cryonics-posts post 1 01-egg-vs-body-composition

Research note 01 — Egg vs human body composition

Purpose: Evaluate Aurelia's framing "eggs are basically a sack of protein, humans are much messier." Is it literally true? How wrong is the approximation? What are the major non-protein components that make "just turn it solid" hard for a body?

Confidence tiers: C1 primary source / C2 credible secondary / C3 inferred / C4 anecdotal / C5 unknown.

1. Chicken egg composition (whole, raw)

Claim: A whole raw egg is about 76% water, 13% protein, 10% lipid, 1% carbohydrate+ash. - Confidence: C2 (textbook secondary, multiple sources) - Source: "In a whole, raw, and freshly laid egg, water, protein, fat, carbohydrates, and ash represent about 76.1%, 12.6%, 9.5%, 0.7%, and 1.1%, respectively." https://pmc.ncbi.nlm.nih.gov/articles/PMC6470839/ ; https://pmc.ncbi.nlm.nih.gov/articles/PMC9407204/ - Date checked: 2026-04-23

Claim: Egg white is ~88% water, 11% protein, 0.2% fat. - Confidence: C2 - Source: "Egg white consists of about 88% water, 11% protein, 0.2% fat and 0.8% ash." https://pmc.ncbi.nlm.nih.gov/articles/PMC9407204/ - Notes: Egg white ("albumen") really is close to the cartoon "sack of protein in water" picture. Yolk is not.

Claim: Egg yolk is ~48% water, 34% lipid, 16% protein. - Confidence: C2 - Source: "Egg yolk consists of approximately 48% water, 34% lipids, and 16% proteins." https://pmc.ncbi.nlm.nih.gov/articles/PMC6470839/

Implication for Aurelia's framing: The "egg = mostly protein" claim is a simplification. Whole eggs are ~76% water. Egg white is the closest thing to the simple picture — it's the part that goes fully white-solid on heating, and disulfide + hydrophobic cross-links between denatured ovalbumin molecules form the gel network.

Dry-weight basis the egg is ~53% protein, ~40% lipid. Still not "basically all protein." The useful fact for Aurelia's intuition is that the protein network and the water go solid together in the albumen because the network traps the water — a hydrogel. The yolk does something different and messier.

2. How egg white sets

Claim: Egg white denatures/coagulates at 62–65 °C; ovalbumin specifically at ~71.5 °C (fresh) to ~92.5 °C (aged "S-ovalbumin"). - Confidence: C2 - Source: "Egg white protein coagulates between 144° F and 149° F (62.2° C and 65° C)." https://www.incredibleegg.org/professionals/manufacturers/real-egg-functionality/coagulation-thickening/ ; "Denaturation temperatures for ovalbumin are 71.5°C... the denaturation temperature of ovalbumin shifts from 84.5°C to 92.5°C for S-ovalbumin." https://pmc.ncbi.nlm.nih.gov/articles/PMC2366979/

Claim: The setting mechanism is unfolding exposing hydrophobic residues plus formation of intermolecular disulfide bonds via sulfhydryl-disulfide exchange. - Confidence: C2 - Source: "The formation of disulfide bonds and the exposure of hydrophobic amino acid residues are thought to be involved in the first step of coagulation. Further heating causes egg albumin to polymerize by intermolecular sulfhydryl-disulfide exchange, forming a network." https://www.mdpi.com/2310-2861/11/3/176 - Source: "Disulfide bonds play the primary role in heat-induced EWP gel formation, followed by hydrophobic interactions, hydrogen bonds, and ionic bonds." https://www.sciencedirect.com/science/article/abs/pii/S0924224423001978

Notes: The key chemistry is that egg white has high concentrations of cysteine-containing proteins (ovalbumin, ovotransferrin, lysozyme, ovomucoid). When heat unfolds them, free cysteines find each other and make S–S bonds; millions of such bonds aggregate into a space-filling gel that also traps the water. This is not aldehyde-type cross-linking — it's disulfide and hydrophobic. Different chemistry, same macroscopic effect: a watery protein solution becomes a solid.

3. Human body composition

Claim: Adult human body is ~60% water by mass, with males ~58±8% and females ~48±6%. - Confidence: C1/C2 - Source: "A man's body is 60 to 65 percent water, compared to 50 to 60 percent for a woman." https://www.medicinenet.com/what_percentage_of_your_body_should_be_water/article.htm - Source (primary): "The figure for water fraction by weight in this sample was found to be 58 ±8% water for males and 48 ±6% for females." https://pmc.ncbi.nlm.nih.gov/articles/PMC10265208/ - Notes: So a human is actually less water than a raw egg (76%) on a whole-object basis. The egg is wetter.

Claim: Adult human is ~16–20% protein by mass. - Confidence: C2 - Source: "Protein makes up approximately 20 percent of the human body." https://psu.pb.unizin.org/nutr100/chapter/7-2-defining-protein/ - Source: "Lean body weight consists of approximately 73% water, 20% protein, 6% mineral, and 1% ash." https://askthescientists.com/body-composition/

Claim: Adult human is roughly 10–25% lipid (huge between-person variance; adipose tissue alone is 61–94% lipid). - Confidence: C2 - Source: "Human fat tissue contains from 61% to 94% lipids, with lean and obese individuals tending towards the low and high ends of this range, respectively." https://pubmed.ncbi.nlm.nih.gov/8148928/ - Source: "Fat mass consists of the specific family of lipids (triglycerides) that makes up approximately 80% of adipose tissue." https://www.quora.com/What-percentage-of-the-body-is-lipid (less authoritative; used only for triangulation)

Implication: By percent-protein a whole egg (~13%) is actually less protein than a lean human (~20%). The egg's advantage isn't protein concentration — it's protein homogeneity. Egg white is basically one reactive species (protein) dissolved in one solvent (water), which then self-networks on heat. A human is a mosaic of tissues each with its own chemistry.

