Impact of psychrotrophic bacteria on the microbiological quality and shelf life of chilled milk: a systematic review of the scientific evidence
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Published:
Jun 18, 2026
Keywords:
Psychrotrophic bacteria; refrigerated milk; microbiological quality; shelf life; microbiological deterioration; thermostable enzymes; Pseudomonas spp.
Main Article Content
Abstract
Introduction: the decrease in the microbiological quality of refrigerated milk is one of the main challenges facing the current industry, in addition to the potential health risks but also due to the economic and technological effects it has on the production chain. Objectives: The current study aims to analyze how psychrotrophic bacteria influence the microbiological quality and shelf life of refrigerated milk, both raw and pasteurized milk. These bacteria could grow at low temperatures and produce thermostable enzymes that affect the proteins and fats in milk, causing them to deteriorate even after heat treatments such as pasteurization. Methodology: A systematic review of scientific articles published between 2015 and 2025 was conducted, which was consulted in indexed databases such as SciELO, Scopus, PubMed, and ScienceDirect. The choice was made using previously defined inclusion and exclusion criteria, for this reason original studies related to psychrotrophic bacteria in refrigerated raw milk and thermostable enzymes were considered, which are those that deteriorate milk. However, after the evaluation process, 14 investigations were included for the final analysis. Results: The results showed that the genus Pseudomonas, especially Pseudomonas fluorescens, was the most frequent microorganism, high bacterial counts are reported during cold storage and the production of thermostable proteases and lipases, which are responsible for proteolysis, lipolysis, and sensory alterations. Conclusions: It is concluded that refrigeration alone does not guarantee the stability of the product, therefore it is essential to reinforce hygiene practices and control throughout the dairy chain to protect and care for quality and thus prolong the shelf life of the product. General area of study: Health Sciences. Specific area of study: Food Microbiology. Type of article: Systematic bibliographic review.
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How to Cite
Arcentales Morocho, J. A., & Gerardo Ortiz, J. (2026). Impact of psychrotrophic bacteria on the microbiological quality and shelf life of chilled milk: a systematic review of the scientific evidence. Anatomía Digital, 9(2), 152-169. https://doi.org/10.33262/anatomiadigital.v9i2.3695
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Articulos de revisión bibliográfica
References
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(10) Condé PR, Pinto CL de O, Gandra SO, Campos RCAB, Silva RR da, Costa JF da, et al. Identification of the contaminating psychrotrophic bacteria in refrigerated bulked raw milk and the assessment of their deteriorating potential. Semina: Ciências Agrárias [Internet]. 2022 [cited 2026Mar.10];43(2):739-750. Available from: https://ojs.uel.br/revistas/uel/index.php/semagrarias/article/view/44325
(11) Marchand S, Vandriesche G, Coorevits A, Coudijzer K, De Jonghe V, Dewettinck K, et al. Heterogeneity of heat-resistant proteases from milk Pseudomonas species. International Journal of Food Microbiology [Internet]. 2009 [cited 2026Mar.10];133(1-2):68–77. Available from: http://dx.doi.org/10.1016/j.ijfoodmicro.2009.04.027
