“Avaliação da eficiência do revestimento de quitosana no "tempo de prateleira" dos ovos de galinha”

Abstract

Chicken eggs are particularly important, being sources of protein with high nutritional value and economic relevance; however, their quality progressively deteriorates during storage due to the exchange of water vapor and carbon dioxide through the porosity of the shell. This research evaluated the performance of chitosan coating formulations in the preservation of eggs stored under non-refrigerated conditions. In the first phase, 168 eggs were distributed between Control (Q0%) and treatments with chitosan at Q0.5%, Q1.0%, and Q1.5% (w/v), prepared in 5% acetic acid and applied by complete immersion, followed by immediate removal after complete coating of the surface. For seven weeks, mass loss, density, Haugh Unit, Yolk Index, yolk proportion, colorimetry, shell strength, and yolk integrity were evaluated using general linear models and robust standard errors (HC3) when necessary. In the second stage, physicochemical and biological characterizations of the eggshell–coating interface were performed using FTIR-ATR, UV-Vis, fluorescence, SEM/EDS, point determination of water activity, and a challenge assay with Salmonella Typhimurium. The week and treatment × week interaction effects were observed (p < 0.001), but there was no overall treatment effect in the average week (p = 0.394); Q1.5% showed a nearly zero slope that was lower than that of the Control (p = 0.003). For the percentage density loss, the main analysis was restricted to weeks 1 to 4, prior to method saturation: the interaction was significant (p < 0.001), and the three coated treatments showed lower slopes than the Control (p < 0.001), with no difference demonstrated between concentrations. The sensitivity analysis for weeks 1 to 5 preserved the direction of the result (interaction: p = 0.031). The Haugh Unit (n = 73) and the Yolk Index (n = 71) decreased with storage (p < 0.001), with no overall treatment effect or significant interaction. The yolk proportion (n = 73) showed a week effect (p = 0.012) and a borderline treatment × week interaction (p = 0.0495), but none of the slopes of the coated treatments differed from that of the Control. In colorimetry, L* showed treatment and interaction effects (p = 0.041 and p = 0.030), while a* and b* were predominantly influenced by time, and shell strength showed no treatment effect or interaction. FTIR-ATR indicated a superficial contribution of functional groups compatible with chitosan, preserving the predominant calcium carbonate bands. SEM and EDS demonstrated localized morphological changes and nitrogen detection only in the coated samples, with EDS being interpreted as semi-quantitative. Optical analyses revealed comparative changes in reflectance, transmittance, absorption, and fluorescence. In the microbiological assay, Q1.5% showed a greater descriptive reduction in the recovery of Salmonella Typhimurium on the eggshell, but the absence of individual counts per replicate prevented inferential comparison between treatments. Taken together, the chitosan formulations modified the surface interface of the eggshell and showed potential as a barrier to water and gas exchange, with more consistent quantitative evidence for maintaining density and specific evidence of a lower mass-loss slope in Q1.5%, without demonstrating universal superiority of one concentration in the evaluated attributes.