Quality characteristics, antioxidant activities and acrylamide formation in cookies added with onion peel powder

Abstract

This study was conducted to investigate the quality characteristics, antioxidant activities and levels of acrylamide formation in cookies containing different amounts of onion peel powder. Onion peel powder was incorporated into the cookies at a level of 2–6% based on the total weight of wheat flour. The contents of moisture, ash, crude protein, total polyphenols, total flavonoids, and acrylamide content of cookies were determined, in addition to their antioxidant activities, pH values, loss rates, spread ratios, color, and texture. Upon increasing the amount of onion peel powder, the moisture and ash contents of the cookies increased, wheareas the pH, loss rate and spread ratio of the cookies decreased. In terms of the chromatic analysis, the L and b values decreased, while the a values increased as the amount of added onion peel powder increased. Furthermore, the total polyphenol and total flavonoid contents increased, while the antioxidant activities were significantly higher than that of the control, increasing proportionally with the concentration of onion peel powder. Moreover, the acrylamide contents of the cookies decreased slightly upon increasing the amount of added onion peel powder, with 6% onion peel powder being particularly effective in inhibiting acrylamide formation. These results suggest that the addition of onion peel powder to cookies will increase the value of cookies by enhancing their antioxidant activities and decreasing acrylamide formation.