How does heating preserve high-acid fruit products?

In fruit processing, heating is a critical thermal method used to preserve high-acid products by destroying spoilage organisms and inactivating enzymes that cause browning, softening, and off-flavors.1

For high-acid fruits (typically those with a pH below 4.5), the primary thermal processes include:

• Canning: Fruit products are either hot-filled or heated within a hermetically sealed container, often at temperatures around 88 °C (190 °F).1
• Pasteurization: This process uses heat to destroy yeasts, molds, and spoilage-causing enzymes like pectinesterase and polygalacturonase. Common conditions for fruit juices include heating to 77 °C (171 °F) for one minute, followed by rapid cooling.2

Because high-acid environments naturally inhibit the growth of many bacteria, the heat treatment focuses on these specific spoilage targets rather than the more severe sterilization required for low-acid foods. To maintain quality, processors often use plate-type heat exchangers for rapid heating and cooling, and may deaerate juices beforehand to minimize oxidative deterioration.23