Evaluation of Alliin, Saccharide Contents and Antioxidant Activities of Black Garlic during Thermal Processing

This study aimed to explore the alliin, saccharides, antioxidant and some other physicochemical changes of black garlic during the thermal processing steps. The contents of alliin and polysaccharides decreased significantly after 10 days of heat treatment, whereas the content of reducing sugars increased correspondingly. The 57.14% of fructose, 6.78% of glucose and 7.62% of sucrose were mainly saccharides in black garlic to answer for its sweet taste. The color value of black garlic increased over time, whereas the pH decreased continually from 6.25 to 4.25 after heating at 70–80C for 10 days, which contributed a characteristic black appearance and a sour taste mouthfeel. The antioxidant activities, including 1,1-diphenyl-2-picrilhydrazyl, hydroxyl radical scavenging and ferric reducing/antioxidant power activities, increased gradually during thermal processing. Practical Applications Black garlic has been used as foods and herbal remedies mainly in Japan, Korea and China, which has a wide range of health benefits, significantly antioxidant properties. Various physicochemical changes have been found to take place during thermal processing of garlic, including alliin, allicin, saccharides, pH, color and antioxidant activities. This is the first study to investigate the changes in the molecular weight distribution of polysaccharides and the monosaccharide composition of black garlic. These changes in saccharide contents and composition could be utilized as quality factors for the production of black garlic. Therefore, the results may have some useful practical implications at both the food technology and nutritional level.