Antioxidant Constituents Of Macadamia Integrifolia

In order to explore the antioxidant activity of macadamia nuts, reveal the oxidative stability of the related products, Folin-phenol, DPPH, FRAP, Rancimat and HPLC method were used to determine the total phenolics, antioxidant activity, and composition and content of polyphenols from the macadamia husk, shell, oil or ethanol extracts. The man results as followings.1. The optimum extraction conditions of total phenols in macadamia husk was determined by single factor and response surface design : 40% ethanol, solid-liquid ratio was 1:50, ultrasonic extraction time was 60 min. Under these conditions, the extraction rate of total phenol was 4.3%.2. The total phenol content of 6 varieties of macadamia husk(900, 695, A16, OC(3), 788, Guire1) were 49.30, 45.28, 35.10, 56.11, 20.92, 27.47 mgGAE/g respectively. While the total phenol content of 6 varieties of macadamia shell(900, 695, A16, OC(3), 788, Guire1) were 10.53, 8.69, 5.79, 5.40, 4.92, 3.88 mgGAE/g respectively. The content of different varieties has significant different, and the content of husk was much higher than that of the shell.3. The EC50 of Vc, rutin, TBHQ and ethanol extracts in macadamia husk were 47.3 μg/m L, 65.27 μg/mL, 80.7 μg/mL and 64.1 μgGAE/m L respectively. The concentration needed to restore 1 mM FeSO4 of TBHQ and ethanol extracts were 31.5 μgGAE/m L and 29.5 μg/m L respectively. It showed that the ethanol extracts in macadamia husk had good antioxidant activity.4. Gallic acid in macadamia was identified by HPLC-MS and HPLC. The content of gallic acid, p-hydroxy benzaldehyde, p-hydroxy benzoic acid, p-hydroxy benzene methanol and 3,4-dihydroxy benzoic acid from macadamia husk, shell and oil were determined by HPLC.5. The IT of the 3 varieties of macadamia oil(Guire1, OC(3), 695) were 4.05, 3.77, and 3.32 h. The IT of OC(3) oil reduced to 1.53 h after the extraction of total phenols. The same amount of p-hydroxy benzaldehyde, p-hydroxy benzoic acid, p-hydroxy benzene methanol and 3,4-dihydroxy benzoic acid were added to OC(3) oil after the extraction of total phenols, and the IT increased to 2.56, 2.01, 2.39 and 2.01 h respectively.6. The formula and process conditions of extract tablet were determined by L9(34) orthogonal design: the amount of magnesium stearate added in extract tablet was 0.3%, the rate of extractum, starch and dextrin were 2: 4: 4, the stirring time was 8 min. The method was simple and the comprehensive score of the tablet was higher, which was 19.69.The above results were reported for the first time, providing the basis for the development of macadamia husk, shell and oil.