EXPERIMENTAL STUDY OF THE DEHYDRATION OF STEVIA LEAVES (REBAUDIANA BERTONI), UNDER CONTROLLED CONDITIONS AND WITH A TUNNEL-TYPE SOLAR DRYER

• DOI: 10.22533/at.ed.3173282323081

• Palavras-chave: Solar drying, stevia solar drying, indirect solar drying, solar tunnel drying.

• Keywords: Solar drying, stevia solar drying, indirect solar drying, solar tunnel drying.

• Abstract:

  Sugar is a natural sweetener, with a high caloric content and its consumption has been associated with some health problems such as obesity, diabetes, heart disease and degenerative diseases. In recent years, various studies have been carried out to find a substitute, resulting in many natural and artificial sweeteners. Among these alternatives is the natural sweetener obtained from the stevia plant (Rebaudiana Bertoni) with zero caloric intake and harmless, with properties such as: oral antibacterial, hypoglycemic, hypertensive and anti-stress. The dry leaves contain 9 to 13% steviolglycosides (sweeteners), the stem less than 3% and nothing in the roots. This paper presents the characteristics and kinetics of dehydration of stevia leaves, using a non-convective oven at controlled temperature conditions: 45, 55 and 65 °C, with drying times of 240, 330 and 420 minutes respectively, and a tunnel-type solar dryer with drying times between 70 and 210 minutes. The initial moisture contents varied between 82 and 85% and the final ones between 10 and 13% on a wet basis, respectively. The tests were carried out in the Solar Drying Laboratory of the Institute of Renewable Energies, IER, of `` Universidad Nacional Autónoma de Mexico`` in Temixco, Morelos. Mexico, located at 18º 51' from NL and 99º 14' from LO, with a warm dry climate, with an average annual relative humidity of 50% and with average maximum irradiance values of 950 W/m2. The results obtained show the technical feasibility of solar drying stevia leaves, obtaining added value and encouraging its production in Mexico.