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Selle valdkonna püsiv URIhttp://hdl.handle.net/10492/8657

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Nüüd näidatakse 1 - 20 75

10-hydroxystearic acid as a potential quantifiable marker of bacterial contamination in meats
(Estonian University of Life Sciences, 2026) Püssa, Tõnu; Rusalepp, Linda; Meremäe, Kadrin; Sünter, Alar; Raudsepp, Piret; Mäesaar, Mihkel; Anton, Dea; Roasto, Mati
10-hydroxystearic acid (10-HSA) is the major oxygenated derivative of oleic (cis-9-octadecenoic) acid, a monounsaturated n-9 fatty acid (MUFA). The corresponding metabolic reaction, which can be classified as both oxidation and hydration (addition of a water molecule to an isolated double bond), is mainly catalyzed by oleate hydratase (OhyA), a member of flavoenzyme family, These enzymes, classified as hydro-lyases (EC 4.2.1.53) are of interest for industrial applications due to their role in the generation of hydroxy fatty acids, which are used in surfactants, lubricants, and biodegradable polymers. 10-HSA, which can be further oxidized to 10-ketostearic (10- KSA) and 9,10-epoxystearic (9,10-ESA) acids, is produced only by bacteria, such as ruminant species (Selenomonas ruminantum, Enterococcus faecalis, etc) or multiple other bacteria (Staphylococcus, Bacillus, Listeria,, Pseudomonas) that live in various contaminated fresh meats (Radka et al, 2021). Porcine and trout meat do not naturally contain 10-HSA, but beef may contain 10-HSA, which is deposited from the rumen to meat and milk. The corresponding OhyA is not found in ruminant meat. The gene encoding OhyA is found in different bacteria and is involved in processes such as surviving stress, modulating membrane composition, etc. However, Pseudomonas aeruginosa that lacks OhyA, is using other enzyme systems, for example lipoxygenase (LoxA) (Morello et al, 2019). There are multiple chemical and biochemical markers of bacterial levels and activities in meat – pH, enzyme activities (such as of catalase or coagulase), metabolic end products (such as hydrogen sulfide, indole, ammonia, volatile organic compounds (VOC) like histamine). Total volatile basic nitrogen (TVB-N) is another quantifiable indicator of bacterial spoilage. The knowledge that 10-HSA is synthesized only by bacteria inspired us to investigate the utility of this oxylipin as a potential biochemical marker for assessing the level of bacterial contamination in meats. We investigated the formation of 10-HSA in minced porcine, bovine, and rainbow trout meat for 8 or 11 days at refrigerator temperatures by LC-MS/ToF and correlated the results with the CFU/g values obtained by enumeration of total microbial counts of mesophilic aerobic microorganisms and separately of Pseudomonas spp by ISO methods. Results: 10-HSA has a common linear positive correlation with bacterial counts for all three studied meats with R2 = 0.96 between 1 and 8 or 11 days. This phenomenon suggests the presence of various bacteria that may have slightly different slopes of the linear regression, the resulting correlation is a combination of these primary correlations. For Pseudomonas spp, there are separate positive linear correlations for all three meat types. Consequently, we can distinguish the meats by the slope of their regression line. Conclusion: These are the first encouraging results, but further research is needed to prove the suitability of 10-HSA as a novel marker of bacterial contamination of various meats.
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.
Antibacterial and antibiofilm activity of potato (Solanum tuberosum cv. Laura) peel-derived extracellular vesicles against Bacillus cereus ATCC 11778
(Universidad de Burgos, 2024) Ekanayake, Gayandi; Sapugahawatte, Dulmini Nanayakkara; Godakumara, Kasun; Midekessa, Getnet; Roasto, Mati; Andronowska, Aneta; Bhat, Rajeev; Fazeli, Alireza
Bacillus cereus is commonly found in many foods and known for causing foodborne illness. Due to their spore-forming and biofilm-forming nature and contamination capability these bacteria are presenting a large challenge to the food industry. The bacterium has become increasingly resistant to multiple drugs necessitating novel preventive strategies. One promising solution is the use of plant-derived extracellular vesicles (EVs), specifically from potato peels, which carry complex bioactive cargos with potential antibacterial properties. Our research explores the effectiveness of these plant-derived EVs against both planktonic phase cells and biofilms of B. cereus ATCC 11778.
