Intoxication by staphylococcal enterotoxins (SE) is among the most common causes of food-poisoning outbreaks resulting from the consumption of raw milk or products made thereof. The aim of our study was to analyze the thermal stability of SE and evaluate the inactivation of SE types A, B, and C (SEA, SEB, SEC) by autoclaving at 100°C, 110°C, and 121°C. Milk samples were inoculated with 38 Staphylococcus aureus strains that possessed the ability to produce SEA, SEB, or SEC and incubated at 37°C for 24 h. This incubation was followed by heat treatment at 100°C, 110°C, or 121°C for 3 min. Samples were analyzed by Staph. aureus plate count method on Baird-Parker agar and specifically for the presence of SE. An enzyme-linked immunofluorescent assay (ELFA) on a MiniVIDAS analyzer (bioMérieux, Marcy l'Étoile, France) was used to detect SE, which were determined semi-quantitatively based on test values. The obtained results were analyzed by means of nonparametric statistical methods. All samples (100%; 38/38) were SE-positive before heat treatment, and the positivity rates decreased after heat treatment at 100°C, 110°C, and 121°C to 36.8% (14/38), 34.2% (13/38), and 31.6% (12/38), respectively. The rates of positive samples differed between SEA, SEB, and SEC producers: SEA was detected in the highest amounts both before and after heat treatment. The amount of SE (expressed as test values) decreased significantly after heat treatment. Comparing amounts of SE in positive and negative samples before and after heat treatment, we can conclude that the success of SE inactivation depends on the amount present before heat treatment. The highest amount of SE and the highest rate of SE-positive samples after all heat treatments were found in samples with strains producing SEA. For SEB and SEC, lower amounts of enterotoxin were present and were inactivated at 100°C. Although temperatures of 100°C, 110°C, and 121°C may inactivate SE in milk, the key measures in prevention of staphylococcal enterotoxicosis are avoiding initial contamination of milk by Staph. aureus, promoting consumption of heat-treated milk, and preventing disruption of the cold chain during milk production and processing.

• MeSH
• chlazení MeSH
• enterotoxiny analýza   chemie   MeSH
• mastitida skotu mikrobiologie   MeSH
• mléko chemie   mikrobiologie   MeSH
• potravinářská mikrobiologie metody   MeSH
• skot MeSH
• stabilita léku MeSH
• stafylokokové infekce veterinární   MeSH
• Staphylococcus aureus metabolismus   MeSH
• vysoká teplota * MeSH
• zvířata MeSH
• Check Tag
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Fungi are commonly involved in dairy product spoilage and the use of bioprotective cultures can be a complementary approach to reduce food waste and economic losses. In this study, the antifungal activity of 89 Lactobacillus and 23 Pediococcus spp. isolates against three spoilage species, e.g., Yarrowia lipolytica, Rhodotorula mucilaginosa and Penicillium brevicompactum, was first evaluated in milk agar. None of the tested pediococci showed antifungal activity while 3, 23 and 43 lactobacilli isolates showed strong antifungal activity or total inhibition against Y. lipolytica, R. mucilaginosa and P. brevicompactum, respectively. Then, the three most promising strains, Lactobacillus paracasei SYR90, Lactobacillus plantarum OVI9 and Lactobacillus rhamnosus BIOIII28 at initial concentrations of 105and 107CFU/ml were tested as bioprotective cultures against the same fungal targets in a yogurt model during a 5-week storage period at 10 °C. While limited effects were observed at 105CFU/ml inoculum level, L. paracasei SYR90 and L. rhamnosus BIOIII28 at 107CFU/ml respectively retarded the growth of R. mucilaginosa and P. brevicompactum as compared to a control without selected cultures. In contrast, growth of Y. lipolytica was only slightly affected. In conclusion, these selected strains may be good candidates for bioprotection of fermented dairy products.

• MeSH
• antifungální látky farmakologie   MeSH
• Lactobacillus fyziologie   MeSH
• mléčné výrobky mikrobiologie   MeSH
• Pediococcus fyziologie   MeSH
• Penicillium růst a vývoj   MeSH
• potravinářská mikrobiologie MeSH
• probiotika MeSH
• Rhodotorula růst a vývoj   MeSH
• Yarrowia růst a vývoj   MeSH
• Publikační typ
• časopisecké články MeSH