Evaluation of the Impact of Solar Exposure on Soluble Solids, Fractal Dimension, and Colorimetry in Oca (Oxalis Tuberosa L.) Under High Altitude Conditions

Torres-Cruz E.; Guerra Lima S.R.; Torres-Cruz F.; Medina Espinoza W.T.; Mayta-Barrios N.Y. · Current Research in Nutrition and Food Science (2026) · DOI: 10.12944/crnfsj.14.1.25

Resumen

Oca (Oxalis tuberosa L.) is an Andean tuber traditionally sun-cured to enhance sweetness and sensory quality; however, quantitative evidence linking changes in total soluble solids (°Brix) with physical and colorimetric modifications remains limited. This study evaluated the effect of a 10-hour sun-curing process on four oca varieties by monitoring total soluble solids (°Brix), fractal dimension, and color attributes. Measurements were recorded every two hours during the sun-curing period and analyzed both individually and within a consolidated dataset. Results showed a consistent increase in total soluble solids (°Brix) across all varieties, with a strong positive correlation between °Brix values and sun-curing time (r = 0.88–0.94). Total soluble solids were strongly associated with fractal dimension and exhibited moderate-to-strong, variety-dependent correlations with color variation (r = 0.76–0.85), indicating that microstructural and chromatic changes accompany increases in °Brix during solar exposure. In contrast, tuber size parameters showed weak, non-significant correlations with °Brix (r < 0.30), suggesting that physical dimensions have limited influence on soluble solid accumulation. Overall, the consolidated analysis confirmed comparably consistent trends among varieties. These findings demonstrate that integrating physicochemical, fractal, and color-based indicators provides a robust approach for evaluating sun-curing effectiveness and postharvest quality in oca.

Instituciones: Universidad Nacional del Altiplano