title: Effect of psychrotrophic growth on the milk fat fraction at different temperatures of storage.
abstract: The use of cooling, without using adequate hygienic practices in primary milk production, allows for the growth of psychrotrophic microorganisms that produce the thermoresistant lipases that give milk a rancid flavor. This study aimed to verify how the variation in temperature influences the lipolytic metabolism of the psychrotrophic organisms. Samples of raw milk were collected and submitted to laboratorial analysis as follows: psychrotrophic bacteria count, lipolytic bacteria count, and free fatty acids dosage. Each sample was divided into 3 aliquots and then incubated at 4, 8, and 12 °C, respectively. For each temperature, analyses were repeated after 12, 24, and 48 h of storage. Despite the psychrotrophs growth increase, according to temperature rise, the lipolytic metabolism was not consistent and presented the lower index at 8 °C, suggesting an intensification of the proteolytic compensatory activity at this temperature.
authors.affiliation: School of Veterinary Medicine and Animal Science, Sao Paulo State University, Sao Paulo, Brazil.
authors.forename: Thiago Braga
authors.initials: TB
authors.lastname: Izidoro
authors.forename: Juliano Gonçalves
authors.initials: JG
authors.lastname: Pereira
authors.forename: Vanessa Mendonça
authors.initials: VM
authors.lastname: Soares
authors.forename: José Paes
authors.initials: JP
authors.lastname: de Almeida Nogueirapinto
mesh_terms: D000818:Animals; D001419:Bacteria / Q000145:classification / Q000302:isolation & purification*; D058491:Bacterial Load; D003080:Cold Temperature; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D061353:Food Storage / Q000379:methods*; D006920:Hygiene; D008049:Lipase / Q000378:metabolism; D008066:Lipolysis; D008892:Milk / Q000382:microbiology*; D013649:Taste
chemical_list: D008049:Lipase