Oxidative quality parameters of royal jelly under different storage conditions: insights into protein oxidation (AOPPs), lipid peroxidation (MDA), and Maillard reaction (HMF)

Abstract Royal jelly (RJ) is a unique bee-derived secretion recognized for its nutritional and bioactive properties; however, its chemical stability shows susceptibility to storage temperature and time. This study systematically evaluated oxidative changes in RJ stored at − 20 °C, + 4 °C, and 25 ± 2 °C for 12 months using advanced oxidation protein products (AOPPs), malondialdehyde (MDA), and 5-hydroxymethylfurfural (HMF) as representative markers of protein oxidation, lipid peroxidation, and Maillard reaction, respectively. Fresh RJ exhibited minimal deterioration, containing 29.19 µg/100 g MDA, undetectable HMF, and 0.93 µmol chloramine-T/g protein AOPPs. In contrast, sample stored at 25 ± 2 °C showed rapid and statistically significant oxidation: AOPPs, MDA, and HMF peaked at 5.57 µmol/g protein, 86.04 µg/100 g, and 5.81 mg/kg, respectively, by the 9th month ( p < 0.05). Refrigerated storage (+ 4 °C) resulted in moderate increases, while frozen storage (− 20 °C) offered optimal protection, restricting levels to 2.17 µmol/g protein, 36.90 µg/100 g, and 1.36 mg/kg after 12 months ( p < 0.05). These findings demonstrate a hierarchy of protection (− 20 °C > + 4 °C > 25 °C), consistent with the suppression of Maillard and lipid peroxidation pathways at low temperatures. This study represents the first application of the AOPPs assay to a food matrix and the first systematic investigation of MDA in royal jelly, while available research on HMF in RJ is limited. The findings establish the novelty and practical significance of this work and underscore the critical importance of cold-chain preservation for sustaining the bioactive potential, consumer safety, and market value of RJ.