Antiyeast Potency of Heated Garlic in Relation to the Content of Allyl Alcohol Thermally Generated from Alliin

ABSTRACT:  The appearance of antiyeast activity in heated garlic extract was influenced by the temperature, heating time, and pH. The maximum antiyeast activity was attained at the temperature range between 110 and 130 °C for the heating time range of 90 and 30 min, respectively. Reduced antiyeast activity occurred above 130 °C. More potent antiyeast activity was generated when the pH of the garlic extract was adjusted to and below 4.0. The sensitivity to the antiyeast activity of heated garlic or heated alliin was quite different depending on the yeast strain. Species belonging to Zygosaccharomyces were the least sensitive, while Candida utilis and Pichia membranaefaciens were among the most sensitive. The alliin content of the garlic was in the range of 0.5% to 1.32%. When garlic extracts were heated at 121 °C for 120 min, the content of allyl alcohol generated from alliin through thermal degradation was in the range of 0.08% to 0.16%. The allyl alcohol produced upon heating was positively proportional to the content of alliin in garlic. The antiyeast potency expressed as the minimum inhibitory concentration (MIC) was negatively proportional to the content of allyl alcohol and thus to the content of alliin.