Undersökning av variabler vid optimering av syrningsprocessen för framställning av cottage cheese

Examensarbete på grundnivå
Kemiteknik 180 hp (högskoleingenjör)
Hansson, Björn
Arla Foods dairy in Falkenberg produces cottage cheese and under the fall of 2018, they had some problems with an uneven acidification, which gave their product an uneven quality. Those problems are now solved but in the continued work their product technicians always work to find methods for a more reliable and stable acidification process, for a product with more even quality. In the work for a more reliable and stable process, two projects have been done. The acidification project performed to examine which conditions that were most optimal regarding the temperature, the percentage of protein in the milk and the amount of starter culture used. The other project, the vat and cooling towers project, was done to examine the change in dry matter content in the cheese curd when there are delays in the production line, i.e. when the cheese curd has to lie in the vat longer than usual and how that affects the curds dry matter content, and how long the curd has to lie in the cooling towers to reach normal dry matter content limits. Both projects were done in laboratory scale. In the acidification project the rate of the acidification were assessed by measuring the pH of the sample every fifteen minutes. The times down to pH 5.7 (when rennet is added) and pH 4.7 (when the coagulum is cut) were measured and used to calculate the results using a 2 sided 95 % confidence interval. The temperature, the percentage of the milk and their factor interaction were significant for the rate of acidification down to pH 5.7. For the acidification rate down to pH 4.7, all the factors and factor interactions were significant except for the three-way factor interaction. A higher temperature made the acidification rate increase while a higher percentage of protein in the milk decreased the acidification rate. In the vat and cooling towers project whey and cheese curd were stirred and heated at 60 ℃ in a beaker, with samples of the curd taken out after 0, 30, 60 and 90 minutes. At these times cheese curd was transferred to a stirred and cooled beaker with 4 ℃ water in them, with samples of the curd taken out after 2, 4 and 6 hours. The dry matter of the cheese curd was then measured with a Milkoscan FT1. Because of the different chemical compositions of the cheese curd taken out from different vats the results were not comparable but a significant drop in dry matter could be seen from all runs after two hours of cooling.
Livsvetenskaper , Kemiska processer , Livsmedelsteknik , Livsmedelsvetenskap , Life Science , Chemical Process Engineering , Food Engineering , Food Science
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