Evaluation of Mandarin and Navel Orange Peels as Natural Sources of Antioxidant in Biscuits

Abstract

The use of navel orange and mandarin peels as natural antioxidant in biscuits production was investigated. Chemical composition showed that peels had high contents of ash, ether extract and crude fiberandlowproteincontent.Navel orange and mandarin peel powders were used in production of hard biscuits (Marie) at three levels of wheat supplementation (5, 10 and 15%). Sensory evaluation and chemical analysis of biscuits indicated that supplementation with 5% and 10% levels were well accepted in all organoleptic properties as compared to the control sample, but at 15% level, low scores indicated unacceptable product. Addition of peel powders increased crude fiber,ashandetherextract contents of biscuits. The results indicated that the mandarin and navel orange peel extracts have antioxidant activity. Mandarin peels had the highest total phenols (780mg/100g dry matter) and the highest antioxidant activity. Also, data indicated that the addition of navel orange and mandarin peels powder increased the shelf life of biscuits as compared to the control. Addition of peels inhibited lipid oxidation as indicated by the peroxide values of navel orange and mandarin biscuits. The peroxide values after 6 months of storage at 25ºC and 40ºC were (8.9 and 10.3 meq./kg fat) and (8.2 and 12.5 meq./kg fat) for navel orange and mandarin biscuits respectively as compared to control (29.5 and 35 meq./kg fat). Consequently, it could be concluded that navel orange and mandarin peel powders might be used instead of synthetic antioxidants, as the addition of peels at 10% level had no adverse effect on the organoleptic properties of biscuits. Moreover, the biological results indicated that the substitution with peels up to 10 % improved the weight gain of rats, decreased the levels of serum total cholesterol, liver lipid and liver cholesterol and glucose blood. Finally, addition of peels as a source of natural antioxidant can be recommended to increase the shelf life of food products containing fats and oils, which is safe and can impart health benefitstotheconsumer