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  • Kirje
    Salmonella enterica prevalence, serotype diversity, antimicrobial resistance and control in the European pork production chain
    (Elsevier, 2023) Roasto, Mati; Bonardi, Silvia; Mäesaar, Mihkel; Alban, Lis; Gomes-Neves, Eduarda; Vieira-Pinto, Madalena; Vågsholm, Ivar; Elias, Terje; Lindegaard, Lene Lund; Blagojevic, Bojan
    A risk assessment conducted by EFSA identified Salmonella enterica (Salmonella) as a high-risk hazard at the EU level in the context of meat inspection of swine. Despite pork being considered an important source of S. Typhimurium and its monophasic variant, Regulation (EC) No 2073/2005 does not set criteria for specific Salmonella serotypes. Enforcing specific criteria for Salmonella target serotypes could result in a reduction in the prevalence of Salmonella in the pork production chain, as has happened in broiler flocks. Scope and approach: This study gives an overview of Salmonella enterica in the European pork chain, discussing prevalence, serotype diversity, antimicrobial resistance and epidemiological importance during the last 20 years. Additionally, future trends and recommendations regarding control of Salmonella in the European pork production chain are introduced. Key findings and conclusions: The highest proportions of Salmonella-positive samples were observed at the fattening pig farm level, whereas the prevalence of Salmonella on pig carcasses was much lower. Among epidemiologically important serotypes, isolates of S. Typhimurium, and its monophasic variant were found to be resistant to ampicillin, sulfamethoxazole, streptomycin and tetracycline. Future Salmonella control in the pork production chain can preferably be conducted through a risk-based meat safety assurance system. In conclu- sion, a fit-for-purpose strategy applied to the pork production chain and adapted to the national epidemio- logical situation can deliver acceptable consumer safety.
  • Kirje
    Fast Protein and Metabolites (Nucleotides and Nucleosides) Liquid Chromatography Technique and Chemical Sensor for the Assessment of Fish and Meat Freshness
    (MDPI, 2023) Kuznetsov, Artur; Frorip, Aleksandr; Sünter, Alar; Kasvand, Nensi; Korsakov, Vadim; Konoplev, Georgii; Stepanova, Oksana; Rusalepp, Linda; Anton, Dea; Püssa, Tõnu; Roasto, Mati; Abramova, Liubov; Kozin, Andrey; Toom, Lauri; Hirsch, Soeren; Mukhin, Nikolay
    Fast protein and metabolite liquid chromatography (FPLMC) was introduced years ago to enable the easy separation of high-molecular compounds such as proteins from small molecules and the identification of the low-molecular substances. In this paper, the method is applied for the rapid evaluation of freshness and monitoring the aging of animal meat and fish. A novel chromatographic sensor was developed with a deep UV LED-based photometric detection unit (255–265 nm), an original flow cuvette and registration scheme; the processing of a chromatogram with the sensor takes approximately 15 min. Strict isochronism between the elution of ATP metabolites, mainly hypoxanthine (Hx) and inosine monophosphate (IMP), and the time of maturation of meat or fish, was discovered. A new freshness index H* = [Hx]/[IMP] was introduced, which is proportional to the instrumental delay time in the FPMLC chromatograms: the H* index < 0.5 indicates the presence of inosine monophosphate (IMP) and the high quality of the meat or fish. Reasonably strong correlations were revealed between data obtained by FPMLC and total volatile basic nitrogen TVB-N (for fish) or volatile fatty acids VFA (for meat) content. Moreover, putative nucleotide salvage and an increase in the concentration of IMP were observed in fish after heat treatment using the FPMLC sensor and NMR technique.
