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. 2025 Jul 31;13(8):e70743.
doi: 10.1002/fsn3.70743. eCollection 2025 Aug.

The Antimicrobial and Antioxidant Properties of Raw, Aged, and Fermented Garlic: Influence of Processing Methods

Luis M Cocom  1 , Hsiao-Chi Wang  2 , Kuo-Chan Tseng  3 , Yung-Lin Chu  3
Affiliations

The Antimicrobial and Antioxidant Properties of Raw, Aged, and Fermented Garlic: Influence of Processing Methods

Luis M Cocom et al. Food Sci Nutr. .

Abstract

Garlic (Allium sativum L.) is widely recognized for its bioactive properties, primarily attributed to its sulfur-containing compounds (SCs), which provide both prophylactic and therapeutic benefits. This study evaluates the antimicrobial and antioxidant activities of raw, aged, and fermented garlic, utilizing ultrasound-assisted extraction (UAE). Processed garlic samples, including fermented garlic in fruit vinegar (FGV), honey (FGH), ethanol (FGE), aged garlic (AGE60), and fresh raw garlic (RAW), were analyzed to determine the effects of different processing methods on their functional properties. Antimicrobial activity was assessed using the agar well diffusion method to measure inhibition zones (IZ) and microdilution techniques to determine the minimum inhibitory concentration (MIC) against Escherichia coli, Aspergillus niger, and Pichia guilliermondii. The results indicate that FGV, FGH, FGE, and AGE60 exhibited notable antimicrobial activity, while RAW garlic demonstrated the strongest antimicrobial effects, primarily due to its high allicin content and other sulfur-containing organosulfur compounds (OSCs), which are recognized as potent antimicrobial agents. Antioxidant capacity was evaluated through free radical scavenging activity (RSA) using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, ferric reducing antioxidant power (FRAP), and total phenolic content (TPC). AGE60, FGH, and FGV exhibited the highest antioxidant activity, with fermentation and aging processes contributing to the production of flavonoids and phenolic compounds, thereby enhancing antioxidative capacity. However, these processing methods did not significantly improve antimicrobial properties. These findings highlight the impact of processing methods on garlic's functional properties, suggesting that different processing techniques may be tailored to optimize specific health benefits.

Keywords: aged garlic; antimicrobial; antioxidation; organosulfur compounds.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

FIGURE 1
FIGURE 1
The comparative antimicrobial analysis of different kinds of fermented garlic against selected microorganisms. Antimicrobial activity of garlic fermented in 95% ethanol (FGE) on E. coli (A), A. niger (B), and P. guilliermondii (C), and garlic fermented in fruit vinegar (FGV) on E. coli (D), A. niger (E), and P. guilliermondii (F). The results are represented as means ± SD of triplicate independent readings. Values carried with different letters show significantly different (p < 0.05).
FIGURE 2
FIGURE 2
The comparative antimicrobial analysis of different kinds of fermented garlic against selected microorganisms. Antimicrobial activity of garlic fermented in honey (FGH) on E. coli (A), A. niger (B), and P. guilliermondii (C), aged black garlic (AGE60) on E. coli (D), A. niger (E), and P. guilliermondii (F) and fresh raw garlic (RAW) on E. coli (G), A. niger (H), and P. guilliermondii (I). The results are represented as means ± SD of triplicate independent readings. Values carried with different letters show significantly different (p < 0.05).
FIGURE 3
FIGURE 3
The free radical scavenging activity (DPPH) analysis of different processing methods of garlic has been detected within 6 months. The garlic fermented in 95% ethanol‐FGE (A), garlic fermented in fruit vinegar‐FGV (B), garlic fermented in honey‐FGH (C), garlic fermented in aged black garlic‐AGE60 (D), and fresh garlic‐RAW (E), expressed as percentage (%). The results are represented as means ± SD of triplicate independent readings. Values carried with different letters show significantly different (p < 0.05).
FIGURE 4
FIGURE 4
The ferric reducing antioxidant power (FRAP) analysis of different processing methods of garlic has been detected within 6 months. The garlic fermented in 95% ethanol‐FGE (A), garlic fermented in fruit vinegar‐FGV (B), garlic fermented in honey‐FGH (C), garlic fermented in aged black garlic‐AGE60 (D), and fresh garlic‐RAW (E) expressed in μmol/L. The results are represented as means ± SD of triplicate independent readings. Values carried with different letters show significantly different (p < 0.05).
FIGURE 5
FIGURE 5
Comparative antioxidant activity of different garlic extracts via total phenolic content (TPC) assay. Total phenolic content of five garlic extracts FGE (A), FGV (B), FGH (C), AGE60 (D), and RAW (E), expressed in mg GAE/g. Bars with different superscripts indicate statistically significant differences among tested samples, analyzed using one‐way ANOVA followed by Tukey's test (p ≤ 0.05). The total phenolic content (TPC) analysis of different processing methods of garlic has been detected within 6 months. The garlic fermented in 95% ethanol‐FGE (A), garlic fermented in fruit vinegar‐FGV (B), garlic fermented in honey‐FGH (C), garlic fermented in aged black garlic‐AGED60 (D), and fresh garlic‐RAW (E), expressed in mg GAE/g. The results are represented as means ± SD of triplicate independent readings. Values carried with different letters show significantly different (p < 0.05).
FIGURE 6
FIGURE 6
Overview of garlic preparations, classification, and evaluation of antimicrobial and antioxidant activities of different processed garlic samples.
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