# A New Approach for the Utilization of Technical Egg Albumen Based on Acid-Thermal Coagulation
## 4 Discussion  
Waste from egg processing plants constitutes a significant amount of the food processing industry. The second in quantity of these wastes is liquid TA waste [12]. Egg waste products are animal by-products (ABP) category 3. The management of these products, due to safety reasons, is strictly regulated by European legislation. The ABP regulations set out rules for the collection, transport, storage, handling, processing and marketing, import, export, and transit of crude ABPs and products derived from them, which are among the strictest in the world. Feed costs are the largest cost of farming livestock in Europe, mainly due to the need to use imported protein ingredients (soybean and fishmeal), and can be reduced by investing in other protein-rich sources. Also, egg products circumvent the prohibitions of Regulation 999/2001 [40] on feeding farm animals with feed containing sources of animal origin. Feed ingredients from egg waste products can be fed to all categories of animals, including ruminants [41]. European legislation allows the use of ABP category 3 as animal feed, and TA is particularly suitable due to its chemical composition (Figure 1). It contains a significant amount of water but also nutrients--mainly proteins and fats. It is known that all the fat in eggs is found in the yolk. During the mechanical breaking of eggs in egg processing plants, the vitelline membrane of the yolk is broken, and part of it falls into the TA. The different amounts of fat in the samples may be due to the different eggs used as raw material. Other factors that have an influence are the speed of breaking the temperature of the eggs. The fat content of this product varies and cannot be predicted. The established amino acid composition confirms the statement that the nutritional completeness of the TA is no less than that of egg white intended for human consumption [42]. The pollution of TA with yolk during processing is the most logical explanation for the increase in the yellow component of the color (b*). In the context of the circular economy, this waste should be considered as raw material for animal feed after appropriate processing meets the feed criteria [8]. The raw TA has an unstable composition and is microbiologically inoculated but does not contain the pathogenic _Salmonella_ spp. The high microbial contamination is a consequence of the method of obtaining this product by crushing the eggshells. For this reason, ref. [43] prohibits its use for human consumption. Our microbiological results of the raw product for TPC, coliforms, and Enterobacteriaceae indicators confirm that TA does not meet the criteria and should be used after heat treatment (Table 3). In order for ABPs to be used, they must first be processed to meet the microbiological criteria specified in Regulation 142/2011 [21]. A method based on acid-thermal coagulation is suitable for processing this material. Heat treatment and subsequent drying of the product ensure a reduction of the microbial population. In the final product, after a month of storage, bacteria from the family Enterobacteriaceae, coliforms, and _E. coli_ are not detected, and TPC has decreased to an acceptable level (Table 7). Our results show that in the pretreatment before drying, the product is partially dehydrated. In the pressing process, the product loses up to 45% of its water content. This treatment facilitates drying because it starts from a lower moisture level. In addition, due to the low energy costs, the drying time and the impact of high temperatures on the product are reduced. This, in turn, reduces the formation of unwanted compounds that can be monitored by measuring the color characteristics. The best yields are obtained using CA 97.79%; this value indicates that the dry matter losses during the whole processing process for this sample are about 2.2%. The dry matter losses in this method of processing liquid egg processing waste are in the serum obtained during pressing. This serum contains varying amounts of non-coagulated soluble proteins and fats.