Antibacterial and antibiofilm activity of potato (Solanum tuberosum cv. Laura) peel-derived extracellular vesicles against Bacillus cereus ATCC 11778 : [poster]
(Estonian University of Life Sciences, 2024) Ekanayake, Gayandi; Sapugahawatte, Dulmini Nanayakkara; Godakumara, Kasun; Midekessa, Getnet Balcha; Roasto, Mati; Andronowska, Aneta; Bhat, Rajeev; Fazeli, Alireza
Plant-derived extracellular vesicles (PDEVs) have recently captivated scientific interest due to their pivotal roles in intercellular communication. This study investigates the functional aspects and biocontrol potential of potato peel-derived extracellular vesicles against foodborne pathogen Bacillus cereus ATCC 11778, aligning with the concept of waste valorization.
Antibacterial and antibiofilm potential of potato peel derived extracellular vesicles against Bacillus cereus ATCC 11778: A proteomic perspective : [poster]
(Estonian University of Life Sciences, 2024) Ekanayake, Gayandi; Sapugahawatte, Dulmini Nanayakkara; Godakumara, Kasun; Midekessa, Getnet; Roasto, Mati; Bhat, Rajeev; Fazeli, Alireza
INTRODUCTION • Plant derived extracellular vesicles show great promise as antimicrobial agents due to their diverse cargos. • Bacillus cereus , a gram positive pathogen, causes infections and food spoilage, making its control crucial for food safety and public health. • Over a series of in vitro microbial assays Potato peel derived EVs (PPEV) have shown potential in controlling growth dynamics of B. cereus. • The aim is to understand the EV proteome’s role in the antimicrobial activity of PPEVs and elucidate their mechanism of action in silico.
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.
Antioxidant and antibacterial activity of tea and mate extracts
(Estonian University of Life Sciences, 2026) Meremäe, Kadrin; Raudsepp, Piret; Rusalepp, Linda; Roasto, Mati
Consumers are increasingly interested in natural, plant-based additives as alternatives to synthetic compounds in food products. This study investigated the polyphenolic profiles, total polyphenol content (TPC), total antioxidant capacity (TAC), and antibacterial activity of aqueous and 30% ethanolic extracts of green tea, matcha tea, black tea, and yerba mate. Commercial teas (Camellia sinensis) and mate (Ilex paraguariensis) were purchased in Tartu, Estonia. The tea and mate leaves were powdered (< 1 mm), and extracts prepared with water or 30% ethanol. Polyphenolic compounds were analysed using HPLC-DAD-MS, TPC was quantified as gallic acid equivalents, and TAC was determined spectrophotometrically using the Folin-Ciocalteu method. Minimum inhibitory concentrations (MICs) against Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Campylobacter jejuni were determined by broth microdilution according to the EVS-EN ISO, 20776–1:2020 standard. In total, 28 polyphenolic compounds were detected, including hydroxybenzoic acids, hydroxycinnamic acids, flavanols, flavonols, and tea pigments. Mate extracts were rich in chlorogenic acids, while tea extracts contained higher proportions of flavanols, particularly epigallocatechin, epicatechin gallate, and epigallocatechin gallate. Ethanolic extracts of mate (5.16 ± 0.02 mg GAE/mL) and green tea (4.68 ± 0.08 mg GAE/mL) had the highest TPC, wheras matcha tea (5.50 ± 0.01 mg GAE/mL) and green tea (5.82 ± 0.00 mg GAE/mL) showed the strongest TAC. In aqueous extracts, mate and green tea had the highest TPC (3.02 ± 0.34 and 1.77 ± 0.03 mg GAE/mL, respectively), and the strongest TAC (4.05 ± 0.01 and 3.48 ± 0.10 mg GAE/mL). All extracts inhibited the growth of S. aureus, with MIC values ranging from 0.06 to 0.27 mg GAE/mL, and green tea extracts showed the strongest antibacterial activity. Mate extracts showed similar TAC and antibacterial activity in both aqueous and ethanolic extracts. TAC correlated most strongly with TPC (rS = 0.8), and among individual compounds, epicatechin gallate showed the strongest correlation (rS = 0.6). A moderate negative correlation (rS = − 0.6) between TPC and MICs indicated that higher polyphenolic content was linked to stronger antibacterial activity. In summary, ethanolic extracts of green tea were the most promising for further application in food composition due to their strong antioxidant and antibacterial properties. These findings highlight the potential of tea and mate extracts as natural alternatives to synthetic additives in the food industry.
