Physicochemical Characterization and Value-added Extrusion Processing of Fiber-rich Food Processing Byproducts

Increasing consumer demand for high fiber food products present the opportunity for the utilization of fiber-rich food processing byproducts as value-added ingredients. These low-cost nutritious ingredients are available in abundance, yet underutilized as food ingredients. Their composition varies significantly across sources, and thus their physicochemical properties, that can impact the characteristics of food products into which they are incorporated. This emphasizes the importance of characterization of their composition and physicochemical properties to understand their potential uses in foods, which was the first objective of this research. Eight byproducts from different sources (blueberry, cranberry, Concord grape, and apple pomaces; oat hull; sugarcane bagasse; pea hull; and potato skin) were analyzed and found to have significantly different composition and physicochemical properties. Three different clusters of these byproducts based upon their composition and physicochemical functional properties were obtained. This enabled us to assign ingredients in each cluster to potential end-uses. The inclusion of fiber-rich food processing byproducts in extruded snacks has posed a great challenge with the reduced expansion and thus poor textural quality of the extrudates enriched with fiber. This has led to lower consumer preference. Hence, the present study was aimed on exploring the potential of inclusion of fiber-rich byproducts in extruded snacks by evaluating the expansion characteristics of extrudates. Extrusion with varying screw speeds (150-250 rpm) was conducted in combinations of waxy and regular cornstarch with apple pomace and sugarcane bagasse in varying inclusion levels (0-30% w/w). Extrusion process responses and product responses were assessed. Higher initial and stable expansions were observed with apple pomace but also higher shrinkage compared to sugarcane bagasse. Inclusion of 15% w/w of apple pomace produced higher initial (4.24-5.38) and stable expansions (3.88-4.43) than control (3.90-4.54 and 3.82-4.27, respectively), with lower mechanical energy. This suggests the potential for apple pomace inclusion in puffed extrudates to obtain high quality products if the post-processing conditions can be controlled to avoid product shrinkage, providing opportunities for the food industry to produce high fiber extruded snacks with acceptable textural quality.