Malakauskas, Mindaugas

The meat industry generates substantial quantities of animal offal, which represents a valuable source of protein; however, its potential for the development of higher value-added products remains underutilised. Enzymatic hydrolysis of animal offal proteins enables the production of peptide hydrolysates exhibiting antioxidant and antibacterial properties and their application in the development of functional food products. The aim of the study was to assess the safety of animal offal and its suitability for processing into protein hydrolysates and the development of functional food products. The tasks of this study were: (I) to evaluate pathological lesions in offal (porcine, bovine, and ovine) identified during veterinary post-mortem inspection and assess their impact on biological and chemical safety, nutritional composition, and the suitability of the raw materials for further processing; (II) to apply an optimal enzymatic hydrolysis model to selected offal to obtain protein hydrolysates with functional properties; (III) to evaluate the antioxidant and antibacterial properties and peptide profiles of offal hydrolysates and to assess their potential application in the development of functional food products; (IV) to develop a prototype of a novel product, evaluate its safety, nutritional composition, and functional properties, and make evidence-based decisions regarding the use of offal in the development of functional food products.

Aiškinamajame veterinarinės medicinos terminų žodyne pateikti dažniausiai vartojami biomedicinos srities veterinarinės medicinos krypties terminai lietuvių, lotynų ir anglų kalbomis bei jų santrumpos. Leidinys apima veterinarinę profesinę leksiką, kuri yra iš gyvūnų anatomijos, fiziologijos, biochemijos, imunologijos, mikrobiologijos, epidemiologijos, farmakologijos, farmacijos, akušerijos ir ginekologijos, chirurgijos, neužkrečiamųjų ir užkrečiamųjų ligų, ichtiologijos bei statistikos sričių. Kai kurie buvę diskusiniai terminai suvienodinti, patikslinti, sunorminti. Terminų paaiškinimai padės tiksliau orientuotis gausioje biomedicinos terminijoje ir išvengti netaiklaus ar neteiktinų terminų vartojimo, o pagrindinė žodyno paskirtis - įtvirtinti lietuviškuosius veterinarinės medicinos terminus. Žodynas bus naudingas veterinarinės medicinos studentams, veterinarijos gydytojams bei platesniam su veterinarinės medicinos kryptimi susijusiam žmonių ratui.

Antimicrobial resistance is a growing concern in poultry production and food safety, where complex microbial communities can influence the persistence and spread of resistance determinants. Poultry farms harbour diverse microbiota that may affect both the development of broiler gut microbiota and the circulation of antimicrobial resistance within farm environments. In this study, shotgun metagenomic sequencing was used to analyse microbial communities and antimicrobial resistance genes in broiler faecal and farm environmental samples, including feeders, drinkers and boot swabs, collected throughout the broiler growing period. Metagenomic analysis revealed differences between environmental and faecal microbial communities. Environmental samples were mainly dominated by Proteobacteria. In contrast, the composition of faecal microbiota changed during broiler growth. In the early stage of the growing period, Proteobacteria were more abundant in the broiler gut microbiota. In contrast, Firmicutes gradually increased and became dominant in the later stage, reflecting the maturation of the intestinal microbiota. Antimicrobial resistance genes were detected throughout the broiler growing period. β-lactam resistance genes, including blaCTX-M and blaTEM, were particularly common during the early stage of broiler growth. In later stages, tetracycline resistance genes (tetA, tetB) and sulphonamide resistance genes (sul1, sul2) were detected more frequently. Mutations associated with quinolone resistance (gyrA, parC) were detected at multiple stages of broiler growth. Although the composition of microbial communities changed substantially during broiler growth, antimicrobial resistance determinants were detected throughout the entire growing period. This indicates that resistance genes may persist within the broiler farm microbiome despite changes in bacterial community composition.