Assessment of meat quality (freshness) with a simple device based on the contents of ATP breakdown products. The effect of plant materials on meat preservation
(Estonian University of Life Sciences, 2025) Sünter, Alar; Raudsepp, Piret; Püssa, Tõnu; Anton, Dea; Mäesaar, Mihkel; Rusalepp, Linda; Kuznetsov, Artur; Roasto, Mati
Plant material that could be used as a raw material for bioactive substances is usually discarded as waste from juice production. Therefore, we need knowledge about the possibilities of using residual plant material, for example, in preserving the freshness of meat during storage. The aim of the study was to evaluate the freshness retention of meats during storage in the refrigerator in the presence of various plant residues. Minced meats of chicken, pork, beef and trout were used. The plant additives were garlic (Allium sativum) bulbs, whole and seedless apples (Malus domestica); press residues of blackcurrant (Ribes nigrum) berries, chokeberries (Aronia melanocarpa), rowan berries (Sorbus sp.) tomatoes (Solanum lycopersicum), and rhubarb petioles (Rheum). The plant materials were dried at 50 °C and ground into a fine powder. The amount of powder mixed into the minced meats was 2%. The experiment lasted 14 days in a refrigerator at 4 °C. Samples were taken daily to analyze the freshness of the meat. One of the best ways to assess meat quality is to monitor the change in the breakdown products of adenosine triphosphate from adenosine triphosphate (ATP) > adenosine diphosphate (ADP) > adenosine monophosphate (AMP) > inosine monophosphate (IMP) > inosine (Ino) > hypoxanthine (Hx) > xanthine > uric acid. In AS Ldiamon, a cheap and simple device was developed to estimate the concentration of ATP and its breakdown products in meat samples. The operation of this instrument is based on well-known gel filtration principle, where the movement of smaller molecules (ATP degradation products) slows down during the run through the column. This device allows measuring the relative amounts of products that increase duringstorage. To correlate our results with information published, HPLC (Agilent 1100 series liquid chromatograph) was used as a second step to estimate the inosine monophosphate (IMP), inosine (Ino) and hypoxanthine (Hx) content of the samples. Fractions obtained by gel filtration, containing compounds below 5 kDa were stored at -20°C until further HPLC analyses. Best plant additives to keep meat freshness were press residues of tomato, blackcurrant and rhubarb. Both apples and garlic were less effective.
Assessment of microbiological safety and quality of plant-based alternative products : [presentation]
(Estonian University of Life Sciences, 2025) Mandel, Tiina; Roasto, Mati; Mäesaar, Mihkel; Meremäe, Kadrin; Sapugahawatte, Dulmini; Reinik, Mari
ACTUALITY OF THE TOPIC • The shift from animal-based proteins to plant-based alternatives has significantly increased in recent years, largely driven by a combination of environmental, health, and animal welfare concerns of consumers. • The market of plant-based alternatives is rapidly expanding and evolving, it is expected to reach around 46 billion euros by 2027. • New technologies and processing methods mostly used for the production of alternative products may pose new food safety risks including microbiological hazards.
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.
Covid-19 mõju mikrobioloogilisele toiduohutusele Euroopa Liidus ja Eestis
(Eesti Maaülikool, 2022) Roasto, Mati; Laikoja, Katrin; Mäesaar, Mihkel
Käesolev artikkel annab ülevaate zoonoossete toidupatogeenide toidus levimuse ning toidutekkeliste haigusjuhtumite suundumustest Euroopa Liidus (EL) k.a. Covid-19 pandeemia võimalikust mõjust toidutekkeliste mikrobioloogiliste haigusjuhtumite esinemisele. Zoonoos on otseselt või kaudselt loomulikul teel looma ja inimese vahel edasikanduv haigus või nakkus (PTA, 2022). Toidutekkelised haigused on infektsioonid või intoksikatsioonid, mis on põhjustatud saastunud toidu või vee kaudu organismi sattunud bakteritest, viirustest, parasiitidest või keemilistest ainetest. Toidu saastumine võib aset leida toidu (esma)tootmise, töötlemise ja tarbimisahela mis tahes etapis ning tuleneda keskkonnasaastest, sealhulgas vee, pinnase või õhu saastumisest, aga ka toidu mitte nõuetekoha- sest ladustamisest, töötlemisest või muul viisil käitlemisest (Roasto, 2019). Salmonellad, kampülobakterid ja enterohemorraagiline Escherichia coli on kõige levinumad toidupatogeenid, põhjustades igal aastal miljonitele inimestele kerge või raske kuluga haigusi, enamasti soolenakkusi, kuid mõnikord võivad need haigused põhjustada ka inimeste surma (WHO, 2022). Kõige sagedamini esinev zoonoos EL-is on juba alates 2005. aastast kampülobakterioos (Whitworth, 2021). Eestis registreeriti inimestel kam- pülobakterioosi rohkem kui salmonelloosi esimest korda 2013. aastal. Nii on see olnud ka järgnevatel aastatel Eestis.
