Composition of free and peptide-bound amino acids in beef chuck, loin, and round cuts1,2

Abstract

Meat is a food for humans. However, beef consumption in the United States has steadily declined by >14% over the past decade due to a variety of factors, including insufficient knowledge of animal protein. This study quantified all proteinogenic AA as well as nutritionally and physiologically significant nonproteinogenic AA and small peptides in beef cuts from 3 subprimals (chuck, round, and loin). Beef carcasses ( = 10) were selected at 3 commercial packing plants in the United States. Retail-cut samples were analyzed for the nitrogenous substances after acid, alkaline, or enzymatic hydrolysis and after deproteinization. In these chuck, round, and loin cuts, total amounts of glutamate (free plus peptide bound) were the highest (69-75 mg/g dry weight) followed by lysine, leucine, arginine, and glutamine in descending order. This is the first study to determine aspartate, asparagine, glutamate, and glutamine in meat proteins of any animal species. In all the beef samples evaluated, glutamine was the most abundant free AA (4.0-5.7 mg/g dry weight) followed by taurine, alanine, glutamate, and β-alanine. Additionally, samples from all beef cuts had high concentrations of anserine, carnosine, and glutathione, which were 2.8 to 3.7, 15.2 to 24.2, and 0.68 to 0.79 mg/g dry weight, respectively. Beef top loin steaks appear to provide higher protein nutrition values than top round steaks and under blade roasts, but all are excellent sources of proteinogenic AA as well as antioxidant AA and peptides to improve human growth, development, and health. Our findings may help guide future decisions regarding human and animal nutrition.

Important roles of dietary taurine, creatine, carnosine, anserine and 4-hydroxyproline in human nutrition and health

“…In contrast, taurine, carnosine, anserine, and creatine are absent from all plants [e.g., corn grains, peanuts, pistachio nuts, potatoes, soybeans, sweet potatoes, wheat flour, and white rice ]. Thus, vegetarians are at great risks for the deficiencies of taurine, carnosine, anserine, and creatine, particularly if they Table 1 The content of crude protein, amino acids, creatine, carnosine, anserine, and 4-hydroxyproline in beef and plant-source foods Adapted from Wu et al (2016), Wu et al (2020), CP crude protein (6.25 × N%), OH-Pro 4-hydroxyproline are active in physical exercise (Rogerson 2017). In addition, most of plant-source foods contained little 4-hydroxyproline and little β-alanine (a precursor of carnosine in humans) (Table 1).…”

Composition of amino acids and related nitrogenous nutrients in feedstuffs for animal diets

“…Dry matter (DM) content was determined by drying approximately 100 mg samples to a constant mass in a 105 °C oven. The content of crude protein, crude fat, ash (minerals), and carbohydrate in feedstuffs was determined as described by Wu et al (2016a). Creatine and creatinine were analyzed by HPLC, as previously described by Kai et al (1983).…”

“…The homogenate was neutralized with 1 ml of 2 M K 2 CO 3 , followed by addition of 2 ml HPLC-grade water. The whole solution was centrifuged at 600 g for 10 min, and the supernatant fluid was analyzed for polyamines and agmatine (Dai et al 2014b), free AAs (Hou et al 2019;Wu and Meininger 2008), carnosine and anserine (Wu et al 2016a), and balenine (Hou et al 2015b) using HPLC methods involving precolumn derivatization with o-phthaldialdehyde. Polyamines, agmatine, carnosine, anserine, balenine, and free AAs in samples were quantified on the basis of known amounts of standards using the Millenium-32 Software (Waters, Milford, MA, USA).…”

Homeostatic regulation of plasma amino acid concentrations

“…As is known, the protein molecules are polymers of amino acid (AA) residues linearly connected by peptide bonds (3,5). Although there are more than 500 naturally occurring AAs (6), only about 20 of them are commonly found in plant and animal proteins, and these 20 AAs, called proteinogenic AAs (7), are alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, muscle protein degradation, because the degradation process can release the lacking AA that is necessary for other more important organs (such as the brain and liver) to function (15,16).…”