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(13) Yuan L, Sadiq FA, Burmølle M, Wang NI, He G. Insights into psychrotrophic bacteria in raw milk: a review. Journal of Food Protection [Internet]. 2019 [cited 2026Mar.10];82(7):1148-1159. Available from: http://dx.doi.org/10.4315/0362-028X.JFP-19-032
(14) Yuan L, Sadiq FA, Liu T-J, Li Y, Gu J-S, Yang H-Y, et al. Spoilage potential of psychrotrophic bacteria isolated from raw milk and the thermo-stability of their enzymes. Journal of Zhejiang University-SCIENCE B [Internet]. 2018 [cited 2026Mar.10];19(8):630-642. Available from: http://dx.doi.org/10.1631/jzus.B1700352
(15) Gasparini GBFB, Amorim FR, de Souza Correa S, Bruzaroski SR, Fagnani R, de Souza CHB, et al. Psychrotrophs in raw milk: effect on texture, proteolysis index, and sensory evaluation of smoked provolone cheese. Journal of Science of Food and Agriculture [Internet]. 2020 [cited 2026Mar.10];100(8):3291-3296. Available from: http://dx.doi.org/10.1002/jsfa.10329
(16) Adams DM, Barach JT, Speck ML. Effect of psychrotrophic bacteria from raw milk on milk proteins and stability of milk proteins to ultrahigh temperature treatment. Journal of Dairy Science [Internet]. 1976 [cited 2026Mar.10];59(5):823-827. Available from: http://dx.doi.org/10.3168/jds.S0022-0302(76)84282-8
(17) Qin X, Cheng J, Qi X, Guan N, Chen Q, Pei X, et al. Effect of thermostable enzymes produced by psychrotrophic bacteria in raw milk on the quality of ultra-high temperature sterilized milk. Foods [Internet]. 2023 [cited 2026Mar.10];12(20):3752. Available from: http://dx.doi.org/10.3390/foods12203752
(18) Hantsis-Zacharov E, Halpern M. Culturable psychrotrophic bacterial communities in raw milk and their proteolytic and lipolytic traits. Applied and Environmental Microbiology [Internet]. 2007 [cited 2026Mar.10];73(22):7162–7168. Available from: http://dx.doi.org/10.1128/AEM.00866-07
(19) Martin NH, Boor KJ, Wiedmann M. Symposium review: effect of post-pasteurization contamination on fluid milk quality. Journal of Dairy Science [Internet]. 2018 [cited 2026Mar.10];101(1):861–870. Available from: http://dx.doi.org/10.3168/jds.2017-13339
(20) Román S, Guerrero L, Pacheco L. Evaluación de la calidad físico química, higiénica y sanitaria de la leche cruda almacenada en frío. Revista Científica de la Facultad de Ciencias Veterinarias [Internet]. 2003 [citado 2026Mar.10];13(2). Disponible en: http://www.produccioncientificaluz.org/index.php/cientifica/article/view/14972
(21) de la Torres–Moreira JA, Montalvo–Lozada MA, Meza–Barrezueta JO, Rivadeneyra–Espín VG, Gallegos–Guerra KA, Villamarin KK. Evaluación de la calidad fisicoquímica y microbiológica de la leche cruda en la industria láctea de Napo, Ecuador. Revista Científica de la Facultad de Ciencias Veterinarias [Internet]. 2025 [citado 2026Mar.10];35(2):10. Disponible en: https://www.produccioncientificaluz.org/index.php/cientifica/article/view/44050
(22) Morandi S, Pica V, Masotti F, Cattaneo S, Brasca M, De Noni I, et al. Proteolytic traits of psychrotrophic bacteria potentially causative of sterilized milk instability: genotypic, phenotypic and peptidomic insight. Foods [Internet]. 2021 [cited 2026Mar.10];10(5):934. Available from: http://dx.doi.org/10.3390/foods10050934
(23) von Neubeck M, Baur C, Krewinkel M, Stoeckel M, Kranz B, Stressler T, et al. Biodiversity of refrigerated raw milk microbiota and their enzymatic spoilage potential. International Journal of Food Microbiology [Internet]. 2015 [cited 2026Mar.10]; 211:57–65. Available from: http://dx.doi.org/10.1016/j.ijfoodmicro.2015.07.001
