrf2 related genes.

• Korean journal of food and cookery science
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• v.27 no.6
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• pp.793-801
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• 2011

We examined the quality characteristics of obtaining the optimal curing conditions for black garlic extract (BGE) added mackerel by using response surface methodology (RSM). The condition of RSM was included in 13 experimental points using two dependent variables: concentration of BGE (2.6~12.5 brix, X1) and curing time of BGE (17.58~102.42 min, X2). An assessment was conducted with four replicates on three independent variables: volatile basic amine (VBN, Y1), thiobarbituric acid (TBA, Y2), and shear force (Y3). The minimum content of VBN was 1.625 mg% at 3.17 brix, for 80.5 min. This was obtained when the BGE concentration was lower and the curing time was longer. The content of the TBA was 3.13~12.24 MA mg/kg at experiment range and the stationary point was at saddle point. Therefore, by using ridge analysis, the minimum point of TBA was 2.414 MA mg/kg at 3.5 brix for 84.4 min. The truth coefficient of the BGE concentration and curing time were 2.9 brix and 75.1 min, respectively, with a shear force ($120.764cm/kg^2$) shown at maximum point. The optimum Hunter color range was estimated from the lowest TBA value. The optimum range of the L color was 39.16~40.26, a and b color were 4.40~4.88 and 12.35~13.20, respectively.

• Korean journal of food and cookery science
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• v.26 no.3
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• pp.307-313
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• 2010

Yogurt base was prepared from skim milk added with 0.5, 1.0 and 1.5% (w/v) black garlic extracts(BGE, 60 brix), fellowed by fermentation with Lactic acid bacteria (the mixed strain of Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus) at $42^{\circ}C$ for 24 hr. The yogurt products were evaluated for acid production (pH, titrable acidity), number of viable cells, viscosity, color value, and sensory properties. The pH of yogurt with BGE was below 6.0 at 6 hr fermentation, after which it was rapidly acidifies. Aftert 24 hr, the titratable acidity of yogurt with 1.5% BGE was 0.74%, which was 5.7 times higher than that before fermentation. There was no significant difference in viable cell count between the samples after 3 hr fermentation. The viscosity of yogurt was decreased by the addition of BGE. As the percentage of BGE increased, the L value (lightness) decreased while the a value (redness) and b value (yellowness) increased. The overall sensory score of yogurt with BGE was lower than that of yogurt with only skim milk. Therefore, moderate addition of BGE was below 1% for the preparation of yogurt.

• Korean Journal of Food Science and Technology
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• v.43 no.6
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• pp.760-765
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• 2011

We investigated the antioxidative effect of black garlic extract (BGE) on paraquat (PQ)- induced oxidative stress in mice. A DPPH radical scavenging activity assay showed that BGE had potent free radical scavenging activity, comparable to that exhibited by vitamin C. Mice were administered with either vitamin C or two levels of BGE by oral gavage for 10 days, with PQ being injected intraperitoneally on day five. It was found that BGE reduced the liver enzyme levels induced by PQ injection in mice. The concentrations of plasma and hepatic malonedialdehyde were both significantly reduced in the BGE groups compared with the levels in the PQ group, whereas the hepatic superoxide dismutase and catalase activities were significantly increased in the BGE groups compared with the PQ group. These findings suggest that BGE has potent antioxidative activities in vivo and thus could prevent the oxidative stress induced by PQ injection in mice by two mechanisms: the induction of antixoxidative enzyme systems and direct scavenging of reactive oxygen species.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.5
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• pp.759-766
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• 2011

We conducted this study to develop a high value black garlic Makgeolli that was made of black garlic extract (BGE) and Sulgidduk. We investigated the quality characteristics of Makgeolli made with three different combinations of materials (control, Sulgidduk only; A, Sulgidduk combined with 15% BGE and water; B, Sulgidduk combined with 15% BGE instead of water). The pH of A and B were higher than the control, but the titratable acidity of A and B were lower. The sugar and alcohol contents of A and B increased during fermentation. A similar growth pattern was observed invisible cells, yeast, and lactic acid bacteria in all three Makgeolli. In A and B, the quantity of lactic acid bacteria was relatively higher than the yeast. The L value (lightness) was highest in the control, and the a value (redness) and b value (yellowness) were higher in A and B. The antioxidant properties of the three types of Makgeolli were evaluated using DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS (2,2'-azino-bis[3-ethylbenzthiazoline-6-sulfonic acid]) radical scavenging activities. In these assays, B showed significantly higher radical scavenging activities than the other two Makgeolli.

