Publikatsioonid

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/8660

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Nüüd näidatakse 1 - 20 20

Adenosine Triphosphate and Adenylate Energy Charge in Ready-to-Eat Food
(MDPI, 2024) Konoplev, Georgii; Sünter, Alar; Kuznetsov, Artur I.; Raudsepp, Piret; Püssa, Tõnu; Toom, Lauri; Rusalepp, Linda; Anton, Dea; Stepanova, Oksana V.; Lyalin, Daniil; Abramova, Liubov; Kozin, Andrey; Stepanova, Oksana S.; Frorip, Aleksandr; Roasto, Mati
It is commonly accepted that dietary nucleotides should be considered as essential nutrients originating mainly but not exclusively from meat and fish dishes. Most research in food science related to nutrition nucleotides is focused on raw products, while the effects of thermal processing of ready-to-eat food on nucleotide content are largely overlooked by the scientific community. The aim of this study is to investigate the impact of thermal processing and cold storage on the content of dietary nucleotides in freshly prepared and canned ready-to-eat meat and fish food. The concentrations of ATP, ADP, AMP, IMP, Ino, and Hx were determined using NMR, HPLC, FPMLC, and ATP bioluminescence analytical techniques; freshness indices K and K1 and adenylate energy charge (AEC) values were estimated to assess the freshness status and confirm a newly unveiled phenomenon of the reappearance of adenylate nucleotides. It was found that in freshly prepared at 65 ◦C ≤ T ≤ +100 ◦C and canned food, the concentration of free nucleotides was in the range of 0.001–0.01 μmol/mL and remained unchanged for a long time during cold storage; the correct distribution of mole fractions of adenylates corresponding to 0 < AEC < 0.5 was observed compared to 0.2 < AEC < 1.0 in the original raw samples, with either a high or low content of residual adenylates. It could be assumed that heating at nonenzymatic temperatures T > 65 ◦C can rupture cell membranes and release residual intracell nucleotides in quite a meaningful concentration. These findings may lead to a conceptual change in the views on food preparation processes, taking into account the phenomenon of the free adenylates renaissance and AEC bioenergetics.
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.
Antimicrobial Resistance of Campylobacter coli Isolated from Caecal Samples of Fattening Pigs at Slaughter
(MDPI, 2023) Tedersoo, 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.
Campylobacter spp. in fresh broiler chicken meat and pig caecal samples in Estonia
(Estonian University of Life Sciences, 2024) Tedersoo, Triin; Meremäe, Kadrin (advisor); Roasto, Mati (advisor); Institute of Veterinary Medicine and Animal Sciences; Zwietering, Marcel (opponent)
ABSTRACT. Campylobacteriosis has been the most frequently reported zoonosis in the European Union (EU) since 2005. A total of 127,840 confirmed cases of human campylobacteriosis were reported in 2021, with a notification rate of 41.1 per 100,000 people in the EU. Campylobacter jejuni and Campylobacter coli are the main Campylobacter species causing 80 and 10% of human infections, respectively. The majority of Campylobacter spp. infections are mild and self-limiting. However, it can result in severe systemic illness or mortality in children, older adults, and immunocompromised individuals. Several studies have confirmed that poultry meat, especially broiler chicken meat, is the primary source of human campylobacteriosis; however, the role of pork in the development of Campylobacter enteritis in humans has not been well studied. Nevertheless, pig-derived C. coli have been linked to Campylobacter infections in humans. The current study revealed that broiler chicken meat of Lithuanian and Latvian origin sold in Estonian retail stores was contaminated with highly resistant Campylobacter spp. High genetic diversity was observed among the Campylobacter isolates from fresh broiler chicken meat samples. Genotyping has revealed a link between campylobacteriosis in Estonia and imported fresh broiler chicken meat. The antimicrobial resistance profile of Lithuanian broiler chicken meat isolates overlapped with those obtained from humans in Estonia. This implies that eating Campylobacter-contaminated broiler chicken meat could pose a potential risk to Estonians. In addition to broiler chicken meat, pork consumption can also pose a potential public health risk, as this study revealed that pigs are carriers of antimicrobial-resistant C. coli. Antimicrobial-resistant bacteria in food can reach consumers and pose a threat to their health. To mitigate the incidence of antimicrobial resistance in Campylobacter spp., it is critical to adhere to treatment guidelines for both humans and animals, as well as implement proper practices at the farm level.