(24) Quigley L, O’Sullivan O, Stanton C, Beresford TP, Ross RP, Fitzgerald GF, Cotter PD. The complex microbiota of raw milk. FEMS Microbiology Reviews [Internet]. 2013 [cited 2026Mar.10];37(5):664-698. Available from: https://doi.org/10.1111/1574-6976.12030
(25) Wang X, Su B, Geng F, Liu Z, Liu X, Sun R, et al. Detection and identification approaches of psychrotrophic bacteria in raw milk and dairy products: a review. Food Chemistry [Internet]. 2026 [cited 2026Mar.10];498(Pt 2):147263. Available from: http://dx.doi.org/10.1016/j.foodchem.2025.147263
(26) Machado SG, da Silva FL, Bazzolli DMS, Heyndrickx M, Costa PM de A, Vanetti MCD. Pseudomonas spp. and serratia liquefaciens as predominant spoilers in cold raw milk: predominant spoilers in cold raw milk. Journal of Food Science [Internet]. 2015 [cited 2026Mar.10];80(8):M1842-849. Available from: http://dx.doi.org/10.1111/1750-3841.12957
(27) Lu Y, Wu Q, Zhu L, Qin Y, Li A, Makalar PK, et al. Dairy spoilage enzymes: a review of impacts and diagnostic tools. Food Research International [Internet]. 2026 [cited 2026Mar.10];227(118272):118272. Available from: http://dx.doi.org/10.1016/j.foodres.2025.118272
(28) Tenecela Valencia EM, Ortiz Tejedor JG. Bacteriological analysis of raw milk sold in Tarqui-Ecuador. Anatomía Digital [Internet]. 2023Jul.20 [cited 2026Mar.10];6(3):116-31. Available from: https://doi.org/10.33262/anatomiadigital.v6i3.2619
(29) Lojano Collantes DJ, Quezada Córdova CF, Pacheco Cárdenas KE. Identifying staphylococcus aureus in goat milk delivered to markets in Cuenca – Ecuador. Anatomía Digital [Internet]. 2023Jun.1 [cited 2026Mar.10];6(2.1):6-17. Available from: https://doi.org/10.33262/anatomiadigital.v6i2.1.2569
(2) Ribeiro Júnior JC, de Oliveira AM, Silva F de G, Tamanini R, de Oliveira ALM, Beloti V. The main spoilage-related psychrotrophic bacteria in refrigerated raw milk. Journal of Dairy Science [Internet]. 2018 [cited 2026Mar.10];101(1):75-83. Available from: http://dx.doi.org/10.3168/jds.2017-13069
(3) Lampugnani C, Was MZ, Montanhini MTM, Nero LA, Bersot L dos S. Quantification of psychrotrophic bacteria and molecular identification of Pseudomonas fluorescens in refrigerated raw milk. Arquivos Do Instituto Biológico [Internet]. 2019 [cited 2026Mar.10]; 86:e1212018. Available from: https://doi.org/10.1590/1808-1657001212018
(4) Zarei M, Elmi Anvari S, Maktabi S, Saris PEJ, Yousefvand A. Identification, proteolytic activity quantification and biofilm-forming characterization of Gram-positive, proteolytic, psychrotrophic bacteria isolated from cold raw milk. PLoS One [Internet]. 2023 [cited 2026Mar.10];18(9): e0290953. Available from: http://dx.doi.org/10.1371/journal.pone.0290953
(5) Qin X, Cheng J, Qiu Y, Guan N, Gupta TB, Wu S, et al. Characterization of psychrotrophic and thermoduric bacteria in raw milk using a multi-omics approach. Microbial Genomics [Internet]. 2024 [cited 2026Mar.10];10(11). Available from: http://dx.doi.org/10.1099/mgen.0.001311
(6) Chang G, Li Q, Wang T, Zhang B, Wu W, Lv C, et al. Characterization of Pseudomonas spp. contamination and in situ spoilage potential in pasteurized milk production process. Food Research International [Internet]. 2024 [cited 2026Mar.10];188(114463):114463. Available from: http://dx.doi.org/10.1016/j.foodres.2024.114463
(7) Mayorga Estrella E, Marcial Coba MS. Detección de bacterias psicrotróficas y enzimas deterioradoras en leche cruda y procesada por Ultra Alta Temperatura (UHT) [Tesis de pregrado, Pontificia Universidad Católica del Ecuador PUCE, Quito, Ecuador] [Internet], 2024 [citado 2026Mar.10]. Disponible en: https://repositorio.puce.edu.ec/items/93cb1325-6227-455f-aa49-5cc0bc01f3a4
