Effect of extrusion parameters on some properties of dietary fiber from lemon (Citrus aurantifolia Swingle) residues

Abstract

Approximately 50% of the original whole fruit mass, after citrus processing for juice, consist of the peel, membranes and seeds. Citrus residues consist mainly of insoluble fiber (celluloses) and a small proportion of soluble fiber (hemicelluloses and pectin). For this reason, citrus residues could be considered as a potential high fiber ingredient that is used for food industry. In this study, lemon residues were extruded to modify and increase their soluble fiber fraction. Surface response methodology with six central points and six axial points was used to evaluate the changes in dietary fiber fractions in lemon residues. The independent variables studied were extrusion temperature (from 59.77 to 110.63°C), moisture content of the sample (from 33.18 to 66.82%) and screw speed (from 3.18 to 36.82). The extrusion process increased the soluble fiber from 38.60% in unprocessed lemon residues to 40.00 to 50.01% in extruded samples. The highest content of soluble fiber was 50.00% when operating conditions were high in temperature (100°C), low in moisture content (40%) and low in screw speed (10 rpm). The results of this study indicate that extrusion is a process that has the capability to transform insoluble fiber to soluble fiber in lemon residues.

Dietary Fiber Concentrates from Fruit and Vegetable By-products: Processing, Modification, and Application as Functional Ingredients

“…They observed a slight reduction in TDF content for all treatments; however, a maximum increase of 89% on the SDF fraction (from 20.1 to 37.9 g•100 g −1 dm, untreated and extruded, respectively) was achieved when processing the feedstock at 35% moisture, 150°C, and 140 rpm. A similar trend was observed by Méndez-García et al (2011) who found an increment of up to 30% of the SDF fraction in lime pomace (from 38.6 to 50.0 g•100 g −1 dm, untreated and extruded, respectively) extruded at 110°C and 30% moisture. Huang and Ma (2016) studied the effect of extrusion conditions in orange pomace using a single screw laboratory scale extruder (temperature 115-135°C, feeding moisture 10-18%, and screw speed 230-350 rpm).…”

Aprovechamiento De Las Propiedades Nutricionales Y Tecnológicas De La Fibra Dietética De Residuos Agroindustriales De Ecuador en La Industria Alimentaria

“…Las investigaciones presentadas en la Tabla 11 demuestran la aplicabilidad de los concentrados de fibra dietética en el país en diversos productos. La mayor parte de las cáscaras de frutas más cultivadas en el país y de las aplicadas en la fabricación de bebidas contienen valores iguales o superiores al 40 % en fibra dietética, siendo la cáscara de limón la más alta con 95,61 % (Méndez et al, 2011), lo que las hace una fuente importante de recursos para la creación de ingredientes alimentarios, sien do así se debería profundizar en su aplicabilidad en productos y en el estudio de sus propiedades según el tipo de fruta. El contenido de humedad, ceniza, grasa, proteína, carbohidratos y fibra en concentrados de fibra dietética obtenidos del procesamiento de cáscaras de fruta cambia según la fruta, lugar de cultivo y estado de maduración.…”