Effects of temperature, pH, and sunlight exposure on the color stability of strawberry juice during processing and storage

• The color of strawberry juices depends on the pH value, temperature of thermal treatment and storage, packaging, etc.
• The Ab510 of clear strawberry juice was closely related to its L*·a* values in most conditions but not always be.
• The values of L*or a* determined by colorimeter was a direct indicator of the strawberry juice color.

The natural color of strawberries and their products easily fades or deteriorates during processing and storage. Temperature, pH, and light are common factors that affect the color stability of strawberry juice (SJ). Clarified SJ was prepared from fresh fruits and diluted with purified water at a ratio of 1:3. The absorbance at 510 nm (Ab510) and the L* and a* values of SJ under different processing or storage conditions were determined to describe the attributes and stability of juice color. SJ color was highly sensitive to thermal treatment, pH and sunlight exposure. Storage temperature also significantly affected the SJ color. SJ could achieve color stability by adjusting pH to 3.0 or below, heating at 80 °C or below for 20 min or less if thermal treatment is necessary, packing with opaque materials, and then storing at 2 °C–4 °C. Ab510 positively correlated with a* under most conditions, except at different pH values. a* could be used as a direct indicator that describes SJ color.