(8) Rincón VG, Fuenmayor BA, Castellano GM, Barrios UR, Colina ChM, Nuñez FG. Factores de virulencia en cepas de aeromonas spp. Kasmera [Internet]. 7 de agosto de 2016 [citado 2026Mar.10];44(2):121-133. Disponible en: https://www.produccioncientificaluz.org/index.php/kasmera/article/view/22504
(9) de Oliveira GB, Favarin L, Luchese RH, McIntosh D. Psychrotrophic bacteria in milk: How much do we really know? Brazilian Journal of Microbiology [Internet]. 2015 [cited 2026Mar.10];46(2):313-321. Available from: http://dx.doi.org/10.1590/S1517-838246220130963. https://pmc.ncbi.nlm.nih.gov/articles/PMC4507522/
(10) Condé PR, Pinto CL de O, Gandra SO, Campos RCAB, Silva RR da, Costa JF da, et al. Identification of the contaminating psychrotrophic bacteria in refrigerated bulked raw milk and the assessment of their deteriorating potential. Semina: Ciências Agrárias [Internet]. 2022 [cited 2026Mar.10];43(2):739-750. Available from: https://ojs.uel.br/revistas/uel/index.php/semagrarias/article/view/44325
(11) Marchand S, Vandriesche G, Coorevits A, Coudijzer K, De Jonghe V, Dewettinck K, et al. Heterogeneity of heat-resistant proteases from milk Pseudomonas species. International Journal of Food Microbiology [Internet]. 2009 [cited 2026Mar.10];133(1-2):68–77. Available from: http://dx.doi.org/10.1016/j.ijfoodmicro.2009.04.027
(12) Peretti GA, Mallmann S, Peretti GL, De Dea Lindner J, Longhi DA, Galvão AC, et al. Modeling lipase and protease production by psychrotrophic bacteria in refrigerated pasteurized milk. International Dairy Journal [Internet]. 2025 [cited 2026Mar.10];167(106284). Available from: http://dx.doi.org/10.1016/j.idairyj.2025.106284
(13) Yuan L, Sadiq FA, Burmølle M, Wang NI, He G. Insights into psychrotrophic bacteria in raw milk: a review. Journal of Food Protection [Internet]. 2019 [cited 2026Mar.10];82(7):1148-1159. Available from: http://dx.doi.org/10.4315/0362-028X.JFP-19-032
(14) Yuan L, Sadiq FA, Liu T-J, Li Y, Gu J-S, Yang H-Y, et al. Spoilage potential of psychrotrophic bacteria isolated from raw milk and the thermo-stability of their enzymes. Journal of Zhejiang University-SCIENCE B [Internet]. 2018 [cited 2026Mar.10];19(8):630-642. Available from: http://dx.doi.org/10.1631/jzus.B1700352
(15) Gasparini GBFB, Amorim FR, de Souza Correa S, Bruzaroski SR, Fagnani R, de Souza CHB, et al. Psychrotrophs in raw milk: effect on texture, proteolysis index, and sensory evaluation of smoked provolone cheese. Journal of Science of Food and Agriculture [Internet]. 2020 [cited 2026Mar.10];100(8):3291-3296. Available from: http://dx.doi.org/10.1002/jsfa.10329
(16) Adams DM, Barach JT, Speck ML. Effect of psychrotrophic bacteria from raw milk on milk proteins and stability of milk proteins to ultrahigh temperature treatment. Journal of Dairy Science [Internet]. 1976 [cited 2026Mar.10];59(5):823-827. Available from: http://dx.doi.org/10.3168/jds.S0022-0302(76)84282-8
(17) Qin X, Cheng J, Qi X, Guan N, Chen Q, Pei X, et al. Effect of thermostable enzymes produced by psychrotrophic bacteria in raw milk on the quality of ultra-high temperature sterilized milk. Foods [Internet]. 2023 [cited 2026Mar.10];12(20):3752. Available from: http://dx.doi.org/10.3390/foods12203752