Improving the nutritional quality of semi-hard cheese through functional ingredients is a growing focus in dairy research. Edible coatings containing probiotic-type bacteria offer a promising strategy to enhance cheese composition and digestibility during ripening. In this study, in vitro digestion simulations of ripened Edam-type cheese samples (control, coated with liquid acid whey protein concentrate (LAWPC) coating, and coated with LAWPC coating containing Lacticaseibacillus paracasei A11 at approximately 7 log10 CFU/g) were performed using the standardized static method (Minekus et al., 2014), combined with size exclusion chromatography for the evaluation of digested protein concentration. Volatile fatty acids (VFA) were quantified by gas chromatography and expressed as percentages of total volatile fatty acids (% of total VFA). After 45 days of ripening, digestion results showed that the soluble protein fraction ranged from 189.2 mg in cheese coated with LAWPC + A11 to 191.1 mg in cheese coated with plain LAWPC and 195.4 mg in control, corresponding to 80.3%, 77.5%, and 76.7% of total soluble protein, respectively. The degree of simulated enzymatic cheese digestion increased significantly from 66.1% in the control cheese to 66.9% in the cheese coated with plain LAWPC coating, and further to 69.4% in the cheese coated with LAWPC + A11 (p < 0.001), demonstrating enhanced enzymatic breakdown due to probiotic incorporation. Moreover, VFA analysis revealed no significant differences among most VFA, except for a significant decrease in lauric acid in cheese coated with LAWPC + A11 (3.09% ± 0.12) compared to cheese with plain LAWPC-coated (3.21% ± 0.01) and control (3.21% ± 0.14) cheeses (p < 0.05), suggesting a beneficial shift toward a healthier fatty acid profile. These results demonstrate that edible coatings, particularly the LAWPC + A11 formulation, enhanced nutritional quality, protein solubilization, and digestibility, highlighting their potential as an effective strategy to improve the properties of cheese.

Aim: To reduce the concentration of biogenic amines (BA) in Edam-type cheese by applying liquid acid whey protein concentrate (LAWPC) based edible coating. Biogenic amines, particularly histamine and tyramine, are safety and quality indicators in cheese, as their accumulation during storage is linked to microbial activity. Elevated levels of these amines may pose health risks to consumers and reflect poor microbiological control. Monitoring BA levels during storage is essential for food quality control. Whey protein-based edible coatings offer a sustainable strategy to reduce BA formation by modulating microbial growth. Method: An edible coating from LAWPC, containing sugar beet pectin, Tween 80, sunflower oil, and glycerol was applied to fresh Edam-type cheese (E-piim, Estonia), which was vacuum-packed and stored for 135 days. The extraction and determination of BA in samples followed the procedures developed by Ben-Gigirey et al. (1999) with some modifications, as described by Bartkiene et al. (2024). Additionally, lactic acid bacteria (LAB) were enumerated according ISO 15214:1998, and total bacteria counts (TBC) were determined following ISO 4833-1:2013 during storage. Results: Histamine was the predominant biogenic amine, increasing in both samples over time, with concentrations reaching 151.06 mg/kg in control cheese and 163.5 mg/kg in coated cheese on day 135 (p ≥ 0.05). However, tyramine sharply increased only in the control, reaching 157.58 mg/kg, while remaining significantly lower in coated sample (13.03 mg/kg; p < 0.05) at the end of storage. This difference may be attributed to significantly higher TBC (8.89 vs. 7.84 log CFU/g) and LAB counts (7.72 vs. 7.18 log CFU/g) in the control compared to coated cheese (p < 0.05). Overall, total BA content was significantly higher (p < 0.05) in the control (339.96 mg/kg) compared to coated cheese (243.46 mg/kg), indicating a protective effect of the coating. Conclusion: The application of a LAWPC-based edible coating reduced total biogenic amine accumulation in Edam-type cheese during storage. Notably, tyramine levels were reduced by 91% in coated samples, indicating a protective effect likely associated with decreased microbial activity. These findings highlight the potential of LAWPC-based edible coatings as a sustainable strategy to improve the safety and quality of cheese.

