Muscle Meat

Description

Meat, defined as the edible muscle tissue of animals, is a complex biological matrix composed predominantly of water, proteins, and lipids, along with minor amounts of carbohydrates, vitamins, and minerals. Chemically, muscle tissue is about 70–75% water, which serves as the solvent for its myriad biochemical reactions, and roughly 20–25% high-quality protein. These proteins—including the contractile elements actin and myosin—provide a complete spectrum of essential amino acids necessary for tissue repair and growth. Lipids in meat, present at levels that can vary from 2–10% depending on the cut and animal species, primarily consist of triglycerides and phospholipids that contribute both to energy supply and the bioavailability of fat-soluble vitamins. In addition to these macronutrients, meat is a rich source of micronutrients such as iron, zinc, phosphorus, and B-complex vitamins (particularly vitamin B12), all of which play critical roles in oxygen transport, enzymatic activity, and overall metabolic regulation.

Chemical Structure

Muscle meat is a complex tissue composed of roughly 75% water (H₂O), 19% proteins, 2.5% fats, and 1–2% carbohydrates, mainly stored as glycogen. The protein fraction is dominated by myofibrillar proteins—primarily actin and myosin—which are organized into repeating sarcomeres; these proteins are polymers of amino acids (general formula H–(CH₂)ₙ–COOH) and drive contraction via ATP hydrolysis (ATP: C₁₀H₁₆N₅O₁₃P₃). Glycogen, with a repeating unit of (C₆H₁₀O₅)ₙ, serves as the immediate energy reserve. Fats are present mainly as triglycerides, consisting of a glycerol backbone (C₃H₅(OH)₃) esterified to three fatty acids (R–COOH), which provide concentrated energy and contribute to flavor and juiciness. Additionally, meat supplies essential vitamins—such as vitamin B₁₂ (a corrinoid with a complex cobalt-containing structure), cholecalciferol (vitamin D₃, C₂₇H₄₄O), and α-tocopherol (vitamin E, C₂₉H₅₀O₂)—and minerals like iron (Fe), zinc (Zn), and phosphorus (P), all vital for oxygen transport, enzymatic reactions, and overall cellular metabolism.

Physiology & Digestion

Meat digestion initiates in the stomach, where the acidic gastric juice (HCl, pH 1.5–3.5) denatures proteins and activates pepsinogen into pepsin, which hydrolyzes protein chains into polypeptides and smaller peptides. Upon entering the duodenum, these peptides are further cleaved by pancreatic proteases—including trypsin, chymotrypsin, and carboxypeptidases—into dipeptides and free amino acids, which are then absorbed via active transport in the jejunum.

Simultaneously, bile acids from the liver emulsify dietary fats, enhancing the activity of pancreatic lipase that hydrolyzes triglycerides into monoglycerides and free fatty acids.

Although present in minor quantities, muscle glycogen is broken down into glucose by brush border enzymes. Once absorbed, amino acids serve as substrates for protein synthesis essential for tissue growth, repair, and the production of enzymes, hormones, and immunoglobulins; fatty acids are utilized via β-oxidation to generate ATP and are incorporated into cell membranes and lipid-soluble hormones.

Meat also supplies critical micronutrients—such as heme iron, which is efficiently absorbed and vital for oxygen transport in hemoglobin, vitamin B₁₂ necessary for neurological function and DNA synthesis, and zinc, a cofactor in numerous enzymatic reactions—thereby supporting overall metabolic regulation and homeostasis.

BIBLIOGRAPHY

  1. Sareen Gropper (2021). Advanced Nutrition And Human Metabolism. 8th ed. S.L.: Cengage Learning Custom P.