Variation in the Physical and Functional Properties of Yam (Dioscorea spp.) Flour Produced by Different Processing Techniques

Abstract

Research on the processing of yam (Dioscorea spp.) into flour is aimed at optimizing techniques to obtain a material with high physicochemical and functional properties. The present study investigates the effect of the processing techniques on the levels of inulin, organic acids, total phenolics (TP), antioxidant capacity, and polyphenol oxidase (PPO) and peroxidase (POD) activities, as well as on the physicochemical properties of flour derived from two yam species—Dioscorea esculenta and Dioscorea bulbifera. All tubers were peeled and sliced, then subjected to different processing techniques through blanching, soaking, and drying. The results revealed that freeze-drying appears to be the best technique in achieving the highest whiteness index of yam flour. This coincided well with the low phenolics content and POD activity, which suggests a reduced enzymatic browning reaction in the freeze-dried yam flour. On the other hand, chemical analyses showed that D. esculenta and D. bulbifera flours have the highest levels of inulin (23.0 and 27.8 g/100 g DW, respectively) and succinic acid (7.96 and 7.65 g/100 g DW, respectively) in the samples subjected to direct oven-drying. Oven drying without pretreatment neither blanching nor water steeping maintained antioxidant activity in the flour derived from both D. esculenta and D. bulbifera.

The Effect of Pre-Drying Treatment and Drying Conditions on Quality and Energy Consumption of Hot Air-Dried Celeriac Slices: Optimisation

“…The figures showed decreased %AA when higher drying temperature was applied; however, the %TPC of not pre-drying treated samples was relatively stable over the experimental region. Setyawan et al [88] also found that oven-dried samples without blanching or water-steeping before drying had the highest total phenolic compounds of yam flour because such pre-drying treatments caused the loss of phenolic compounds, which were watersoluble.…”

Dioscorea spp.: Comprehensive Review of Antioxidant Properties and Their Relation to Phytochemicals and Health Benefits

“…Processing techniques such as blanching, thermal treatment, soaking, oven-drying, and freeze-drying had different effects on the content of phenolics, DPPH • scavenging and polyphenol oxidase activity in D. esculenta and D. bulbifera tuber flour [124]. Chung et al [88] reported the effects of blanching, drying and extraction with 50% EtOH, hot water, and water on the antioxidant activities of Taiwanese yam (D. alata).…”

The effect of gembili flour (Dioscorea esculenta L.) substitution on dietary fiber contents, sensory, and chemical characteristics of cookies

“…Gembili tubers contain glucomannan, which can slow stomach emptying and is therefore a good diet component for people with diabetes (17,18). Gembili tubers have also been shown to have anticolon cancer activity (19) and can reduce menstrual pain and improve symptoms of premenstrual syndrome (20); furthermore, they contain phenolic components, alkaloids, succinic acid, saponins, and cardiac glycosides and have antioxidant and antidiabetic capacities (21,22). Unfortunately, the high potential of gembili tubers has not been widely utilized in processed food products.…”