Water-soluble fluorescent carbon dots (CDs) were synthesized by a hydrothermal method using citric acid as the carbon source and ethylenediamine as the nitrogen source. The repeated and scale-up synthetic experiments were carried out to explore the feasibility of macroscopic preparation of CDs. The CDs/Fe³⁺ composite was prepared by the interaction of the CDs solution and Fe³⁺ solution. The optical properties, pH dependence and stability behavior of CDs or the CDs/Fe³⁺ composite were studied by ultraviolet spectroscopy and fluorescence spectroscopy. Following the principles of fluorescence quenching after the addition of Fe³⁺ and then the fluorescence recovery after the addition of asorbic acid, the fluorescence intensity of the carbon dots was measured at λex = 360 nm, λem = 460 nm. The content of ascorbic acid was calculated by quantitative analysis of the changing fluorescence intensity. The CDs/Fe³⁺ composite was applied to the determination of different active molecules, and it was found that the composite had specific recognition of ascorbic acid and showed an excellent linear relationship in 5.0–350.0 μmol·L⁻¹. Moreover, the detection limit was 3.11 μmol·L⁻¹. Satisfactory results were achieved when the method was applied to the ascorbic acid determination in jujube fruit. The fluorescent carbon dots composites prepared in this study may have broad application prospects in a rapid, sensitive and trace determination of ascorbic acid content during food processing.

Postharvest Hupingzao jujubes are prone to softening and reddening during storage. To investigate the influence of glycine betaine on the fruit quality of cold-stored jujubes, the jujubes were immersed in a 15 mmol L⁻¹ glycine betaine solution for 10 min, then stored at 0 ± 1 °C for 100 days. The relevant physical and chemical quality indicators were determined every 20 days. The results indicated that glycine betaine treatment effectively maintained fruit firmness, reduced weight loss, slowed down the respiration rate, and lessened the redness of the fruit peel. Compared with the control group, the malondialdehyde and H₂O₂ contents in glycine betaine-treated fruit decreased by 26.65% and 9.04%, respectively. In addition, glycine betaine treatment elevated the contents of non-enzymatic antioxidants, including ascorbic acid, total flavonoids, total phenols, and proanthocyanidins. Meanwhile, the activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase in the jujube fruit were enhanced after glycine betaine treatment. In conclusion, glycine betaine treatment preserved the quality of the jujube fruits by enhancing the antioxidant metabolism. The results establish a scientific basis for the potential application of glycine betaine in postharvest fruit preservation, providing a strategy to mitigate storage-related quality deterioration.

Sodium chloride (NaCl) serves multiple functions in meat product processing, including flavor enhancement, preservation, and texture regulation. However, excessive sodium intake significantly increases the risks of chronic diseases, including cardiovascular disease, hypertension, and gastric cancer. Globally, sodium intake among the general population consistently exceeds the daily upper limit recommended by the World Health Organization (less than 2000 mg sodium per day, equivalent to <5 g salt per day). In certain regions, processed meat products are an important source of dietary sodium intake. Consequently, the development of low-sodium meat products has emerged as a critical priority in both the food industry and public health. This review reviews and summarizes the multifunctional roles of sodium chloride in meat products and the underlying mechanisms of these functions, and evaluates mainstream sodium reduction strategies, namely direct sodium reduction, physical modification, salt substitutes, flavor enhancement, odor-induced saltiness enhancement (OISE), and non-thermal processing. The analysis indicates that individual strategies exhibit limitations in terms of sensory quality, safety, or cost. Future efforts should focus on achieving effective sodium reduction through the synergistic application of multiple strategies, without compromising product quality or safety. This review further proposes a product-type-oriented strategy matrix, and multi-strategy synergy combined with AI optimization which is put forward as a promising potential pathway for the industrialization of sodium reduction in meat products, which remains to be validated by further research.