Basil ( Ocimum basilicum) is a popular herb prized for its distinctive sweet and slightly peppery flavor, but its delicate nature makes proper preservation a challenge. Unlike many other herbs, basil is highly sensitive to cold temperatures, which can cause chilling injury. Exposure to temperatures below 54°F (12°C) can lead to blackening and wilting. Successfully storing basil depends on whether the goal is short-term freshness or long-term preservation, requiring different approaches to maintain its vibrant color and strong aromatic compounds.
Maximizing Freshness: Countertop Storage
To keep fresh basil leaves viable for up to a week, the best technique mimics how cut flowers are maintained. Begin by trimming the stems at a slight angle to expose fresh tissue, which allows for maximum water absorption. Place the basil upright in a glass jar or a clean container filled with an inch or two of fresh, room-temperature water. This method provides the continuous hydration needed for the leaves to remain turgid and green.
The herb should then be loosely covered to manage humidity and protect against dust, such as by draping a plastic bag over the top of the jar. Keep the setup away from direct sunlight or heat sources, as excessive warmth can cause the leaves to wilt quickly. Change the water daily or every other day to prevent the growth of bacteria, which can accelerate spoilage. Crucially, the leaves should not be washed until immediately before they are used, as residual moisture can encourage the development of mold and dark spots.
Long-Term Preservation Through Freezing
Freezing is an excellent method for preserving basil’s vibrant green color and intense flavor for six months or longer. Simply placing fresh leaves in the freezer results in blackening and texture loss due to enzyme activity. To prevent this oxidative damage, a brief blanching process is recommended: submerge the leaves in boiling water for a few seconds, then immediately transfer them to an ice bath to stop the cooking.
One popular freezing technique is to blend the blanched leaves with olive oil to form a paste, then spoon this mixture into ice cube trays. The oil protects the herb from freezer burn and preserves the flavor compounds. Once frozen solid, the cubes can be transferred to an airtight freezer bag, offering pre-portioned servings ready for use in sauces or soups. Alternatively, basil can be blanched and pureed without oil, or just briefly blanched and patted dry, then frozen in a single layer on a baking sheet before being collected in a container for later use in recipes like pesto.
Long-Term Preservation Through Drying
Drying provides the most shelf-stable form of preservation, removing moisture to inhibit spoilage. The resulting product can be stored in a dark pantry for up to a year. Drying significantly alters the herb’s flavor profile, concentrating some compounds while diminishing the fresh, bright notes associated with fresh basil.
Air drying is a simple, traditional method that involves tying small bundles of stems together and hanging them upside down. The bundles must be placed in a warm, dry area with good air circulation and kept away from direct sunlight, which would bleach the color and degrade the flavor compounds. For a faster and more controlled result, a food dehydrator or a low-temperature oven can be used.
When using a dehydrator, a temperature setting around 95°F (35°C) is ideal for herbs, while an oven should be set to its lowest possible temperature, typically between 170°F and 180°F, with the door left slightly ajar. Once the leaves are completely brittle and crumble easily between the fingers, they should be crushed and stored immediately in an opaque, airtight container to protect from light and moisture.