Pentopan mono BG pretreatment of palm kernels modified the aroma of palm kernel oil after kernel roasting

Abstract

With an interest to enhance the aroma of palm kernel oil (PKO), Pentopan mono BG (xylanase) was applied to alter the carbohydrates in palm kernels (PK) so as to modulate the formation of volatiles during kernel roasting. The result showed that a 1.3-fold increment of total soluble sugars was found in PK after Pentopan treatment, which promoted the generation of O-heterocyclic volatile compounds during kernel roasting. Overall, an increment of 1.5-, 1.4- and 1.3-fold of O-heterocyclic compounds were found in PKO derived from treated PK after light, medium and dark roasting, of which the elevation in furfural and 2-furanmethanol contents was the most obvious. Principal component analysis (PCA) clearly discriminated treated PKO with various kernel roasting degrees from that of control PKO on the basis of all aroma-active compounds; the aroma in PKO from treated, roasted PK was highly correlated with 2-[(methyldithio)methyl]-furan, 5-methyl-2-furancarboxaldehyde, 2-furanmethanol, 2,5-dimethylpyrazine and ethyl pyrazine. Sensory evaluation showed that PKO derived from medium roasted PK imparted more caramelic, nutty and smoky odor notes relative to the untreated PKO. This study suggests Pentopan pretreatment of PK followed by roasting may be a novel way to modulate PKO aroma and potentially widen its application.