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Spanish team flags up ‘right’ formulation for functional bread

February 25th, 2011

A blend of oat, rye, and buckwheat flours with wheat flour ensures a bread with added value in terms of nutrition, palatability, shelf life and handling during processing, in comparison to bread from whole grain flours, finds a Spanish study.

The researchers, based at the Institute of Agrochemistry and Food Technology in Valencia, published their findings in the Journal of the Science of Food and Agriculture.

Scientific evidence shows that regular consumption of cereal-based foods provides health benefits, note the authors, citing previous findings that show intake of cereal-based products may help regulate blood glucose levels and manage obesity and lowers risk of mortality from cardiovascular disease.

As a result of this growing awareness, they argue, breads containing whole grain, multigrain or other functional ingredients are becoming more important in the bakery industry.

Crops such as buckwheat, oat, barley, spelt, rye, quinoa and amaranth constitute highly nutritional grain ingredients for healthy food production and special dietary uses, add the authors.

“The production of multigrain products makes it possible to increase both the variety of breads and the diversity in fermentable soluble fibres, particularly arabinoxylans and ?-glucans, and other bioactive components,” they commented.

The researchers said they aimed to explore the suitability of cereals and pseudocereals other than common wheat (oat, Kamut, spelt, rye, buckwheat) to be included in mixed matrices with wheat to produce baked goods that meet functional and sensory standards.

Their investigation involved the analysis of single and multigrain flours in doughs and breads in terms of nutritional added value, palatability, shelf and handling during processing.

Method

The suitability of minor/ancient cereals (rye, oat, Kamut wheat, spelt wheat) and pseudocereals (buckwheat) was assessed in single (100 per cent of wheat flour replacement) and multigrain matrices, said the researchers.

Commercial common wheat flour (white) and whole flours from spelt, Kamut, buckwheat, rye and oat were purchased from the Spanish market.

Bread dough consisted of fermented sponge, flour, water and salt. Sponge was prepared by mixing ingredients (50 per cent flour, 50 per cent water, 2 per cent commercial compressed yeast, flour basis) and fermented for 2 hours at 28°C, overnight at 5°C and 1.5 hours at 28°C before being added to the remaining ingredients (50 per cent flour, 50 per cent water, 1.5 per cent salt, flour basis) to make dough of a consistency of 500 BU.

They added that fermented doughs were obtained after bulk fermentation of 10 minutes, dividing (100 g of dough), moulding and proofing up to maximum volume increment (1 hour) and were baked at 170°C for 20 minutes to make bread.

For the preparation of multigrain breads, wheat flour was partially replaced with single minor cereals and pseudocereals to make quaternary grain flour blends, said the team.

“The substitution levels of the quaternary mixtures of oat, rye, buckwheat and wheat were (w/w/w/w) 15:15:15:55 (blend A), 20:20:20:40 (blend B) and 25:25:25:25 (blend C). Two trials were performed per baking test.”

And they explained that for common wheat flour replacement purposes a high-grade refined wheat flour was used to keep the viscoelasticity and gas retention ability of the basic wheat dough matrix as high as possible in order to avoid the diluting effect of bran on gluten strength in wholemeal wheat flours.

The researchers said that viscometric profile, dynamic and static rheological behaviour, crumb hardness and grain, sensory scores, antiradical activity and nutritional factors were measured to quantify significant differences among samples and to test the potential dietary added value of several minor grains.

“Sensory analysis of fresh breads was performed with a panel of eight trained judges,” they reported.

Results

In terms of single grain use in dough and bread from a nutritional and quality characteristic perspective, the team noted that oat and rye hydrated flours showed the best and the worst pasting and gelling characteristics respectively, while Kamut and spelt doughs achieved mechanical and fundamental rheological properties close to those obtained for wheat.

“Oat, rye and buckwheat gave stiff (high values for hardness and storage modulus) and less cohesive doughs, which may hinder dough machinability during processing,” commented the scientists.

They observed that oat, rye and buckwheat gave breads with enhanced nutritional features (high RS, mineral, bioactive component and dietary fibre contents, low eGI and HI) but tough and closed crumb grain and low ratings by consumers

And the researchers concluded that the quality profile the mix of oat, rye, buckwheat and common wheat flours of Blend B (20:20:20:40 w/w/w/w) was the most suitable to make highly nutritious (improved dietary fibre fractions, minerals and antioxidant activity, slower starch hydrolysis), palatable, bread with good shelf life and easy handling during processing.

 

Source: Journal of the Science of Food and Agriculture

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