IMPROVEMENT OF THE RHEOLOGICAL PROPERTIES OF WHEAT FLOURDOUGHS CONTAINING VARIOUS CONCENTRATIONS OF GRAPE SEED FLOUR BYUSING GLUCOSE OXIDASE

2. International Conference on "Agriculture, Forestry & Life Sciences", Praha, Çek Cumhuriyeti, 18 - 20 Nisan 2019, ss.212-220, (Tam Metin Bildiri)

The purpose of this study was to improve the rheological parameters of the wheat flour dough

substituted with grape seed flours (GSF) by using glucose oxidase (GO). GSF were obtained by

separating, drying and grinding of the seeds from the grape pomace that is the by-product of wine

industry. Öküzgözü (red grape variety) seed flour (ÖSF) and Narince (white grape variety) seed

flour (NSF) was added at 0, 5, and 10% levels in replacement with bread wheat flour. GO was

added at 0, 50, and 100 ppm concentrations. The rheological properties of the dough, substituted

with ÖSF, NSF and GO were recorded in the texture analyser device by using Kieffer dough

extensibility system and the Dobraszczyk/Roberts (D/R) dough inflation system. The substitution of

ÖSF and NSF was showed a significant decreasing effect on the area (KArea) under Kieffer force–

distance curve simultaneously with the increase of the substitution level. Addition of 50 ppm GO in

to ÖSF doughs was led to a significant increase at both Kieffer maximum extensibility (Kext) and

KArea. (from 12.80 mm to 20.92 mm and from 164.57 g.s to 325.18 g.s respectively) while addition

of 100 ppm GO was not had a similar improving effect. On the other hand improving effect of GO

on NSF containing doughs were found at the 100 ppm usage levels of GO by measuring with

Kieffer dough extensibility system. Extensional rheology of experimental doughs was measured

with the D/R dough inflation system. The substitution of ÖSF or NSF had the significant effect

(P<0.01) of decreasing the tenacity (P, mm), extensibility (L, mm) and baking strength (W)

simultaneously with the increase of the substitution level. The advantage of using GO is clearly

evident in dough D/R inflation system values. With the addition of GO, P, L and W values of the

doughs increased significantly compared to the ones without GO. In particular, both P and W values

of 5% ÖSF or NSF doughs gave similar results with the control sample by using 50 ppm GO. On

the other hand, it was found that the rheological properties of dough containing 10% NSF and 10%

ÖSF could be partially improved in the case of using 100 ppm GO. As a conclusion, by regarding

Kieffer and D/R together; ÖSF or NSF at 5% levels can be added in to bread formulations to benefit

their functional properties without impairing dough rheological properties much more. Furthermore

rheological properties of their doughs can be improved by using 50 ppm GO.