title: Short communication: Variation in the composition and properties of Swedish raw milk for ultra-high-temperature processing.
abstract: The composition and properties of raw milk are of great importance for the quality and shelf life of the final dairy product, especially in products with a long shelf life [e.g., ultra-high-temperature (UHT)-treated milk]. The objective of this study was to investigate the compositional variation in raw milk samples before processing at the dairy plant. Moreover, we wanted to investigate the effect of the UHT process on this variation (i.e., if the same variation could be observed in the corresponding UHT milk). The quality traits analyzed included detailed milk composition, counts of total and psychrotrophic bacteria, proteolytic activity, and color, as well as predictive measures of stability (i.e., ethanol stability and heat coagulating time). Samples of raw milk and the corresponding produced UHT milk were collected and analyzed on a monthly basis during 1 yr. Principal component analysis was used to identify months showing similarities and differences with respect to total variation. In contrast to previous studies, we observed only small variations between months and no clear effect of season for the raw milk. For the UHT milk, July and the winter months (December, January, and February) tended to separate from the other months. Quality traits showing significant variation were only to some extent identical in raw milk and UHT-processed milk. A better understanding of the natural variation in raw milk quality will provide opportunities to improve the shelf life of UHT-treated milk products.
authors.affiliation: Department of Molecular Sciences, BioCenter, Swedish University of Agricultural Sciences, PO 7015, 75007 Uppsala, Sweden. Electronic address: maria.a.karlsson@slu.se.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Karlsson
authors.affiliation: Department of Molecular Sciences, BioCenter, Swedish University of Agricultural Sciences, PO 7015, 75007 Uppsala, Sweden.
authors.forename: Maud
authors.initials: M
authors.lastname: Langton
authors.affiliation: Tetra Pak Processing Systems AB, Bryggaregatan 23, 22736 Lund, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Innings
authors.affiliation: Norrmejerier Ek. Förening, Mariehemsvägen 210, 90650 Umeå, Sweden.
authors.forename: Malin
authors.initials: M
authors.lastname: Wikström
authors.affiliation: Department of Molecular Sciences, BioCenter, Swedish University of Agricultural Sciences, PO 7015, 75007 Uppsala, Sweden.
authors.forename: Åse Sternesjö
authors.initials: ÅS
authors.lastname: Lundh
mesh_terms: D000818:Animals; D006358:Hot Temperature; D008892:Milk / Q000382:microbiology*; D012621:Seasons; D013548:Sweden; D013696:Temperature
keywords: principal component analysis; raw milk quality; seasonal variation; ultra-high-temperature milk