Comparison of european surveillance and control programs for Salmonella in broiler and Turkey chains
(Elsevier, 2024) Cota, João B.; Langkabel, Nina; Barco, Lisa; Olsen, Abbey; Bonardi, Silvia; Vieira-Pinto, Madalena; Roasto, Mati; Huneau-Salaün, Adeline; Sandberg, Marianne; Alvseike, Ole; Kautto, Arja H.; Blagojevic, Bojan; Majewski, Michał; Laukkanen-Ninios, Riikka; Nagel-Alne, Gunvor Elise; Le Bouquin-Leneveu, Sophie; Fredriksson-Ahomaa, Maria; Kaukonen, Eija
For the past years, Salmonella has been one of the major foodborne pathogens in Europe, leading to the development of several control efforts to reduce its impact on human health. Poultry meat has been consistently implicated in foodborne cases of salmonellosis. One of the strategies to lessen the burden of salmonellosis in humans was the implementation of national control programs (NCPs) for Salmonella in broilers and turkeys aiming for reductions in these animal populations. In this paper, a description and comparison of the Salmonella surveillance and control programs that are currently implemented for the broiler and turkey chains in different European countries was performed. All the countries studied have set multiple surveillance and control actions for Salmonella at different stages of the broiler and turkey chains, namely the feed, farm and meat levels. Although most of the control programs are aligned with European Union (EU) regulations, some differences were observed, mostly regarding feed controls, farm surveillance schemes, target serovars and the handling of positive flocks. Overall, these differences had a regional pattern, with the Nordic countries having more detailed control programs with a zero-tolerance in meat. The remaining countries generally follow EU legislation, but in some cases, additional specifications were identified by this study. Despite the positive impact of these control programs on the reduction of human cases of salmonellosis, the decreasing tendency has reached a stall. The authors suggest that the NCPs are regularly revised within the framework of risk-based meat assurance systems, and the inclusion of additional target serovars which are simultaneously prevalent in broiler and turkey flocks and relevant in terms of public health within a country or a region. Furthermore, within the revision of NCPs, sampling schemes and strategies need to be consistent, following the risk management approach that has led to very low prevalences of Salmonella in poultry meat in some European countries.
The Effect of Fruit and Berry Pomaces on the Growth Dynamics of Microorganisms and Sensory Properties of Marinated Rainbow Trout
(MDPI, 2023) Roasto, Mati; Mäesaar, Mihkel; Püssa, Tõnu; Anton, Dea; Rätsep, Reelika; Elias, Terje; Jortikka, Salli; Pärna, Merilin; Kapp, Karmen; Tepper, Marek; Kerner, Kristi; Meremäe, Kadrin
Plant pomaces in suitable forms (powders, extracts) can be used in foods of animal origin to increase the nutritional value and safety of these foods. In the present study, water extracts of apple, black currant, rhubarb and tomato pomaces were used in fish marinade solutions to evaluate their effect on the growth dynamics of microorganisms and the growth potential of Listeria monocytogenes by challenge testing. The results showed that mesophilic aerobic microorganisms, Pseudomonas spp., yeasts and moulds remained at acceptable levels throughout the predetermined storage period. The challenge test results showed that the overall growth potential of L. monocytogenes in all marinated rainbow trout samples remained at ≤0.5 log10 cfu/g during the study period, and none of the marinated fish samples supported the growth of L. monocytogenes. In addition, the effect of fruit and berry pomaces on the sensory properties of marinated rainbow trout samples was evaluated. The results revealed that it is possible to effectively use fruit and berry pomaces in marinated fish products, ensuring food safety, high microbiological quality, acceptable sensory characteristics and a sufficiently long shelf life of the products.
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.
Harnessing Nature’s Defence: The Antimicrobial Efficacy of Pasteurised Cattle Milk-Derived Extracellular Vesicles on Staphylococcus aureus ATCC 25923
(MDPI, 2024) Sapugahawatte, Dulmini Nanayakkara; Godakumara, Kasun; Mäesaar, Mihkel; Ekanayake, Gayandi; Midekessa, Getnet Balcha; Prasadani, Madhusha; Kodithuwakku, Suranga; Roasto, Mati; Andronowska, Aneta; Fazeli, Alireza
Increasing antimicrobial resistance (AMR) challenges conventional antibiotics, prompting the search for alternatives. Extracellular vesicles (EVs) from pasteurised cattle milk offer promise, due to their unique properties. This study investigates their efficacy against five pathogenic bacteria, including Staphylococcus aureus ATCC 25923, aiming to combat AMR and to develop new therapies. EVs were characterised and tested using various methods. Co-culture experiments with S. aureus showed significant growth inhibition, with colony-forming units decreasing from 2.4 × 105 CFU/mL (single dose) to 7.4 × 104 CFU/mL (triple doses) after 12 h. Milk EVs extended lag time (6 to 9 h) and increased generation time (2.8 to 4.8 h) dose-dependently, compared to controls. In conclusion, milk EVs exhibit dose-dependent inhibition against S. aureus, prolonging lag and generation times. Despite limitations, this suggests their potential in addressing AMR.
