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

Nurdi Setyawan,Yoshiharu Fujii,Sakae Suzuki,John Solomon Maninang

doi:10.3390/foods10061341

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.

Highlights

Indonesia has a wide variety of carbohydrate-rich foods, among which is yam tuber (Dioscorea spp.)
Functional properties of yam flour prepared by different processing techniques have been determined
Total phenolic content and succinic acid were highly preserved by direct oven drying without pretreatment

Summary

Introduction

Indonesia has a wide variety of carbohydrate-rich foods, among which is yam tuber (Dioscorea spp.). Antioxidant refers to a compound that can delay or inhibit the oxidation of lipids or other molecules by inhibiting the initiation or propagation of oxidative chain reactions and which can prevent or repair damage done to the body’s cells by oxygen. It acts by one or more of the following mechanisms: reducing activity, free radical-scavenging, potential complexing of pro-oxidant metals and quenching of singlet oxygen [13]. These findings underscore the potential use of yam tubers as an energy source, but as a component of a disease-preventive diet [14]

Methods

Results

Conclusion