Macadamia nuts have high nutritional value and positive health attributes. Changes to the composition and availability of these compounds during roasting contribute to product quality. In this study, changes to the chemical composition of lipids (fatty acids, triglycerides, and free fatty acids) and other phytochemicals were analyzed, and a sensory evaluation was carried out of two major varieties of macadamia nuts planted in China, after roasting. Only small changes in fatty acid (FA) content and a slight decrease in total triglycerides (TAGs) were observed after roasting. The free fatty acid (FFA) content and the peroxide value were increased by roasting. The total available polyphenol content increased by 25.6% and the oxidative stability index of kernels increased by 21.6%. The sensory scores for taste and aroma were doubled by roasting. Overall, the sensory, nutritional quality, and oxidative stability of roasted macadamia nuts were greatly improved, compared with raw nuts.

Production of structured lipid 1,3-dioleoyl-2-palmitoylglycerol (OPO), from tripalmitin (PPP) and oleic acid (OA) using lipases and ultrasonic pretreatment was conducted. Factors influencing both the ultrasonic conditions and enzymatic reaction were investigated. Optimum conditions could be attained with 6 min pretreatment time, 50% ultrasonic power, 3 s/9 s (work/pause) cycle of ultrasonic pulse, 1:8 PPP/OA molar ratio, 12% enzyme dosage and 50 °C temperature of. At the optimum conditions, the OPO yield of 51.8% could be achieved in 4h. Studies showed that the OPO content increased to 35.9% in 1h with ultrasonic pretreatment, in comparison to 4h without ultrasonic pretreatment. Reuse of Lipozyme RM IM for 10 cycles under ultrasonic irradiation did not cause essential damage to its lipase activity. Reaction kinetic model fitted well with the proposed Ping-Pong mechanism. The apparent kinetic constant (Vm'/K₂) of ultrasound pretreatment reaction was 2.52 times higher than the conventional mechanical stirring, indicating that ultrasound pretreatment enhanced the substrates affinity to the enzyme. This study confirmed that ultrasonic pretreatment was more efficient in OPO production than conventional mechanical agitation.