Decomposition Kinetics of Solution and Lyophilized Powder of S-Nitroso-N-Cetylcysteine

Recently, S-nitrosothiols (RSNO) have received increased attention in the food industry as replacements for nitrite salts in meat products. However, their industrial applications are limited because of their high instability in concentrated aqueous solutions. In this study, S-nitroso-N-acetylcysteine solutions (NAC-SNO_Sol) of different concentrations (200, 300, and 400 mM) were stabilized, impregnated with salt, and freeze-dried (NAC-SNO_Pow). The decomposition kinetics of the solutions at 4°C and the resulting powders at different storage temperatures (-18 to 30°C) were evaluated using zero-, first-, and second-order ordinary differential equations. The NAC-SNO decomposition followed a first-order reaction in non-stabilized solutions and a zero-order reaction in stabilized solutions, with the half-life (t_1/2) increasing from 1.1 to 9.9 days and decreasing in more concentrated solutions. The decomposition of NAC-SNO_Pow had a better fit for second-order decay, with an average activation energy (E_a) of 92 kJ/mol and a Q₁₀ of 4.0. The stability of the powders increased with concentration, with t_1/2 values reaching up to 100 days at the highest concentration and refrigeration temperature (2°C). Stabilizing and obtaining NAC-SNO_Pow at higher concentrations and refrigerated or frozen storage is an interesting optimization strategy for industrial use, as it presents good yield (approximately 79%), stability, and practical use. PRACTICAL APPLICATIONS: Previous studies demonstrated the potential use of RSNO solutions to replace the nitrite additive in meat products, maintaining the desired characteristics and reducing the risks of carcinogenic compound formation. However, the high instability of these compounds in solution limits their practical use. This research introduced an innovative approach by developing a more stable solid form of NAC-SNO_Sol and determining the best storage conditions for use as a food additive. This advancement is crucial for enabling the industrial application of RSNO, making them a more accessible and efficient alternative for nitrite replacement in meat products.