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
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
References (32)
- et al.
Study on the reduction of acrylamide in mixed rye bread by fermentation with bacteriocin-like inhibitory substances producing lactic acid bacteria in combination with Aspergillus Niger glucoamylase
Food Control
(2013) - et al.
Rapid species identification within two groups of closely related lactobacilli using PCR primers that target the 16S/23S rRNA spacer region
FEMS Microbiology Letters
(1998) - et al.
Generation of aroma compounds during sourdough fermentation: Applied and fundamental aspects
Trends in Food Science & Technology
(2005) - et al.
Evaluation of probiotic characteristics of newly isolated Lactobacillus spp.: Immune modulation and longevity
International Journal of Food Microbiology
(2011) - et al.
Characterization of lactic acid bacteria isolated from wheat bran sourdough
LWT - Food Science and Technology
(2016) - et al.
Identification of Pediococcus acidilactici and Pediococcus pentosaceus based on 16S rRNA and ldhD gene-targeted multiplex PCR analysis
FEMS Microbiology Letters
(1997) - et al.
Purification and characterisation of amylolytic enzymes from thermophilic fungus. Thermomyces lanuginosus strain ATCC 34626
Enzyme and Microbial Technology
(2002) - et al.
Acrylamide and 5-hydroxymethylfurfural formation during baking of biscuits: Part I: Effects of sugar type
Food Chemistry
(2016) - et al.
Sourdough volatile compounds and their contribution to bread: A review
Trends in Food Science & Technology
(2017) - et al.
Use of a species-specific multiplex PCR for the identification of pediococci
International Journal of Food Microbiology
(2008)
Rapid identification of 11 human intestinal Lactobacillus species by multiplex PCR assays using group- and species-specific primers derived from the 16S-23S rRNA intergenic spacer region and its flanking 23S rRNA
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
Cited by (41)
Unlocking the potential of low FODMAPs sourdough technology for management of irritable bowel syndrome
2023, Food Research InternationalCarcinogenic and neurotoxic risks of acrylamide consumed through bread, kaak, toast, and crackers among the Lebanese Population
2022, Regulatory Toxicology and PharmacologyRecent research advances of lactic acid bacteria in sourdough: Origin, diversity, and function
2021, Current Opinion in Food ScienceCitation Excerpt :In mixed rye-wheat bread, sourdough made by adding Lacp. plantarum at amounts of 5 and 15% significantly decreased the acrylamide content [41]. Fungus-induced spoilage is also a matter of continuing concern for both baked bread and Chinese steamed bread [42].
Industrial production of sourdoughs for the baking branch – An overview
2019, International Journal of Food MicrobiologyCitation Excerpt :One reason is the drop in pH, as it lowers the Maillard reaction rate by favouring protonation of the amine group of asparagine and therefore the formation of a Schiff base. However, chemical acidification is less effective in acrylamide reduction than biological acidification (Bartkiene et al., 2017), because in the latter sugars are consumed by microorganisms during fermentation. In baking, dried sourdoughs are used in low amounts (1–10% of flour) so they contribute only in small amounts to the acrylamide content of the final bread.
Strategies to Reduce Acrylamide Formation During Food Processing Focusing on Cereals, Children and Toddler Consumption: A Review
2024, Food Reviews InternationalFormulation and Processing Strategies to Reduce Acrylamide in Thermally Processed Cereal-Based Foods
2023, International Journal of Environmental Research and Public Health