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With an interest to enhance the aroma of palm kernel oil (PKO), Viscozyme L, an enzyme complex containing a wide range of carbohydrases, was applied to alter the carbohydrates in palm kernels (PK) to modulate the formation of volatiles upon kernel roasting. After Viscozyme treatment, the content of simple sugars and free amino acids in PK increased by 4.4-fold and 4.5-fold, respectively. After kernel roasting and oil extraction, significantly more 2,5-dimethylfuran, 2-[(methylthio)methyl]-furan, 1-(2-furanyl)-ethanone, 1-(2-furyl)-2-propanone, 5-methyl-2-furancarboxaldehyde and 2-acetyl-5-methylfuran but less 2-furanmethanol and 2-furanmethanol acetate were found in treated PKO; the correlation between their formation and simple sugar profile was estimated by using partial least square regression (PLS1). Obvious differences in pyrroles and Strecker aldehydes were also found between the control and treated PKOs. Principal component analysis (PCA) clearly discriminated the treated PKOs from that of control PKOs on the basis of all volatile compounds. Such changes in volatiles translated into distinct sensory attributes, whereby treated PKO was more caramelic and burnt after aqueous extraction and more nutty, roasty, caramelic and smoky after solvent extraction. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

BACKGROUND The aroma of palm kernel oil ( PKO) affects its applications. Little information is available on how enzymatic modification of palm kernels ( PK) affects PK and PKO aroma after kernel roasting. RESULTS Celluclast (cellulase) pretreatment of PK resulted in a 2.4-fold increment in the concentration of soluble sugars, with glucose being increased by 6.0-fold. Higher levels of 1.7-, 1.8- and 1.9-fold of O-heterocyclic volatile compounds were found in the treated PK after roasting at 180 °C for 8, 14 and 20 min respectively relative to the corresponding control, with furfural, 5-methyl-2-furancarboxaldehyde, 2-furanmethanol and maltol in particularly higher amounts. Volatile differences between PKOs from control and treated PK were also found, though less obvious owing to the aqueous extraction process. Principal component analysis based on aroma-active compounds revealed that upon the proceeding of roasting, the differentiation between control and treated PK was enlarged while that of corresponding PKOs was less clear-cut. Celluclast pretreatment enabled the medium roasted PK to impart more nutty, roasty and caramelic odor and the corresponding PKO to impart more caramelic but less roasty and burnt notes. CONCLUSION Celluclast pretreatment of PK followed by roasting may be a promising new way of improving PKO aroma. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Palm kernel oil (PKO) is obtained from the seeds of oil palm ( Elaeis guineensis Jackqu ). In this study, volatiles and aroma-active compounds of PKO were studied by head-space solid-phase microextraction/gas chromatography/mass spectrometry/flame ionisation detector (HS-SPME/GC/MS/FID) and solvent-assisted flavour evaporation -gas chromatography/olfactometry/mass spectrometry (SAFE-GC/O/MS), respectively. An optimised HS-SPME sampling method was obtained for extraction at 60 °C for 40 min. With this method, the volatiles of PKO from palm kernels subjected to different roasting times (up to 30 min) at 180 °C were analysed. Totally 73 volatiles were found, including 19 O-heterocyclic compounds (16 furans and 3 pyrans), 15 N-heterocyclic compounds (10 pyrazines and 5 others), 15 carbonyl compounds (5 aldehydes and 10 ketones), 11 acids, 4 alcohols, 3 esters, 3 sulphur and 3 volatile phenols. With the extension of roasting times, peak areas of O-heterocyclic compounds, N-heterocyclic compounds, aldehydes and cyclic ketones increased significantly whereas those of acids, alcohols and esters generally decreased. Results of GC/O/MS showed that 2-nonanone, octanoic acid and methyl octanoate were the most aroma-active compounds in unroasted PKO, while in roasted PKO, the most active volatiles were ethyl pyrazine, 2-nonanone, 2-hydroxy-3-methyl-2-cyclopenten-1-one, maltol, 2,6-dimethylpyrazine, 2,5-dimethylpyrazine, 2,3-dimethylpyrazine, benzoic acid ethyl ester, octanoic acid, 5-methyl-2-furancarboxaldehyde and isomaltol. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Protease modified the flavour of coconut oil (CO) obtained from coconut kernels (CK). • Flavourzyme treated CK released more precursors for Maillard reaction and caramelisation. • Flavourzyme treated coconut kernels increased in furans and pyranones. [ABSTRACT FROM AUTHOR]