The Effect of Arabinoxylan and Wheat Bran Incorporation on Dough Rheology and Thermal Processing of Rotary-Moulded Biscuits.

María Teresa Molina,Pedro Bouchon,Deniz Z Gunes,Lisa Lamothe,Sandra M Vaz

doi:10.3390/foods10102335

María Teresa Molina, Pedro Bouchon + Show 3 more

Open Access

https://doi.org/10.3390/foods10102335

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Abstract

Wheat bran incorporation into biscuits may increase their nutritional value, however, it may affect dough rheology and baking performance, due to the effect of bran particles on dough structure and an increase in water absorption. This study analyzed the enrichment effect of wheat bran and arabinoxylans, the most important non-starch polysaccharides found in whole wheat flour, on dough rheology and thermal behaviour during processing of rotary-moulded biscuits. The objective was to understand the contribution of arabinoxylans during biscuit-making and their impact when incorporated as wheat bran. Refined flour was replaced at 25, 50, 75, or 100% by whole flour with different bran particle sizes (fine: 4% > 500 μm; coarse: 72% > 500 μm). The isolated effect of arabinoxylans was examined by preparing model flours, where refined flour was enriched with water-extractable and water-unextractable arabinoxylans. Wheat bran had the greatest impact on dough firmness and arabinoxylans had the greatest impact on the elastic response. The degree of starch gelatinization increased from 24 to 36% in biscuits enriched with arabinoxylans or whole flour and coarse bran. The microstructural analysis (SEM, micro-CT) suggested that fibre micropores may retain water inside their capillaries which can be released in a controlled manner during baking.

Highlights

Wheat bran constitutes about 16% of the weight of the wheat grain
The water-unextractable arabinoxylan (WUAX) fraction, an important structural component in the cell wall of the endosperm and bran [32], constituted the greatest proportion of arabinoxylans. These results align with those of Kiszonas et al [22] and Saulnier et al [33], who reported that soft whole flour contains about 3.5–5.9% total arabinoxylan (TAX) and 0.3–0.6% water-extractable arabinoxylan (WEAX), whereas refined flour contains about 2.2% TAX, and approximately 0.5% WEAX
A significant increase (p-value < 0.05) was observed in the water retained by flour blends enriched with whole flour, in particular at a replacement equal or over 50%

Summary

Introduction

Wheat bran constitutes about 16% of the weight of the wheat grain. It is the main by-product of wheat milling and is mostly used for animal feed [1]. Wheat bran is a convenient and inexpensive source of dietary fibre and of insoluble fibre, which has beneficial effects on human health. Said effects include the acceleration of intestinal transit time and prevention/relief of constipation, where coarse insoluble fibres (e.g., wheat bran) mechanically irritate the gut mucosa stimulating water and mucous secretion (as a defense mechanism to protect from abrasion), and gel-forming soluble fibres resist feces dehydration, resulting in hydrated, bulky and easy-to-pass feces [3,4]. Viscous-soluble fibres may reduce the serum total and LDL-cholesterol due to an increased binding of bile acids in the small intestine resulting in their subsequent excretion [5]

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