Abstract:In order to further explore the alterations in non-enzymatic browning of concentrated peach juice during storage, a range of analytical techniques, including UV-visible spectrophotometry, colorimetry, high-performance liquid chromatography, and liquid chromatography-mass spectrometry, were employed to assess indicators relevant to the visual characteristics and non-enzymatic browning of the juice at different storage temperatures. It was found that as the storage temperature increased, both the optical density at 420 nm and the color difference (ΔE) of the concentrated peach juice exhibited a gradual increase. During storage at temperatures of 4, 25, and 37 ℃, a significant reduction in the levels of ascorbic acid, reducing sugars, amino acids, and amino acid nitrogen—key precursors to browning—was observed over time; conversely, the concentration of 5-hydroxymethylfurfural (5-HMF) increased. Correlation analysis further demonstrated a positive relationship between ΔE and reducing sugars, as well as the color parameters a*, b*, browning degree, and 5-HMF; meanwhile, the lightness parameter (L*) showed a positive correlation with total phenolic content, four specific amino acids, amino acid nitrogen, and ascorbic acid. Notably, as the storage temperature rose, the disparities in non-enzymatic browning indicators of concentrated peach juice became increasingly pronounced. Consequently, it was concluded that mitigating the formation of 5-HMF could significantly reduce the browning degree of concentrated peach juice, while an appropriate increase in the levels of total phenols, amino acids, and ascorbic acid could improve the glossiness of the juice. The outcomes of this investigation provide a scientific foundation for the storage of concentrated peach juice and offer practical recommendations for the preservation of commercially available fruit juices.
