Quality Assessment and Comparative Analysis of Mineral, Amino Acid, Polyphenol and Antioxidant Activity in Different Varieties of Macadamia Nuts

This study investigated 11 types of macadamia nuts using advanced analytical techniques to quantify 17 minerals, 17 amino acids, and polyphenols, along with assessing their antioxidant activity. Employing multivariate statistical methods, including correlation analysis, principal component analysis, and cluster analysis, the intrinsic relationships and distinct characteristics among these indicators were explored. The results showed that the content of 9 harmful mineral elements in 11 types of macadamia nuts was within the safe allowable range, and they were rich in various beneficial mineral elements, especially the selenium content in varieties HAES294 and JW, which met the daily needs of the human body by more than 20% and had outstanding nutritional value. The amino acid ratio coefficients ranged from 28.22 to 60.01, with HAES508, A16, and HAES788 demonstrating high total amino acid content, suggesting significant protein nutritional value. Polyphenol content varied from 99.00 to 125.25 mg GAE/100 g, with HAES294 showing the strongest antioxidant activity across three evaluation methods. Correlation and principal component analyses revealed significant relationships among 35 indicators (P<0.05) and a highly significant correlation among 79 indicators (P<0.01), underscoring the interconnectedness of the 29 indicators. The top three varieties based on comprehensive scores were HAES508, A16, and JW, excelling in multiple functional metrics. The clustering analysis results divided the 11 macadamia nuts into three categories: the first category included A4, JW, HAES294, HAES508, HAES741, HAES788, HAES791, its antioxidant activity was outstanding, with abundant iron and zinc content, making it suitable for development as an antioxidant functional product; The second category covered A16 and Gui Re 1, which had high contents of amino acids, selenium, and phosphorus, and was suitable for making amino acid functional products; The third category consisted of OC and HAES695, which was rich in minerals such as sodium, potassium, magnesium, and calcium, and could be developed as mineral supplement products. This study systematically analyzes and evaluates the functional factor content and antioxidant activity of 11 types of macadamia nuts for the first time, clarifying the key indicator system and classification mode for evaluating the functional factors of macadamia nuts. It provides solid theoretical support for the development and processing utilization of refined macadamia nuts, and has important scientific value and practical guidance significance.