Occurrence and antibiotic resistance of enterotoxigenic Staphylococcus aureus in raw ovine and caprine milk in Greece

International audienceAbstractOvine (n = 140) and caprine (n = 35) raw bulk tank milk samples from farms in central Greece were examined for the occurrence of enterotoxigenic Staphylococcus aureus. The S. aureus isolates were screened for staphylococcal enterotoxin (SE) production, the presence of enterotoxin genes, antibiotic resistance (AR), and methicillin resistance. S. aureus was isolated from 24.3% and 31.4% of ovine and caprine milk samples, respectively. Among the S. aureus isolates of ovine milk (n = 34) and caprine (n = 11) milk, the enterotoxigenic (SEA-SED) isolates were 21 (61.8%) and 7 (63.6%) for the ovine and caprine milk, respectively. Most toxigenic isolates harbored more than one toxin gene and a total of 11 distinct toxinotypes were detected. The most frequent toxin-gene combinations were “sec, tst” (8 isolates), “seb, seg, sei, tst” (4), “seb, seg, sei” (3), and “seb” (3). Six isolates displayed multiple AR towards up to five antimicrobials. Among ovine milk isolates, the highest resistance frequency was observed towards erythromycin (11.8% of the isolates) and tetracycline (8.8%). Among caprine milk isolates, the most frequent resistance was observed towards erythromycin (18.2%). One methicillin-resistant S. aureus (MRSA) isolate was detected in an ovine milk sample and belonged to spa type t4038. This spa type has been isolated for the first time in Greece and, to our knowledge, has not been previously reported among MRSA isolates from raw milk or dairy products worldwide

A new production technology for gyros and study of parameters affecting the quality of the final product

