Partially substitution of wheat flour by coconut residues in bakery products and their physical and sensorial properties

Abstract

The food process generates certain amounts of agricultural wastes and by-products. These materials are considerably non-valuable and normally sold for livestock feed. Coconut residue is one of the by-products obtained from coconut milk extraction. Thus, this study was aimed to valorise coconut residue powder (CRP) by partial substitution of wheat flour in deep fried donut and butter cookies and to investigate how different CRP substitution levels affect the physical and sensorial qualities of these bakery products. CRP was prepared by drying coconut residues at 55oC for 9 hrs, size reducing with a blender at 24,000 rpm for 40 s and sieving through a 35-mesh sifter. Protein, ash, fat and carbohydrate contents of coconut flour were 3.82, 0.72, 39.83 and 55.64% on dry basis, respectively. After the utilization of CRP by partial substitution wheat flour in deep fried donut (5%, 10% and 15%) and butter cookies (10%, 15% and 20%), it was found that CRP can substitute wheat flour in the donut and cookies productions by 10% and 15%, respectively. Donuts with higher substitution levels had lower specific volume but higher L*, a*, ∆E*-values, hardness and chewiness. For butter cookies, an increase in CRP substitution level led to higher hardness but it did not significantly affect the fracturability and the ∆E*-value. An increase in CRP substitution level also reduced the overall-liking score. The overall-liking scores of fried donuts with 10% CRP substitution level and butter cookies with 15% CRP substitution level were 6.43 (slightly like) and 7.00 (moderately like), respectively. This study showed the value-adding of agricultural waste such as coconut residue by its application in food production.