Comparisons of some functional and pasting properties of tiger nut (Cyperus esculentus) flours produced under different processing conditions

Abstract

Cyperus esculentus is an underutilized and readily available crop. Successful utilization of its flour for food products will depend on its functional and pasting characteristics which are usually affected by different processing conditions. The objective of this study, therefore, was to determine and compare the extent to which the different processing conditions will affect the properties of tiger nut flours. Fresh and dry yellow tiger nuts were purchased from the Ojo market in Ibadan, Nigeria. They were cleaned, sorted, washed, and separated into four major batches for both the fresh and dry samples. These were subjected to different processing conditions of fermentation, germination, and roasting. The untreated fresh and dry samples were used as controls. Flours were produced from the samples using standard procedures. The functional and pasting characteristics of the samples were evaluated. Water absorption capacity increased to 2.70 and 2.20 g/g for fresh roasted and dry fermented samples respectively. Oil absorption capacity increased to 1.40 g/g for the dry germinated sample and 1.35 g/g for dry fermented, dry roasted, and fresh fermented samples. There were increases in swelling power with germination, fermentation, and roasting. Peak viscosity increased from 710 to 779 RVU and breakdown from 6 to 14 RVU while setback decreased from about 90 to about 10 RVU with all processing methods. Final viscosity was generally not affected by all processing methods. The results of the pasting temperatures and peak time combinations indicated that the dry germinated sample will be easier to cook than all other samples.