Transformation of eggshell waste to egg white protein solution, calcium chloride dihydrate, and eggshell membrane powder

Abstract

The present study investigated the possibility of complete utilization of eggshell waste (ESW) transforming it to adherent egg white protein solution, calcium chloride dihydrate, and eggshell membranes (ESM). Adherent egg white protein solution was obtained by washing ESW three times with distilled water at 25°C, followed by filtration, and analyzed for the protein content and lysozyme activity. ESM and calcium chloride were obtained simultaneously by the exposure of washed eggshells to 5% hydrochloric acid treatment at 25°C for 3 h, followed by separation by filtration. The separated ESM were washed, dried, and milled to powder and analyzed for protein and lipid content. The calcium chloride solution was exposed to the neutralization of excess hydrochloric acid by calcium hydroxide, followed by evaporation to one-tenth of volume. Calcium chloride crystals were precipitated from the concentrated solution with acetone, separated by filtration, dried at 110°C, and analyzed for chemical composition and purity. The obtained results revealed that 100 g of ESW can be transformed to 1.61 ± 0.34 g of adherent white proteins containing 485,821 U of lysozyme activity, 2.84 ± 0.16 g of ESM powder, and 108.74 ± 3.62 g of calcium chloride dihydrate of high purity.

Eggshell-Waste-Derived Calcium Acetate, Calcium Hydrogen Phosphate and Corresponding Eggshell Membranes

“…Huge amounts of eggshell waste (ESW) have been produced worldwide annually, but the majority of it unfortunately ends up in landfills, presenting a significant ecological burden, as well as a potential biohazard [1][2][3][4]. This is quite surprising since numerous scientific reports and patents [3,[5][6][7][8][9][10][11][12][13][14][15][16] clearly show the multiple usage possibilities of ESW.…”

“…ESW originating from fresh hen egg breaking in households, restaurants, as well as egg breaking plants, could be roughly divided into three structurally different parts each containing unique set of high value molecules of potential use (Figure 1). Adherent egg white layer comprising the inner part of ESW, present in the amount of about 3% of ESW on dry weight basis, is a rich source of valuable egg white proteins, such as ovalbumin, ovotransferrin and lysozyme [1,4,5,17]. This sticky egg white layer is adhered to the eggshell membranes (ESM) that comprise about 3% of ESW on dry weight basis, and presents a rich source of collagen fibers, hyaluronic acid and other valuable glycosaminoglycans [1,[18][19][20][21].…”

“…Adherent egg white layer comprising the inner part of ESW, present in the amount of about 3% of ESW on dry weight basis, is a rich source of valuable egg white proteins, such as ovalbumin, ovotransferrin and lysozyme [1,4,5,17]. This sticky egg white layer is adhered to the eggshell membranes (ESM) that comprise about 3% of ESW on dry weight basis, and presents a rich source of collagen fibers, hyaluronic acid and other valuable glycosaminoglycans [1,[18][19][20][21]. Finally, the outer part of ESW is a calcified matrix mainly composed of calcium carbonate comprising between 92 and 95% of ESW on dry weight basis, and some highly valuable antimicrobial eggshell proteins present in low amounts [1,4,16,22,23].…”

“…This sticky egg white layer is adhered to the eggshell membranes (ESM) that comprise about 3% of ESW on dry weight basis, and presents a rich source of collagen fibers, hyaluronic acid and other valuable glycosaminoglycans [1,[18][19][20][21]. Finally, the outer part of ESW is a calcified matrix mainly composed of calcium carbonate comprising between 92 and 95% of ESW on dry weight basis, and some highly valuable antimicrobial eggshell proteins present in low amounts [1,4,16,22,23]. As we have just stated, each part of ESW could be used for the production of high value-added products, instead of being used partially, or in the worst-case scenario discarded on landfills.…”

“…Structural parts of eggshell waste and their most valuable components. Contribution of each structurally different part of eggshell waste in total eggshell waste amount is approximated on the basis of reports by Strelec et al [1], while the most valuable components of each part of eggshell waste comes from references [1,2,4,5,[17][18][19][20][21][22][23][24][25][26].…”