Optimization of Aging Time for Improved Antioxidant Activity and Bacteriostatic Capacity of Fresh and Black Garlic

Tsan-Chang Chang,Hung-Der Jang

doi:10.3390/app11052377

Abstract

To determine the optimization of aging time for improved antioxidant activity and bacteriostatic capacity of garlic during its aging, garlic produced in Yunlin region, Taiwan, was employed as the test material in an analysis of the allicin content, total phenol content, antioxidant activity, and bacteriostatic capacity of fresh and aged garlic extracts. Allicin content of the aging garlic decreased to a minor level, whereas total phenol content increased to 16.96 mg gallic acid equivalent (GAE)/mL after 35 days of the aging process. The results of antioxidant testing demonstrated favorable positive correlations among IC50 of DPPH scavenging capacity, Trolox equivalent antioxidant activity, and superoxide dismutase activity for both the fresh and aged garlic extracts. The analytical results showed that aging of garlic at 70 °C and 85% relative humidity for 40 days substantially increased the quantity of phenolics, DPPH scavenging capacity, Trolox equivalent antioxidant activity, and superoxide dismutase activity and enhanced the antioxidant activity. The extracts exhibited higher bacteriostatic capacity against Gram-positive bacteria such as Bacillus subtilis and Staphylococcus aureus than against Gram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa. In conclusion, black garlic aged under the optimum conditions exhibited favorable antioxidant activity and bacteriostatic ability.

Highlights

Since the 18th century, when Carl Linnaeus (1707–1778) first described the genusAllium, more than 1200 Allium species have been categorized under Alliaceae
The culture media for the test bacteria employed in this study, including nutrient agar (NA), nutrient broth (NB), and Mueller–Hinton agar (MHA), were bought from Difco Chemical Co. (Sparks, ML, USA)
minimal bactericidal concentration (MBC) were 1.0 and 2.0 mg, respectively. These results demonstrated that the extracts from fresh garlic and black garlic (BG) had higher bacteriostatic capacity against Gram-positive bacteria such as B. subtilis (ATCC 6051) and S. aureus (ATCC 6538) than against Gram-negative bacteria such as P. aeruginosa (ATCC 9027) and E. coli (ATCC 10536)

Summary

Introduction

Since the 18th century, when Carl Linnaeus (1707–1778) first described the genusAllium, more than 1200 Allium species have been categorized under Alliaceae. Allium species in Taiwan include A. fistulosum, A. sativum, A. cepa, A. ascalonicum, and A. tuberosum, and they are critical vegetables and seasonings in some of the world’s most popular dishes. In 1844, Theodor Wertheim (1820–1864) extracted a pungent substance from garlic and named it “allyl”, the Latin name for garlic [1]. Later, scholars studied this substance and discovered that it was a sulfur compound containing allicin. Among the types of Allium, garlic (A. sativum L.) is the most commonly used seasoning in Asia. It has various biological properties such as antioxidant, anticancer, and bacteriostatic effects

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Results

Discussion

Conclusion