Acidification of Garlic and Herbs for Consumer Preparation of Infused Oils

Consumer interest in producing flavored oils by infusing oil with garlic and herbs has grown in recent decades. However, storage of low-acid plant material in oil is a known botulism risk. Commercial production of garlic-inoil mixtures is safely accomplished by acidifying the garlic to a pH value below the growth range for Clostridium botulinum. Procedures were developed that consumers could use to acidify garlic, basil, oregano and rosemary for safe addition to oils for flavor infusion. For garlic, cloves were peeled, chopped and soaked for 24 h in 3% citric acid solution at a ratio of 1 part garlic to 3 parts acid solution, by weight. This procedure reduced the pH of garlic (Allium sativum L) samples from 8 cultivars and of elephant garlic (Allium ampeloprasum) from an initial pH of 6.0–6.4 to a final pH of 3.7 or less. Garlic samples were obtained over 2 crop years and from three growing regions. For fresh herbs, basil, oregano, or rosemary were immersed in 3% citric acid at a ratio of 1 part herb to 10 parts acid solution, by weight, for 24 h. The initial herb pH of 6.3 to 6.7 was reduced to pH 2.8 to 4.1 by this procedure.