Wet separation of wheat flours into starch and gluten fractions: the combined effects of water to flour ratio–dough maturation time and the effects of flour aging and ascorbic acid addition

Abstract

The process of making a dough, allowing time for maturation, dispersing the dough in water and wet sieving/washing to obtain a protein fraction and starch milk was studied using response surface methodology by changing the water to¯our ratio in dough making (400±710 g kg À1 ), maturation time (45±660 s) and the type of¯our. Two grades of bread wheat¯our and durum clear¯our were studied. The effects of aging at ambient temperature for up to 29 days and the addition of ascorbic acid at 100 or 500 mg kg À1¯o ur on separation behaviour were also studied for freshly milled high-grade (65% extraction) bread wheat¯ours at constant maturation time, 600 s, and at optimum farinograph water absorption value. The quantities and dry matter contents of the protein fraction and starch milk were measured; a sample of starch milk was centrifuged to obtain decantate, tailings and prime starch fractions, and the dry matter contents of each were determined. All the dried samples were also analysed for protein content. The fractional recoveries of dry matter and protein in the protein fraction, prime starch, tailings and decantate were calculated for each experiment. The acid values of our oils were also determined on some aged¯our samples. The results indicated superior separation characteristics in high-grade wheat¯our compared with lower-grade¯ours. The water to¯our ratio was more in¯uential than maturation time within the range studied. Contrary to the initial expectation, no statistically signi®cant effect of¯our aging was observed in the studies with no additive, and ascorbic acid addition was not found to improve the wet separation behaviour, the separation behaviour becoming even worse at the 100 mg kg À1 level. Acid value showed a slight increase with time.

Separation of bread wheat flours into starch and gluten fractions: effect of water temperature alone or in combination with water to flour ratio

“…A process similar to that described by Dik et al ,8 consisting of dough making with water at three or four levels of water to flour ratio in the vicinity of the OFWA, allowing 300 or 600 s for maturation, dispersing the dough and wet sieving with water in an amount three times the amount of flour, was used.…”

“…The model determination strategy described by Dik et al 8 with the following second‐order response surface equation as a starting point was used: where Y i are the objective functions and β 0 , β 1 , β 2 , β 12 , β 11 and β 22 are the model parameters. The model parameters, adjusted regression coefficient $(R_{\rm adj}^{2})$ and F reg (the ratio of the variance due to model to the variance due to residual error) were computed using Microsoft Excel Version 7.0, and Mathematica Version 2.2 was used to construct the three‐dimensional plots.…”

Migration of gluten under shear flow: Influence of process parameters on separation behaviour

“…All current processes produce waste streams, carrying soluble protein, damaged starch and fibre (Day, Augustin, Batey, & Wrigley, 2006). In most published research, conventional separation seems to be heavily dependent on the flour quality (Dik, Yöndem-Makascioglu, Aytac, & Kincal, 2002;Hamer, Weegels, Marseille, & Kelfkens, 1989;Kelfkens & Hamer, 1991;Weegels, Marseille, & Hamer, 1988). Process parameters (i.e.…”

Amidolysis of Oxirane: Effect of Protein Type, Oils, and ZnCl2 on the Rheological Properties of Cross-Linked Protein and Oxirane

“…Gluten can aggregate and forms new intermolecular disulphide bonds, which changes dough rheology and gluten extractability as a result of heating [8]. Wheat gluten can be isolated from wheat flour by washing away other flour components of the dough [9]. Vital gluten is a by-product of wheat starch industry and is commercially available.…”