(18) Hantsis-Zacharov E, Halpern M. Culturable psychrotrophic bacterial communities in raw milk and their proteolytic and lipolytic traits. Applied and Environmental Microbiology [Internet]. 2007 [cited 2026Mar.10];73(22):7162–7168. Available from: http://dx.doi.org/10.1128/AEM.00866-07
(19) Martin NH, Boor KJ, Wiedmann M. Symposium review: effect of post-pasteurization contamination on fluid milk quality. Journal of Dairy Science [Internet]. 2018 [cited 2026Mar.10];101(1):861–870. Available from: http://dx.doi.org/10.3168/jds.2017-13339
(20) Román S, Guerrero L, Pacheco L. Evaluación de la calidad físico química, higiénica y sanitaria de la leche cruda almacenada en frío. Revista Científica de la Facultad de Ciencias Veterinarias [Internet]. 2003 [citado 2026Mar.10];13(2). Disponible en: http://www.produccioncientificaluz.org/index.php/cientifica/article/view/14972
(21) de la Torres–Moreira JA, Montalvo–Lozada MA, Meza–Barrezueta JO, Rivadeneyra–Espín VG, Gallegos–Guerra KA, Villamarin KK. Evaluación de la calidad fisicoquímica y microbiológica de la leche cruda en la industria láctea de Napo, Ecuador. Revista Científica de la Facultad de Ciencias Veterinarias [Internet]. 2025 [citado 2026Mar.10];35(2):10. Disponible en: https://www.produccioncientificaluz.org/index.php/cientifica/article/view/44050
(22) Morandi S, Pica V, Masotti F, Cattaneo S, Brasca M, De Noni I, et al. Proteolytic traits of psychrotrophic bacteria potentially causative of sterilized milk instability: genotypic, phenotypic and peptidomic insight. Foods [Internet]. 2021 [cited 2026Mar.10];10(5):934. Available from: http://dx.doi.org/10.3390/foods10050934
(23) von Neubeck M, Baur C, Krewinkel M, Stoeckel M, Kranz B, Stressler T, et al. Biodiversity of refrigerated raw milk microbiota and their enzymatic spoilage potential. International Journal of Food Microbiology [Internet]. 2015 [cited 2026Mar.10]; 211:57–65. Available from: http://dx.doi.org/10.1016/j.ijfoodmicro.2015.07.001
(24) Quigley L, O’Sullivan O, Stanton C, Beresford TP, Ross RP, Fitzgerald GF, Cotter PD. The complex microbiota of raw milk. FEMS Microbiology Reviews [Internet]. 2013 [cited 2026Mar.10];37(5):664-698. Available from: https://doi.org/10.1111/1574-6976.12030
(25) Wang X, Su B, Geng F, Liu Z, Liu X, Sun R, et al. Detection and identification approaches of psychrotrophic bacteria in raw milk and dairy products: a review. Food Chemistry [Internet]. 2026 [cited 2026Mar.10];498(Pt 2):147263. Available from: http://dx.doi.org/10.1016/j.foodchem.2025.147263
(26) Machado SG, da Silva FL, Bazzolli DMS, Heyndrickx M, Costa PM de A, Vanetti MCD. Pseudomonas spp. and serratia liquefaciens as predominant spoilers in cold raw milk: predominant spoilers in cold raw milk. Journal of Food Science [Internet]. 2015 [cited 2026Mar.10];80(8):M1842-849. Available from: http://dx.doi.org/10.1111/1750-3841.12957
(27) Lu Y, Wu Q, Zhu L, Qin Y, Li A, Makalar PK, et al. Dairy spoilage enzymes: a review of impacts and diagnostic tools. Food Research International [Internet]. 2026 [cited 2026Mar.10];227(118272):118272. Available from: http://dx.doi.org/10.1016/j.foodres.2025.118272
(28) Tenecela Valencia EM, Ortiz Tejedor JG. Bacteriological analysis of raw milk sold in Tarqui-Ecuador. Anatomía Digital [Internet]. 2023Jul.20 [cited 2026Mar.10];6(3):116-31. Available from: https://doi.org/10.33262/anatomiadigital.v6i3.2619
(29) Lojano Collantes DJ, Quezada Córdova CF, Pacheco Cárdenas KE. Identifying staphylococcus aureus in goat milk delivered to markets in Cuenca – Ecuador. Anatomía Digital [Internet]. 2023Jun.1 [cited 2026Mar.10];6(2.1):6-17. Available from: https://doi.org/10.33262/anatomiadigital.v6i2.1.2569