The nutritive value of egg by‐products and their potential bactericidal activity: in vitro and in vivo studies

Abstract

Technical-grade egg albumen (TA) and whole egg (WE) by-products are produced in substantial quantities by egg-breaking facilities across North America. TA and WE products are recovered during processing but are not approved for human consumption. Both products are known to be rich in fat, maternal antibodies, protein and lysozyme, a bactericidal enzyme. The objective of this research was to explore the potential for egg by-products to be used as a valuable protein, energy and bactericidal supplement in animal nutrition. To improve the nutritive value of TA and WE, spray-dried samples were heat treated at various temperatures and their digestible protein content was determined in vitro using a pepsin/pancreatin digestion/dialysis system. In addition, enhancement of lysozyme activity towards Gram-negative bacteria (GNB) by heat or irradiation was examined. Optimal protein digestibility for TA averaged 80% following heat treatment at 105-110 • C for 10 min. In contrast, protein digestibility of spray-dried TA was only 55%. Heat treatment (100-122 • C) of spray-dried WE or hot room storage of spray-dried TA and WE products at 70 • C for up to 14 days had a minimal effect on protein digestibility in vitro. Heat treatment or γ -irradiation of lysozyme for at least 20 min at 80 • C or 0.5 kGy, respectively, increased antimicrobial activity towards GNB. When compared with either the heat or radiation control treatments, reductions in Escherichia coli and Salmonella enterica serovar Typhimurium populations increased by at least 1 and 0.5 log 10 , respectively. In contrast, the effect of irradiation (2 kGy) on the antimicrobial activity of spray-dried TA was less pronounced. In a feeding trial, rats fed spray-dried TA and spray-dried TA subjected to either radiation (1.8 kGy) or heat (80 • C, 20 min) treatment exhibited a body weight gain and protein utilisation equal to or higher than the control (casein diet). In contrast, feeding spray-dried WE or TA and WE previously maintained in a hot room (70 • C) for 3 days had a negative effect on rat growth and protein utilisation. In the case of WE products this was substantiated by poor digestibility of essential amino acids, including lysine, threonine and, to some extent, methionine. When compared with the control treatments, inclusion of heat-treated or irradiated TA in the rat diets reduced the population of Enterobacteriaceae.

Quality Changes of N-3 PUFAs Enriched and Conventional Eggs under Different Home Storage Conditions with Wireless Sensor Network

“…As the storage goes on, the egg yolk gradually expanded and led to the weakening of the strength of vitelline membrane [41], which happened because water gradually permeated from the albumen through the vitelline membrane to yolk. The process finally changed the yolk shape from a spheroid to an oblateness [36].…”

Value of spray-dried egg in pig nursery diets

“…Egg production and how to produce spray-dried egg billion (3% of the total eggs produced) eggs are unsuitable for human consumption (Norberg et al, 2004). Eggs that do not meet grade B or equivalent standards are used to make liquid, frozen, dried egg products for cooking, or by-products for animal feeds (Cunningham and Acker, 2001;Norberg et al, 2004;Schmidt et al, 2007). Norberg et al (2004) IV.…”

“…This catalytic activity can damage bacterial cell walls, but it is only effective against gram positive bacteria. However, several researches showed enhancement of this catalytic activity of lysozyme by heating or irradiation can reduce the survival rate of gram negative bacteria as well as gram positive bacteria (Ibrahim et al, 1996;Schmidt et al, 2007). Therefore, SDE may contribute benefits beyond provision of nutrients.…”

Effects of dietary spray-dried egg on growth performance and health of weaned pigs1

“…The specifi city of the egg antibodies is unknown. Second, SDE also contains lysozyme, an antimicrobial protein (Schmidt et al, 2007). It can damage bacterial cell walls (Cunningham et al, 1991), and this catalytic activity can reduce survival rate of gram-positive or -negative bacteria (Ibrahim et al, 1996;Schmidt et al, 2007).…”

“…It is an excellent nutrient source (Norberg et al, 2004;Harmon and Richert, 2007) because of high digestibility, favorable balance of AA, increased fat content, and increased ME value. Beyond the provision of bioavailable nutrients, SDE may also provide specifi c physiological benefi ts because it contains physiologically active components such as immunoglobulins (IgY in egg yolk; Rose et al, 1974;Akita and Nakai, 1992;Harmon et al, 2002) and lysozyme, an antimicrobial protein (Cunningham et al, 1991;Ibrahim et al, 1996;Schmidt et al, 2007). Therefore, SDE may provide 2 important contributions to nursery pig diets, both bioavailable nutrients and specifi c physiological benefi ts to improve health.…”