Do phospholipolysis and bacteria primarily regulate linoleic acid oxidation in fresh meats?
(Estonian University of Life Sciences, 2026) Püssa, Tõnu; Rusalepp, Linda; Meremäe, Kadrin; Sünter, Alar; Raudsepp, Piret; Mäesaar, Mihkel; Anton, Dea; Elias, Terje
The release of polyunsaturated fatty acids (PUFA) from cell membranes by phospholipolysis followed by (per)oxidation, is the major integrated process in the oxidative spoilage of meat. Only free PUFAs are susceptible to oxidation. Rancid meat is an excellent medium for the growth of various microbes, which in turn contribute to the release and oxidation of new PUFA molecules. Due to dominance of linoleic acid (LA) among PUFAs, its oxidation of is the most important in meats. This study is the first attempt to quantitatively describe the oxidation of LA from start to finish, specifically to the toxic secondary oxidation product malondialdehyde (MDA). Oxidation begins after the release of LA from cell membrane phosphatidylcholines (PL), during which lysophosphatidylcholines (LPC) are formed under the catalysis of lipolytic phospholipases A (PLA 1 and 2) (EC 3.1.14). Process continues with combined sequential enzymatic and free-radical formation primary oxidation products called oxylipins (OL), and ends with the formation of secondary oxidation products, mostly various aldehydes, including MDA, which is toxic and mutagenic especially for bacteria. The two main enzymatic routes involved in LA oxidation are lipoxygenase (LOX) and cytochrome P450 oxidase (CYP450) pathways. Experimental. The lipolytic and oxidative processes in minced porcine, bovine, rainbow trout, and chicken meats were modified by six natural additives (powders of apple, black currant, aronia, tomato, garlic, and garden rhubarb (all 2% w/w)). During the 14-day storage at refrigerator temperature, the concentrations of LPCs 1 and 2 and MDA were determined periodically by LC-Q-ToF-MS and HPLC-DAD, respectively. Total counts of aerobic microorganisms and Pseudomonas spp. were estimated using ISO methods. Results. There is no clear correlation between concentration of MDA (or OLs) and LPC, but a zigzag temporal pattern exists that generally reflects the two main (lag- and log-) phases of the growth of aerobic microorganisms and Pseudomonas spp. During the first 1–4(6) days, the content of LPCs and MDA is positively correlated due to the autooxidation of LA. Mostly between days 6–8, the LPC content drops, whereas the production of OLs and MDA continues. The reserve of LPCs from autooxidation is obviously depleted around the 8th day. However, here the log phase of microbial growth starts, providing a fresh supply of LA and other PUFAs. The rapid increase in the content of LPCs and MDA after the 8th day is especially distinct in meat with tomato powder. Plant additives modulate the process by either accelerating or slowing down different phases. The described pattern is best visible in porcine meat, less so in beef and not at all in trout and chicken meats due to the low level of free LA throughout the whole oxidation process. Conclusion: In order to purposefully extend the shelf life of minced meats, in addition to the antibacterial and antioxidant (mostly radical scavenging) effects, the antilipolytic effects of additives should also be taken into account. The research in this topic is ongoing.
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.
