# A New Approach for the Utilization of Technical Egg Albumen Based on Acid-Thermal Coagulation
## 1 Introduction  
Eggs are an excellent source of nutritional and biologically active substances--proteins and lipids, as well as all essential amino acids. They are defined as the cheapest animal source of protein [1]. Apart from being nutritious, eggs also have functional properties, such as foaming, emulsifying, and gelling ability [2].  
Approximately 30% of the egg supply in developed countries is processed into various processed products and not sold as shell eggs [3]. This percentage reaches up to 50% in some countries of the European Union [4]. Egg products are eggs that have been processed and packaged in a convenient form. Some examples of egg products include dried, liquid, or frozen egg white, yolk, or whole egg. These egg products are used in the food industry after heat treatment to remove bacterial contamination [5, 6]. Industrialized production of egg products offers economic benefits, but a significant amount of waste is generated [7].  
Under the European Commission's proposals, the circular economy package will aim to minimize waste so that when a product reaches the end of its life, its materials remain in the economy as much as possible. Therefore, what was previously considered \"waste\"becomes a valuable resource [8]. The 3R principles (reduce, reuse, and recycle) are at the heart of the \"circular economy\" [9].  
Food waste is one of the important factors for the carbon footprint. The consequences of increasing greenhouse gas emissions are climate change, water scarcity, pollution, soil erosion, and a reduction in biodiversity above and below ground. The treatment of food waste through various sustainable methods is of primary importance to reduce the anthropogenic impact on nature [10]. The wastes in the production of egg products are eggshell -70%, eggshell membrane ~10-15% (solid waste), and adherent (technical) egg white ~10-15% (liquid waste) [11]. It can be estimated that at least 7,894,962 t of egg processing waste is produced annually worldwide, of which 777,000 t is low in the Union [12]. According to European legislation, waste from the processing of eggs with animal by-products is category 3, and the legislation allows it to be processed into feed [13]. Feed materials from egg products are present in the EU feed materials catalog [14].  
The conversion of food waste into animal feed is preferable to composting and anaerobic digestion for biogas production or disposal in landfills [15]. Technical albumen (TA) is a viable animal feed after proper processing due to its excellent amino acid profile, energy content, and presence of antimicrobial proteins, but it has received little attention from the industry [16]. The proteins contained in the technical egg white are identical to those of the egg white proteins [12]. An example of protein utilization from this waste product is application in feed for broiler chickens [17] and weanling pigs [18]. Egg waste spray drying technology is a common method of producing animal feed from this type of waste. According to [PERSON] et al., spray drying is used to process egg by-products into feed, but the biggest disadvantage of this type of processing is the high investment costs [19].  
In our previous research, we found that acid-thermal coagulation is a possible alternative way to treat liquid waste from egg processing. In our preliminary study, we used four different types of acids. From them, the most suitable acids for pH correction are citric acid (CA) and phosphoric acid (PA), which showed the best values of the production indicators yield and pressing efficiency [20]. In this study, we characterized the raw TA and the final product from it. We evaluate the most suitable pretreatment to reduce moisture before drying in order to reduce the cost and heat impact on dry egg products. The initial characteristics of produced dried egg products from TA will be evaluated, as well as their changes during storage. We describe and compare the obtained characteristics of the finished product