ICYTAC   23898
INSTITUTO DE CIENCIA Y TECNOLOGIA DE ALIMENTOS CORDOBA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Modelado cinético de pardeamiento y encogimiento de rodajas de yacón
Autor/es:
LEÓN, ALBERTO E.; BUSTOS, MARIELA C.; PALAVECINO, PABLO M.
Lugar:
Córdoba
Reunión:
Congreso; VI Congreso Internacional de Ciencia y Tecnología de los Alimentos (CICYTAC 2016); 2016
Institución organizadora:
Ministerio de Ciencia y Tecnología de la Provincia de Córdoba
Resumen:
Yacon is a native root of the Andean region that offers nutritional benefits due to the high content of soluble fiber. However, it is poorly studied and underutilized, mainly due to the degradation of fructooligosaccharides and the high susceptibility to browning during processing. Also, presents a pronounced shrinkage during drying, because it is a plant material with high water content. The aim of this study was to investigate and kinetically model these two phenomena: browning and shrinkage. Yacon slices, 2.5 to 3.5 mm thickness, were evaluated for their rate of browning at 23 °C for 20 min (every 30 s) and shrinkage degree during drying at 65 ° C (300 s each) until constant weight on a moisture balance. Lyophilized tuber slices were rehydrated and color parameters changes (L*, a* and b*) and reduction of the slice area were evaluated. For this, images were acquired with a scanner (HP Scanjet G3010) and evaluated by ImageJ software (v1.51d). Different order kinetic models were adjusted using the Microsoft Excel Solver tool. Two distinctly different areas were detected in reference to the kinetics of color change: an external area adjacent to the pericarp and an internal, both with first-order kinetics. The outer ring is mainly characterized by the loss of luminosity of ~ 16% (k = 7.18 x10-3 s-1), the fast shift of a* values from green to red (k = 2.96 x10-3 s-1) and growth until 65% of the total sample area. The interior of samples also showed a marked reduction in luminosity (k = 2.65 x10-3 s-1), while during the first 360 s the green tone increased to subsequently retrieve a* value close to the initial. Furthermore, yellowness decreased ~ 20% (k = 3.40 x10-3 s-1). Drying the yacon slices to constant weight took 420 s from an initial water content of 70 %. Under these conditions, the slices exhibited an area reduction close to 20 %, following a first order kinetics with a K= 1.2 x10-3 s-1. The abrupt changes in color, texture and chemical composition of yacon should be carefully inhibited to ensure the main quality factors perceived by the consumer. Then, study of the kinetics of color deterioration and shrinkage constitutes a fundamental contribution to promote the production of new functional foods rich in this ingredient. Thus, it will be possible to predict the effect on the technological properties under different conditions of processing and storage. Keywords: yacon, shrinkage, browning, kinetic modeling, image analysis.