Eggshell membrane separation is a

recycling Recycling is the process of converting waste materials into new materials and objects. The recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability to reacquire the p ...

process to separate the protein-rich

eggshell membrane Eggshell membrane or shell membrane is the clear film lining eggshells, visible when one peels a boiled bird egg. Chicken eggshell membranes are used as a dietary supplement. Eggshell membrane is derived commercially from the eggshells of industri ...

from the

eggshell An eggshell is the outer covering of a hard-shelled egg and of some forms of eggs with soft outer coats. Diversity Worm eggs Nematode eggs present a two layered structure: an external vitellin layer made of chitin that confers mechanical ...

. Nearly 30% of the

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

consumed each year are broken and processed or powdered into foods such as cakes, mixes, mayonnaise, noodles and fast foods. The US food industry generates 150,000 tons of shell waste a year.Hecht J: Eggshells break into collagen market. New Scientist 1999, 161:6-6. The disposal methods for waste

s are 26.6% as fertilizer, 21.1% as

animal feed Animal feed is food given to domestic animals, especially livestock, in the course of animal husbandry. There are two basic types: fodder and forage. Used alone, the word ''feed'' more often refers to fodder. Animal feed is an important input to ...

ingredients, 26.3% discarded in municipal dumps, and 15.8% used in other ways.Daengprok W, Garnjanagoonchorn W, Mine Y: Fermented pork sausage fortified with commercial or hen eggshell calcium lactate. Meat Science 2002, 62:199-204. Many landfills are unwilling to take the waste because the shells and the attached membrane attract vermin. When unseparated, the calcium carbonate eggshell and protein-rich membrane have little or no value or use;Wei Z, Li B, Xu C: Application of waste eggshell as low-cost solid catalyst for biodiesel production lectronic resource Bioresource Technology 2009, 100:2883-2885. however, the invention of an eggshell and membrane separator has allowed for the recycling of these two products.

Chemical background

Chicken eggshells are made up of 95% calcium carbonate by weight and the remaining material is primarily organic matrix.Daengprok W, Issigonis K, Mine Y, Pornsinpatip P, Garnjanagoonchorn W, Naivikul O: Chicken eggshell matrix proteins enhance calcium transport in the human intestinal epithelial cells, Caco-Journal of Agricultural and Food Chemistry 2003, 51:6056-6061.

Eggshell membrane Eggshell membrane or shell membrane is the clear film lining eggshells, visible when one peels a boiled bird egg. Chicken eggshell membranes are used as a dietary supplement. Eggshell membrane is derived commercially from the eggshells of industri ...

is primarily composed of fibrous

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s such as

collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole ...

type I.

Methods

Non-chemical separators

Scraping

Joseph H. MacNeil, Professor of Food Science at

Penn State University The Pennsylvania State University (Penn State or PSU) is a public state-related land-grant research university with campuses and facilities throughout Pennsylvania. Founded in 1855 as the Farmers' High School of Pennsylvania, Penn State became ...

, developed a machine that uses a delicate multi-bladed knife to scrape the membrane from the surface of shell fragments.MacNeil JH: Method and apparatus for separating a protein membrane and shell material in waste egg shells. In United States Patent (Foundation TPSR ed., vol. 6,176,376. United States: The Penn State Research Foundation; 2001. This invention uses a water-based method to separate the eggshell and protein membrane. The two products are processed in two streams to yield mm size particles of dry membrane and mm size particles of dried shell.

Cyclone

Another non-chemical separation technique utilizes steam heat, mechanical abrasion, and a light vacuum to separate the hard eggshell from the protein-containing membranes.Adams: Egghell membrane separation method. In US Patent 7,017,277, United States: ESM Technologies, LLC; 2006. This invention passes shell fragments obtained from egg-breaking facilities through a series of heated augers. Once the shell and membrane flakes reach the appropriate moisture content, the vacuum pulls them into a cyclone device. The cyclonic action further separates the heavier eggshell flakes from the lighter membrane flakes. This invention has been commercialized and can easily separate multiple metric tons per day, allowing for the production of valuable products including commercial volumes of natural eggshell membrane or NEM.

Venturi

Levi New invented a non-chemical and non-thermal separation technique that utilizes airflow to pull egg shells through a venturi. The material is subjected to pressure waves while passing through the venturi.New: Eggshell membrane separation process. In US Patent 8,448,884 B2, United States; 2013. A PulverDryer machine configured with a venturi sized to process egg shell pulverizes the shell component into fine powder and discharges the membrane as an intact dry flake material. The two components are separated in post processing by a standard shaker screen table, then the membrane is cleaned via one of several standard washing processes, depending on end use. Up to several tons of egg shell material can be processed per hour.

Dissolved air-flotation separation unit

The waste eggshells are put into water and then ground to separate the eggshell from the protein membrane.Yoo S, Kokoszka J, Zou P, Hsieh JS: Utilization of calcium carbonate particles from eggshell waste as coating pigments for ink-jet printing paper lectronic resource Bioresource Technology 2009, 100:6416-6421. Then the ground eggshell is placed in a separate vessel where air is injected into the water flow. The air and water mixture causes the lighter component (protein membrane) to float and the heavier (calcium carbonate eggshells) to sink. This unit recovers 96% of eggshell membrane and 99% of eggshell calcium carbonate in two hours.

Water and acetic acid

The inventor of this method is Vladimir Vlad. The machine uses unseparated eggshells that are placed in a fluid tank, applying

cavitation Cavitation is a phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, cal ...

to separate the eggshell membrane from the eggshell. The fluid tank in this case contains

distilled water Distilled water is water that has been boiled into vapor and condensed back into liquid in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container. Thus, di ...

and

acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main component ...

to provide continuous processing. Also this invention has a method for collecting separated eggshells to grind them into an eggshell powder.Vlad: Eggshell membrane separation method. In US Patent, vol. 7534909. United States: Biova, L.L.C; 2009.

Uses of products

Eggshell, as a source of food-safe calcium carbonate, has uses in pharmaceuticals, food, and in general industry. Eggshell membrane is generally used as a dietary supplement.

References

{{Reflist Eggs (food) Recycling