Rheological and functional properties of composite sweet potato – wheat dough as affected by transglutaminase and ascorbic acid

Abstract

Effect of transglutaminase (TGM) and ascorbic acid (AA) on composite sweet potato - wheat dough functional and rheological properties was studied. Partial substitution of wheat flour with sweet potato flour at the level of 20 % significantly (P ≤ 0.05) reduced glutenin, gliadin, dough stability, protein weakening, storage modulus (G') and viscous modulus (G″). Mixolab revealed that both TGM and AA treated dough had stability and protein weakening closed to wheat dough (control), with TGM treated dough having the highest values. TGM Introduced new cross-link bonds as shown by the change of amino acid concentration, leading to an increase in storage modulus (G') and viscous modulus (G″), with G' being higher at all levels of TGM concentration. The opposite was observed for composite dough treated with AA as measured by controlled - stress rheometer. TGM treatment increased glutenin and gliadin content. Compared with the control, dough treated with AA exhibited high molecular weight of polymers than TGM treated dough. The results indicate that the TGM and AA modification of the mixolab and dynamic rheological characteristics (G' and G″) dependent on the changes of GMP, glutenin, gliadin and protein weakening in the composite dough. TGM and AA treatment could improve functional and rheological properties of sweet potato - wheat dough to levels that might be achieved with normal wheat bread. However, it's extremely important to optimize the concentrations of both additives to obtain the optimum response.

Nutrient and specification enhancement of fortified Asian noodles by chickpea flour substitution and transglutaminase treatment

“…In general, water absorption decreased with the increasing TGase dosage, regardless of the addition ratio of CF. Similar results have been reported on TGase-treated wheat-buckwheat flour, [33] wheatsweet potato flour, [34] and oat flour. [27] Development time is relevant to the necessary time to hydrate all the compounds in flour during mixing.…”

Changes in rheological properties of wheat due to storage

“…This also justified the highest breaking stress ( σ b ) of flour dough from this storage. The lowest cross‐over frequency and highest modulii also implies that the dough prepared from wheat stored under ambient conditions produces a resistant, rigid and stiff material …”

Functional properties of sweet potato flour and its role in product development: a review

“…[49] Setback viscosity is an index of retrogradation tendency of a paste prepared from a flour [32,36,50] and its value is related to the amylose content and retrogradation of starch. [6,20] Setback viscosity that ranged from 62 to 865 cP is reported by Nabubuya et al [22] for the flours of the sweet potato from different varieties. Fetuga et al [10] reported a range of 1.90 to 80.13 RVU for setback viscosity for sweet potato flours prepared from different varieties and using different drying methods (Table 3).…”

“…[3] Bread making potential of flour is largely related to the gluten proteins. [20] Gluten free products exhibits poor mouthfeel and flavor with low quality. However, tropical tubers flour do not have gluten that provides a stabilizing network for retention of gas during baking.…”

“…[49] However, long peak time is not desired in baking industries as its related to dough development time, in turn, that is related to high energy input. [20] The viscosity of the breakdown is an indicator of the paste's resistance to disintegration in response to heat and shear. [24,32] It's occurred as a result of holding slurries at high temperature and its difference between the peak viscosity and the trough viscosity.…”