Staphylococcus aureus is a gram-positive bacterium, commonly found in the nostrils, on the skin and on the hair of warm-blooded animals, including humans. It can produce a wide variety of virulence factors, including staphylococcal enterotoxins (SEs). In literature, 24 different SEs and many variants have been identified; among these, only five (the so-called classic enterotoxins) have been well-defined. Due to their emetic activity, SEs are frequently responsible for staphylococcal food poisoning, when consumers ingest contaminated food. SEs are proteins with a high tolerance of denaturing and can maintain their activity, even when the vegetative form of the bacteria is inactivated during food processing. The enterotoxin encoding genes are found in a variety of different genetic elements and, as a result, enterotoxin production varies widely between different populations of S. aureus. SEs production is modulated by multiple, and often overlapping, regulatory pathways, which are influenced by environmental factors. Furthermore, complex food matrices possess many characteristics (storage temperature, pH, sugar or salt concentration, presence of competitive microorganisms, etc.) that have a high impact on S. aureus behaviour. The multiple factors influencing S. aureus growth in food matrices and the production of SE complicates risk assessment procedures. In this review, we focus on enterotoxin production by S. aureus in food of animal origin, its regulation and detection and on the most recent developments in predictive microbiology and risk assessment models.

Food security, as part as public health protection, constitutes one of the main objectives for countries aiming to ensure the health of all their citizens. However, food security is compromised worldwide by conflict, political instability, or economic crises, both in developed and developing countries. Conversely, because of the importance of agriculture to the economies of rural areas both in developed and developing countries, this sector can contribute to improving food stability, as well as to furthering food security. Thus, livestock and traditional meat products represent a key factor in ensuring food availability. Overall, biosecurity measures improve animal welfare by decreasing the occurrence of diseases that compromise the stability by causing fluctuations in the availability of meat and animal-derived food products such as milk, eggs, or traditional fermented products. As a consequence, an absence of biosecurity measures affects food security (in its quantitative definition, as described above) as well as the productive, sanitary, and environmental sustainability of the rural environment. Products of animal origin support local trade and the regional economy, while contributing to the availability of foods without great external dependence. The manufacture of foods of animal origin aims to create products that are durable and that maintain food availability for long periods of time, even during seasons with scarce resources. Thus, dry-cured or fermented meat products play an important role in food availability. Food security also refers to food access under healthy economic conditions; therefore, knowledge of the main tools that guarantee the safety of these kinds of food products is essential to achieving food stability and further food security.

From the point of public health, the objective of the slaughterhouse is to guarantee the safety of meat in which meat inspection represent an essential tool to control animal diseases and guarantee the public health. The slaughterhouse can be used as surveillance center for livestock diseases. However, other aspects related with animal and human health, such as epidemiology and disease control in primary production, control of animal welfare on the farm, surveillance of zoonotic agents responsible for food poisoning, as well as surveillance and control of antimicrobial resistance, can be monitored. These controls should not be seen as a last defensive barrier but rather as a complement to the controls carried out on the farm. Regarding the control of diseases in livestock, scientific research is scarce and outdated, not taking advantage of the potential for disease control. Animal welfare in primary production and during transport can be monitored throughout ante-mortem and post-mortem inspection at the slaughterhouse, providing valuable individual data on animal welfare. Surveillance and research regarding antimicrobial resistance (AMR) at slaughterhouses is scarce, mainly in cattle, sheep, and goats. However, most of the zoonotic pathogens are sensitive to the antibiotics studied. Moreover, the prevalence at the slaughterhouse of zoonotic and foodborne agents seems to be low, but a lack of harmonization in terms of control and communication may lead to underestimate its real prevalence.

The term ‘packaging’ refers to the technological intervention aimed at the protection of food from a variety of factors, which provokes the product detriment. Packaging is considered as one of the most interesting technological aspects and a constantly evolving issue in food production. This paper aims at the evaluation of the properties of packaging currently used in the meat industry and analyses the advantages, the disadvantages and the microbiota involved. Packaging is a coordinated system, which prepares the products for transportation, distribution, storage, marketing and consumption. Even if several packaging alternatives are proposed, the common purpose is to guarantee high standards, yet maintaining the required characteristics as long as possible. Meat is a dynamic system with a limited shelf-life and the nutritional and sensory properties may change during storage due to microbial activity and physical or chemical changes. Microbial spoilage, for instance, determines an impact in meat, producing unattractive odours, flavours, discolouration, gas and slime.

Currently, there is an increasing interest to valorise agri-food waste containing bioactive compounds with potential health benefits. In this paper, the recovery of functional molecules from apple pomace, the most abundant by-product of the apple processing industry, was carried out by ultrasound-assisted extraction (UAE) on fresh and freeze-dried samples. UAE extract, obtained by double extraction of freeze-dried apple pomace, was subjected to chromatographic and spectrophotometric characterization. It showed good levels of total phenol content, high antioxidant activity, and interesting antioxidant compounds (quercetin derivatives, chlorogenic acid, phloridzin). Subsequently, freeze-dried apple pomace, containing 40.19% of dietary fibre, was used as a fortifying agent for beef burgers (4% and 8%). The results concerning colour and sensory analysis of the fortified products were graded even better than the control (0%). The improved fibre and phenol content, together with the neutral flavour, represent the most interesting characteristics of fortified burgers. The results confirm that UAE was a successful technique for extracting phenol compounds and that the addition of apple pomace represents a valid approach to increase the health properties and palatability of beef burgers, including for consumers who do not like meat.

Staphylococcus aureus is not only a common cause of bovine mastitis, but also an agent of food poisoning in humans. In an attempt to determine whether staphylococci causing bovine mastitis could also cause food poisoning, 60 isolates of presumed S. aureus were isolated in the period between March and August 2017 from 3,384 routine, composite, quarter milk samples of individual cows raised on 12 dairy farms in central Italy. Seventeen out of 60 isolates were confirmed as S. aureus after coagulase, thermonuclease, and biochemical tests. These isolates were analyzed by PCR for the presence of the nuc, sea, seb, sec, sed, and see genes. The positive isolates were nuc, 100% (17); sea, 35.29% (6); seb, 5.88% (1); sec, 5.88% (1); sed, 29.41% (5); and see, 47.06% (8). The isolates were also tested with 2 enzyme immunoassay diagnostic kits, one for the screening detection of the production of staphylococcal enterotoxins (SEA, SEB, SEC, SED, SEE) and one for the detection of specific enterotoxin produced by each isolate. Seven out of 17 (41.18%) were enterotoxin producers: 7 produced SEA (41.18%), 1 SEB (5.88%), 1 SEC (5.88%), 5 SED (29.41%), and 6 SEE (35.29%). To further characterize the isolates, they were analyzed by the Kirby Bauer test for susceptibility to 13 antimicrobials (ampicillin, ciprofloxacin, kanamycin, tetracycline, gentamicin, methicillin, nalidixic acid, erythromycin, amoxicillin/clavulanic acid, streptomycin, vancomycin, neomycin, and enrofloxacin), and we detected resistance to ampicillin (52.94%), nalidixic acid (70.59%), erythromycin (5.88%), and amoxicillin/clavulanic acid (17.65%). The isolates were sensitive to the main classes of antimicrobials used for the treatment of bovine subclinical mastitis. The presence of enterotoxin-producing isolates of S. aureus in bovine milk means that a temperature abuse or a breakdown in the thermal treatment of the milk could present a food safety risk, particularly if all enterotoxigenic isolates could potentially produce SEA in milk.