Title : Development of an Extruded Product using Stem and Rootstock from Apio Criollo Arracacia xanthorrhiza
Abstract:
Apio criollo (Arracacia xanthorrhiza) grown in Puerto Rico has a unique structure with three distinctive fractions: stem, rootstock and storage roots. The main component of this root-crop is carbohydrates, but from a nutritional viewpoint it represents a good source of fiber. The rootstock is commonly consumed boiled in artisanal dishes; however, the stem and storage root are not fully exploited. The aim of this study is to provide an alternative to Arracacia xanthorrhiza perishability through dehydration process and extrusion cooking while incorporating both rootstock (75%) and stem (25%). The raw material of Arracacia xanthorrhiza was processed into flour for the determination of physicochemical properties, thermal properties and the development of the expanded snack. Amylose and amylopectin content, available starch and sugar content were determined. A single screw laboratory extruder and a central composite rotatable design were used, where the independent variables examined were feed moisture (10 to
14%) and temperature of the barrel central zone (140 to 160ºC). The extrusion was optimized by response surface methodology (RSM). Pre-extrusion flavoring technique was used by adding aroma precursors cysteine (0.2g/100g) and butyric acid (0.4g/100g) to the flour 24 hours prior to extrusion. After extrusion, salt (1.0g/100g) and sunflower oil (6g/100g) were added to the snack. The protein and fiber content obtained for the apio criollo flour ranged from 2.12% to 6.69% and 1.93% to 2.20%, respectively. The available starch content for stem and rootstock were not significantly different. In terms of the thermal properties determined, initial and final gelatinization temperatures for stem and rootstock were 54.3ºC and 63.5ºC, and 53.1 ºC and 61.4ºC, respectively. The highest expansion index and best texture were obtained at feed moisture content of 11% and central zone temperature of 150ºC. This study showed that Arracacia xanthorrhiza flour can be used as a substitute to conventional flours in the development of products with higher nutritional value. Moreover, it was demonstrated that through conditions that promote the maximum expansion ratio, extrusion cooking and pre-extrusion flavoring produced a highly acceptable expanded snack based on apio criollo.