In Vitro Antibacterial and Antioxidative Activity and Polyphenolic Profile of the Extracts of Chokeberry, Blackcurrant, and Rowan Berries and Their Pomaces
(MDPI, 2024) Meremäe, Kadrin; Raudsepp, Piret; Rusalepp, Linda; Anton, Dea; Bleive, Uko; Roasto, Mati
The chemical composition of berries and berry pomaces is diverse, containing polyphenolic components that may have both antibacterial and antioxidative properties. In the present study, in vitro antibacterial effect of the extracts of chokeberry, blackcurrant, and rowan berries and berry pomaces against L. monocytogenes, S. aureus, E. coli, and C. jejuni was studied. In addition, the polyphenolic profile and antioxidant activity of these extracts were investigated. The polyphenolic profiles in the aqueous and 30% ethanolic extracts were determined chromatographically by HPLCMS, and the total polyphenol content was estimated spectrophotometrically by HPLC-DAD-UV. The minimal inhibition concentrations (MICs) of the extracts against tested bacteria were determined by the broth microdilution method. The content of total polyphenols was highest and good antioxidative properties of the extracts were determined for chokeberry and blackcurrant berries and their pomaces. The highest proportions of total quercetin derivatives and anthocyanins were found in the extracts of chokeberry berry/pomace and blackcurrant berry/pomace, respectively. The sensitivity of tested microbes to the extracts of berries and berry pomaces was as follows: S. aureus > L. monocytogenes > E. coli and C. jejuni. In vitro antibacterial activity of tested extracts depended on the extraction solvent, mainly for the ethanolic extracts. Findings suggest that chokeberry and blackcurrant berries and their pomaces can be used as a good source of polyphenols with antioxidative properties, and they also have antibacterial activity against some foodborne pathogenic bacteria. It is important that the valuable compounds are extracted from juice press residues before their disposal.
Looduslike bioaktiivsete ainete toimete mehhanismide uurimine loomsetes toitudes : [Eesti Maaülikooli kogemuslugu]
(Tartumaa Arenduskeskus, 2025) Roasto, Mati
Eesti Maaülikooli (EMÜ) toiduhügieeni ja -ohutuse üksus tegeleb toiduohutuse ja toidukvaliteedi valdkonna õpetamise ning teadusuuringutega. Rakendusuuringute põhifookuses on toidu mikrobioloogiline ja keemiline ohutus ning toidu kvaliteedi ja tervislikkuse tõstmise võimaluste hindamine. Toiduinnovatsiooni osas väärib esile tõstmist Eesti Teadusagentuuri rahastusega uurimustöö „Looduslike bioaktiivsete ainete toimete mehhanismide uurimine loomsetes toitudes” (rühmagrant PRG1441).
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.
Microbial counts, lipid oxidation, and phenolic compound dynamics in minced chicken enriched with plant powders
(Elsevier, 2026) Meremäe, Kadrin; Püssa, Tõnu; Rusalepp, Linda; Raudsepp, Piret; Anton, Dea; Sünter, Alar; Elias, Terje; Mäesaar, Mihkel; Roasto, Mati
Minced chicken is susceptible to microbial spoilage and lipid oxidation. This study aimed to assess microbial counts, lipid oxidation, and phenolic compound dynamics in minced chicken enriched with selected plant powders (garlic, apple, and pomace powders of tomato, rhubarb, blackcurrant, chokeberry, rowan berry), focusing on their interrelationships during refrigerated storage. The counts of aerobic mesophilic microorganisms, Pseudomonas spp., yeasts and moulds in powder-enriched samples were approximately 1 log unit lower than in the control, suggesting a potential extension of shelf life from 4 to 6–8 days based on microbiological spoilage thresholds. Rhubarb pomace powder showed a statistically significant inhibitory effect on microbial growth (p < 0.05). The relative contents of phenolic compounds increased during the first 8 days of storage, coinciding with the period of inhibited microbial growth, and then decreased at later stages. Berry pomace powders resulted in lower lipid oxidation, whereas garlic powder showed increased oxidation, indicating a trade-off between microbial inhibition and oxidative stability. Overall, the results indicate that the antimicrobial activity of the powders and their effects on oxidative processes in minced chicken may be associated with phenolic composition and its changes during storage, suggesting links between these processes. These findings support the use of plantderived powders, including pomace powders, to improve the microbial and oxidative stability of minced chicken.
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.
