Effects of Sulfhydryl Compounds, Carbohydrates, Organic Acids, and Sodium Sulfite on the Formation of Lysinoalanine in Preserved Egg

Abstract

To identify inhibitors for lysinoalanine formation in preserved egg, sulfhydryl compounds (glutathione, L-cysteine), carbohydrates (sucrose, D-glucose, maltose), organic acids (L-ascorbic acid, citric acid, DL-malic acid, lactic acid), and sodium sulfite were individually added at different concentrations to a pickling solution to prepare preserved eggs. Lysinoalanine formation as an index of these 10 substances was determined. Results indicate that glutathione, D-glucose, maltose, L-ascorbic acid, citric acid, lactic acid, and sodium sulfite all effectively diminished lysinoalanine formation in preserved egg albumen and yolk. When 40 and 80 mmol/L of sodium sulfite, citric acid, L-ascorbic acid, and D-glucose were individually added into the pickling solution, the inhibition rates of lysinoalanine in the produced preserved egg albumen and yolk were higher. However, the attempt of minimizing lysinoalanine formation was combined with the premise of ensuring preserved eggs quality. Moreover, the addition of 40 and 80 mmol/L of sodium sulfite, 40 and 80 mmol/L of D-glucose, 40 mmol/L of citric acid, and 40 mmol/L of L-ascorbic acid was optimal to produce preserved eggs. The corresponding inhibition rates of lysinoalanine in the albumen were approximately 76.3% to 76.5%, 67.6% to 67.8%, 74.6%, and 74.6%, and the corresponding inhibition rates of lysinoalanine in the yolk were about 68.7% to 69.7%, 50.6% to 51.8%, 70.4%, and 57.8%. It was concluded that sodium sulfite, D-glucose, L-ascorbic, and citric acid at suitable concentrations can be used to control the formation of lysinoalanine during preserved egg processing.

Sodium tripolyphosphate inhibits the formation of lysinoalanine in heat-treated whey protein

“…It was reported that LAL content of WPC was as high as 145 mg/kg (Friedman, ), which was further increased under processing conditions including heat treatment, sterilization, and alkaline pH. Whey protein contains high level of LAL precursors (such as cystine residues) and the reactants formed by interaction between lysine and dehydroalanine groups (Faist et al, ; Luo et al, ; Rombouts, Lambrecht, Carpentier, & Delcour, ). Increased protein content provided more LAL precursors.…”

“…Consistent with these previous reports, we found that LAL content in the heat treated WPC samples increased by 23% ( p < .05) when the pH was adjusted from 7.5 to 8.5. Formation of LAL is highly dependent on pH value (Friedman, ; Luo et al, ) . Shetty and Kinsella () found that LAL level in yeast proteins formed during a high‐alkali, low‐temperature, and short‐time process (pH 12.5, 65 °C for 2 hr) was seven times greater than the value observed during a low‐alkali, high‐temperature, and long‐time process (pH 10.5, 85 °C for 4 hr).…”

“…Whey protein contains high level of LAL precursors (such as cystine residues) and the reactants formed by interaction between lysine and dehydroalanine groups (Faist et al, 2000;Luo et al, 2014;Rombouts, Lambrecht, Carpentier, & Delcour, 2016). Increased protein content provided more LAL precursors.…”

“…LAL can impair the action of digestive enzymes, which resulted in adverse effects on protein digestibility and utilization (D'Agostina, Bocshin, Rinaldi, & Arnoldi, 2003). LAL has also been reported to cause lesions in the rat kidney leading to nephrocitomegaly (Cattaneo, Masotti, & Pellegrino, 2009;Luo et al, 2014;Montilla et al, 2007). Therefore, the LAL content should be minimized and fully controlled in food products.…”

“…To prevent LAL formation, many additives like sulfhydryl compounds, sodium sulfite, glucose, ascorbic acid, malic acid, ammonia, biogenic amines, and metal salts were used in various food products including casein, wheat gluten, soy proteins, and eggs (Al‐Saadi et al, ; Friedman, ; Luo et al, ). However, there is limited information about LAL formation in heat‐treated whey protein.…”