Impact of storage at freezing temperatures on casein micelle size, coagulation properties and curd yield in bovine milk
Frozen storage is an efficient and convenient way to preserve and transport milk, but the effect from frozen storage needs to be further researched. The objective of this study was to investigate how storage at freezing temperatures (-80°C and -20°C) of frozen and freeze-dried bovine milk samples, r...
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| Formato: | Second cycle, A2E |
| Lenguaje: | sueco Inglés |
| Publicado: |
2022
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| Acceso en línea: | https://stud.epsilon.slu.se/17596/ |
| _version_ | 1855572922165362688 |
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| author | Bondesson, Ebba |
| author_browse | Bondesson, Ebba |
| author_facet | Bondesson, Ebba |
| author_sort | Bondesson, Ebba |
| collection | Epsilon Archive for Student Projects |
| description | Frozen storage is an efficient and convenient way to preserve and transport milk, but the effect from frozen storage needs to be further researched. The objective of this study was to investigate how storage at freezing temperatures (-80°C and -20°C) of frozen and freeze-dried bovine milk samples, respectively, affects pH, casein micelle size, ethanol stability, rheological properties and curd yield. The short-term changes after cold storage at 4°C were also examined. The results were evaluated using one-way ANOVA and Tukey’s pairwise comparison test. A significant decrease in pH was observed during the short-term storage at 4°C. A significant difference was shown in ethanol stability after storage of the freeze-dried milk samples in week 4 while comparing the freezing temperatures. The pH measurements showed a significant difference between frozen and freeze-dried samples stored at -20°C and in week 1 and 2. The result from the coagulation time measurements showed significant difference in all treatments, except during the first week. The gel firmness was significantly different when comparing frozen milk samples stored at -80°C and -20°C, respectively for 2, 3, 5 and 6 weeks. The study concluded that milk is affected by frozen storage, resulting in softer cheese curd, prolonged coagulation time and decreased gel firmness. The study indicated that the optimal freezing temperature and time for frozen bovine milk samples are one week at -80°C. Further research with higher number of replicates and longer storage time could result in stronger conclusions about the effects of frozen storage of milk. Inclusion of caprine and ovine milk samples would make the results more useful for small-scale cheese manufacturers. |
| format | Second cycle, A2E |
| id | RepoSLU17596 |
| institution | Swedish University of Agricultural Sciences |
| language | Swedish Inglés |
| publishDate | 2022 |
| publishDateSort | 2022 |
| record_format | eprints |
| spelling | RepoSLU175962022-03-11T02:02:27Z https://stud.epsilon.slu.se/17596/ Impact of storage at freezing temperatures on casein micelle size, coagulation properties and curd yield in bovine milk Bondesson, Ebba Food science and technology Frozen storage is an efficient and convenient way to preserve and transport milk, but the effect from frozen storage needs to be further researched. The objective of this study was to investigate how storage at freezing temperatures (-80°C and -20°C) of frozen and freeze-dried bovine milk samples, respectively, affects pH, casein micelle size, ethanol stability, rheological properties and curd yield. The short-term changes after cold storage at 4°C were also examined. The results were evaluated using one-way ANOVA and Tukey’s pairwise comparison test. A significant decrease in pH was observed during the short-term storage at 4°C. A significant difference was shown in ethanol stability after storage of the freeze-dried milk samples in week 4 while comparing the freezing temperatures. The pH measurements showed a significant difference between frozen and freeze-dried samples stored at -20°C and in week 1 and 2. The result from the coagulation time measurements showed significant difference in all treatments, except during the first week. The gel firmness was significantly different when comparing frozen milk samples stored at -80°C and -20°C, respectively for 2, 3, 5 and 6 weeks. The study concluded that milk is affected by frozen storage, resulting in softer cheese curd, prolonged coagulation time and decreased gel firmness. The study indicated that the optimal freezing temperature and time for frozen bovine milk samples are one week at -80°C. Further research with higher number of replicates and longer storage time could result in stronger conclusions about the effects of frozen storage of milk. Inclusion of caprine and ovine milk samples would make the results more useful for small-scale cheese manufacturers. Frysning är ett effektivt och enkelt sätt att konservera och transportera mjölk, men mer forskning om infrysningens effekter på mjölk behövs. Studiens syfte var att undersöka hur frysta och frystorkade komjölkprover påverkas av lagring i -80°C och -20°C genom att mäta pH, kaseinmicellstorlek, etanolstabilitet, reologiska egenskaper och ostutbyte före och under som längst sex veckors fryslagring. Resultatet utvärderades statistiskt med envägs-ANOVA och Tukey’s post-hoc test. Förändringarna i samtliga parametrar mättes även under kylförvaring i +4°C under tre dagar. Resultatet påvisade en signifikant minskning i pH under kylförvaringen. Under frysningen påvisades en statistisk skillnad i etanolstabilitet för frystorkade prover lagrade i -80°C och inom vecka 4 vid jämförelse av provmedelvärde. Även för pH påvisades statistiska skillnader under lagring av frysta och frystorkade prover i -20°C och inom vecka 1 och 2. Statistiska skillnader mellan ?? påvisades även för resultatet för de reologiska egenskaperna. Statistisk skillnad påvisades inom alla jämförelser i koaguleringstid, förutom från vecka 1. Skillnader i gelstyrka påvisade statistisk signifikans från de frysta mjölkproverna lagrade i -80°C, -20°C och inom vecka 2, 3, 5 och 6. Studien påvisade att mjölk påverkas av infrysning med ökat ostutbyte, förlängd koaguleringstid och försvagad gelstyrka. Resultatet indikerade att den optimala infrysningstiden och -temperaturen för komjölksprover som ska användas för ostproduktion är en vecka i -80°C. Vidare forskning med högre antal replikat och förlängd infrysningstid skulle kunna resultera i tydligare utvärdering av effekter av frysförvaring av mjölk som ska användas för ystning. Inkludering av get- och fårmjölk i studien skulle göra resultatet användbart även för småskaliga get- och fåroststillverkare. 2022-03-03 Second cycle, A2E NonPeerReviewed application/pdf sv https://stud.epsilon.slu.se/17596/1/bondesson-e-220303.pdf Bondesson, Ebba, 2022. Impact of storage at freezing temperatures on casein micelle size, coagulation properties and curd yield in bovine milk. Second cycle, A2E. Uppsala: (NL, NJ) > Department of Molecular Sciences <https://stud.epsilon.slu.se/view/divisions/OID-425.html> urn:nbn:se:slu:epsilon-s-17596 eng |
| spellingShingle | Food science and technology Bondesson, Ebba Impact of storage at freezing temperatures on casein micelle size, coagulation properties and curd yield in bovine milk |
| title | Impact of storage at freezing temperatures on casein micelle size, coagulation properties and curd yield in bovine milk |
| title_full | Impact of storage at freezing temperatures on casein micelle size, coagulation properties and curd yield in bovine milk |
| title_fullStr | Impact of storage at freezing temperatures on casein micelle size, coagulation properties and curd yield in bovine milk |
| title_full_unstemmed | Impact of storage at freezing temperatures on casein micelle size, coagulation properties and curd yield in bovine milk |
| title_short | Impact of storage at freezing temperatures on casein micelle size, coagulation properties and curd yield in bovine milk |
| title_sort | impact of storage at freezing temperatures on casein micelle size, coagulation properties and curd yield in bovine milk |
| topic | Food science and technology |
| url | https://stud.epsilon.slu.se/17596/ https://stud.epsilon.slu.se/17596/ |