  • Kirje
    Antimicrobial Resistance of Campylobacter coli Isolated from Caecal Samples of Fattening Pigs at Slaughter
    (MDPI, 2023) Tedresoo, Triin; Roasto, Mati; Mäesaar, Mihkel; Fredriksson-Ahomaa, Maria; Meremäe, Kadrin
    Pigs are known as the main Campylobacter coli reservoirs. Campylobacteriosis, the most commonly reported gastrointestinal disease in humans, is mainly caused by the consumption of poultry meat, and little is known about the role of pork. Pigs are often associated with C. coli, including antimicrobial-resistant isolates. Therefore, the entire pork production chain must be considered as an important source of antimicrobial-resistant C. coli. This study aimed to determine the antimicrobial resistance of Campylobacter spp. isolated from caecal samples of fattening pigs at the Estonian slaughterhouse level over a five-year period. The proportion of Campylobacter-positive caecal samples was 52%. All Campylobacter isolates were identified as C. coli. A high proportion of the isolates were resistant to most of the studied antimicrobials. The resistance to streptomycin, tetracycline, ciprofloxacin and nalidixic acid was 74.8%, 54.4%, 34.4% and 31.9%, respectively. In addition, a high proportion (15.1%) of the isolates were multidrug-resistant and, in total, 93.3% were resistant to at least one antimicrobial.
  • Kirje
    Manifestation of Heat-Induced Valuable Dietary Nucleotide Salvage in Food Prepared from Aged Fish in Fast Protein and Metabolites Liquid Chromatography, ATP-Bioluminescence Assay, and NMR Spectra
    (MDPI, 2023) Sünter, Alar; Kuznetsov, Artur; Rausepp, Piret; Püssa, Tõnu; Toom, Lauri; Konoplev, Georgii; Stepanova, Oksana S.; Stepanova, Oksana V.; Lyalin, Daniil; Frorip, Aleksandr; Roasto, Mati
    Dietary nucleotides and nucleosides, primarily inosine monophosphate (IMP) and the adenine nucleotide pool (ANP), are widely considered as essential nutrients responsible for multiple biological functions. Food prepared from meat and fish is the main source of these substances in the human diet, and it is extremely important to implement storage and processing techniques ensuring their maximum preservation and even accumulation during maturation or conditioning. In experiments with freshly refrigerated grass carp and defrosted Alaska pollock fillets it was discovered, initially using Fast Protein and Metabolites Liquid Chromatography and the ATP- bioluminescence test, and afterwards validated by NMR spectroscopy, that heat treatment identical to conventional culinary processing in aqueous or wet media at temperatures above 62 ◦C leads to nucleotide salvage (recovery) in aged fish. A significant increase in the concentration of IMP, and even an emergence of ANP substances, were reliably demonstrated in fish samples which had already partially or fully lost these components during prolonged storage due to the ATP breakdown metabolic reactions. Owing to this recovery, the nutritive value of ready-to-eat food can be higher than was initially evaluated in raw products before heat treatment: an effect that should certainly be considered in practical nutrition. Moreover, it is necessary to reconsider the widely acknowledged system of indices of freshness based on nucleotides and nucleosides elaborated a long time ago for raw meat and fish products.
  • Kirje
    Ülevaade taimsete lisandite antimikroobse toime uuringutest in vitro ja tooretes seahakklihatoodetes
    (Estonian Academic Agricultural Society, 2023) Meremäe, Kadrin; Koskar, Julia; Püssa, Tõnu; Raudsepp, Piret; Anton, Dea; Roasto, Mati
    Plant additives can be used in food technologies as natural additives to replace synthetic food additives partially or completely. The present work aims to give an overview of studies that have been carried out over the years 2011–2019 in the Department of Food Hygiene and Safety at the Estonian University of Life Sciences on the antimicrobial activity of plant additives in vitro as well as in raw minced pork products in the perspective to find effective candidates to use them further in meat products. The findings of the in vitro studies showed that the strongest bacterial growth inhibition was observed in the 96% ethanol extracts of rhubarb root and petiole as well as berries of blackcurrant and chokeberry. In the present in vitro study, plant extracts had the strongest antimicrobial activity against Campylobacter jejuni. In raw minced pork studies, the total microbes as well as yeasts and molds were inhibited in raw minced pork samples only in the presence of powders of rhubarb petioles and tomato or their mixture. In conclusion, this work revealed that powders of rhubarb, tomato and berries of blackcurrant and chokeberry are perspective candidates for inhibiting microbial growth in raw minced pork products.
