Physical, colour, and mechanical properties of pearls (citrus caviar) from three finger lime (Citrus australasica) varieties: Implications for economic value, quality grading, and benchmarking

Citrus australasica, the Australian finger lime or caviar lime have garnered interest both in culinary and scientific communities. Despite extensive studies on their metabolomic and volatilomic profiles, research on the physical properties of finger lime pearls, especially their diameter, colour, and mechanical properties, remains limited. Understanding these attributes is crucial for quality assessment, consumer preference, and marketability in the food industry. This study aims to investigate the diameter, visual appearance, and mechanical properties of finger lime pearls from three different varieties (‘Champagne Red’, ‘Emerald’, and ‘Chartreuse’), comparing them with similar foods and assessing their implications for culinary use and market value. Colour properties were analysed using the CIELAB system, and mechanical properties were assessed through texture analysis, focusing on bursting strength and strain. Finger lime pearl diameters ranged between 1.62 and 3.60 mm, aligning with sizes of comparative foods. Colour analysis revealed distinct differences among varieties. Mechanical properties, particularly bursting strength, and strain, varied significantly across varieties, with ‘Champagne Red’ and ‘Chartreuse’ showing higher bursting strengths. These properties suggest different culinary applications and potential for a grading system based on sensory experience. The study highlights the importance of physical and mechanical properties in determining the quality and marketability of finger lime pearls. It introduces a novel framework for assessing these attributes, suggesting that finger lime varieties can be differentiated and graded for culinary use based on pearl diameter, colour, and mechanical properties. This research lays the groundwork for future sensory-based studies and the development of quality grading systems for finger limes.