Impact of variety type and particle size distribution on starch enzymatic hydrolysis and functional properties of tef flours

Abstract

Tef grain is becoming very attractive in the Western countries since it is a gluten-free grain with appreciated nutritional advantages. However there is little information of its functional properties and starch digestibility and how they are affected by variety type and particle size distribution. This work evaluates the effect of the grain variety and the mill used on tef flour physico-chemical and functional properties, mainly derived from starch behavior. In vitro starch digestibility of the flours by Englyst method was assessed. Two types of mills were used to obtain whole flours of different granulation. Rice and wheat flours were analyzed as references. Protein molecular weight distribution and flour structure by SEM were also analyzed to justify some of the differences found among the cereals studied. Tef cultivar and mill type exhibited important effect on granulation, bulking density and starch damage, affecting the processing performance of the flours and determining the hydration and pasting properties. The color was darker although one of the white varieties had a lightness near the reference flours. Different granulation of tef flour induced different in vitro starch digestibility. The disc attrition mill led to higher starch digestibility rate index and rapidly available glucose, probably as consequence of a higher damaged starch content. The results confirm the adequacy of tef flour as ingredient in the formulation of new cereal based foods and the importance of the variety and the mill on its functional properties.

Effect of tef [Eragrostis tef (Zucc.) Trotter] grain flour addition on viscoelastic properties and stickiness of wheat dough matrices and bread loaf volume

“…A general-purpose bread improver Toupan Puratos® (Puratos, Barcelona, Spain) containing mono-and diglyceride of fatty acids, ascorbic acid, α-amylase and xylanase was used. The chemical compositions of the three tef variety grain flours were reported in Abebe et al [2]. The wheat flour used in this study contained 12.2 % moisture, 14.5 % protein, 0.66 % ash, 1.47 % fat, 85.1 % carbohydrate and 78.8 % starch, and its starch had 23.2 % of amylase.…”

“…The mean particle size (D 50 ) and size dispersion of the flours were reported in [2] as 90.7 μm and 2.17 for DZ-01-99, 94.7 μm and 2.14 for DZ-Cr-37 and 94.2 μm and 2.10 for DZ.Cr-387, respectively.…”

“…Hence, based on such as polyphenols and phytates [6]. In addition, tef grain and derived starch have suitable techno-functional properties like high water absorption capacity, foaming stability and a slow amylose retrogradation, dependent on tef variety type, that could have a positive impact on the quality of cereal-based products [2,8]. These merits of tef make the grain a good alternative ingredient in addressing the aforementioned demand.…”

Teff: Suitability for Different Food Applications and as a Raw Material of Gluten-free, a Literature Review

“…Teff grain (Figure 1) size is known to be extremely small with mean length ranging 0.61-1.17m and mean width ranging 0.13-0.59mm, that gives an average thousand kernel weight of 0.264g [10]. Teff grain commands premium price among other cereals cultivated in Ethiopia.…”

“…The grain proteins offer an excellent balance among the essential amino acids [10]. Teff is rich in carbohydrates, fibre and has a complete set of essential amino acids.…”