The relationship of chlorination and protein and lipid content to baking quality of soft wheat flour

Abstract

The purpose of this research was to examine the relationship of the protein and lipid content of soft wheat flour to baking quality and their changes as a result of chlorination. Coker 916, soft red winter wheat, was grown under different fertilization treatments involving rate and application time to alter protein content. One-half of all flour treatments were subjected to chlorination.

The lipid and protein content, gliadin and glutenin composition, microstructure, rheological properties, ash, pH and color were examined. Baked angel food cakes were evaluated by volume, tenderness, color, cohesiveness, crumb structure and microstructure (SEM). Gelatinization temperatures of batters were measured by Differential Scanning Calorimetry (DSC). Sensory analysis was judged by quantitative descriptive analysis (QDA).

Increased levels of fertilization of the grain increased the protein content (8-11%) of the flour. Cakes from flours of Increased protein content were significantly lower in volume than cakes of flours of lower protein content. Chlorination decreased protein content in flour which affected the glutenin composition in some flours. Gliadin content remained unchanged. Doughs of chlorinated flours were significantly less stable as measured by mixing time stability and mixing time index.

Chlorination decreased the unsaturated fatty acid methyl esters (FAME). There was strong correlation between evenness of cell structure and the decrease of fatty acids 18:1, 18:2, and 18:3 with chlorination. Phospholipids which were qualitatively evaluated were implicated with cell evenness.

Cakes of chlorinated flours were significantly less in volume and tenderness, but the structure showed complete starch gelatinization, increased whiteness and cell evenness. Sensory data correlated significantly with objective data.

Chlorination of flour stabilized the structure of the baked product. Low protein and decreased FAME content improved the baking properties of the flour. Flours of lower protein and a lower lipid content that are chlorinated are recommended for baked products such as cakes and biscuits.