Articles
DIGITAL IMAGING ANALYSIS – A NEW METHOD FOR EVALUATION OF POTATO AFTER-COOKING DARKENING
Article number
619_47
Pages
399 – 404
Language
English
Abstract
After-cooking darkening (ACD) phenomenon occurs when boiled or steamed potato tubers become grayish dark on exposure to air.
The degree of darkening is controlled genetically and is strongly influenced by environmental factors.
The pigment responsible for ACD is a complex of chlorogenic acid and iron, which is formed during cooking and oxidizes during cooling to a colored ferric di-chlorogenic acid complex.
The evaluation of ACD is thus based either on the amount of chlorogenic acid in tubers (destructive method) or on the determination of the degree of color intensity on cut tuber surfaces (non-destructive method). The destructive method is HPLC based, complicated, and time consuming, particularly when a large number of samples is being evaluated.
Thus, despite its deficiency, non-destructive visual examination is routinely utilized in many breeding programs.
The objective of this study was to determine whether digital imaging analysis can be adapted to the evaluation of ACD. The method is based on the direct capture of the cooked and cut tuber surface image using a cooled CCD camera attached to a digital imaging system.
The degree of the dark color is then measured by pixels using an imaging acquisition software.
The system is calibrated at 0-255 pixel levels (0 as black, 255 as white) as standard, therefore the read values directly reflect the degree of darkening.
The measurement procedure is fast, reliable, simple, and particularly applicable for handling a large number of samples.
This is the first report on evaluation of ACD using a digital imaging system.
The degree of darkening is controlled genetically and is strongly influenced by environmental factors.
The pigment responsible for ACD is a complex of chlorogenic acid and iron, which is formed during cooking and oxidizes during cooling to a colored ferric di-chlorogenic acid complex.
The evaluation of ACD is thus based either on the amount of chlorogenic acid in tubers (destructive method) or on the determination of the degree of color intensity on cut tuber surfaces (non-destructive method). The destructive method is HPLC based, complicated, and time consuming, particularly when a large number of samples is being evaluated.
Thus, despite its deficiency, non-destructive visual examination is routinely utilized in many breeding programs.
The objective of this study was to determine whether digital imaging analysis can be adapted to the evaluation of ACD. The method is based on the direct capture of the cooked and cut tuber surface image using a cooled CCD camera attached to a digital imaging system.
The degree of the dark color is then measured by pixels using an imaging acquisition software.
The system is calibrated at 0-255 pixel levels (0 as black, 255 as white) as standard, therefore the read values directly reflect the degree of darkening.
The measurement procedure is fast, reliable, simple, and particularly applicable for handling a large number of samples.
This is the first report on evaluation of ACD using a digital imaging system.
Authors
G. Wang-Pruski, T.R. Tarn
Keywords
After-cooking darkening, potato tubers, visual and evaluation, pixels
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