Sirvi Autor "Raudsepp, Piret" järgi

Nüüd näidatakse 1 - 20 29

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.
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.
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.
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.
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 inhibition by the use of selected plant powders in minced meat
(Estonian University of Life Sciences, 2025) Roasto, Mati; Meremäe, Kadrin; Mäesaar, Mihkel; Elias, Terje; Anton, Dea; Raudsepp, Piret; Rusalepp, Linda
This study aimed to evaluate the microbial growth inhibition effect of plant powders in minced pork and beef. Additionally, polyphenolic profiles of the plant powders were determined. Pomace powders of berries of blackcurrant, chokeberry, rowan and tomato were used. Additionally the powders of petioles of rhubarb, bulbs of garlic and apples were used. Apple powders were whole apples and apples without seeds. Plant material was dried at 50 °C, then the dried material was milled into a fine powder using a grinder and finally sieved to obtain a fraction of ≤1 mm. The plant powder was added at 2% (w/w) of the minced meat. Fresh minced pork with 28% fat content and minced beef with 18% fat content were used. The minced meats were purchased from a large-scale Estonian meat industry. The total phenolic content of the plant powder extracts in 60% aqueous ethanol was measured spectrophotometrically using the Folin–Ciocalteu method. Two percent of plant powders were added to the minced meats, and a mixer was used to ensure the plant powders were thoroughly incorporated. Pure minced meat was used as the control. The samples were packed in sterile screw-top cups and stored in the refrigerator at 4 ± 2 °C. All analyses were performed in duplicate on days 1, 4, 6, and 8, with additional analyses on days 11 and 14 for the rhubarb samples, which exhibited strong inhibition of microbial growth. Enumeration of aerobic mesophilic microorganisms, yeasts and moulds and presumptive Pseudomonas spp. was performed according to the ISO standards. At all time points, an estimation of pH and water activity was performed. We found that rhubarb powder in minced meat reduced the average total microbial counts by 10-fold, and the counts of Pseudomonas spp., yeasts, and molds by 100-fold compared to the control. Also, samples containing powders, such as blackcurrant, garlic, tomato and chokeberry showed lower total microbial counts than the controls. The low microbial growth inhibition effect was found for rowan berry pomace and apple powders in minced meat. Apart from organic acids, 27 distinct polyphenolic compounds from the classes of anthocyanins, dihydrochalcones, flavanols, flavonols, and hydroxycinnamic acids were tentatively identified in the plant powders. The highest number of polyphenolic compounds (n = 20), were found in blackcurrant, chokeberry and rowan berry powders, followed by rhubarb powder, which contained 16 different compounds. In the present study, rich composition of polyphenols was found in blackcurrant, which also showed good inhibition of microbial growth in enriched minced pork and beef samples. The lower pH and the presence of organic acids in samples can explain the best microbial growth inhibition effect of rhubarb powder. We suggest that plant powders with a rich composition of polyphenols can be applied for the valorization of different foods, both animal and plant-based food products.
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.
