Two papers have been published about impact of wheat bran bioprocessing: on nutritional qualities of bran (Coda et al 2014) and on dough and wheat bread quality (Hartikainen et al 2014). The work of Coda et al (2014) is a continuation to that of Nordlund et al (2013) in revealing effects of bioprocessing on the nutritional value of bran.
Coda et al (2013) studied the influence of bioprocessing on the nutritional quality and health effects of wheat bran of different particle sizes (750, 400, 160, 50 μm). Bioprocessing was carried out by a 24 h-fermentation using Lactobacillus brevis E95612 and Kazachstania exigua C81116 as starters, with or without the addition of an enzyme mixture with specific carbohydrase activities. Bioprocessing clearly affected the microstructure and chemical and nutritional features of wheat bran depending on the particle size. Bioprocessing significantly improved the antioxidant and phytase activities (up to 3.7 fold, respectively), peptides and total free amino acids and content (up to 40%) and the in vitro digestibility of proteins. The antioxidant power and nutritional indexes were higher for the bioprocessed brans compared to the native, mainly in bran having smaller particle size. In every case, the addition of the enzymes further improved the positive effect of the microbial fermentation.
Hartikainen et al (2014) aimed to assess the influence of wheat bran addition on the rheological properties of dough and on subsequent wheat bread volume and texture. Two types of bioprocessed bran (fermentation with yeast or with yeast plus enzymes) were studied in breadmaking at a substitution level of 20%. This amount is sufficient to deliver 6 g of dietary fiber per 100 g of product which is the minimum amount for the European Food Safety Authority high-fiber nutrition claim. Fermentation activated endogenous enzymes of bran, which together with exogenous enzymes modified the state of fiber in bran, resulting in solubilization of arabinoxylans and slight degradation of the insoluble fiber. Fermentation and enzyme treatment of bran compensated for the increased hardness (+100%) and the volume-decreasing (–21%) effect observed with untreated bran. Analysis with partial least squares regression suggested the efficacy of bioprocessing to be based on solubilization of arabinoxylans, smaller particle size of bran, lower pasting viscosity of starch, improved resistance to extension, and accelerated CO2 production.
Coda, R., Rizzello, C. G., Curiel, J. A., Poutanen, K., & Katina, K.Effect of bioprocessing and particle size on the nutritional properties of wheat bran fractions. Innovative Food Science & Emerging Technologies, (In press)
Nordlund, E., Katina, K., Aura, A., & Poutanen, K. (2013). Changes in bran structure by bioprocessing with enzymes and yeast modifies the in vitro digestibility and fermentability of bran protein and dietary fibre complex. Journal of Cereal Science, 58(1), 200-208.
Hartikainen, K., Poutanen, K., Katina, K. (2014). Influence of Bioprocessed Wheat Bran on the Physical and Chemical Properties of Dough and on Wheat Bread Texture. Cereal Chemistry, 91(2), 115-123.
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