Pre-treatment of coconut kernels by proteases to modulate the flavour of coconut oil

This study investigated the impact of protease pre-treatment of coconut kernels (CK) on the flavour modification of the resultant coconut oil (CO). The effects of four proteases (Alcalase, Flavourzyme, Neutrase and Protamex) pre-treatment on volatile modification of CO was screened and Flavourzyme was chosen for detailed investigation. Flavourzyme was found to release not only free amino acids but also simple sugars, increasing the contents of soluble sugars and free amino acids in CK by 1.5- and 1.3-fold, respectively, compared to the untreated control. The increments of these thermal reaction precursors accelerated the Maillard reaction and caramelisation during kernel roasting, resulting in the rise of volatile compounds in obtained CO by 2.1-, 1.4- and 1.4-fold with light, medium and dark kernel roastings, respectively. Besides, volatile profiles of CO extracted from Flavourzyme treated CK differed significantly from those of the untreated control by having increments in furans and pyranones but decreases in furanones and pyrazines. Principal component analysis (PCA) revealed that flavour of CO from Flavourzyme treated CK upon roasting was highly correlated with furans and pyranones. Pre-treatment by Flavourzyme of CK prior to oil production is a potential strategy to modulate and enhance the flavour of obtained CO and hence to widen its application in food industry.