Mealworms provide a viable option for transforming agricultural and food processing by-products that can be converted into a valuable source of high-quality protein and fat suitable for both animals and humans. Hence, our investigation was aimed at employing sprouted and green potatoes, wheat bran, and by-products from brewers’ production as a comprehensive substrate for rearing mealworms. The nutritional value (fat and protein content) and composition of amino acids (AAs) and fatty acids (FAs) were tested in lyophilized and milled larvae. The results showed that the highest amount of protein was detected in sample 3L (59.18 ± 007%), grown on brewers’ spent grain, whereas sample 2S (with wheat bran) comes out with the highest fat content (34.22 ± 0.491%). It was found that the amount of FAs in the larvae depended on the substrate used: the statistically highest amount of monounsaturated FAs was detected in the sample with sprouted potatoes (1L), the highest content of omega-3 FAs was found in the control sample (4CL), with agar–agar gels, and the sample with brewers spent grains (3L) showed a statistically higher amount of oleic acid. Meanwhile, the highest content of total polyunsaturated FAs (36.23%) was detected in the sample with wheat bran (2L). During the study, 16 distinct AAs have been analyzed, and sample 3L has demonstrated the highest content in 11 instances. It is noteworthy that the sample containing brewers’ spent grain exhibited the highest peroxide levels, indicating oxidation. Meanwhile, the determined number of volatile fatty acids did not exceed the regulatory limits for meat. In summary, it can be asserted that adjusting the substrate is essential for extracting specific amino acids and FAs. However, this could potentially affect the content of peroxides. This adaptation enables the desired chemical composition in larvae, making it suitable for specific purposes such as animal or human nutrition and health enhancement.

The meat industry generates large amounts of by-products, and their mass represents approximately one-third of the live weight of animals. Most by-products are disposed of and not used for processing, although they meet hygiene requirements and are suitable for human consumption or for the processing of food supplements. The aim of this study was to investigate the effect of lyophilization on the nutritional value and retention of functional ingredients in ovine and porcine by-products: liver, kidneys, hearts, and lungs. For this purpose, meat by-products of the third category were selected in X and Y slaughterhouses and divided into two parts: one part was freeze-dried at −80 °C for 72 h, and the other part was left raw. Fatty acid composition was determined by gas chromatography–mass spectrometry (GC-MS), and amino acid analysis was performed by AccQ Tag technology (Waters Corp., Milford, MA, USA) and HPLC. Our study shows that the lyophilization process did not significantly affect protein and fat content. The largest decrease in the amount of proteins was determined in samples of ovine kidneys, at 0.8%, while the difference in protein in ovine liver samples before and after lyophilization was 0.38%. The composition of essential amino acids did not change after lyophilization, except a decrease in Leu and Thr in porcine samples and Leu, Thr, and Met in ovine samples (p < 0.05). The lyophilization process did not significantly affect the polyunsaturated fatty acid content, including the amounts of omega 3 and omega 6 fatty acids. The optimal ratio of omega 6 and 3 fatty acids was determined in samples of lyophilized ovine livers (2.65), and the largest ratio was found in samples of lyophilized porcine hearts (16.67). The study results show that, after lyophilization, meat by-products of the third category (according to Regulation (EC) No. 1069/2009, Categorization, Article 10), especially ovine liver, can be used as a source of amino acids and polyunsaturated fatty acids for functional food processing. The process of lyophilization is also appropriate for preserving meat by-products without losing the nutritional value and beneficial components.

The aim of this work is to evaluate the effect of taxifolin on the physicochemical and microbiological properties of cold-smoked pork sausages produced using different commercial starter cultures with Leuconostoc carnosum and with a mixture of Pediococcus pentosaceus and Staphylococcus xylosus. Ultra performance liquid chromatography analysis demonstrated that after 181 days of storage total taxifolin content was the highest in samples with taxifolin and L. carnosum (60 %), compared to the first day of storage. The sausages with taxifolin and the mixture of P. pentosaceus and S. xylosus (56 %) followed next. Taxifolin improved the hygienic quality of sausages without significant effect on the growth of lactic acid bacteria. The accumulation of biogenic amines, including histamine and putrescine, was more effectively reduced in sausages inoculated with the taxifolin and P. pentosaceus and S. xylosus mixture. Using this mixture, the rate of lipolysis and lipid oxidation were effectively slowed down. Samples with taxifolin and L. carnosum showed the highest free radical scavenging activity on the first day of the study ((77.4±1.3) %) (p<0.05 in all samples). Mixtures containing taxifolin and starter cultures bound free radicals better than taxifolin alone. The colour parameters (L*, a* and b*) of preparations and final products were significantly influenced by taxifolin and starter cultures and storage time (p<0.05 in all samples).

