Optimising White Wheat Bread Fortification with Vitamin D3 and Dietary Fibre: Balancing Nutritional Enhancement and Technological Quality

Abstract

Inadequate vitamin D and dietary fibre intake are growing public health concerns in Western countries, especially in regions with limited sunlight and diets rich in processed foods. Bakery products, widely consumed, offer a promising opportunity for nutritional fortification. This study explored the possibility of fortifying white wheat bread-a staple food but low in fibre-with vitamin D₃ and various dietary fibres (oat fibre, pectin, cellulose, and beta-glucan). The goal was to enhance its nutritional profile while maintaining desirable bread qualities. Using Response Surface Methodology (RSM), an empirical model, optimised the fibre combination. A range of dough and bread analyses were conducted-including assessments of gluten structure, starch pasting, fermentation activity, crumb hardness, specific volume, and colourimetry. The results showed fibre addition weakened the gluten network and altered starch properties (reduced peak, final and breakdown viscosities)-reducing loaf volume (4.2 ± 0.4 mL/g vs. 4.8 ± 0.1 mL/g for the control)-though to a lesser extent than in wholemeal bread (2.4 ± 0.1 mL/g), while vitamin D₃ inclusion had a minimal impact (4.0 ± 0.4 mL/g for white bread, 2.1 ± 0.0 mL/g for wholemeal bread). The study identified an optimal mix of soluble and insoluble fibres with vitamin D₃ that preserved the texture, crumb structure, and appearance of standard white bread. The final product offered fibre levels (Total Dietary Fibre, TDF = 10.72 ± 0.31 g/100 g bread, vs. 3.81 ± 0.06 g/100 g for the control) comparable to those of wholemeal bread (TDF = 9.54 ± 0.67 g/100 g), with improved texture and volume. This approach presents an effective strategy to enhance staple foods, potentially improving public health through better nutrient intake without compromising consumer acceptance.

Keywords: bread fortification; dietary fibres; response surface methodology; vitamin D deficiency; vitamin D3; wholemeal.

Figure A1

Correlation of fibre addition and bread quality characteristics in form of heat map obtained following the Design of Experiment (significance level α = 0.05). Red indicates positive correlation; blue indicates negative correlation.

Figure A2

Mixolab torque curves (Nm) over time (s) obtained using the “Chopin+” protocol, illustrating dough behaviour under combined mechanical and thermal stress.

Figure 1

Bread loaves obtained according to Design of Experiment (DoE) recipes. Run 7 is shown as representation of four centre points. Photo of run 14 is missing.

Figure 2

Gluten network development represented as torque (BU) profile over time (s) at 36 °C.

Figure 3

Starch pasting represented as viscosity (cP) profile over time (s).

Figure 4

Baked loaves. (A) White wheat bread (control), (B) fibre-fortified white wheat bread, (C) wholemeal bread, (D) vitamin D₃ + fibre-fortified white wheat bread, (E) vitamin D₃-fortified wholemeal bread.