  • Kirje
    Redutseerivate suhkrute sisaldus Eestis enimkasvatatud köögiviljades saagikoristusjärgselt ja pärast säilitamist
    (Estonian Academic Agricultural Society, 2022) Jalakas, Sirje; Roasto, Mati; Kaart, Tanel; Praakle, Kristi; Mäesaar, Mihkel; Elias, Terje
    The study examined the content of reducing sugars in various varieties of potato, beetroot, turnip and pumpkin most commonly grown in Estonia. This study aimed to determine the varieties of vegetables with the lowest levels of reducing sugars after harvesting and after storage at two different temperatures (3 and 8 C). In the present study it was found that the potato variety with the lowest content of reducing sugars after harvesting and after six months of storage was potato variety 'Birgit' with 0.19 g 100 g–1after harvesting, 0.98 g 100 g–1 after storage at 3 C and 0.38 g 100 g–1 after storage at 8 C, respectively. All three varieties of the beetroot, after harvest, contained a similar amount of reducing sugars. After six months of storage, the lowest content of reducing sugars was determined for variety 'Boro' with 1.22 g 100 g–1 at 3 C and 0.96 g 100 g–1 at 8 C, respectively. The lowest average concentrations of reducing sugars from turnips were after harvest in the variety 'Kohalik sinine' with 3.38 g 100 g–1. Also after storage, the same variety had the lowest content of reducing sugars with 8.36 g 100 g–1 at 3 C and 3.76 g 100 g–1 at 8 C, respectively. From the pumpkin varieties, the lowest reducing sugars contents were determined for variety 'Gold Medal' with 2.64 g 100 g–1after harvesting, 2.40 g 100 g–1 after storage at 3 C and 1.90 g 100 g–1 after storage at 8 C. It can be concluded that all studied vegetables stored at 3 °C contained higher amounts of reducing sugars than those stored at 8 °C.
  • Kirje
    Microbial Growth Dynamics in Minced Meat Enriched with Plant Powders
    (MDPI, 2022) Koskar, Julia; Meremäe, Kadrin; Püssa, Tõnu; Anton, Dea; Elias, Terje; Rätsep, Reelika; Mäesaar, Mihkel; Kapp, Karmen; Roasto, Mati
    Plant powders with antimicrobial properties can be used in food manufacturing and must comply with the demands of consumers regarding microbiological safety, nutritional value, and sensory properties of foods. The present study aimed to assess the microbial growth inhibitory ability of different plant powders, including by-products of horticultural primary processing (e.g., pomace) in raw and cooked minced pork. The total counts of aerobic mesophilic bacteria, pseudomonads, yeasts, and moulds were studied to assess the microbial growth dynamics in meat samples. Additionally, for the plant powders, which were able to suppress the microbial growth in a total counts dynamics study, the growth potential of Listeria monocytogenes in ready-to-eat (RTE) minced meat samples was estimated by challenge testing. The results showed that the most effective combinations of plant powders in raw minced pork, in relation to the total counts of microorganisms, were 3% apple+1% onion+2% blackcurrant berries (Apple+On+BCber); 3% apple+1% garlic+2% tomato (Apple+Ga+Tom); and 3% apple+2% tomato+1% rhubarb petioles (Apple+Tom+Rhub). However, challenge tests revealed that some plant powders were unable to inhibit the growth of L. monocytogenes. The lowest L. monocytogenes growth potential (δ = 2.74 log cfu/g) was determined for cooked minced pork samples enriched with 2% rhubarb petioles, followed by Apple+On+BCber (δ = 3.63 log cfu/g) and Apple+Tom+Rhub (δ = 3.74 log cfu/g). In minced pork samples without plant additives, the L. monocytogenes growth potential was 7.30 log cfu/g. In conclusion, blends of plant powders may have good potential for developing meat products with acceptable microbiological quality.