Microbial Growth Inhibition Effect, Polyphenolic Profile, and Antioxidative Capacity of Plant Powders in Minced Pork and Beef
(MDPI, 2024) Meremäe, Kadrin; Rusalepp, Linda; Sünter, Alar; Raudsepp, Piret; Anton, Dea; Mäesaar, Mihkel; Elias, Terje; Püssa, Tõnu; Roasto, Mati
Consumer interest in healthier meat products has grown in recent years. Therefore, the use of plant powders as natural preservatives in the composition of pork and beef products could be an alternative to traditional meat products. This study aimed to assess the effect of different powders, such as blackcurrant, chokeberry, rowan berries, apple, tomato, garlic, and rhubarb, on the microbial growth dynamics in minced pork and beef during refrigerated storage. The total counts of aerobic microorganisms, Pseudomonas spp., yeasts, and molds were examined according to ISO methods. The polyphenolic profiles of plant powders and supplemented minced pork and beef samples were determined by HPLC-MS. The antioxidative capacity of the plant powders was analyzed using a spectrophotometric method. The findings of the study revealed that supplemented minced pork and beef samples had similar polyphenolic profiles and microbial growth dynamics. The highest antioxidative capacity was observed for anthocyanin-rich berry powders. In both minced pork and beef, rhubarb powder was the most effective plant material for inhibiting microbial growth, followed by blackcurrant pomace powder. In conclusion, all of the plant powders used in the present study can be used for the valorization of minced meat products, providing both antimicrobial and antioxidant effects.
Polyphenolic profiles, antioxidant capacity, and antibacterial activity of green tea, matcha tea, black tea, and yerba mate extracts
(Elsevier, 2025) Meremäe, Kadrin; Raudsepp, Piret; Rusalepp, Linda; Laun, Tiina; Roasto, Mati
Tea is widely consumed for its beneficial bioactive compounds with potential health benefits. This study investigated the polyphenolic profiles, total antioxidant capacity (TAC), and antibacterial activity of aqueous and 30 % ethanolic extracts prepared from commercially available green tea, matcha tea, black tea, and yerba mate. The polyphenolic profiles were analyzed using HPLC-DAD-MS, with 28 compounds identified and semiquantified based on extracted ion chromatogram areas. Total polyphenol content (TPC) was quantified as gallic acid equivalent using external calibration and UV chromatogram area at 280 nm. TAC was measured by the DPPH and Folin-Ciocalteu methods. Minimum inhibitory concentrations (MICs) against Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Campylobacter jejuni were determined using the broth microdilution method. Mate ethanolic extracts had the highest TPC (5.16 ± 0.02 mg GAE/mL), followed by green (4.68 ± 0.08 mg GAE/mL), black (4.26 ± 0.08 mg GAE/mL), and matcha tea extracts (3.55 ± 0.01 mg GAE/mL). The hierarchical dendrogram showed that mate extracts differed significantly (p < 0.001) from the others, containing mainly chlorogenic acids and giving similar TAC, and MIC results for both aqueous and ethanolic extracts. Tea extracts exhibited the highest proportions of flavanols, mainly epigallocatechin, epicatechin gallate, and epigallocatechin gallate, which showed strong negative correlations (rS = 􀀀 0.7 to 􀀀 0.8) with MICs against E. coli and strong positive correlations (rS = 0.7 to 0.9) with TAC. S. aureus was the most susceptible to the studied plant extracts demonstrating the lowest MIC values ranging from 0.06 to 0.27 mg GAE/mL. Green tea extracts showed the strongest TAC and antibacterial activity. These findings highlight the potential of tea and mate extracts as natural antibacterial and antioxidant agents for food applications.
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 (advisor); 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.
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.
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.
Sources of Human Campylobacteriosis Cases in Estonia and the Genomic Associations with Broiler Chicken Meat Isolates
(MDPI, 2026) Ivanov, Ilijana; Takkinen, Hanna Katriina; Takkinen, Johanna; Roasto, Mati; Mäesaar, Mihkel
This study used three complementary datasets to investigate the relationship between human Campylobacter infections in Estonia and potential sources. A targeted dataset of 15 C. jejuni genomes with overlapping sequence types from human cases and broiler chicken meat was analysed using genotyping and in silico antimicrobial resistance profiling, alongside 20 human isolates for source attribution. Additionally, 12,111 isolates were analysed to provide population-level context. The core genome multilocus sequence typing showed a high similarity (less than three allelic differences) between the human and broiler isolates of ST122, ST464, and ST7355, indicating poultry as a likely source, whereas ST9882 was more divergent (13–18 allelic differences). The resistance profiles were consistent within ST122, ST464, and ST7355, and all were resistant to ciprofloxacin, nalidixic acid, ampicillin, and tetracycline, while ST9882 additionally exhibited aminoglycoside (streptomycin) resistance. The source attribution linked 77.8% of the human cases to chicken and 22.2% to cattle. A novel genotype, ST11001, was identified in humans and attributed to cattle source, while C. coli isolates were linked to birds and sheep. Poultry dominated the larger dataset (87.3%). Gastroenteritis was the predominant clinical presentation (98.5%), whereas ST22 and ST122 were associated with Guillain–Barré syndrome. These findings support poultry as a major reservoir of human Campylobacter infections and highlight the need for coordinated crossborder surveillance.
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.

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