In the present thesis the First Part (Chapters 1 and 2) is devoted to a literature review concerning gyros and similar meat products, and the food preparation technology with cook-chill systems, among which is the technology sous vide. Subjects regarding “Reduced” and “Low-fat” meat products were also examined. In the Second Part the experiment of the thesis is presented. The studies and their findings are as follows: ¦ Using a production technology based in the principles of sous vide technology, the effect of percentage of salt, water and oil addition, with or without the addition of phosphates, were tested in order the ideal addition to be determined. The under assessment parameters were the processing yield, chemical composition, pH and shear-force values. A 10-member panel evaluated the sensory attributes of the product (Chapter 3). Yield was 71.94% when salt and water were added in 1.5% and 15%, respectively. The addition of phosphates did not increase the yield. On the contrary, simultaneous addition of corn oil and phosphates in 0.2% increased yield significantly. When 50 ml oil per Kg meat was added, the addition of phosphates resulted in increase of yield from 74.90 to 78.23%. Respectively, when the oil addition was 75 ml per Kg meat, yield increased from 74.14 to 79.19% by the phosphates addition. Oil addition resulted in pH values decrease of samples, from 6.4 without the oil addition to 6.2, when oil was added in 5%. The overall palatability of the product during sensory evaluation was high, while the fat content despite the oil addition did not exceed 6%. ¦ The effect of various parameters of the technology production on the processing yield and qualitative characteristics of the final product was evaluated. These parameters related to meat pieces size, the thermal process, the quantity of brine, the duration of tumbling process and the way of storage (refrigerated or frozen). The aim of these studies was the development of alternative “gyros” production technologies. The ability of microwave reheating of the product was also examined (Chapter 4). From preliminary results and experimentations, apart from the technology developed in Chapter 3 (Technology A), three more technologies arose, that could be proposed for “gyros” production (Technologies B, C, D). In technology A the product was refrigerated, while Technologies B, C, D provided the capability for frozen storage of products. Technology D, moreover enabled product reheating easily and quickly using microwaves. Processing yield of Technology A was 74.24%. For Technology B, yield was 82.07% when product was refrigerated and 77.07% when was frozen. Similarly, for Technology C the corresponding values were 75.08% and 68.77%, respectively. For Technology D, for both ways of storage, yield surpassed 84%. Frozen products of Technologies B and C had lower preference scores than the refrigerated ones. For the product of Technology D, panellists did not detected differences between refrigerated and frozen storage. The protein, humidity, fat and ash content of the refrigerated products varied from 22.6 to 28.2%, 64.2 to 68.0%, 5.1 to 7.3% and 1.9 to 2.5%, respectively. In frozen products the corresponding values were from 23.8 to 22.9, 65.7 to 67.9% and 2.0 to 2.5%. ¦ In final products produced according to the proposed technologies and in samples of traditional gyros the fat content was determined. These products were also subjected in consumer evaluation (Chapter 5). The new “gyros” products had significantly reduced fat content compared to traditional gyros samples. The reduction exceeded 60% for products A, B, C and was almost 49% for product D. During evaluation from a consumer panel, it was realized that these new products achieved satisfactory acceptability. Despite the fact that the new products achieved moderate scores for appearance and taste in comparison to traditional gyros, the 85, 77.5, 75 and 80% of participating consumers would have chosen to consume products A, B, C and D respectively, instead of traditional gyros. This percentage reached 87.5% if the new products were labelled as “reduced fat gyros”.Στη παρούσα διατριβή, στο Πρώτο Μέρος (Κεφάλαια 1 και 2) έγινε μια βιβλιογραφική ανασκόπηση θεμάτων που αφορούν στο γύρο και τα συναφή προϊόντα και την τεχνολογία παρασκευής τροφίμων με τα «συστήματα θερμικής επεξεργασίας-ψύξης» (cook-chill systems), μεταξύ των οποίων συγκαταλέγεται και το «σύστημα θερμικής επεξεργασίας υπό κενό» (sous vide). Επίσης, εξετάστηκαν θέματα που αφορούσαν στα προϊόντα με βάση το κρέας με μειωμένη και/ή χαμηλή λιποπεριεκτικότητα (“Reduced fat” / “Low fat” meat products). Στο Δεύτερο Μέρος παρουσιάζονται τα αποτελέσματα της πειραματικής έρευνας που πραγματοποιήθηκε: ¦ Χρησιμοποιώντας μια τεχνολογία παρασκευής, η οποία στηρίζεται στις βασικές αρχές των τροφίμων sous vide, διερευνήθηκε η επίδραση της ποσότητας προσθήκης του άλατος, του νερού και του ελαίου, με ή χωρίς την προσθήκη φωσφορικών αλάτων, στην απόδοση σε τελικό προϊόν και στη χημική σύνθεση, στη δύναμη κοπής (shear force value) και στην τιμή του pH του παραγόμενου προϊόντος. Μια ομάδα από 10 εκπαιδευμένους δοκιμαστές αξιολογούσε τα οργανοληπτικά χαρακτηριστικά του παραγόμενου προϊόντος (Κεφάλαιο 3). Στη νέα αυτή τεχνολογία χρησιμοποιούνταν άπαχο κρέας ως πρώτη ύλη, τεμαχιζόταν σε μικρά τεμαχίδια, υποβαλόταν σε μάλαξη με τα διάφορα πρόσθετα, ακολουθούσε η συσκευασία υπό κενό και η θερμική επεξεργασία σε υδατόλουτρο. Το προϊόν στο σημείο πώλησης απαιτούσε μόνο ψήσιμο σε θερμαινόμενες πλάκες για σύντομο χρόνο για να μοιάζει με τον παραδοσιακό γύρο. Διαπιστώθηκε ότι, όταν το αλάτι και το νερό προστέθονταν σε αναλογία 1,5% και 15,0% αντίστοιχα, η απόδοση σε τελικό προϊόν ήταν 71,94%. Η προσθήκη φωσφορικών αλάτων δεν επέφερε στατιστικά σημαντική αύξηση στην απόδοση σε τελικό προϊόν. Αντίθετα, η ταυτόχρονη προσθήκη στο κρέας αραβοσιτέλαιου και 0,2% φωσφορικών αλάτων είχε ως αποτέλεσμα την αύξηση της απόδοσης. Έτσι, όταν προσθέτονταν 5% και 7,5% ελαίου η απόδοση με την προσθήκη των φωσφορικών αλάτων αυξανόταν από 74,90 σε 78,23% και από 74,14 σε 79,19% αντίστοιχα. Η προσθήκη του ελαίου σε ποσοστό 5% είχε ως αποτέλεσμα και τη μείωση της τιμής του pH των δειγμάτων, από 6,4 σε 6,2. Η αποδεκτικότητα του παραγόμενου προϊόντος κατά την οργανοληπτική εξέταση ήταν αρκετά υψηλή, ενώ η λιποπεριεκτικότητά του παρά την προσθήκη του ελαίου δεν ξεπερνούσε το 6%

Inactivation of Foodborne Viruses by High-Pressure Processing (HPP)

