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Modification of physiochemical properties of copra meal by dilute acid hydrolysis



Coconut residue or copra meal (CM), a by-product after pressing cream and oil out of the coconut meat, is a good source of dietary fibre (DF), but high water-holding capacity (WHC) of CM limits the quantity of fibre incorporated into food products. This study focused on the modification of CM physiochemical properties using acid hydrolysis to improve its potential utilisation as source of food fibres or low-calories bulk ingredients in food applications. Acid hydrolysis using 0.5% HCl significantly reduced swelling capacity (SC) and water retention capacity, whereas bulk density (BD) and soluble DF content of the modified CM significantly increased. Monosaccharide composition profile, gel penetration profile and FT-IR spectra indicated the destruction of CM matrix structure. This destruction increased compactness of the structure and lessened the ability of CM to hold water. Substituting the modified CM for wheat flour in bread and cookies significantly improved bread and cookies qualities compared with the use of the untreated CM. Response surface methodology showed that HCl concentration, hydrolysis temperature and time influenced properties of the modified CM. The models predicting their relationships were also generated.