  • Kirje
    Prevalence and counts of Listeria monocytogenes and Campylobacter spp. in food and molecular characterisation of the isolates in Estonia
    (Estonian University of Life Sciences, 2022) Mäesaar, Mihkel; Roasto, Mati; Institute of Veterinary Medicine and Animal Sciences; Møller Nielsen, Eva (opponent)
    Listeria monocytogenes is a bacterial zoonotic agent and a major cause of listeriosis in humans. The invasive form of listeriosis causes severe illness and can be fatal. In the European Union (EU), 2,621 cases of listeriosis were reported in humans in 2019, with a 17.6% case fatality rate. A study carried out in 2012–2013 found that 16.8% of the 185 samples of ready-to-eat fish (RTE) products tested positive, but only one salted and sliced salmon fillet product exceeded the European Union food safety criterion of 100 CFU/g at the end of its shelf-life. Unlike L. monocytogenes, infections caused by Campylobacter jejuni are significantly more common in humans. Campylobacteriosis usually affects people with mild symptoms and is typically a self-limiting disease. In 2019, 220,682 cases of campylobacteriosis were registered in the EU, but the mortality rate per case was only 0.03% compared to listeriosis. A survey conducted in 2012 found that 35.0% of the 220 samples of fresh broiler chicken meat from Estonia, Latvia and Lithuania sold in Estonia were contaminated with campylobacters. Higher prevalence, counts and antibiotic resistance of campylobacters were associated with imported chicken broiler products. These indicators were low in fresh broiler chicken meat products of Estonian origin. The molecular methods used in the study allowed the strain of L. monocytogenes isolated from Estonian food to be associated with a multi-country outbreak of listeriosis in several European countries in 2014–2019. A retrospective survey also revealed that the same strain was already in the company's RTE fish products before the outbreak was first registered. Molecular studies also showed that the primary source of human cases of campylobacteriosis in Estonia is mainly related to poultry, including poultry meat. Systematic application of whole-genome sequencing in routine surveillance will contribute to the effectiveness of investigating food-borne outbreaks and thus to the prevention of related cases.
  • Kirje
    Antibiotic Resistance in Campylobacter spp. Isolated from Broiler Chicken Meat and Human Patients in Estonia
    (MDPI, 2022) Tedersoo, Triin; Roasto, Mati; Mäesaar, Mihkel; Häkkinen, Liidia; Kisand, Veljo; Ivanova, Marina; Valli, Marikki Heidi; Meremäe, Kadrin
    Poultry meat is considered the most important source of Campylobacter spp. Because of ris- ing antimicrobial resistance in Campylobacter spp., this study investigated the antimicrobial resistance of Campylobacter isolates from fresh broiler chicken meat originating from the Baltic countries sold in Estonian retail settings. Additionally, human clinical isolates obtained from patients with Campylobacter enteritis in Estonia were analysed. The aim of this study was to investigate the susceptibility of Campylobacter spp. to nalidixic acid, ciprofloxacin, tetracycline, streptomycin, erythromycin and gen- tamicin. The broth microdilution method with the EUCAMP2 panel was used for MIC determination and antimicrobial mechanisms were analysed using WGS data. A total of 46 Campylobacter strains were analysed, of which 26 (42.6%) originated from Lithuanian, 16 (26.2%) from Latvian, and 4 (6.6%) from Estonian fresh broiler chicken meat. In addition, 15 (24.6%) Campylobacter strains of patients with campylobacteriosis were tested. The antimicrobial resistance patterns of Campylobacter spp. isolated from fresh broiler chicken meat samples of Estonian, Latvian and Lithuanian origin collected in Estonian retail, and from patients with Campylobacter enteric infections, were determined. A total of 46 (75%) of the isolates tested were C. jejuni and 15 (25%) were C. coli. Campylobacter resistance was highest to nalidixic acid (90.2% of strains) and ciprofloxacin (90.2%), followed by tetracycline (57.4%), streptomycin (42.6%) and erythromycin (6.6%). All strains were sensitive to gentamicin. Additionally, antimicrobial resistance genes and point mutations were detected in 27 C. jejuni and 8 C. coli isolates previously assigned as resistant with the phenotypic method. A high antibiotic resistance of Campylobacter spp. in Lithuanian- and Latvian-origin broiler chicken meat and Estonian clinical isolates was found. Similar antibiotic resistance patterns were found for broiler chicken meat and human Campylobacter isolates.