Chalk Yeasts Cause Gluten-Free Bread Spoilage
Four different yeast strains were isolated from industrial gluten-free bread (GFB) purchased from a local supermarket. These strains, including <i>Hyphopichia burtonii</i>, <i>Wickerhamomyces anomalus</i>, <i>Saccharomycopsis fibuligera</i>, and <i>Cyberlind...
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MDPI AG
2025-06-01
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| author | Michela Pellegrini Lucilla Iacumin Francesca Coppola Federica Barbieri Chiara Montanari Fausto Gardini Giuseppe Comi |
| author_facet | Michela Pellegrini Lucilla Iacumin Francesca Coppola Federica Barbieri Chiara Montanari Fausto Gardini Giuseppe Comi |
| author_sort | Michela Pellegrini |
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| description | Four different yeast strains were isolated from industrial gluten-free bread (GFB) purchased from a local supermarket. These strains, including <i>Hyphopichia burtonii</i>, <i>Wickerhamomyces anomalus</i>, <i>Saccharomycopsis fibuligera</i>, and <i>Cyberlindnera fabianii</i>, are responsible for spoilage, which consists of white powdery and filamentous colonies due to the fragmentation of hyphae into short-length fragments (dust-type spots) that is typical of the spoilage produced by chalk yeasts. The isolated strains were identified using genomic analysis. Among them, <i>C. fabianii</i> was also isolated, which is a rare ascomycetous opportunistic yeast species with low virulence attributes, uncommonly implicated in bread spoilage. The yeast growth was studied in vitro on Malt Extract Agar (MEA) at two temperatures (20 and 25 °C) and at different Aws (from 0.99 to 0.90). It was inferred that the temperature did not influence the growth. On the contrary, different Aws reduced the growth, but all the yeast strains could grow until a minimum Aw of about 0.90. Different preservatives (ethanol, hop extract, and sorbic and propionic acids) were used to prevent the growth. In MEA, the growth was reduced but not inhibited. In addition, the vapor-phase antimicrobial activity of different preservatives such as ethanol and hop extract was studied in MEA. Both preservatives completely inhibited the yeast growth either at 20 or at 25 °C. Both preservatives were found in GFB slices. Contrary to hop extract, 2% (<i>v</i>/<i>w</i>) ethanol completely inhibited all the strains. The spoilage was also confirmed by the presence of various compounds typically present in yeasts, derived from sugar fermentation and amino acid degradation. These compounds included alcohols, ketones, organic acids, and esters, and they were identified at higher concentrations in the spoiled samples than in the unspoiled samples. The concentration of acetic acid was low only in the spoiled samples, as this compound was consumed by yeasts, which are predominately present in the spoiled samples, to produce acetate esters. |
| format | Article |
| id | doaj-art-02932462a76b445bb5bb0b3c3a7d37d9 |
| institution | DOAJ |
| issn | 2076-2607 |
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| publishDate | 2025-06-01 |
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| spelling | doaj-art-02932462a76b445bb5bb0b3c3a7d37d92025-08-20T03:16:35ZengMDPI AGMicroorganisms2076-26072025-06-01136138510.3390/microorganisms13061385Chalk Yeasts Cause Gluten-Free Bread SpoilageMichela Pellegrini0Lucilla Iacumin1Francesca Coppola2Federica Barbieri3Chiara Montanari4Fausto Gardini5Giuseppe Comi6Department of Agricultural, Food, Environmental and Animal Science, University of Udine, 33100 Udine, ItalyDepartment of Agricultural, Food, Environmental and Animal Science, University of Udine, 33100 Udine, ItalyFood Sciences Institute, National Research Council, Via Roma, 64, 83100 Avellino, ItalyDepartment of Agricultural and Food Sciences, University of Bologna, 47521 Cesena, ItalyDepartment of Agricultural and Food Sciences, University of Bologna, 47521 Cesena, ItalyDepartment of Agricultural and Food Sciences, University of Bologna, 47521 Cesena, ItalyDepartment of Agricultural, Food, Environmental and Animal Science, University of Udine, 33100 Udine, ItalyFour different yeast strains were isolated from industrial gluten-free bread (GFB) purchased from a local supermarket. These strains, including <i>Hyphopichia burtonii</i>, <i>Wickerhamomyces anomalus</i>, <i>Saccharomycopsis fibuligera</i>, and <i>Cyberlindnera fabianii</i>, are responsible for spoilage, which consists of white powdery and filamentous colonies due to the fragmentation of hyphae into short-length fragments (dust-type spots) that is typical of the spoilage produced by chalk yeasts. The isolated strains were identified using genomic analysis. Among them, <i>C. fabianii</i> was also isolated, which is a rare ascomycetous opportunistic yeast species with low virulence attributes, uncommonly implicated in bread spoilage. The yeast growth was studied in vitro on Malt Extract Agar (MEA) at two temperatures (20 and 25 °C) and at different Aws (from 0.99 to 0.90). It was inferred that the temperature did not influence the growth. On the contrary, different Aws reduced the growth, but all the yeast strains could grow until a minimum Aw of about 0.90. Different preservatives (ethanol, hop extract, and sorbic and propionic acids) were used to prevent the growth. In MEA, the growth was reduced but not inhibited. In addition, the vapor-phase antimicrobial activity of different preservatives such as ethanol and hop extract was studied in MEA. Both preservatives completely inhibited the yeast growth either at 20 or at 25 °C. Both preservatives were found in GFB slices. Contrary to hop extract, 2% (<i>v</i>/<i>w</i>) ethanol completely inhibited all the strains. The spoilage was also confirmed by the presence of various compounds typically present in yeasts, derived from sugar fermentation and amino acid degradation. These compounds included alcohols, ketones, organic acids, and esters, and they were identified at higher concentrations in the spoiled samples than in the unspoiled samples. The concentration of acetic acid was low only in the spoiled samples, as this compound was consumed by yeasts, which are predominately present in the spoiled samples, to produce acetate esters.https://www.mdpi.com/2076-2607/13/6/1385chalk yeastsgluten-free breadspoilagepreservativesvolatile compounds |
| spellingShingle | Michela Pellegrini Lucilla Iacumin Francesca Coppola Federica Barbieri Chiara Montanari Fausto Gardini Giuseppe Comi Chalk Yeasts Cause Gluten-Free Bread Spoilage Microorganisms chalk yeasts gluten-free bread spoilage preservatives volatile compounds |
| title | Chalk Yeasts Cause Gluten-Free Bread Spoilage |
| title_full | Chalk Yeasts Cause Gluten-Free Bread Spoilage |
| title_fullStr | Chalk Yeasts Cause Gluten-Free Bread Spoilage |
| title_full_unstemmed | Chalk Yeasts Cause Gluten-Free Bread Spoilage |
| title_short | Chalk Yeasts Cause Gluten-Free Bread Spoilage |
| title_sort | chalk yeasts cause gluten free bread spoilage |
| topic | chalk yeasts gluten-free bread spoilage preservatives volatile compounds |
| url | https://www.mdpi.com/2076-2607/13/6/1385 |
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