Computerized video image analysis to quantify color of potato chips

Abstract

Color analysis is a critical quality evaluation procedure in the potato processing industry. This research sought to determine whether potato chip color could be quantified by video image analysis. Russet Burbank and Shepody potatoes, stored at 8 and 5 C, were processed into 8 mm thick chips, which were fried for three time periods. Chip color was characterised by mean gray level values. Changes in video equipment operation and sample presentation were investigated to establish the most reproducible conditions for chip color measurements. The use of image analysis software to analyze mean gray level values from specific regions of the chip was demonstrated. Differences in chip color from potatoes stored at the two temperatures could be distinguished by mean gray level values. For potatoes that had been stored at 5 C, different chip frying times were distinguished on the basis of mean gray level. Chips of 1 mm thickness were prepared from 13 selections and 2 cultivars and color measured by mean gray level, Lvalue (Hunterlab D25L-2 colorimeter) and by Agtron value (Agtron M31A color meter, green mode). Good correlation was found between color assessed by mean gray level and color measured by the Agtron and Hunterlab. A repeatability study showed that image analysis color was not as repeatable as color measured by the two other techniques. Nevertheless, video image analysis appears to have potential as an objective assessor of chip color, and through software development, has specific advantages over other color assessment techniques.