• Journal of Life Science
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• v.22 no.11
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• pp.1529-1537
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• 2012

In order to determine the effective concentration, 2, 7, and 14 brix black garlic extracts (BGE) were fed to restraint stressed rats and the lipid metabolism was analyzed. The dietary intake of the 14 brix BGE-fed group was $547.64{\pm}13.99$ g/4 weeks and it was significantly higher than that of the control group. The weight of all organs from the all BGE-fed groups showed no significant differences. While BGE concentration increased, BGE-fed groups tend to have low content of blood glucose. It was the lowest in the 14 brix BGE-fed group ($121.32{\pm}3.50$ mg/dl). Total cholesterol content was $54.54{\pm}1.63{\sim}65.84{\pm}2.61$ mg/dl. Total cholesterol content of the 14 brix BGE-fed group was the lowest and, in addition, lower than the normal group. Triglyceride content of serum showed the same tendency. HDL-cholesterol concentrations of the restraint stressed control (RSC) group were significantly higher than those of 7 and 14 brix BGE-fed groups. LDL and VLDL-cholesterol contents showed contrary results. GOT, GTP, and ALP activity of serum were lower when BGE concentration was higher. It is expected that BGE has a liver protective activity. In the liver, total lipids and triglyceride contents were significantly lower in BGE-fed groups than in the ISC group. However, total cholesterol content showed no significant difference between groups. TBARS content in liver of the 2 brix BGE-fed group was not significantly different than control, while 7 and 14 brix BGE-fed groups were lower than control. Glycogen content in the liver was only significantly lower in the 14 brix BGE-fed group than in the RSC group. Findings indicate that feed of BGE over 7 brix contributes to resolving the restraint-stressed rats by improving the lipid metabolism and liver protective activity.

• Journal of Life Science
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• v.31 no.1
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• pp.37-46
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• 2021

The effects of freeze-dried powder from fresh and black garlic hot water extracts on the lipid metabolism in Sprague-Dawley rats fed a high-cholesterol diet were analyzed. The experimental group was classified into the normal group (NG), the high-fat (HF) and high-cholesterol diet group (CG), the HFC and 1% fresh garlic hot water extract powder-added diet group (FGEG), and the HFC and 1% black garlic hot water extract powder-added diet group (BGEG), respectively. The serum total lipid content was 381.52±7.30 mg/ml and 368.80±4.40 mg/ml in the FGEG and the BGEG, respectively, and was significantly lower than that of the CG. The total cholesterol and triglyceride contents of the FGEG and BGEG were also significantly lower than that of the CG. The high-density lipoprotein (HDL) cholesterol was significantly higher, and the low-density lipoprotein (LDL) and the very low-density lipoprotein (VLDL) cholesterol content was lower in the FGEG and BGEG than in the CG. The serum ALT and AST activities were significantly lower than those of the CG, and especially the BGEG was lower. The total cholesterol content and the triglyceride levels of the liver tissue were 36.0% and 14.3% lower in the BGEG than in the CG, respectively. The thiobarbituric acid reactive substance (TBARS) concentrations in the serum and the liver tissue were higher in the CG than in the FGEG and BGEG, but there was no difference between them. Based on these results, garlic extract powders significantly reduced the lipid profile and increased the antioxidant activity in rats in vivo. The black garlic hot water extract powder was more effective than raw garlic because of the total number of phenolic compounds and browning substances in the black garlic.