Physico-Chemical Properties of Biscuits Enriched with Dried Microwave-Blanched Fruit Peelings

Aims: To investigate the dough rheological properties as well as physical, nutritional, antioxidant and sensory properties of biscuits supplemented with dried microwave-blanched orange, apple and pomegranate peels at various levels (0-10%, wheat flour substitution).

Methodology: Water absorption capacity and pasting properties of wheat flour blended with fruit peels were assessed using farinograph and micro viscoamylograph. Physico-chemical properties as well as antioxidant activities were measured using standard methods. The sensory analysis was performed by trained panelists.

Results: Water absorption capacity of the dough increased significantly with increasing levels of orange and apple peels while it decreased with pomegranate peels. However, peak, hot paste, cold paste and breakdown viscosities of the dough significantly decreased with increasing proportions of apple and orange peels while they increased with pomegranate peels. The breaking force and weight of the biscuits supplemented with pomegranate peels were the lowest. Supplementation of biscuits with fruit peelings enhanced the ash and fibre content of the biscuits but had no significant effect on their antioxidant activities except for biscuits containing 10% apple peels which had higher antioxidant activity compared to biscuit controls. Biscuits supplemented with 5% of fruit peels were the most appreciated in terms of surface character, crumb colour and texture.

Conclusion: This study showed that dried microwave-blanched apple peels can be incorporated into biscuits to enhance both their nutritional and antioxidant properties.