Methods for Determination Reactive Lysine in Heat-Treated Foods and Feeds

Abstract

Lysine is an essential amino acid, which is limited in foods of plant origin, especially in cereals. The heat-treatment of products containing proteins and reducing sugars results in formation of Maillard reactions during which the cross-linkages among epsilon amino groups (ε-NH2) and reducing sugars are created. Thus the protein-carbohydrate complex is formed. This complex contains an unreactive (unavailable) lysine, which is bound to reducing sugars and is not available in body. Hereby, the nutritive value of feeds and foods decreases. When a standard analytical method for analyses of amino acids is used, in products containing protein-carbohydrate complexes, it is not possible to analyze the content of reactive (available) and unreactive (unavailable) lysine, but only the content of total lysine. Therefore, when the standard amino acid analysis is used, the content of lysine in heat-treated feeds and foods is overestimated. In order to avoid this, some methods for determination of reactive lysine were developed. Among the best known, the homoarginine and furosine methods are included. Using these methods, in evaluation of nutritive value of feeds and foods, is of great importance because they allow to determine the extent of proteins, which were damaged during the heat treatment and thus we obtain information on objective nutritional protein quality of the product.

Extrusion modifies some physicochemical properties of milk protein concentrate for improved performance in high‐protein nutrition bars

“…Despite reduction, HPN bar free amine concentrations (Table ) consistently decreased throughout storage ( P < 0.05) as a result of glycation of the lysine residues with glucose, fructose and lactose, as well as by Maillard‐induced protein aggregation previously related to worsening of model HPN bar texture . Although there remains discrepancy concerning the effect of Maillard browning on HPN bar texture change, glycation of lysine decreases its nutritional value . Sulfur containing amino acids are limiting in MPC and initial lysine glycation by extrusion and that seen during HPN bar storage are unlikely a major nutritional concern …”

“…Even though OPA registers both ϵ ‐ and α ‐amino groups, this method is favored for measuring reactive or nutritionally active lysine over the total lysine technique, which includes nutritionally unavailable lysine . Protein solubility in the free amine buffer ranged from 3.1 to 4.2 g L –1 and, with similar solubility, differences in free amine concentrations were attributable to the different processing conditions.…”

Over-processed meat and bone meal and phytase effects on broilers challenged with subclinical necrotic enteritis: Part 1. Performance, intestinal lesions and pH, bacterial counts and apparent ileal digestibility

“…Foremost, heat processing under pressure caused nutritional damage to MBM and reduced its lysine availability and quality due to conformational changes ( Hendriks et al., 1999 , Buckley et al., 2012 ). Lysine has a free amino group; therefore, it is often damaged following exposure to heat ( Moughan and Rutherfurd, 1996 , Mavromichalis and Baker, 2000 , Brestenský et al., 2014 ). In addition, Shirley and Parsons (2000) determined the effect of pressure processing on AA digestibility of MBM and found that the true digestibility of most AA, especially cysteine and lysine significantly decreased with increasing pressure.…”

Karakteristik Saus Jeroan Cumi-Cumi dengan Penambahan Karagenan Sebagai Stabilizer

“…Pada proses reaksi Maillard gula-gula pereduksi yang terkandung pada produk akan berkaitan dengan protein, sehingga jumlah protein pada produk akan menurun. Brestensky et al (2014) menyatakan bahwa reaksi Maillard dapat menurunkan asam amino lisin karena adanya ikatan dengan gula pereduksi, sehingga gugus amino lisin interaktif dengan senyawa lain dan kandungan liain pada suatu produk lebih sedikit atau bahkan hilang. Menurut Anggo et al (2018) penurunan kadar protein dapat diakibatkan oleh adanya protein yang terlarut menguap bersama dengan air pada proses pemanasan.…”