4. Collagen and extracellular matrix — the "messy" part

Claim: Collagen is ~25–30% of total human protein mass, i.e. the single most abundant protein in the body. - Confidence: C2 - Source: "Approximately 25% to 30% of human protein mass is from collagen molecules." https://en.wikipedia.org/wiki/Extracellular_matrix (orientation); https://www.physio-pedia.com/Extracellular_Matrix - Notes: Most collagen is extracellular — it's the scaffolding between cells, not cytoplasm. Heat-setting the cytoplasmic proteins doesn't do much about this.

Claim: Tendon is 60–85% collagen by dry weight; bone matrix is up to 70% collagen/calcium-phosphate; cartilage has ~25% type II collagen dry weight. - Confidence: C2 - Source: "The ECM of tendon is composed predominantly of collagen, which accounts for ~60–85% of the dry weight of the tissue"; "Bone... Type I collagen mixed with a matrix of calcium phosphate crystal (which is up to 70% of the dry weight)." https://www.nature.com/articles/s41598-019-46896-0

Key point: An egg has essentially no extracellular matrix. A human body is mostly ECM if you weight by volume of connective tissue. Heat-setting the cytosol doesn't touch collagen triple helices meaningfully (collagen denatures around 40–65 °C but re-sets into gelatin, not a useful fixed structure).

5. Brain-specific composition — relevant for ASC

Claim: Brain gray matter is ~36–40% lipid by dry weight; white matter 49–66%; myelin 78–81%. - Confidence: C1 - Source: "Myelin had a much higher lipid content (78–81% of the dry weight) than white matter (49–66%) or gray matter (36–40%)." https://www.jlr.org/article/S0022-2275(20)39619-X/pdf (O'Brien & Sampson 1965, J. Lipid Res.) - Notes: This is the primary source for brain lipid fractions; still the most-cited 60 years later.

Claim: Myelin in situ is ~40% water, meaning wet-weight lipid in myelin is ~47–49%. - Confidence: C3 (inferred from combining dry-weight lipid and water content) - Source: https://www.ncbi.nlm.nih.gov/books/NBK28221/ (Basic Neurochemistry, Ch. "Characteristic Composition of Myelin")

Claim: Brain extracellular space occupies ~20% of brain volume in vivo. - Confidence: C1 - Source: "Based on electron microscopy (EM) work, the extracellular space (ECS) volume fraction (α) has been estimated at an average 20%, in excellent agreement with the RTI-TMA method." https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2020.570750/full - Notes: This is critical for brain preservation — 20% of brain volume is neither cells nor myelin but aqueous extracellular fluid containing neurotransmitters, ions, and ECM components.

Claim: Chemical fixation collapses extracellular space from ~20% to <5% by volume, i.e. the fixed brain is substantially shrunk and reorganized relative to the living brain. - Confidence: C1 - Source: "Conventional tissue fixation causes extracellular space (ECS) loss, complicating the segmentation of cellular objects from electron microscopy datasets." https://pmc.ncbi.nlm.nih.gov/articles/PMC10391564/ - Source: "Chemical fixation induced total volume shrinkage in the somatosensory neocortex of 30%." https://pubmed.ncbi.nlm.nih.gov/37533653/ (Mikula group, Cell Reports Methods 2023) - Source: "In mammalian brains, there is about 20% extracellular space (ECS), which drops to less than 5% after chemical fixation with aldehydes." - Notes: This is a serious artifact, and partially addressable — osmolarity-tuned fixatives (Pallotto et al. 2015, eLife; Mikula's "preserving ECS" protocols) can keep ECS fraction close to native.

6. Summary for the post

Aurelia's framing is a useful simplification, but it's not literally "eggs are just protein." What's true and load-bearing:

  1. Egg white is a nearly-pure protein/water system. Its set is a two-component problem: denature and cross-link the proteins, and the water gets trapped in the resulting gel. Heat supplies the energy; disulfide and hydrophobic chemistry provides the cross-links.

  2. Human tissue is fundamentally multi-component. At the very least you have to think about: - Intracellular proteins (cytoskeleton, enzymes, membrane proteins) - Extracellular matrix (collagen, elastin, glycosaminoglycans — ~25–30% of all body protein mass is collagen) - Lipid membranes (phospholipid bilayers, cholesterol, sphingolipids) - Myelin (up to ~80% lipid by dry weight in CNS) - Aqueous extracellular fluid (~20% of brain volume) - Bone/mineral (calcium phosphate crystals in an organic matrix) - Blood and ECF (dissolved proteins + cells + electrolytes)

  3. "Heat to set" does not work for humans. You'd denature and aggregate the cytoplasmic proteins, but: - You would not meaningfully cross-link the lipid membranes — they'd rupture, aggregate, and re-form in chaotic arrangements - Collagen would denature to gelatin, destroying ECM mechanics - You'd have no control over what ends up cross-linked to what; thermal aggregation is blind - Most importantly: heat destroys the ultrastructure (synapses, membrane topology) you want to preserve

  4. Aldehyde fixation solves a specific subproblem. It cross-links proteins, using cytoplasmic and ECM proteins as a scaffold. Lipids mostly survive as a mechanical inclusion in that scaffold. The egg-white analogy is roughly "heat does for albumen what glutaraldehyde does for brain tissue" — but with very different chemistry, and glutaraldehyde leaves the non-protein fractions more or less in place rather than scrambling them.

Open questions / uncertainty

ai gen