Abstract The skimmed goat milk was submitted to the nanofiltration process using a volume reduction factor (VRF) equal to 2. It was verified a rapid decrease of the permeate flux at a low time, with a continuous flux, caused by the reversible resistance, which is characterized by the standard and complete blocking. The combined fouling model was evaluated, including complete pore blocking and cake filtration mechanism, which described the skimmed goat milk nanofiltration behavior. For the VRF equal to 2 was determined the total solids, protein, lactose, ash, mineral fraction content, which increased successfully with the nanofiltration process. The Power Law and Herschel-Buckley models were fitting to describe the flow behavior for retentate, which presented the higher apparent viscosity.

RESUMEN Antecedentes: los β-glucanos (1-3: 1-4) son fibras solubles aplicadas a los alimentos debido a sus propiedades tecnológicas (capacidad de retención de agua, viscosidad, emulsificación y estabilización) y a sus efectos beneficiosos en la salud. Las propiedades funcionales de los β-glucanos pueden perderse durante los procesos de extracción y purificación. La alta viscosidad de los β-glucanos está relacionada con un alto peso molecular y con sus propiedades fisiológicas en el intestino. Por lo tanto, caracterizar la fibra después de su extracción y purificación es fundamental para comprender sus posibles aplicaciones en alimentos. Objetivos: caracterizar β-glucanos extraídos (EβG) y compararlos con tres marcas comerciales (CβG-A, CβG-B y CβG-C) para identificar su futura aplicación en alimentos y evaluar si la purificación enzimática afecta molecular y estructuralmente los β-glucanos. Métodos: se extrajeron β-glucanos de cebada (EβG), caracterizados por análisis químicos, comportamiento reológico y color, y se compararon con tres muestras comerciales. Posteriormente, el extracto (EβG) se purificó y se identificaron sus características estructurales y su peso molecular. Resultados: EβG contenía 64.38 ± 3.54% de β-glucanos, alta contaminación con almidón (12.70 ± 1.73%), alto contenido de calcio (8894 mg / kg), comportamiento pseudoplástico y color oscuro (L* = 52.77 ± 0.7). Todas las muestras comerciales mostraron una baja contaminación con almidón, color más claro y comportamiento newtoniano. Después de la purificación de EβG, la contaminación con almidón y proteína disminuyó (0.85 ± 0.46% y 5.50 ± 0.12%, respectivamente), aumentó el contenido de βG (69.45 ± 0.81%) y aumentó su luminosidad (L* = 92.60 ± 1.70). Los β-glucanos purificados (PβG) mostraron un peso molar de 690 ± 1,6 kDa y se identificaron en la estructura especies con grado de polimerización desde 3 (GP3) hasta 11 (GP11). Conclusiones: los EβG antes de la purificación presentaron alta viscosidad y contaminación. El proceso de purificación enzimática fue efectivo y permitió mantener una alta masa molar de la fibra y sus estructuras moleculares características (especies con GP3 y GP4). Las muestras comerciales CβG-A y CβG-B mostraron un bajo contenido de β-glucanos. Finalmente, la CβG-C presentó las mejores propiedades fisicoquímicas y reológicas para su posterior aplicación en alimentos.

ABSTRACT Background: β-glucans (1-3: 1-4) are soluble fibers applied to foods due to their technological properties (water binding capacity, viscosity, emulsification and stabilization) and their beneficial effects on health. The functional properties of β-glucans can be lost during the extraction and purification processes. The high viscosity of β-glucans is related to a high molecular weight and its physiological properties in the intestine. Therefore, to characterize the fiber after its extraction and purification is fundamental to understand its possible applications in foods. Objectives: characterize β-glucans extracted (EβG) and compare them with three commercial β-glucans (CβG-A, CβG-B and CβG-C) to identify its possible applications in foods and to evaluate if enzymatic purification affects molecular and structurally the β-glucans. Methods: barley β-glucans were extracted (EβG), characterized by chemical analyzes, rheological behavior, and color, and compared to three commercial β-glucans samples. Then, the extract was purified and its structural and molecular characteristics were calculated. Results: EβG contained 64.38 ± 3.54% of β-glucans, high starch contamination (12.70 ± 1.73%), high content of calcium (8894 mg/kg), pseudoplastic behavior, and dark color (L* = 52.77 ± 0.7). All commercial samples showed low starch contamination, lighter color, and Newtonian behavior. After purification starch and protein contamination decreased (0.85 ± 0.46% and 5.50 ± 0.12% respectively), increased the content of βG (69.45 ± 0.81%) and increased brightness (L* = 92.60 ± 1.70). Purified β-glucans (PβG) showed a molar weight of 690 ± 1.6 kDa and species with degree polymerization 3 (DP3) to 11 (DP11) were identified on the structure. Conclusions: EβG extracts before the purification presented a high viscosity and contamination. The enzymatic purification process was effective and allowed to maintain a high molar mass of PβG and its distinctive molecular structures (species with DP3 and DP4). The commercial samples CβG-A and CβG-B showed a low content of β-glucans. Finally, CβG-C presented the best physicochemical and rheological properties for its subsequent application in food.