Effect of pH, Certain Chemicals and Holding Time‐Temperature on the Color of Lowbush Blueberry Puree

Main effects of pH, several chemicals, and holding time at 50°C and −20°C on the color of lowbush blueberry puree were evaluated. As pH shifted from low to high, the puree became darker and more bluish-purple. Chemicals such as EDTA and AlCl3 tended to produce a redder and yellower puree whereas SnCl2 and SnCl4 would make the color bluish-purple. The combining effect of pH and chemicals showed a stabilizing effect on puree color which was independent of holding time of 24 hr at 50°C or 4 wk at −20°C. Hue values were recommended to be used rather than absorbance ratios A510A410 to judge color of blueberry puree.