Detection and impact of protease and lipase activities in milk and milk powders

Chen, L.; Daniel, Roy M.; Coolbear, Tim

doi:10.1016/s0958-6946(02)00171-1

Cited by 236 publications

(200 citation statements)

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“…Porém, pode ocasionar problemas tecnológicos associados à atividade de enzimas proteolíticas e lipolíticas de bactérias psicrotróficas. Muitas destas enzimas são termorresistentes [23,33] e estão relacionadas às perdas de qualidade e à redução da vida de prateleira do leite UHT e de outros produtos lácteos [8,9,11,17,18,22,24,28,35,39,40].…”

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Qualidade microbiológica de leite cru refrigerado e isolamento de bactérias psicrotróficas proteolíticas

Pinto¹,

Martins²,

Vanetti³

2006

Ciênc. Tecnol. Aliment.

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RESUMOA estocagem do leite cru refrigerado na fonte de produção reduz perdas econômicas por atividade acidificante de bactérias mesofílicas, mas permite a seleção de bactérias psicrotróficas relacionadas a problemas tecnológicos e econômicos na indústria de laticínios. Com o objetivo de avaliar a qualidade microbiológica de leite cru, foram analisadas amostras provenientes de tanques de refrigeração individual, coletivos e do silo de uma indústria processadora de leite. Além disso, bactérias psicrotróficas proteolíticas foram isoladas do leite cru refrigerado e caracterizadas quanto à reação ao Gram e fermentação de glicose. O leite cru refrigerado mantido no silo industrial não atendeu ao padrão microbiológico legal e apresentou contagens microbianas significativamente superiores às do leite mantido em tanques individuais ou coletivos. Diferença significativa na contaminação por mesófilos e psicrotrófilos proteolíticos e não proteolíticos e por Pseudomonas foi observada entre as amostras coletadas nos tanques de refrigeração e no silo industrial. A microbiota Gram-negativa foi isolada com maior freqüência, especialmente bactérias Gram-negativas não fermentadoras de glicose. Palavras-chave: leite refrigerado, microbiota psicrotrófica, qualidade microbiológica. SUMMARYMICROBIAL QUALITY OF RAW REFRIGERATED MILK AND ISOLATION OF PSYCHROTROPHIC PROTEOLYTIC BACTERIA. Storing refrigerated raw milk in the source of production reduces economic losses which occur due to the acidifying activity of mesophilic bacteria. Nevertheless, this process selects psychrotrophic bacteria that cause technological and economic problems to the dairy industry. Samples of individual and collective refrigerated tanks and samples from an industrial silo in a dairy industry were collected and analyzed to evaluate the microbiological quality of raw milk. Furthermore, proteolytic psychrotrophic bacteria were isolated from refrigerated raw milk and characterized according to the Gram reaction and glucose fermentation. The refrigerated raw milk from the industrial silo was not compatible with legal microbiological standards, and its microbial count was significantly higher than milk from individual and collective tanks. A significant difference of contamination by mesophiles, proteolytic and non-proteolytic psychrotrophs, and Pseudomonas was observed in samples collected from refrigeration tanks compared to samples collected from the industrial silo. The Gram-negative microbiota was isolated more often, especially the glucose non-fermentative Gram-negative bacteria.

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Qualidade microbiológica de leite cru refrigerado e isolamento de bactérias psicrotróficas proteolíticas

Pinto¹,

Martins²,

Vanetti³

2006

Ciênc. Tecnol. Aliment.

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“…Although such practice on farms and in processing plants reduces the spoilage by mesophilic microorganisms, it will not prevent deterioration by psychrotrophic microorganisms (12,26). Therefore, psychrotrophic microorganisms are predominant in raw milk microbiota during the storage, producing hydrolytic enzymes such as proteases and lipases which are responsible for many quality issues, defects and deterioration, resulting in the limited shelf-life of dairy products (3,20). Although psychrotrophs are usually destroyed by heat treatments, the extracellular enzymes produced by these microorganisms are usually thermostable, keeping their activities even after pasteurization and even ultrahigh temperature (UHT) treatments (8,25).…”

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“…LBSA1 isolated from raw milk produced only one extracellular protease. The majority of Pseudomonas species, and other psychrotrophs, produce a single type of monomeric (40-55 kDa) neutral metalloprotease, with optimum pH of 6.5-8.0 (3,20,26).…”

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“…Pseudomonas 1A4R showed higher lipolytic activity on CWPB, followed by SMB. Milk is a good medium for lipase production, since the synthesis of such enzymes can be stimulated by lipids, such as milkfat (3). In this sense, lipase activity is generally higher in whole milk than in skimmed milk (6).…”

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“…The hydrolysis of as little as l% of the milk triglycerides could lead to rancid off-flavors (3,12). Specifically, Dogan and Boor (7) reported that of 338…”

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Hydrolytic potential of a psychrotrophic Pseudomonas isolated from refrigerated raw milk

Corrêa¹,

Daroit²,

Velho³

et al. 2011

Braz. J. Microbiol.

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The production of extracellular hydrolases by a psychrotrophic bacterium isolated from refrigerated raw milk, and identified as a Pseudomonas sp. belonging to the Pseudomonas jenssenii group, was studied. This bacterium produced proteolytic and lipolytic enzymes in all media investigated (skim milk, cheese whey, casein broth, and tryptone soy broth). High levels of α-glucosidase were produced in skim milk broth.Hydrolytic enzymes detected in skim milk broth are of particular concern, indicating that these enzymes could be produced by Pseudomonas sp. during the cold storage of raw milk, contributing to the spoilage problem in milk and dairy products.

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UHT and Aseptic Processing of Milk and Milk Products

Datta¹,

Deeth²

2007

Advances in Thermal and Non‐Thermal Food Preservation

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Detection and impact of protease and lipase activities in milk and milk powders

Cited by 236 publications

References 115 publications

Qualidade microbiológica de leite cru refrigerado e isolamento de bactérias psicrotróficas proteolíticas

Qualidade microbiológica de leite cru refrigerado e isolamento de bactérias psicrotróficas proteolíticas

Hydrolytic potential of a psychrotrophic Pseudomonas isolated from refrigerated raw milk

UHT and Aseptic Processing of Milk and Milk Products

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