Minimal inhibitory concentrations, polyphenolic prophile and antioxidative properties of the extracts of selected berries and their pomaces
(Estonian University of Life Sciences, 2024) Raudsepp, Piret; Meremäe, Kadrin; Rusalepp, Linda; Roasto, Mati
The aim of the study was to establish minimal inhibitory concentrations (MIC) of the aqueous vs 30% aqueous ethanolic extracts of Aronia melanocarpa (Michx.) Elliott i.e. chokeberry (CB), Ribes nigrum L. i.e. blackcurrant (BC), and Sorbus aucuparia L. i.e. rowan berries (RB) and the corresponding pomaces (+P) against bacterial species L. monocytogenes, S. aureus, E. coli, and C. jejuni. Polyphenolic prophile and antioxidative properties of the extracts were also determined. Aqueous extracts and 30% aqueous ethanolic extracts were prepared of the powders of dried berries and corresponding pomaces in the ratio 1:20 (w/v). The extracts were chromatographically analyzed using a 1290 Infinity system (Agilent Technologies, Germany), coupled to an Agilent 6450 Q-TOF mass spectrometer equipped with a Jetstream ESI source and to an Agilent 1290 Infinity Diode Array Detector. The minimal inhibitory concentration (MIC) values of the extracts were determined against tested bacteria by the broth microdilution method in 96-well microplates, according to the EVS-EN ISO 20776- 1:2020 guidelines. Analyses of antioxidative properties (AO) of plant extracts were performed using the DPPH free-radical-scavenging method on an Infinite 200 Pro M Plex plate reader instrument (Tecan Austria Gmbh, Austria). The total content of polyphenols (TCP) was significantly (P < 0.05) higher in the ethanolic extracts than in the aqueous extracts. The TCP of plant extracts was in descending order as follows: CB > CBP > BC > BCP > RB > RBP in etahnolic, whereas in aqueous extracts the order was different: CB > BC > CBP > RB > BCP > RBP. The berry pomaces contained 60 – 70% of the polyphenols of the corresponding berries. The sensitivity of tested bacteria to the extracts of berries and berry pomaces starting from the most sensitive bacteria was as follows: S. aureus > L. monocytogenes > E. coli ≈ C. jejuni. No correlation was established between TCP and antibacterial (AB) properties of the plant extracts. The antioxidative properties in extracts with both solvents from highest to lowest were as follows: CB > CBP > BC > BCP ≈ RB > RBP. The AO properties were significantly (P < 0.05) higher in the ethanolic extracts than in the aqueous extracts. TCP correlated strongly positively with AO, both in aqueous (r = 0.92) and in 30% ethanolic extracts (r = 0.93). The extracts of CB and BC berries and berry pomaces had higher TCP, they also had better AB and AO properties compared to RB and its pomace. Among studied plant extracts TCP did not correlate with MIC values, indicating that other compounds besides polyphenols e.g. organic acids can cause the AB effect in the studied plant extracts. As berry pomaces, left over from juice pressing contain 60 – 70% of the TCP of corresponding berries, they should be further used as a source of beneficial compounds and not discarded as waste.
Minimal inhibitory concentrations, total polyphenol content and antioxidative properties of the extracts of selected berries and their pomaces : [poster]
(Estonian University of Life Sciences, 2024) Raudsepp, Piret; Meremäe, Kadrin; Rusalepp, Linda; Roasto, Mati
INTRODUCTION. The economical use of the planet's resources is undoubtedly very important. Therefore, the by products of juicing should be used as a source of valuable compounds and not discarded as waste In the present study (1) aqueous and 30% ethanol extracts prepared from powders of various dried berries and their residues were compared for their antibacterial (AB) and antioxidant (AO) properties.
Plants – antioxidants or antibacterials or both in meat
(Institute of Agrifood Research and Technology, 2025) Raudsepp, Piret; Püssa, Tõnu; Sünter, Alar; Meremäe, Kadrin; Anton, Dea; Rusalepp, Linda; Mäesaar, Mihkel; Roasto, Mati
The use of plant powders as natural preservatives in the composition of meat can be an alternative to traditional products, because by adding plant materials, we can not only extend the shelf life, but also increase the content of fiber and bioactive compounds in meat products. In the present study, selected plant materials were used to test their antimicrobial and antioxidative properties in minced pork. Plant materials were powders of berry pomaces of blackcurrant, aronia, and tomato fruits, and pomace of petioles of rhubarb. Powders of garlic cloves and apples were also used.
