Characterization and comparison of tiger nuts (Cyperus esculentus L.) from different geographical origin Physico-chemical characteristics and protein fractionation

In the present work, four types of marketable tiger nuts (Cyperus esculentus L.) from different geographical origins (Spain, Burkina Faso and Niger) were compared according to their physico-chemical characteristics and protein characterization. All batches presented a mixture of tubers of different shape, size and weight, of which the Spanish were the largest. Differences observed between their colors pointed to the variability in the skin color of tiger nuts in the market. The Spanish tubers were the richest in fat and protein (35.21 and 8.45%, respectively), while similar values were observed in the African tubers (from 25.35 to 28.19% in fat and 3.28 to 7.32% in protein). Fairly low percentages of tannins and phytates were also detected in all of them (0.08-0.18 g/100 g and 9.31-22.55 mg/100 g, respectively). Similar results were obtained in the protein fractionation and characterization in tubers. These data showed the albumins to be the main protein fraction (82.23-91.93%), while globulins, prolamins and glutelins were represented by a remaining similar to 3-7.5%. Albumins were characterized by a wide range of different molecular weight polypeptides (20, 25, 37, 55, 75 and similar to 106 kDa), whereas in the other fractions, a lower number of bands was detected (at 18-78 kDa). These results suggested that physico-chemical characteristics and proximate composition of tiger nut batches in the current market are the most variable parameters, which are mainly dependable on their geographical origin. (C) 2014 Elsevier B.V. All rights reserved.