Changes in size and chemical characteristics of roselle (Hibiscus sabdariffa L.) calyces during maturation

In the roselle plant (Hibiscus sabdariffa L.), the transition from flowering to fruiting is gradual, resulting in both mature and immature calyces during harvest. To determine optimal harvest time, changes in size (diameter and length) and chemical characteristics (dry matter, pH and anthocyanin content) of calyces of three ecotypes (China, Reina and Criolla) in nine stages of maturity (flowering stage and then every four days until 32 days after flowering) were analyzed. Calyx size increased progressively until 20 to 24 days after flowering (stages 6 and 7, respectively), but the increase in subsequent stages was not significant. Calyx diameters ranged from 14.34 to 30.96 mm and length from 18.60 to 56.76 mm. The Reina ecotype had larger calyces and China the greatest diameter. Anthocyanin content ranged from 205.93 to 1110.74 mg.100 g-1 of dried calyces; China had the highest content from flowering until stage 6, whereas in Reina it increased gradually until stage 7 and in Criolla it peaked in stage 4. Anthocyanin content decreased after 20 to 24 days of flowering. Dry matter content decreased as the calyces matured, falling from 17.86 % to 10.43 % throughout the maturation stages, while pH showed slight fluctuations with values from 2.11 to 2.81. These results suggest that calyces reach harvest maturity 20-24 days after flowering. ADDITIONAL