Towards the development of a starter culture for improvement of grain storage through biopreservation
In temperate countries such as Sweden, where much rain falls during the harvest period, problems can occur later during preservation of feed grains because of too high water contents in the grains. Drying by heated air is the most commonly used operation in Sweden to reduce water content in grains....
| Autor principal: | |
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| Formato: | Otro |
| Lenguaje: | sueco Inglés |
| Publicado: |
2009
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| Materias: | |
| Acceso en línea: | https://stud.epsilon.slu.se/11794/ |
| _version_ | 1855571940746461184 |
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| author | Larsson, Malin |
| author_browse | Larsson, Malin |
| author_facet | Larsson, Malin |
| author_sort | Larsson, Malin |
| collection | Epsilon Archive for Student Projects |
| description | In temperate countries such as Sweden, where much rain falls during the harvest period, problems can occur later during preservation of feed grains because of too high water contents in the grains. Drying by heated air is the most commonly used operation in Sweden to reduce water content in grains. If airtight storage is used instead, energy and money can be saved, as airtight storage only consumes 2 % of energy needed for heated air drying.
Through biopreservation, where added microorganisms enhance the stability of the cereals in the airtight storage system by preventing mould growth, a more stable preservation can be obtained. To achieve a safe storage, insensitive to air leakage, the starter culture must work properly independently of the moisture content in the grains. To expand the acceptable region of moisture content, combinations of several organisms can be used as a starter culture. A mixture of the yeast Pichia anomala J121, a lactic acid bacteria (LAB) and a propionic acid bacteria (PAB) may be an ideal starter culture, as the yeast can work in relative dry grains and the bacteria in more moist grains. However, having several organisms in the starter culture can cause problems. For example, P. anomala J121 can metabolize lactic acid produced by LAB, as oxygen enters the system in the moist grains. This results in an increase in pH, allowing detrimental organisms to grow. The ability of different LAB and PAB isolates to inhibit P. anomala J121 was therefore investigated. Slight inhibition of the yeast was only observed for Propionibacterium freundenreichii subsp. shermanii MP5, P. freundenreichii MP23 and P. thoenii MP11. To work as a starter culture, the microorganisms must be able to grow and produce organic acids and/or other antifungal compounds. Therefore, we investigated the ability of different combinations of PAB, Lactobacillus plantarum MiLAB393(pLV100) and P. anomala J121 to inhibit the mould species Penicillium roqueforti J5 at moisture contents of 25 % and 33 % in a mini silo system. The mould growth was mainly affected by P. anomala J121. Since the yeast seemed to have lower ability to grow at moisture content of 33 %, a starter culture with several organisms seems to be preferred. Of the PAB investigated in the study, Propionibacteria thoenii MP11 is the most suitable PAB in a starter culture, due to its ability to grow and produce organic acids. However, additional LAB and PAB need to be characterized and tested in different combinations. |
| format | Otro |
| id | RepoSLU11794 |
| institution | Swedish University of Agricultural Sciences |
| language | Swedish Inglés |
| publishDate | 2009 |
| publishDateSort | 2009 |
| record_format | eprints |
| spelling | RepoSLU117942017-10-17T07:32:48Z https://stud.epsilon.slu.se/11794/ Towards the development of a starter culture for improvement of grain storage through biopreservation Larsson, Malin Dept. of Microbiology Handling, transport, storage and protection of agricultural products In temperate countries such as Sweden, where much rain falls during the harvest period, problems can occur later during preservation of feed grains because of too high water contents in the grains. Drying by heated air is the most commonly used operation in Sweden to reduce water content in grains. If airtight storage is used instead, energy and money can be saved, as airtight storage only consumes 2 % of energy needed for heated air drying. Through biopreservation, where added microorganisms enhance the stability of the cereals in the airtight storage system by preventing mould growth, a more stable preservation can be obtained. To achieve a safe storage, insensitive to air leakage, the starter culture must work properly independently of the moisture content in the grains. To expand the acceptable region of moisture content, combinations of several organisms can be used as a starter culture. A mixture of the yeast Pichia anomala J121, a lactic acid bacteria (LAB) and a propionic acid bacteria (PAB) may be an ideal starter culture, as the yeast can work in relative dry grains and the bacteria in more moist grains. However, having several organisms in the starter culture can cause problems. For example, P. anomala J121 