Egg products are a convenient and safe form of eggs, possessing valuable nutritional and functional properties. The egg processing industry is responsible for the enormous amounts of biomass in the form of animal by-products (ABPs). According to EU legislation, the ABPs are under strict control from the formation to the disposal of biomass, as they carry a risk to the ecosystem and public health. For this reason, restrictions have been introduced on their use after disposal, ranging from bioactive applications in medical, cosmetic, and pharmaceutical products, as well as feed. The shells are subject to special conditions for processing and use. The by-products of egg breaking are divided into solid (eggshells and eggshell membranes) and liquid (technical albumen) by-products. The biological value is determined by the composition, which varies significantly across the by-products. In the context of the circular economy, all egg by-products contain valuable substances that can be used in food and non-food industries. First, eggshells are the leading by-product, composing 95% of the inorganic substance calcium carbonate, which, after processing, can be used in agriculture, food and feed industries, and medicine. Second, there is a liquid by-product containing proteins from the egg white and a small part of fats from the yolk. Literature data on this by-product are scarce, but there is information about its use as a feed additive, while the extracted and purified proteins can be useful in pharmacy. Egg membranes constitute only 1% of the egg mass, but humanity has long known about the benefits of collagen, keratin, and glycosaminoglycans, including hyaluronic acid, which compose this material. The processed membranes can be used as a food additive, in cosmetics, medicine, or pharmacy, just like other egg by-products mentioned above. This literature review focuses on the possible methods and techniques for processing by-products and their potential application. The literature sources in this review have been selected according to their scientific and practical applicability. The utilization of these by-products not only reduces the impact on the environment but also facilitates the creation of value-added materials.

Eggs are a good source of balanced nutritional and biologically active substances - proteins, lipids, some irreplaceable nutritional components such as amino acids, polyunsaturated fatty acids, vitamins, macro- and microelements, etc. It is identified as the cheapest animal source of proteins, lipids, vitamins A, B12, riboflavin, choline, iron, zinc, phosphorus and calcium. At the same time, the dangers to human health that eggs can carry are also taken into account. Material/Methods: The literature used is based on databases PubMed, Embase and as well as data from own studies. Review Results: In the present review, we provide data on the importance of the composition of eggs in human nutrition are presented and the risk of their use is evaluated. Conclusions: The high biological and nutritional value of eggs are grounds for their use in the daily life of healthy people, without additional restrictions of cardiovascular diseases. There is a risk of food poisoning, which can be limited to acceptable levels by following good hygiene practices.

Technical albumen (TA) is liquid waste from egg processing enterprises and occupies a share of 10–15% of the waste. Proteins have the property at the isoelectric point of weakening their repulsive forces. This property is the basis of a TA recovery method using pretreatment to reduce moisture before drying. In this study, we present the results of a TA processing method using two types of citric and phosphoric acids based on thermal–acid coagulation as an alternative to spray drying. By analyzing physicochemical and microbiological indicators, the raw TA and the finished product are described. In this study, the characteristics of raw TA and its final product are presented. TA contains mainly water, fat, and protein, including all essential amino acids, all of the proteins of the egg white, and some of the yolk. Initially, TA is significantly microbiologically contaminated. A better yield was obtained when using citric acid 97.79% instead of phosphoric acid. The final dried egg product from TA has a protein content of 46% and a fat content of 33%. The dried egg products undergo changes in the lipid and protein fraction during storage, but the values remain low TBARS to 4 mg MDA/kg. Microbiological contamination has decreased due to a decrease in water activity to a level that meets the requirements of European legislation for the processing of animal by-products (ABPs) and uses as feed.