Epazote solar drying under different conditions: Kinetics, modeling, and colorimetry

Abstract

Epazote (Chenopodium ambrosioides L.) is a plant used as a condiment in food and has antioxidant properties promoting human health. Unfortunately, epazote is highly perishable due to its high moisture content. In this work, epazote solar drying is carried out using two different dryers: an indirect solar dryer with a titanium oxide cover (SIT) and a direct one with a polycarbonate cover (SDP) to increase its shelf life. Titanium oxide is a novel material with thermal properties helping solar drying by allowing the preservation of epazote's medicinal and organoleptic properties, which is very sensitive to solar radiation. The drying kinetics show that both dryings were carried out in 2.6 hours, obtaining a final humidity of 0.9 and 0.4 g water/g ss in SIT and SDP, respectively. The highest drying rate (27 g water/g ss∙ hr) was achieved with the SIT. The model that best fit the drying kinetics for both cases was the Weibull model, with a minimum r2 of 0.9979. The colorimetric study found that the SIT allows a superior quality in the product with an ∆E of 9.56