can metabolize lactic acid produced by LAB, as oxygen enters the system in the moist grains. This results in an increase in pH, allowing detrimental organisms to grow. The ability of different LAB and PAB isolates to inhibit P. anomala J121 was therefore investigated. Slight inhibition of the yeast was only observed for Propionibacterium freundenreichii subsp. shermanii MP5, P. freundenreichii MP23 and P. thoenii MP11. To work as a starter culture, the microorganisms must be able to grow and produce organic acids and/or other antifungal compounds. Therefore, we investigated the ability of different combinations of PAB, Lactobacillus plantarum MiLAB393(pLV100) and P. anomala J121 to inhibit the mould species Penicillium roqueforti J5 at moisture contents of 25 % and 33 % in a mini silo system. The mould growth was mainly affected by P. anomala J121. Since the yeast seemed to have lower ability to grow at moisture content of 33 %, a starter culture with several organisms seems to be preferred. Of the PAB investigated in the study, Propionibacteria thoenii MP11 is the most suitable PAB in a starter culture, due to its ability to grow and produce organic acids. However, additional LAB and PAB need to be characterized and tested in different combinations. I tempererade länder som Sverige, där det faller mycket nederbörd under skördeperioden, kan höga vattenhalter i spannmålen orsaka problem vid lagerhållningen. Varmluftstorkning är den mest använda metoden i Sverige för att reducera spannmålens vattenhalt. Om lufttät lagring skulle användas istället kan energi och pengar sparas, då lufttät lagring endast förbrukar 2 % av energin som krävs vid torkning. Biokonservering, där tillsatta mikroorganismer ökar kvalitén på lufttät lagrad spannmål genom att inhibera mögeltillväxt, kan ge mer stabila lagringsförhållanden. För att uppnå en säker lagring som är stabil mot syreläckage, är det viktigt att startkulturen fungera oberoende av spannmålens fukthalter. För att öka området för acceptabla fukthalter kan en kombination av flera organismer användas i startkulturen. En blandning av Pichia anomala J121, en mjölksyrabakterie (LAB) och en propionsyrabakterie (PAB) skulle kunna vara en ideal startkultur, eftersom jästen är verksam i relativt torra spannmål och bakterierna i mer fuktiga spannmål. Problem kan dock uppstå då flera organismer ingår i startkulturen. Till exempel kan P. anomala J121 metabolisera mjölksyra, producerat av LAB i fuktigt spannmål, då syre blir tillgängligt i systemet. Detta resulterar i stigande pH-värde, vilket tillåter skadliga organismer att växa. Följaktligen studerades olika LAB och PAB isolats förmåga att inhibera P. anomala J121. Marginell inhibering av jästen inträffade enbart för Propionibacterium freundenreichii subsp. shermanii MP5, P. freundenreichii MP23 och P. thoenii MP11. För att vara en fungerande startkultur måste mikroorgansimerna ha förmåga att växa och producera organiska syror och/eller andra hämmande föreningar. Därför undersöktes förmågan att inhibera mögelarten Penicillium roqueforti J5 vid fukthalterna 25 % samt 33 % i ett minisilosystem för olika kombinationer av PAB, Lactobacillus plantarum MiLAB393(pLV100) och P. anomala J121. Mögeltillväxten påverkades i huvudsak av P. anomala J121. Eftersom jästen tycktes ha en sämre förmåga att växa vid en fukthalt av 33 %, tycks en blandning av flera organismer vara att föredra. Av de undersökta PAB, var P. thoenii MP11 mest lämpad att ha i en startkultur, på grund av dess förmåga att växa och producera organiska syror. Fler olika kombinationer av tillsatta LAB och PAB bör dock studeras för att en väl fungerande startkultur ska kunna sättas samman. 2009-01-29 Other NonPeerReviewed application/pdf sv https://stud.epsilon.slu.se/11794/1/larsson_m_171017.pdf Larsson, Malin, 2009. Towards the development of a starter culture for improvement of grain storage through biopreservation. UNSPECIFIED, Uppsala. Uppsala: (NL, NJ) > Dept. of Microbiology <https://stud.epsilon.slu.se/view/divisions/4024.html> urn:nbn:se:slu:epsilon-s-7895 eng |
| spellingShingle | Dept. of Microbiology Handling, transport, storage and protection of agricultural products Larsson, Malin Towards the development of a starter culture for improvement of grain storage through biopreservation |
| title | Towards the development of a starter culture for improvement of grain storage through biopreservation |
| title_full | Towards the development of a starter culture for improvement of grain storage through biopreservation |
| title_fullStr | Towards the development of a starter culture for improvement of grain storage through biopreservation |
| title_full_unstemmed | Towards the development of a starter culture for improvement of grain storage through biopreservation |
| title_short | Towards the development of a starter culture for improvement of grain storage through biopreservation |
| title_sort | towards the development of a starter culture for improvement of grain storage through biopreservation |
| topic | Dept. of Microbiology Handling, transport, storage and protection of agricultural products |
| url | https://stud.epsilon.slu.se/11794/ https://stud.epsilon.slu.se/11794/ |