Since 2005 campylobacteriosis has been the most commonly reported gastrointestinal infection in humans in the European Union with more than 200,000 cases annually. Also Campylobacter is one of the most frequent cause of food-borne outbreaks with 319 outbreaks reported to EFSA, involving 1,254 cases of disease and 125 hospitalizations in EU in 2019. Importantly poultry meat is one of the most common source for the sporadic Campylobacter infections and for strong-evidence campylobacteriosis food-borne outbreaks in EU.

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 HPLC-MS, 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.

It is a challenge for scientists to find new plant-based food constituents simultaneously possessing antimicrobial and antioxidative properties to prolong the shelf life of meat products. In this study, various plant powders and their blends were added to minced pork to carry out a complex study of their effect on sensory characteristics, microbial growth, and lipid oxidation of the meat in raw and cooked forms during storage. Microbiological shelf life parameters were evaluated by determining the total counts of microorganisms, yeasts, and molds. The growth potential of Listeria monocytogenes was estimated by challenge testing. The impact on lipid oxidation processes was assessed using thiobarbituric acid reactive substances (TBARS) and high performance liquid chromatography (HPLC) methods. The results showed that the blend of rhubarb petioles and tomato powder added a pleasant color and a combined taste to the product, similar to the taste of salt. In raw samples, considerable microbial growth inhibition was achieved with rhubarb petioles, tomato, and their mixture. Nine treatments of cooked samples had a stronger inhibitory effect on microbial growth compared to control treatments. Among all plant powders, tomato was the most effective inhibitor of yeast and mold growth. However, the challenge test revealed that L. monocytogenes growth in cooked samples was not inhibited during shelf life. In raw samples, rhubarb roots combined with blackcurrant or chokeberry berries effectively inhibited lipid oxidation, and in cooked samples, rhubarb petioles showed a similar effect. In conclusion, it was found that powdered plant materials are well suited for use as antimicrobial and antioxidative agents in minced meat products.

Poultry meat is considered the most important source of Campylobacter spp. Because of rising 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 gentamicin. 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.

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.