The use of animal by-products to produce bioactive peptides is a promising and sustainable approach in the food and nutrition industry. Meat by-products can be used as a key raw material for the production of high-value-added components, such as bioactive peptides, to ensure sustainability. Porcine livers and hearts classified as category three by-products were selected for the study, together with those intended for human consumption, in which no changes were observed after veterinary post-mortem examination. Hydrolysis was performed at three different times 3 h, 6 h, and 24 h, using pepsin and papain. The influence of different hydrolysis times and enzymes on the degree of hydrolysis (DH) value was determined. The highest value of DH was found in porcine hearts after 24 h following hydrolysis with pepsin enzymes (33.56 ± 0.31). The antiradical activity was assessed by measuring the absorbance of DPPH• and ABTS•+ in hydrolysates obtained from porcine meat by-products. Porcine livers hydrolysates treated with papain for 24 h showed the highest radical scavenging abilities ABTS•+ (97.2 ± 1.79%) and DPPH• (92.07 ± 2.23%). The identification and quantification of peptides from porcine livers and hearts were conducted using SWATH-MS technology. The most abundant peptides that showed a relationship with antioxidant capacity were WGKVNVDEVGGEALGRL, WGKVNVDEVGGEAL, and GLWGKVNVDEVGGEALGRL from beta hemoglobin.

This study aimed to develop innovative functional gummy candies enriched with protein hydrolysates derived from porcine liver, enhancing their antioxidant and antimicrobial properties. First, the overall consumer acceptability (OA) was assessed to determine the most suitable combination of gummy matrix components. Selected combinations were then analyzed for antioxidant activity (ABTS•+, DPPH•), antimicrobial effects, microbiological safety, and physicochemical characteristics. The incorporation of liver hydrolysates significantly increased antioxidant capacity. The highest activity was observed in sample GC5Pa24Ag, hydrolyzed with papain for 24 h and formulated with agar, showing ABTS•+ and DPPH• scavenging activities of (67.6 ± 0.98 µmol/g) and (49.14 ± 1.00%), respectively (p ≤ 0.05). Pepsin hydrolyzed samples (GC2Pe3Gl, GC2Pe6Gl, GC2Pe24Gl) exhibited significantly larger inhibition zones against Listeria monocytogenes ATCC 13932, Escherichia coli ATCC 25922, and Salmonella enterica subsp. enterica serovar Typhimurium ATCC 14028 compared to the control (p < 0.05). Among all, GC5Pa24Ag demonstrated the broadest antimicrobial activity, with a 29.0 ± 0.2 mm inhibition zone against all tested pathogens. These findings suggest that porcine liver hydrolysates can be successfully incorporated into confectionery products to create functional gummies with potential health benefits, offering antioxidant protection and antimicrobial effects in a consumer-friendly form.

Semi-natural grasslands support biodiversity, but their capacity to combine conservation with beef production remains insufficiently quantified. This case study compared a sown ley and a permanent semi-natural grassland in Lithuania during the 2019–2020 grazing seasons, using eight bulls annually (16 animal observations; four per field per year). Plant diversity, herbage yield and composition, liveweight change, and beef quality were evaluated. Soil phosphorus status differed, with lower extractable phosphorus in the permanent grassland. Species richness was higher in permanent grassland than in sown ley (84 vs. 12 species), whereas herbage dry matter yield was lower (1.45 vs. 2.92 t DM ha ⁻¹). Permanent grassland had half the livestock unit density and twice the land area per animal, resulting in similar dry matter yield per animal. Despite the greater land requirement, unadjusted growth differences varied in direction between years, and the adjusted difference in final liveweight was imprecisely estimated (permanent grassland minus ley: −10.1 kg; 95% CI: −39.7 to 19.5 kg). Beef from the studied permanent grassland had less saturated and more unsaturated fatty acids, lower atherogenicity and thrombogenicity indices, and a higher hypocholesterolaemic-to-hypercholesterolaemic fatty acid ratio. Multi-site studies are needed to assess the broader applicability of these differences.