Optimizing Acetic Acid Pretreatment and Pickling Duration to Reduce Cholesterol, Trimethylamine, and Malondialdehyde While Enhancing Physicochemical Quality of Pidan Duck Eggs

Pidan eggs, a traditional alkaline-preserved food product widely consumed in Indonesia, require process optimization to improve safety and quality attributes. This study evaluated the impact of 5% acetic acid pretreatment combined with varying pickling durations (1 to 4 weeks) on the physicochemical and biochemical characteristics of pidan duck eggs (Anas platyrhynchos), with a specific focus on cholesterol, malondialdehyde (MDA), and trimethylamine (TMA) levels. Utilizing a factorial completely randomized design, 300 eggs with an initial cholesterol concentration of 333.25 mg/100 g were subjected to pretreatment followed by immersion in an alkaline pickling solution containing 4.2% NaOH, 0.2% ZnCl₂, 5% black tea extract, and 5% NaCl. The results indicated that a 30-minute pretreatment significantly influenced yolk and albumen properties, including enhanced brown color intensity, improved textural firmness, reduced water activity (aw), and stabilized pH values. Importantly, pretreatment effectively decreased TMA and cholesterol concentrations, markers associated with lipid degradation and off-flavor formation, alongside the modulation of MDA content, indicating reduced lipid oxidation. The optimal condition identified was a 30-minute pretreatment followed by three weeks of alkaline pickling, yielding samples with notably lowered cholesterol (276.2 mg/100 g), TMA (0.75 mg/100 g), MDA (0.52 mg/100 g), and acceptable aw (0.85–0.89), indicative of enhanced safety, sensory qualities, and shelf stability. This research contributes critical insight into the biochemical and physical transformations during pidan production, offering a scientifically substantiated protocol to improve the quality and health aspects of this culturally significant preserved egg product.