Phytochemicals, antioxidant activity and quality properties of fibre enriched cookies incorporated with orange peel powder

Abstract

Orange peels are a rich source of dietary fibre, phenolic compounds and have effective antioxidant activity. Therefore, they can be used as a natural source in fortifying bakery products. The aim of the study was to evaluate the effect of substituting wheat flour at 5, 10, 15 and 20% with orange peel powder on the physicochemical, antioxidants and organoleptic properties of cookies. Results indicated that the orange peel powder was significantly higher in ash and crude fibres which were 4.13 and 13.20%, compared to wheat flour being 1.37 and 0.50%, respectively. It is a good source of total phenolic compounds (13.94 mg GAE/g) and it had high antioxidant activity (84.33%). Minerals and crude fibre in cookies samples were gradually increased in the levels of orange peel powder up to 20% compared to control. The highest values of phenolic contents 9.12, 8.31 and 6.10 mg GAE/g resulted in cookies that had 10, 15 and 20% of orange peel powder incorporated into it, respectively as compared to control (1.15 mg GAE/g). Cookies with all ratios of orange peel powder displayed good ability in radical scavenging activity ranged from 4.55% to 40.92%, while it was 2.65% in the control. Redness (a) and yellowness (b) of cookies were significantly high with the addition of orange peel powder in all the levels studied when compared to control, these results may be due to a slight yellow colour of orange peel powder from its carotenoid pigments in the albedo layer. The results showed no significant difference in cookies appearance and taste, up until a substitution level of 10% compared to the control, and an acceptance of the cookies sample containing 15% of orange peel powder was observed. It could be concluded that incorporation up to 15% of orange peel powder in cookies manufacturing improved the physicochemical, nutritional quality with respect to sensorial characteristics of cookies.