Authenticity evaluation method for shiikuwasha (Citrus depressa Hayata) juice

Abstract

Shiikuwasha (Citrus depressa Hayata) has attracted attention in recent years for its anti-cancer, anti-inflammatory, and other health-promoting properties, leading to a rapid increase in demand and a chronic shortage of fruit for processing. To compensate for this shortage, adulteration of shiikuwasha juice with calamondin (Citrus madurensis Lour.) juice has become a major concern. The aim of this study was to develop a reliable methodology to assess the authenticity of shiikuwasha juice. The developed approaches include: (1) sensory evaluation, a low-cost and direct technique capable of detecting contamination levels above 50% in calamondin juice; (2) a thin-layer chromatography (TLC) method developed to detect 3',5'-di-C-β-glucopyranosylphloretin, a chemical marker specific to calamondins; and (3) high performance liquid chromatography (HPLC) and solid-phase microextraction–gas chromatography (SPME-GC) methods to identify polymethoxyflavonoids and γ-terpinene, the main characteristic compounds of shiikuwasha, as chemical markers. To further ensure product authenticity, DNA marker-based methods have also been developed. It is anticipated that these evaluation methods will be extensively employed in a wide range of fields, from production and processing to distribution, in order to accurately identify shiikuwasha products.