Edible coatings offer an approach for probiotic delivery in food. While some lactic acid bacteria (LAB) survive well in vitro, their viability may decline when incorporated into an edible matrix. This study employed a standardized static method (Minekus et al., 2014) to simulate in vitro digestion of acid-curd cheese coated with Lacticaseibacillus paracasei A11-incorporated films, derived from liquid acid whey protein concentrate and liquid acid whey permeate. A11 counts in the samples were assessed using 16S rRNA gene amplicon sequencing (MiSeq, Illumina). Results demonstrated that LAB counts decreased by 31% post-digestion in uncoated samples, while coated samples with A11 maintained higher stability (P < 0.05). In coated samples, pre-digestion A11 counts were 6.40 ± 0.18 log CFU/g (day 1) and 6.38 ± 0.08 log CFU/g (day 10). Postdigestion, A11 counts did not decrease, reaching 6.71 ± 0.17 log CFU/g (day 1) and 6.46 ± 0.12 log CFU/g (day 10). In conclusion, coatings from dairy by-products enhanced A11 stability, achieving 100% survival and preventing a 31% LAB loss post-digestion, highlighting their potential for probiotic delivery in functional foods.

Recent studies have demonstrated that edible films serve as an effective vehicle for delivering functional components such as probiotics and prebiotics. However, the incorporation of probiotic lactic acid bacteria (LAB) may alter the structural and functional properties of these films. In this study, edible films formulated from liquid acid whey protein concentrate (LAWPC) or liquid acid whey permeate (LAWP), containing sugar beet pectin, Tween 80, sunflower oil, and glycerol, were enriched with Lacticaseibacillus paracasei and Lactobacillus helveticus (~7 log CFU/g). The films were evaluated for their physicomechanical attributes, including thickness, tensile strength, elongation at break, water solubility, moisture content, and water vapor permeability (WVP). The plain LAWP film exhibited significantly higher moisture content (28%), reduced thickness (54%), and greater stretchability (70%) compared to the plain LAWPC film (p 0.05). Incorporation of both L. paracasei and L. helveticus into LAWPC films significantly enhanced their stretchability and tensile strength (p 0.05). Additionally, L. helveticus reduced the thickness of LAWPC films, while L. paracasei increased the solubility of LAWP films (p 0.05). However, the film type and LAB strain used did not affect water solubility, with mean values of 69.41% for LAWPC films and 77.26% for LAWP films (p ≥ 0.05). No statistically significant differences were observed in WVP among the film samples, with an overall mean of 2.60 × 10−6 ± 1.03 × 10−7 (g/(m.s.Pa)) (p ≥ 0.05). These findings indicate that the combination of dairy by-products and LAB in edible films has a positive effect on their physicomechanical properties. Moreover, embedding the bacteria in an edible hydrocolloid matrix provides an excellent way to integrate probiotics into food products.

This dissertation investigates the application of Tenebrio molitor (yellow mealworm) larvae reared on various agro-industrial by-products for the development of safe, more sustainable, and value-added innovative products. Three experimental and one control group of larvae were formed using substrates composed of brewery by-products, grain processing residues, and solanized and sprouting-affected potatoes. The chemical composition and nutritional value of the larvae were evaluated, along with the accumulation of potential contaminants, including heavy metals, biogenic amines, pesticides, nitrates, nitrites, glycoalkaloids, peroxides, and volatile fatty acids. Chemical safety assessments showed that all regulated contaminants in the larvae remained within the limits established by legislation. Meanwhile, some unregulated compounds, such as certain biogenic amines and glycoalkaloids, demonstrated significant accumulation in the larvae powder. The impact of the larvae powder on the quality, safety indicators, and sensory acceptability of wheat bread and sausages was also evaluated. It was determined that the inclusion of freeze-dried larvae powder ensured chemical safety and improved nutritional composition, while the addition of 5–10% preserved sensory acceptability. The findings are relevant for the development of sustainable protein sources and the reduction of food waste through the application of circular economy principles. Santrauka (lt)

Bacterial infections in hospital settings, particularly within the gastro¬intestinal tract (GIT), present a significant challenge to healthcare systems worldwide. Hospital-acquired infections (HAIs), also known as nosocomial infections (NIs), are often linked to invasive procedures, antibiotic use, and compromised immune systems of patients. In the GIT, various bacterial pathogens such as Escherichia coli, Clostridium difficile, and especially Klebsiella species can cause infections ranging from mild gastroenteritis to severe conditions such as colitis and life-threatening sepsis. Notably, Kleb¬siella species, was currently named in the top of World Health Organisation (WHO) superbugs list, because of its widespread resistance to third-gene¬ration antibiotics in the European Region.

