Relationship Between Visual Rating and Chromaticity Values in 'Delicious' Apple Strains

Abstract

Fruit of 37 'Delicious' apple ( Malus domesticaBorkh.) strains were harvested 149 days after full bloom in 1988, and visually evaluated by panelists on a 1 to 10 scale, where 10 = excellent color. Fruit color was measured at the mid point between the stem and calyx end on the blushed surface of each fruit with a Minolta Chroma Meter CR-200b portable tristimulus colorimeter. A simple linear regression of color panel rating on L* value provided a R ²= 0.55, indicating that this parameter influences visual color evaluation. However, the a*/b* ratio was the best single predictor of color rating (R ²= 0.63). Although several models were tested, and many were statistically significant, none appeared to be better than the a*/b* ratio from a practical standpoint. Assessing fruit color with a colorimeter eliminates the problems of subjectivity associated with visual ratings and permits color to be reported in internationally accepted units.