Polyphenolic composition of rhubarb (Rheum rhaponticum L.) and blackcurrant (Ribes nigrum L.), antibacterial and free radical scavenging properties of these plants in comparison with some other food plants
(Eesti Maaülikool, 2021) Raudsepp, Piret; Püssa, Tõnu (advisor); Kikas, Ave (advisor); Yang, Baoru (opponent)
Antibacterial and antioxidative compounds are used in food processing to extend shelf life. Consumers are increasingly demanding these compounds to be as natural as possible. Polyphenols are a very diverse group of compounds found in plants, comprising molecules with both antibacterial and antioxidative properties. In the present study, the polyphenolic composition of blackcurrant berries and leaves and rhubarb petioles and roots were investigated by means of liquid chromatography-UV-Vis detector, coupled with ion trap mass detector and comparing the obtained results with scientific literature data. The antibacterial activity and free radical scavenging ability (considered as an antioxidative activity) of extracts made from the same plant parts were compared with the effects of different food plants in two different experiments. Comparison included tomato fruits, bilberry, sea buckthorn, blue honeysuckle and chokeberry berries. It was found that the high content of polyphenols in the plant material does not yet make it possible to say whether the material has good antibacterial or antioxidant properties. These properties seem to depend on different polyphenolic and other compounds. For example, in rhubarb the high levels of polyphenols are due to anthraquinones and stilbenes, which are known to have relatively strong antibacterial properties but weak antioxidative properties. In the blue and red berries, most of the polyphenols are composed of anthocyanins, which have strong antioxidative but weak antibacterial properties. In addition, berries contain vitamin C, which also has an antioxidative effect. By combining different food plants and adding them to other foods, it is possible to achieve both antibacterial and antioxidative properties, while keeping in mind the food safety and sensory properties of the food. Among other results, it was found, that the tested plant extracts (in paper III) had stronger AB effect against B. subtilis, K. rhizophila, L. acidophilus, B. bifidum, L. monocytogenes, E. coli and C. jejuni than sodium nitrite solutions, nevertheless, none of the authors recommends substituting sodium nitrite in the processed meat products entirely with plant materials. Many more studies are needed before such recommendations can be made, especially taking into account hazards, related to bacterial species like Clostridium botulinum and other Clostridia. At the moment, such studies can not be conducted in Estonia. In the later works of our research group, we have used many of the above mentioned plant materials in meat products and achieved both antibacterial and antioxidative activities.
Polyphenolic content, antibacterial and antioxidative properties of some berries and their influence on inosine monophosphate formation in minced pork
(Università degli Studi di Milano Statale, 2024) Sünter, Alar; Meremäe, Kadrin; Rusalepp, Linda; Roasto, Mati; Anton, Dea; Püssa, Tõnu; Kuznetsov, Artur; Raudsepp, Piret
Introduction: Total polyphenol content (TPC), antibacterial and antioxidative properties [1] of chokeberry, blackcurrant, and rowan berries and their press residues were alnalysed together with meat taste enhancing inosine monophosphate (IMP) formation [2] during 14 days of storage of the minced pork, enriched with these berry powders.
Polyphenolic content, antibacterial and antioxidative properties of some berries and their influence on inosine monophosphate relative content in minced pork : [poster]
(Estonian University of Life Sciences, 2024) Sünter, Alar; Meremäe, Kadrin; Rusalepp, Linda; Roasto, Mati; Anton, Dea; Püssa, Tõnu; Kuznetsov, Artur; Raudsepp, Piret
INTRODUCTION. Total polyphenol content (TPC) antibacterial and free radical scavenging properties of chokeberry, blackcurrant, and rowan berries and their press residues were analysed [1] together with umami taste enhancing inosine monophosphate (IMP) relative content [2] during 14 days of refrigerated storage of minced pork, enriched with these berry powders.
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.
Relationships between the effects of plant additives on linoleic acid oxidation and microbial growth in minced pork
(Estonian University of Life Sciences, 2024) Püssa, Tõnu; Rusalepp, Linda; Meremäe, Kadrin; Anton, Dea; Raudsepp, Piret; Roasto, Mati
