Chinese Academy of Thermal Sciences Advances Macadamia Green Peel Research: Polyphenol Analysis and Antioxidant Activity Breakthroughs

In a breakthrough study, the leisure agriculture research team at the South Asian Institute of the Chinese Academy of Thermal Sciences has delved into the realm of macadamia nuts' green bark polyphenols in Australia, uncovering new insights into their composition and antioxidant properties. This pioneering research sheds light on the theoretical foundations for the valuable utilization of macadamia green peel.

Macadamia nuts, native to Australia, have transformed into a cornerstone for rural revitalization in regions like Yunnan, Guangxi, Guangdong, and Guizhou since their introduction in the 1970s. The green skin of macadamia nuts, constituting approximately 42% of the total nut, boasts rich phenolic substances with potent antioxidant and biological activities. Despite this, the green skin has long been discarded as processing waste, resulting in a significant resource wastage.

The recent study employed an ultrasound-assisted method for phenolic substance extraction from macadamia green peel. Subsequent analysis, purification, and liquid mass spectrometry technology were utilized to decipher the phenolic composition and characterize its antioxidant activity through both chemical and cell models.

The research team utilized the response surface optimization method to determine the optimal conditions for ultrasound-assisted extraction, achieving a phenolic substance extraction rate of 18.23 mg GAE/g DW. Adsorption kinetics and thermodynamics models identified ADS17 as a macroporous adsorption resin suitable for purifying macadamia green bark polyphenols. Liquid mass spectrometry revealed 60 phenolic substances, including antioxidants like 3,4-dihydroxybenzaldehyde, vanillic acid, p-hydroxybenzoic acid, gallocatechin, and proanthocyanidin B1. The study found a significant positive correlation between antioxidant activity and the content of catechin and proanthocyanidin B1.