Bread mold delayed with prawn by-product chitosan, find Teagasc researchers

By Oliver Nieburg

- Last updated on GMT

Chitosan is the second most abundant polymer in nature. It provides structural support to crustacean shells and for Basidomycete mushroom stalks.
Chitosan is the second most abundant polymer in nature. It provides structural support to crustacean shells and for Basidomycete mushroom stalks.

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The polymer chitosan acts as an antimicrobial agent in bread to inhibit mould and rope formation, according to new research by scientists at the Irish Agriculture and Food Development Authority Teagasc.

Findings published online ahead of publication in the Journal of Agricultural and Food Chemistry ​said that replacing 1% of flour with chitosan could held bread withstand mold for three days at 30°C in an incubator compared to just one day for control bread.

“Chitosan bread was made with the potential to extend the shelf life of bread without adversely affecting the taste and structure of bread,”​ said the article by Lafarga et al.​ at Teagasc.

“These results showed that the inclusion of chitosan (1%) into bread formulations produced a slight decrease in loaf specific volume but has no significant effect on the overall quality or acceptance of bread.”

Previous studies had suggested that adding chitosan to bread produced a much darker color, but the Teagasc researchers found no significant variations compared to a control loaf. The texture was also said to be largely unchanged.

Preventing rope spoilage

The researchers tested chitosan bread compared to a control loaf in an incubator at 30°C to recreate conditions conducive to rope spoilage.

Rope spoilage, the most common bacterial decomposition of bread, typically occurs under warm conditions, which allow the dangerous bacterium Bacillus cereus to grow.

The researchers found that chitosan was twice as effective at delaying rope spoilage in bread compared to a standard loaf.

With the daily trip to the bakery no longer the norm and the industry making efforts to limit use of shelf-preserving additives, chitosan could prove a natural alternative.

Chitosan bread health benefits

Chitosan has been added to bread formulations before and has been suggested to produce some positive health effects.

A 2003 study by Ausar et al. ​found that chitosan-containing bread decreased LDL-cholesterol in type 2 diabetics. Kerch et al​.​ 2010 also said that chitosan breads had a higher content of antioxidants in the crust compared to non-fortified bread.

J. Agric. Food Chem.,​ Just Accepted Manuscript
DOI: 10.1021/jf402248a
'Chitosan-containing bread made using marine shellfisheries byproducts: functional, bioactive and quality assessment of the end product’
Authors: Tomas Lafarga, Emeir Gallagher, Desmond Walsh, Juan Valverde, and Maria Hayes

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Chitosan inhibition of bread mould

Posted by Maria Hayes,

Bread mould is caused by the fungal mould Rhizopus stolonifer - a Mucorale. Mould and mushrooms, especially the Basidomycetes, contain chitin, often in the form of chitin-glucan. Previous studies carried - out by Hernández-Lauxardo et al (Fruits, Volume 4, July 2010, 245-253), identified that chitosan at a concentration of 2mg/ml prevented the growth of Rhizopus stolonifer on peach, papaya and tomatoes. This is the same agent that causes black bread mould, caused by the chitosan containing mould Rhizopus stolonifer. Chitosan use as an antifungal agent is well known. The antifungal activity of prawn derived chitosan may be due to the degree of acetylation and molecular weight of this and the difference between it and the DA of the Rhizopus stolonifer chitosan, if present. The study did not access the fatty acid content of the chitosan but it is unlikely that antimicrobial activity is present due to the chitosan extraction procedure used.

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Chitosan inhibition of bread mold

Posted by G.L.Cuffari,

It would seem unlikely that chitosan itself (a partially de-acetylated heterpolymer of N-acetylglucosamine) is the active compoound providing inhibitory effect on the growth of mold. Chitosan is a naturally occurring polymer found not only in shrimp shells, but also in the cell walls of certain varieties of common mold, notably the Mucorales, strains often associated with bread spoilage. More likely, the effect observed is due a secondary substance, perhaps a fatty acid, present in the chitosan, which is underlying the growth inhibiting properties. I suggest addtional investigation be undertaken to confirm or refute this association.

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