Cinética de secagem de resíduos de abacaxi (Ananas comosus L.) enriquecidos com a levedura saccharomyces Cerevisiae.

Abstract

Growing concerns with the environment have been mobilizing several segments of the market. Countless government offices and industries are preparing to employ an environmental politics that reduces negative impacts on nature. After they are generated, industrial residues need appropriate disposal for they create potential environmental problems and represent loss of raw materials and energy. Brazil is the largest producer of pineapple in South America and one of the largest in the world. The fruit is the marketable part of the plant; however, this portion represents only 23% of the plant total, while the remaining (formed by stem, leaves, peel, crowns and shafts) is considered agricultural residue and has not been properly used, thus, resulting in economic loss. The objective of this work was to study the drying of enriched pineapple residues (peel and crowns) by using Saccharomyces cerevisiae yeast in static bed in fine layer. In natura and enriched residues characterization consisted of the determination of moisture content, total titratable acidity, pH, ashes and organic matter, soluble solids (oBrix), neutral detergent fiber (NDF), acid detergent fiber (ADF), pectin, total reducer sugars (RS; TS), Dried matter and Rude protein. Desorption isotherms of in natura and enriched residues were determined in order to know the values of balance humidity, obtained through the gravimetric static method, at temperatures that ranged from 25 to 40 °C. The best fittings to data of desorption isotherms of humidity of in natura and enriched residues were obtained by using the GAB model. In the study of drying kinetics the methodology of factorial experimental planning 22 was used, which assessed temperature and air speed influences in the respouses: moisture content after 120 and 60 minutes for peel and crown, respectively, and protein of dried residue. Drying experiments were carried out with temperature varying from 40 to 60 °C and air speed from 0,8 to 1,8 m.s-1. According to data analyses, drying kinetics happened in the period of decreasing rate. The experimental data were adjusted to Page, Henderson & Pabis, and Lewis’ models, and the three represented experimental data satisfactorily. Influence of the variable temperature was verified only for the respouses variable humidity; no statistically significant influence of drying air speed was observed.