Red peppers may darken in color during the drying process. This is due to pigment changes caused by heat treatment and oxidation reactions. The pigments in red peppers are mainly carotenoids and flavonoids, which give peppers their bright red color. However, high temperatures and oxidative environments can cause structural changes in these pigment molecules, affecting their absorption spectrum and color.

During the drying process, after the pepper is heated, the temperature may exceed its tolerance range, causing the structure of the pigment molecules to be destroyed and changed. In addition, contact between peppers and oxygen in the air may trigger an oxidation reaction, further leading to the degradation of pigments and darkening of the color.

In order to prevent red peppers from turning black during drying, the following measures can be taken:

1. Control the drying temperature: Choose the appropriate drying temperature to avoid damage to peppers caused by excessive temperature. Generally speaking, the drying temperature of peppers should be controlled between 50-60 degrees Celsius.

2. Reduce oxygen contact: During the drying process, measures can be taken to seal or reduce oxygen contact to reduce the occurrence of oxidation reactions. For example, an inert gas such as nitrogen can be added to the drying chamber to reduce the oxygen content.

3. Control the drying time: Excessive drying time may also cause the peppers to turn black. Therefore, the drying time should be controlled according to the specific situation to avoid over-drying.

In short, by controlling the drying temperature, reducing oxygen exposure, and controlling the drying time, the possibility of blackening can be reduced.

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