Peroxidation of polyunsaturated fatty acids (PUFA), especially unconjugated linoleic (9,12- octadecadienoic) acid and microbial degradation of various constituents are the main integrated processes of spoilage of muscle foods. Peroxidation of linoleic acid in meat occurs through the combination of enzymatic and free radical mechanisms, the most important oxidation enzymes being lipoxygenase (LOX) and cytochrome oxidase P450 (CYP450). The aim of this study was to describe the relationship between these two processes in minced pork in the presence of nine plant-derived additives. Powders of freeze-dried apple (Malus domestica), also without seeds, blackcurrant (Ribes nigrum), rhubarb (Rheum rhaponticum), tomato (Lycopersicon esculentum), chokeberry (Aronia melanocarpa), garlic (Allium sativum), and rowan berries (Sorbus aucuparia) were mixed with fresh minced pork (2% w/w) and stored at 6 °C during 8 or 14 days. Samples were taken at days 1, 4, 6, 8 and additionally at days 11 and 14 for rhubarb. Enumeration of aerobic mesophilic microorganisms, yeasts and moulds, and presumptive Pseudomonas spp. was performed according to the ISO standards. The main primary oxidation products of linoleic acid (oxylipins) were quantified by LC-MS performed on a 1290 Infinity system liquid chromatograph coupled to 6450 Q-ToF mass spectrometer (Agilent Technologies, Germany). Concentration of malondialdehyde (MDA) as a main secondary oxidation product of linoleic acid was estimated using 2-thiobarbituric acid reactive substances (TBARS) method on an Agilent 1100 series LC-UV/Vis chromatograph. All additives inhibited the growth of tested microorganisms compared to meat, but to different extents. Blackcurrant (BC) powder had both high antioxidant and antimicrobial activity. The antioxidant activity of BC is mainly due to the free radical scavenging and LOX inhibiting effect of polyphenols of the anthocyanin group, there are various hypotheses about the mechanisms of the BC`s strong antimicrobial effect. Chokeberry (CB), with higher anthocyanins content, showed lowest MDA value, but had lower antimicrobial activity than BC. Rowan berries, which contained less anthocyanins than CB or BC, also had lower antioxidant capacity, but moderate antimicrobial activity. Garlic and rhubarb had by far the lowest antioxidant activity, showing the highest values of both MDA and total oxylipins already at days 4 and 6, respectively. However, these additives were most effective in inhibiting microbial growth that could be caused by MDA and oxylipins. According to the literature, MDA is also synthesized by the corresponding bacterial enzymes. As an efficient cross-linker of macromolecules such as DNA, MDA is particularly toxic to microorganisms. Removal of seeds significantly reduced the antibacterial and antifungal activity of apples, while maintaining high antioxidant capacity. Apparently, seedspecific substances such as furocoumarins or phloretin, which have no antioxidant effect, are responsible for the antimicrobial effect of apples. Seedless tomato significantly inhibited linoleic acid oxidation, while like seedless apple, was relatively powerless against microorganisms. Considering both antioxidant and antimicrobial effects, it is difficult to achieve reasonable extension of the shelf life of minced pork when combined with a single plant.
Relationships between the effects of plant derived supplements on linoleic acid oxidation and microbial growth in minced pork : [presentation]
(Estonian University of Life Sciences, 2024) Püssa, Tõnu; Rusalepp, Linda; Meremäe, Kadrin; Anton, Dea; Raudsepp, Piret; Roasto, Mati
This presentation discusses some of the results of ongoing Estonian Research Council grant (PRG 1441) project Effects and mechanisms of plant bioactive substances in foods of animal origin”.
Screening for new natural food additives with antibacterial properties against pathogenic bacteria
(Faculty of Pharmacy, University of Helsinki, 2023) Kapp, Karmen; Cruz, Cristina D.; Laakso, Riina; Chic-Lorente, Helena; Raudsepp, Piret; Meremäe, Kadrin; Roasto, Mati; Tammela, Päivi
Due to increasing customer awareness, there is a trend to seek new natural food additives that can be used as antibacterial and/or antioxidative agents in food products [1]. The shelf-life of a food product is mainly affected by oxidation of lipids and proteins and the growth of the spoilage microorganisms. Plant-based extracts consist of various compounds that can possess antibacterial properties and thus may extend the shelf-life and enhance food safety [2].
Screening for new natural food additives with antibacterial properties against pathogenic bacteria : [poster]
(Estonian University of Life Sciences, 2023) Kapp, Karmen; Cruz, Cristina D.; Chic Lorente, Helena; Laakso, Riina; Nicoletti, Anita; Raudsepp, Piret; Meremäe, Kadrin; Roasto, Mati; Tammela, Päivi
• Due to increasing customer awareness, there is a trend to seek new natural food additives that can be used as antibacterial and/or antioxidative agents in food products [1] • Plant-based extracts consist of compounds that can possess antibacterial properties and may extend the shelf-life and enhance food safety [2] Aim: Find potential natural antimicrobials for food industry by testing antimicrobial properties of plant extracts against pathogenic bacteria.

Sirvi Autor "Raudsepp, Piret" järgi

Tulemused lehekülje kohta

Sorteerimisvalikud