Klebsiella pneumoniae and Klebsiella quasipneumoniae are Gram-negative, rod-shaped, facultative anaerobic bacteria commonly found in hospital settings, these bacteria can be opportunistic pathogens, often colo¬nizing the human GIT and nasopharynx. However, these bacteria are also regularly associated with secondary infections, including pneumonia and urinary tract infections. Their presence in hospitals is concerning, especially in patients with compromised immune systems or those undergoing invasive procedures, as they can lead to severe infections with high morbidity and mortality rates. Additionally, their growing resistance to antibiotics further complicates treatment options, making these infections even harder to manage.

Despite antibiotic treatment being one of the main methods in modern medicine to combat bacterial infections, the abundant and inappropriate use of antimicrobial agents leads to the emergence of multi-drug resistant bacteria (MDR). Globally, resistance of Klebsiella bacteria to antimicrobial drugs currently reaches up to 70%, with mortality rates ranging from 40% to 70%. Bacteriocins are antibacterial peptides or small proteins synthesized by bacterial ribosomes, capable of acting against the same or closely related species of bacteria. These antimicrobial agents are currently being globally investigated as a promising option for novel antibiotic-resistant bacterial infections, offering unique advantages over traditional antibiotics. Bacte¬riocins have a narrow spectrum of bacterial inhibition and are less prone to develop resistance compared to antibiotics. Therefore, recombinant bacte¬riocins – KvarIa and KvarM – were chosen as the investigational therapeutic agent for treating drug resistant infections.

To address the growing need for microbiome-sparing antimicrobial strategies, this study investigated the therapeutic potential of bacteriocin-based interventions against Klebsiella species, a group of clinically signi¬ficant pathogens exhibiting increasing multidrug resistance. Gastrointes¬tinal infection models were employed to assess both pathogen virulence and treatment efficacy under conditions that reflect clinically relevant challenges. The main novel scientific contributions of the study, including the develop¬ment of a novel infection model, characterization of pH-dependent drug release, identification of species-specific treatment needs, and evaluation of targeted bacteriocins with minimal impact on the gut microbiota.

Edible film-forming solutions typically undergo thermal treatment to ensure microbial safety before being applied to food products. The aim of this study was to assess the effects of two different heating methods—conventional heating (CH) and ohmic heating (OH)—on the physical, chemical, and microbiological properties of liquid acid whey permeate (AWP) and liquid acid whey protein concentrate (AWPC) edible films. Composition of edible film-forming solutions consisted of AWPC, sunflower oil, sugar beet pectin, and glycerol, whereas AWP-based films were produced with sugar beet pectin and glycerol. The following parameters were tested to assess the effect of heating treatments on the film-forming solutions: rheology, contact angle [CA] and microbial counts and mechanical properties (tensile strength [TS] and elongation at break [EB]), water vapor permeability [WVP], moisture content [MC], solubility (Sol), and thickness with optical properties of produced edible films. In addition, film surface was investigated by scanning electron microscopy [SEM]. Microbiological analysis of the untreated film-forming solutions revealed that the AWPC-based solution had a higher initial load of lactic acid bacteria (3.96 log10 CFU/mL) (p < 0.05). Both heating treatments successfully reduced microbial counts to below detection limits in both film-forming solutions. Additionally, OH treatment resulted in lower CA values in both solutions (p < 0.05). OH also led to an increase in TS for AWP-based edible films (p < 0.05) and significantly reduced the thickness of both AWP and AWPC films, while reducing the Sol of AWP-based films and increasing the Sol of AWPC-based films (p < 0.05). The study highlights the effectiveness of the two pasteurization methods and offers insights into improving whey-based edible films.