The contribution of P. acidilactici, L. plantarum, and L. curvatus starters and L-(+)-lactic acid to the acrylamide content and quality parameters of mixed rye - Wheat bread

doi:10.1016/j.lwt.2017.02.005

LWT

Volume 80, July 2017, Pages 43-50

https://doi.org/10.1016/j.lwt.2017.02.005 Get rights and content

Highlights

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Spontaneous rye sourdough is a good source for the isolation of acid tolerant LAB.
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P. acidilactici, L. plantarum, L. curvatus have versatile carbohydrate metabolism.
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Isolated LAB could be used for the production of rye sourdough.
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Rye flour - selected LAB sourdough improves the quality of bread.
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Selected LAB strains could be recommend for acrylamide reduction in bread.

Abstract

Lactic acid bacteria (LAB) from spontaneous rye sourdough were isolated, identified, and characterized by their growth, acidification rate, and carbohydrate metabolism. The isolated LAB were used for production of rye sourdough, and the influence of sourdough on mixed rye - wheat bread quality and acrylamide formation was evaluated. In addition, comparative studies by using acidification with L-(+)-lactic acid for mixed rye – wheat bread production were performed.

Isolated LAB (P. acidilactici, L. plantarum, L. curvatus) demonstrated versatile carbohydrate metabolism, grown at 30 °C and 37 °C, and acidic tolerance. When the isolated strains were used for rye sourdough production, they showed good growth, acidification rates while excreting amylolytic and proteolytic enzymes. Rye sourdoughs delay bread staling, and there was a significant effect of type of dough acidification (with LAB or L-(+)-lactic acid) and the quantity of acidification agent used (5% or 15%) on most of the analyzed bread quality parameters. L. plantarum sourdough (added in the amount of 5% and 15%) decreased the acrylamide content in bread samples (p < 0.0001), unlike dough acidification with L-(+)-lactic acid. Thus the selected LAB could be recommended for improving the quality of bread, including the reduction of acrylamide content.

Introduction

Among the many types of bread baked worldwide, one of the most popular varieties in the countries of Northern Europe is mixed rye – wheat bread. This type of bread is of higher nutritional value than those made from refined wheat flour only, which contains only the endosperm of wheat grains. The wholemeal rye flour provides good bread in terms of nutritional value and health benefits, while, refined wheat flour has higher energy content and enhances the porous texture of bread. Since the market demand for pure wheat flour bread is better than that of wholemeal rye flour bread, there is a reasonable market for mixed rye – wheat bread as well.

The recent consumer trend towards foods that are marketed as “natural” seeks additional health benefits beyond the basic nutritional requirements, and one of the possibilities to ensure the quality and safety of bread in a natural way is the selection and application of suitable lactic acid bacteria (LAB) starters for the production of such bread. LAB starters could improve the quality of bread in several different ways: by increasing dough elasticity, specific volume of loaves, reducing the hardness of bread crumb and delaying the staling process during storage, and by decreasing the acrylamide content in the bread (Bartkiene et al., 2013). Metabolism of carbohydrates during fermentation depends on the particular LAB strain, and not just affects the quality parameters of bread, but also the formation of acrylamide. The European Food Safety Authority (EFSA) Panel on Contaminants in the Food Chain has endorsed its draft Scientific Opinion on the risks to public health related to the presence of acrylamide in food, and has confirmed that acrylamide is genotoxic and carcinogenic (EFSA, 2015). Acrylamide is formed during the Maillard reaction involving sugar-derived carbonyl compounds and asparagine. On the other hand, during this reaction desirable flavors associated with baked bread are also formed. Bread contains relatively low levels of acrylamide, but as a staple of diet in many regions of the world it is a main contributor to total dietary intake of acrylamide. The reduction of acrylamide levels in bread thus remains a very important issue.

In this study LAB from spontaneous rye sourdough were isolated, identified, and characterized by their growth, acidification rate, and carbohydrate metabolism. The isolated LAB starters were used for production of rye sourdough, and the influence of sourdough on mixed rye - wheat bread quality parameters and acrylamide formation was evaluated. In addition, comparative studies by using acidification with L-(+)-lactic acid for mixed rye – wheat bread production were performed.

Section snippets

Materials used for sourdough and bread production

Rye flour (type 1370, falling number > 130 s, ash 1.31%), wheat flour (type 550D, falling number 350 s, gluten 27%, ash 0.68%) obtained from Kauno Grudai Ltd. mill (Kaunas, Lithuania) were used for the preparation of rye sourdough and baking of mixed rye - wheat bread.

Spontaneous rye sourdough preparation

Spontaneous rye sourdough was prepared by using the following scheme: mixing of 100 g rye flour with 1% of acetic acid, 1% of salt and 150 mL of water; fermentation for 48 h at 30 °C; addition of 50 g rye flour and 50 mL water;

The properties of isolated LAB strains

Sequencing according to 16S rDNA showed that the isolated LAB contained P. acidilactici, L. plantarum, and L. curvatus strains. Identification of the isolated LAB strains by using the BioNumerics v4.0 software package, as well as carbohydrate metabolism, gas production, tolerance to temperature and low pH conditions (pH 2.5 for 2 h of incubation) are shown in Table 1.

All the tested strains were able to ferment l-arabinose, d-ribose, d-galactose, d-glucose, d-fructose, d-mannose, N

Conclusions

P. acidilactici, L. plantarum, and L. curvatus strains demonstrated versatile carbohydrate metabolism, grown at 30 °C and 37 °C, and acidic tolerance, as well as a good growth rate, acidification rate, and excretion of amylolytic and proteolytic enzymes in rye sourdough. The use of rye sourdoughs delays bread staling, and there was a significant effect of type of dough acidification (with LAB or L-(+)-lactic acid) and the quantity of acidification agent used (5% or 15% of acidified sourdough

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View full text

The contribution of P. acidilactici, L. plantarum, and L. curvatus starters and L-(+)-lactic acid to the acrylamide content and quality parameters of mixed rye - Wheat bread

Highlights

Abstract

Introduction

Section snippets

Materials used for sourdough and bread production

Spontaneous rye sourdough preparation

The properties of isolated LAB strains

Conclusions

Food Control

FEMS Microbiology Letters

Trends in Food Science & Technology

International Journal of Food Microbiology

LWT - Food Science and Technology

FEMS Microbiology Letters

Enzyme and Microbial Technology

Food Chemistry

Trends in Food Science & Technology

International Journal of Food Microbiology

FEMS Microbiology Letters

Approved methods of the American Association of Cereal Chemists

Guidelines for measurement of volume by rapeseed displacement. Approved Methods of Analysis

Impact of sourdough on the texture of bread

Food Microbiology

Quality evaluation of the sourdough rye breads

The Annals of the University Dunarea de Jos of Galati Fascicle VI – Food Technology

Selection of promising lactic acid bacteria as starter cultures for sourdough: Using a step-by-step approach through quantitative analyses and statistics

Journal of the Science of Food and Agriculture