The study aimed to compare the physical-chemical attributes of table eggs from three laying hen breeds housed in the cage and cage-free conditions and to characterize the morphological characteristics of the eggshell interior. A morphological and elemental analysis performed by scanning electron microscope coupled with energy dispersive X-ray spectroscopy revealed no abnormalities in the structural integrity of eggshells. The thickness of the eggshell varied in the range from 356.2 to 366.4 µm, with no statistically significant differences between the values. Eggshell membrane thickness was between 20.0 and 59.9 µm, with eggs derived from cage-housed hens, i.e., H/LS/CCE and H/HN/CCE having thinner membrane layers. The results revealed no direct relationships between eggshell and membrane thickness and physical-chemical parameters’ change. However, the presence of thick and long spider-like microcracks on the eggshell surface of eggs from cage-free housed hens H/D/BWE was the main factor that presumably contributed to substantial weight loss during 36 days of egg storage. A noticeable decline in eggshell-breaking strength along with the enlargement of air cells was observed in eggs produced under an enriched cage system H/LS/CCE after 28 days. In contrast, the minor changes in air cell size occurred in eggs from cage-free housed laying hens H/D/BWE. Protein quality indicators such as albumen height and Haugh units were well correlated with each other, and the intensity of their changes during egg storage, to a greater extent, was found to be storage time-dependent. No significant depletion of egg albumen was revealed during the first 15 days of egg storage. According to the United States Department of Agriculture, the quality corresponded to grade A (reasonably firm). However, after 18 days of storage, Haugh unit values were lower than 60, corresponding to grade B (weak and watery). The most apparent reduction in the Haugh unit was observed in eggs produced by enriched cage H/HN/CCE and cage-free H/D/BWE hens. The egg quality was storage time-dependent, and their deterioration rate was primarily associated with the genetic background of laying hens and housing conditions.

This study aimed to determine the ability of high-density polyethylene, polyethylene terephthalate, Tetra Rex^® Bio-based packaging, and Doypack (stand-up pouches) packaging to maintain the nutritional quality and safety of liquid whole egg products for 35 days of refrigerated storage. High-grade hen eggs were used for the preparation of liquid whole egg products (LWEPs). The conformity of eggs quality to grade A was supported by the initial screening of the raw materials’ physical–chemical attributes, which remained unchanged during the 25 days of storage. The obtained results indicated that the content of fatty acids in LWEPs was affected by both storage time and packaging material. However, the better preservation of monounsaturated fatty acids was achieved by polyethylene terephthalate, followed by high-density polyethylene packaging. Meanwhile, a statistically significant advantage of polyethylene terephthalate over other packaging materials was also confirmed regarding the maintenance of polyunsaturated fatty acids during 35 days of LWEPs storage. Relative fluctuations in the number of fatty acids in Tetra Rex^® Bio-based and Doypack-stored LWEPs revealed their disadvantages manifested by exfoliation of composite layers, which perhaps was the main cause of extensive moisture loss. Overall, due to superior barrier properties, polyethylene terephthalate packaging demonstrated better preservation of amino acids. Only as much as a 2.1% decrease was observed between the initial value and the 35th day of LWEP storage. From a microbiological standpoint, all materials demonstrated the ability to ensure the microbiological safety of products during 35 days of storage, as the maximum allowed limit of 10⁵ CFU g⁻¹ was not exceeded.

This study explores the integration of chicken manure management into a circular economy framework, highlighting its potential as a renewable resource for organic fertilizer and bioenergy production. The rapid development of poultry farming in the Baltic region has exacerbated the problem of sustainable manure disposal, which has created a need for innovative, cost-effective and environmentally friendly solutions. Through life cycle assessment (LCA), techno-economic analysis, and a review of existing manure treatment technologies, the research evaluates the environmental impact, nutrient recovery efficiency, and economic feasibility of anaerobic digestion and composting systems. The results show that chicken manure, rich in essential nutrients such as nitrogen (N), phosphorus (P) and potassium (K), is effectively converted into high-quality organic fertilizer and renewable biogas. The economic analysis indicates that these technologies become profitable at medium to large farm scales, with a potential net benefit of 285 000 EUR annually for farms processing 5 000 tons of manure, with profitability thresholds identified at around 3 000 laying hens for composting and not less than 10 000 laying hens for biogas production. Furthermore, adopting these technologies contributes to greenhouse gas emission reductions, improved soil quality, and greater energy independence for rural farms. By closing the nutrient and energy loops, this approach aligns with EU sustainability goals and promotes resilient agricultural systems. The findings support the transition toward more circular, low emission farming practices, transforming poultry waste from an environmental liability into a valuable resource.