Effect of Psychrotrophic Growth on the Milk Fat Fraction at Different Temperatures of Storage

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 lipolyt...

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Bibliographic Details
Published in:Journal of food science 2013-04, Vol.78 (4), p.S615-S618
Main Authors: Izidoro, Thiago Braga, Pereira, Juliano Gonçalves, Soares, Vanessa Mendonça, de Almeida NogueiraPinto, José Paes
Format: Article
Language:English
Subjects:
Animals
Bacteria
Bacteria - classification
Bacteria - isolation & purification
Bacterial Load
Biological and medical sciences
Cold Temperature
cooling
cooling, free fatty acids, lipolysis
Counting
Fatty acids
Food Contamination - analysis
Food industries
Food Microbiology
Food preservation
Food Storage - methods
free fatty acids
Fundamental and applied biological sciences. Psychology
Hygiene
Lipase - metabolism
Lipases
Lipolysis
Metabolism
Microorganisms
Milk
Milk - microbiology
Milk and cheese industries. Ice creams
psychrotrophic microorganisms
Strategy
Taste
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Summary: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. Practical Application As the psychrotrophic microbiota is the most important in the process of lipolytic milk spoilage, the study and quantification of this metabolic activity is crucial for the development of control strategies, increasing the sensory quality and the milk shelf life.
ISSN:0022-1147
1750-3841
DOI:10.1111/1750-3841.12091