The effect of pasteurized milk extracellular vesicles on bacterial growth
(Estonian University of Life Sciences, 2023) Sapugahawatte, Dulmini Nanayakkara; Midekessa, Getnet Balcha; Godakumara, Kasun; Prasadini, Madhusha; Kodithuwakku, Suranga; Roasto, Mati; Andronowska, Aneta; Fazeli, Alireza
Extracellular vesicles (EVs) are released by cells and have a lipid bilayer structure. EVs harbor various molecules, including proteins, RNAs, and DNAs. Studies of mammalian EVs are increasingly attracting the interest of researchers; however, there are only few studies of nanoparticles in food. Milk-derived EVs can survive high temperatures and digestion process, while retaining their biological activity. This study investigated the effect of pasteurized cows’ milk derived EVs on growth of five different bacteria. Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 53868, Bacillus subtilis, Bacillus cereus and Pseudomonas aeruginosa with a concentration of 1x107 CFU/ml were separately co-cultured with pasteurized milk derived EVs (1x109 EVs/μl) in Muller Hinton broth. The bacterial growth was monitored as absorbance at 620 nm over 24 hours. Bacteria treated with phosphate buffer solution (PBS) were considered negative control throughout the experiment. The percentage bacterial growth difference was COMBIVET & OH-BOOST JOINT CONFERENCE 2023 55 determined with respect to negative control and results expressed as mean ± standard error of mean. All analyses were performed in three biological triplicates and each biological replicate consisted of three technical replicates. Co-culture of bacteria with milk EVs demonstrated that EVs could decrease the growth of S. aureus, B. subtilis, B. cereus and P. aeruginosa. Highest growth inhibition was observed for B. subtilis (33.9% ± 2.4) followed by B. cereus (18.1% ± 3.7) at 6 hours of incubation. S. aureus and P. aeruginosa growth were inhibited by 12.9% ± 1.3 and 9.9% ± 3.5 respectively after 9 hours incubation. Only the S. aureus growth inhibition at 9 hours was statistically significant (P=0.022) according to T-test. However, E. coli growth was not affected by milk EVs compared to the control. In conclusion, the dietary EVs can be absorbed by bacteria and pasteurized milk derived EVs has a selective inhibitory activity on the growth of some bacteria.
The Effect of Pasteurized Milk Extracellular vesicles on Bacterial Growth : [poster]
(Estonian University of Life Sciences, 2023) Sapugahawatte, Dulmini Nanayakkara; Midekessa, Getnet Balcha; Godakumara, Kasun; Prasadini, Madhusha; Kodithuwakku, Suranga; Roasto, Mati; Andronowska, Aneta; Fazeli, Alireza
Milk-derived extracellular vesicles (mEVs) have gained attention for their potential biological activities, including antibacterial properties and they can carry bioactive molecules. The mEVs can survive high temperatures and digestion processes while retaining their biological activity. Studies of mammalian EVs are increasingly attracting the interest of researchers; however, there are only a few studies of mEVs’ antimicrobial effect.
Effective suppression of Staphylococcus aureus ATCC 25923 growth by pasteurized milk-derived extracellular vesicles : [poster]
(Estonian University of Life Sciences, 2024) Sapugahawtte, Dulmini Nanayakkara; Godakumara, Kasun; Mäesaar, Mihkel; Ekanayake, Gayandi; Midekessa, Getnet Balcha; Prasadini, Madhusha; Kodithuwakku, Suranga; Roasto, Mati; Andronowska, Aneta; Fazeli, Alireza
Research highlights the potential of pasteurized cattle milk-derived extracellular vesicles (EVs) as natural antimicrobials against Staphylococcus aureus, addressing food spoilage and safety concerns. These bioactive membrane-bound particles present promising avenues for enhancing microbial food quality and safety, featuring the significance of exploring EVs as novel antimicrobial additives in food preservation strategies.
Effective suppression of Staphylococcus aureus ATCC 25923 growth through periodic dosing of pasteurized milk-derived extracellular vesicles
(Universidad de Burgos, 2024) Sapugahawtte, Dulmini Nanayakkara; Godakumara, Kasun; Mäesaar, Mihkel; Ekanayake, Gayandi; Midekessa, Getnet Balcha; Prasadini, Madhusha; Kodithuwakku, Suranga; Roasto, Mati; Andronowska, Aneta; Fazeli, Alireza
There is rising interest in extracellular vesicles (EVs) as natural antimicrobials against food spoilage and ensuring food safety. These membrane-bound particles exhibit bioactive properties, making them intriguing for scientific exploration. Our investigation outlines the antimicrobial efficacy of pasteurized cattle milk-derived EVs against Staphylococcus aureus, offering novel insights into natural antimicrobial agents for addressing microbial food quality and safety.
EMÜ VLI toiduhügieeni ja -ohutuse üksuse õppe ja teadustöö : [esitlus]
(Eesti Maaülikool, 2024) Roasto, Mati
Toiduohutuse seminar "EMÜ VLI toiduhügieeni ja –ohutuse üksuse õppe- ja teadustöö, projektide PRG1441 ja TEM-TA52 tutvustus Regionaal- ja Põllumajandusministeeriumi Toiduohutuse osakonnale", 14.11.2024, Eesti Maaülikool, Tartu.

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