Ripening is the complex biological process where a tomato transitions from a mature green state to a colorful, soft, and flavorful fruit. This transformation involves significant changes in texture, the accumulation of sugars, and the development of characteristic color pigments. When tomatoes are picked before they have fully ripened, acceleration becomes necessary to prevent spoilage while still achieving a palatable result. Accelerating the ripening of green or partially colored tomatoes allows them to develop their full flavor profile before they lose quality.
The Mechanism of Accelerated Ripening
Tomatoes are classified as a climacteric fruit, meaning they continue ripening even after being detached from the parent plant. This process is coordinated by ethylene, a naturally produced gaseous plant hormone. Ethylene acts as a signaling molecule, triggering a surge in its own production, which initiates the ripening cascade.
The goal of acceleration is to concentrate ethylene gas around the fruit to hasten color change and softening. Temperature plays a significant part, as the enzymes responsible for ripening are most active within a specific range. Optimal conditions for rapid acceleration fall between 64° and 70°F (18° to 21°C).
Applying Maximum Ethylene Gas for Speed
The fastest technique for maximizing ethylene exposure involves utilizing the gas produced by other fruits within a confined space. This method requires a high-ethylene emitting fruit, such as a ripe banana or apple, and a container that can trap the gas. Select tomatoes that have reached their full mature size, even if they are completely green, as immature fruit will not respond reliably.
Place the tomatoes in a single layer inside a brown paper bag or small cardboard box, ensuring they are not stacked heavily. Add one ripe banana or apple, which produces a substantial amount of ethylene, to the container. Gently close the container to trap the hormone-rich atmosphere around the fruit.
The container should be placed in a warm location, ideally within the 64° to 70°F temperature range, away from direct sunlight. This warmth enhances the activity of the ripening enzymes, while the sealed environment creates a high concentration of ethylene gas, pushing the fruit toward a quicker color change.
What to Expect After the “Overnight” Period
It is important to manage the expectation that a completely green tomato will turn fully red in a single night. The term “overnight” refers to a 12 to 24-hour period of maximum acceleration, which is usually enough time to initiate significant changes. After this period, examine the fruit for the first visible signs of ripening, known as the “breaker stage.”
Successful acceleration typically results in a slight blush of color, often a pink or yellowish tint, near the bottom of the fruit. You may also notice minor softening of the surface texture. If the tomatoes have reached this initial stage, they are actively producing their own ethylene and can be removed from the bag. They can then be left on a counter at room temperature to complete the ripening process naturally. If the tomatoes remain very hard and show no color change, repeat the sealed bag process with a fresh ethylene-producing fruit for another 12 to 24 hours.