The microbiological quality of pasteurized milk sold by automatic vending machines

A S Angelidis; S Tsiota; A Pexara; A Govaris

doi:10.1111/lam.12572

The microbiological quality of pasteurized milk sold by automatic vending machines

Lett Appl Microbiol. 2016 Jun;62(6):472-9. doi: 10.1111/lam.12572.

Authors

A S Angelidis¹, S Tsiota², A Pexara³, A Govaris³

Affiliations

¹ Laboratory of Milk Hygiene and Technology, Department of Food Hygiene and Technology, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece.
² Department of Hygiene and Epidemiology, Faculty of Medicine, University of Thessaly, Larissa, Greece.
³ Laboratory of Hygiene of Foods of Animal Origin, Faculty of Veterinary Medicine, University of Thessaly, Karditsa, Greece.

PMID: 27116619
DOI: 10.1111/lam.12572

Abstract

The microbiological quality of pasteurized milk samples (n = 39) collected during 13 weekly intervals from three automatic vending machines (AVM) in Greece was investigated. Microbiological counts (total aerobic (TAC), total psychrotrophic (TPC), Enterobacteriaceae (EC), and psychrotrophic aerobic bacterial spore counts (PABSC)) were obtained at the time of sampling and at the end of shelf-life (3 days) after storage of the samples at 4 or 8°C. TAC were found to be below the 10(7 ) CFU ml(-1) limit of pasteurized milk spoilage both during sampling as well as when milk samples were stored at either storage temperature for 3 days. Enterobacteriaceae populations were below 1 CFU ml(-1) in 69·2% of the samples tested at the time of sampling, whereas the remaining samples contained low numbers, typically less than 10 CFU ml(-1) . All samples tested negative for the presence of Listeria monocytogenes. Analogous microbiological data were also obtained by sampling and testing prepackaged, retail samples of pasteurized milk from two dairy companies in Greece (n = 26). From a microbiological standpoint, the data indicate that the AVM milk samples meet the quality standards of pasteurized milk. However, the prepackaged, retail milk samples yielded better results in terms of TAC, TPC and EC, compared to the AVM samples at the end of shelf-life.

Significance and impact of the study: Recently, Greek dairy farmers organized in cooperatives launched the sale of pasteurized milk via AVM and this study reports on the microbiological quality of this product. The data show that AVM milk is sold at proper refrigeration temperatures and meets the quality standards of pasteurized milk throughout the manufacturer's specified shelf-life. However, based on the microbiological indicators tested, the keeping quality of the tested prepackaged, retail samples of pasteurized milk at the end of shelf-life upon storage under suboptimal refrigeration temperature (8°C) was better.

Keywords: automatic vending machines; microbiological quality; milk microbiology; pasteurized milk; psychrotrophs.

MeSH terms

Animals
Colony Count, Microbial
Enterobacteriaceae / isolation & purification*
Food Dispensers, Automatic*
Food Microbiology
Greece
Listeria monocytogenes / isolation & purification*
Milk / microbiology*
Temperature