Carotenoid contents of extruded and non-extruded sweetpotato flours from Papua New Guinea and Australia

摘要

Carotenoid contents of extruded and non-extruded flours of Papua New Guinean and Australian sweet-potato cultivars were studied, using spectrophotometry and high performance liquid chromatography (HPLC). The cultivars differed (p < 0.05) in their total carotenoid and p-carotene contents, and the Original Beauregard cultivar had the highest total carotenoid and p-carotene contents among the cultivars. The spectrophotometry (84-1720 μg/g solids) method generally over-estimated the total carotenoid content compared to the more specific HPLC (23-355 ug/g solids) method. Extrusion significantly (p < 0.05) decreased the ΔL~* Hunter colour values, while the Δa~*, Δb~*, total colour change (ΔE), chroma (CR), and browning indices (BI) increased. With the extruder and screw configuration used, extrusion at 40% moisture and 300 rpm screw speed retained carotenoid maximally at more than 80%. This study reports, for the first time, carotenoids of flours from south Pacific sweetpotato cultivars, and carotenoid retention during extrusion.