Effect of Tea Tree Essential Oil on the Quality, Antioxidant Activity, and Microbiological Safety of Lightly Processed Lily (Lilium brownii var. viridulum) during Storage.

The Lanzhou lily is a regionally distinctive vegetable; the emergence of lightly processed lilies has addressed the inconvenience of consuming fresh lilies. However, the cleaning and impurity removal during the processing of lightly processed lily may strip off its original protective barrier and affect the edible quality. As one of the preservation methods, tea tree essential oil (TTEO) has the characteristics of being green, safe, and efficient preservative properties. This study focused on investigating the effects of different concentrations (25 µL/L, 50 µL/L, and 100 µL/L) of TTEO on the quality and microbiological safety of lightly processed lily. The results showed that compared with the control, appropriate concentrations of TTEO treatment could delay weight loss, improve appearance, firmness, and sensory quality, and maintain microbiological safety with the best effect observed at 50 µL/L. Meanwhile, TTEO treatment induced phenylalanine ammonia-lyase activity, thereby increasing the total phenolic content. Furthermore, TTEO enhanced the superoxide dismutase (SOD) and ascorbate peroxidase (APX) activity, which reduced O2-· production rate and H2O2 content. TTEO inhibited lipoxygenase (LOX) activity, reducing the relative conductivity and malondialdehyde content, thereby delaying lipid peroxidation and quality deterioration. This indicates that TTEO could enhance antioxidant capacity by regulating reactive oxygen species (ROS) metabolism and delay the quality deterioration of lightly processed lily by inhibiting lipid peroxidation.

Tea Polyphenols Inhibit the Occurrence of Enzymatic Browning in Fresh-Cut Potatoes by Regulating Phenylpropanoid and ROS Metabolism.

During fresh-cut processing, potatoes lose their inherent protective cellular structure, leading to enzymatic browning that compromises sensory and edible quality. Tea polyphenols (TPs), natural preservatives with potent reducing properties, are hypothesized to impact this browning process. However, their influence and regulatory mechanism on the enzymatic browning of fresh-cut potatoes remain poorly understood. This study used the "Holland Seven" potato as the research material to explore the effects of a treatment with different TP concentrations (0.1 g L-1, 0.2 g L-1, and 0.3 g L-1) on the browning phenomenon and quality of fresh-cut potatoes during storage. The results showed that appropriate concentrations of TP treatment had a good preservation effect on the appearance and edible quality of fresh-cut potatoes. Furthermore, exogenous TP treatment reduced the content of enzymatic browning substrates (caffeic acid, p-coumaric acid, and ferulic acid) by regulating phenylpropanoid metabolism. Meanwhile, TP treatment augmented the activities of antioxidative enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase), maintained higher levels of ascorbic acid (Vc), and reduced glutathione (GSH). Consequently, the TP treatment could inhibit enzymatic browning by regulating reactive oxygen species (ROS) metabolism and the Vc-GSH cycle in fresh-cut potatoes.