Evaluation of sweet potato cultivars and heating methods for control of maltose production, viscosity and sensory quality

Two varieties of sweet potato were subjected to four cooking temperature-time combinations. A fifth treatment involved adding maltose syrup. Raw comminuted sweet potato mash and cooked sweet potato puree were evaluated for total solids, alcohol insoluble solids, commonly occurring sugars, viscosity (puree only) and for starch gelatinization temperatures. The uncooked Owairaka Red variety was higher in total solids and in alcohol insoluble solids than the Toka Toka Gold. With the exception of the cooked puree with added maltose, baking at 200C resulted in puree with the highest maltose levels. A very fast cooking procedure tended to result in puree with lower levels of maltose and high viscosity. Sensory studies revealed that the Owairaka Red variety produced puree with more viscous and adhesive mouth feel. It was concluded that cooking alone could not be used to optimize both maltose production and viscosity.