High-pressure processing (HPP) is an innovative non-thermal food preservation method. HPP can inactivate microorganisms, including viruses, with minimal influence on the physicochemical and sensory properties of foods. The most significant foodborne viruses are human norovirus (HuNoV), hepatitis A virus (HAV), human rotavirus (HRV), hepatitis E virus (HEV), human astrovirus (HAstV), human adenovirus (HuAdV), Aichi virus (AiV), sapovirus (SaV), and enterovirus (EV), which have also been implicated in foodborne outbreaks in various countries. The HPP inactivation of foodborne viruses in foods depends on high-pressure processing parameters (pressure, temperature, and duration time) or non-processing parameters such as virus type, food matrix, water activity (aw), and the pH of foods. HPP was found to be effective for the inactivation of foodborne viruses such as HuNoV, HAV, HAstV, and HuAdV in foods. HPP treatments have been found to be effective at eliminating foodborne viruses in high-risk foods such as shellfish and vegetables. The present work reviews the published data on the effect of HPP processing on foodborne viruses in laboratory media and foods

Inactivation of Foodborne Viruses by High-Pressure Processing (HPP)

High-pressure processing (HPP) is an innovative non-thermal food preservation method. HPP can inactivate microorganisms, including viruses, with minimal influence on the physicochemical and sensory properties of foods. The most significant foodborne viruses are human norovirus (HuNoV), hepatitis A virus (HAV), human rotavirus (HRV), hepatitis E virus (HEV), human astrovirus (HAstV), human adenovirus (HuAdV), Aichi virus (AiV), sapovirus (SaV), and enterovirus (EV), which have also been implicated in foodborne outbreaks in various countries. The HPP inactivation of foodborne viruses in foods depends on high-pressure processing parameters (pressure, temperature, and duration time) or non-processing parameters such as virus type, food matrix, water activity (aw), and the pH of foods. HPP was found to be effective for the inactivation of foodborne viruses such as HuNoV, HAV, HAstV, and HuAdV in foods. HPP treatments have been found to be effective at eliminating foodborne viruses in high-risk foods such as shellfish and vegetables. The present work reviews the published data on the effect of HPP processing on foodborne viruses in laboratory media and foods

Ochratoxin A in Slaughtered Pigs and Pork Products

Ochratoxin A (OTA) is a mycotoxin that is produced after the growth of several Aspergillus and Penicillium spp. in feeds or foods. OTA has been proved to possess nephrotoxic, hepatotoxic, teratogenic, neurotoxic, genotoxic, carcinogenic and immunotoxic effects in animals and humans. OTA has been classified as possibly carcinogenic to humans (Group 2B) by the IARC in 2016. OTA can be mainly found in animals as a result of indirect transmission from naturally contaminated feed. OTA found in feed can also contaminate pigs and produced pork products. Additionally, the presence of OTA in pork meat products could be derived from the direct growth of OTA-producing fungi or the addition of contaminated materials such as contaminated spices. Studies accomplished in various countries have revealed that pork meat and pork meat products are important sources of chronic dietary exposure to OTA in humans. Various levels of OTA have been found in pork meat from slaughtered pigs in many countries, while OTA levels were particularly high in the blood serum and kidneys of pigs. Pork products made from pig blood or organs such as the kidney or liver have been often found to becontaminated with OTA. The European Union (EU) has established maximum levels (ML) for OTA in a variety of foods since 2006, but not for meat or pork products. However, the establishement of an ML for OTA in pork meat and meat by-products is necessary to protect human health

Ochratoxin A in Slaughtered Pigs and Pork Products

Ochratoxin A (OTA) is a mycotoxin that is produced after the growth of several Aspergillus and Penicillium spp. in feeds or foods. OTA has been proved to possess nephrotoxic, hepatotoxic, teratogenic, neurotoxic, genotoxic, carcinogenic and immunotoxic effects in animals and humans. OTA has been classified as possibly carcinogenic to humans (Group 2B) by the IARC in 2016. OTA can be mainly found in animals as a result of indirect transmission from naturally contaminated feed. OTA found in feed can also contaminate pigs and produced pork products. Additionally, the presence of OTA in pork meat products could be derived from the direct growth of OTA-producing fungi or the addition of contaminated materials such as contaminated spices. Studies accomplished in various countries have revealed that pork meat and pork meat products are important sources of chronic dietary exposure to OTA in humans. Various levels of OTA have been found in pork meat from slaughtered pigs in many countries, while OTA levels were particularly high in the blood serum and kidneys of pigs. Pork products made from pig blood or organs such as the kidney or liver have been often found to becontaminated with OTA. The European Union (EU) has established maximum levels (ML) for OTA in a variety of foods since 2006, but not for meat or pork products. However, the establishement of an ML for OTA in pork meat and meat by-products is necessary to protect human health