Research Progress on the Effects of Magnetic Field-Assisted Treatment on the Texture, Color, and Enzyme Activity of Fruits and Vegetables.

Abstract

Softening texture and fading color are the main reasons for the reduced marketability of freshly harvested fruits and vegetables, and these adverse quality changes are caused by a series of enzymatic reactions. Magnetic field treatment, as a promising nonthermal physical preservation technology, has excellent biological safety, zero chemical residue, and superior penetration performance, and is an effective strategy to alleviate the postharvest quality deterioration of fruits and vegetables. This paper systematically reviews the relationship between parameters such as magnetic field intensity, frequency, and duration of action and their preservation effects, discusses the current research limitations, and looks forward to the future exploration directions of molecular mechanisms and potential technological applications. The optimized magnetic field intervention can effectively inhibit the senescence process of fruits and vegetables after harvest and significantly suppress the activities of key catabolic enzymes, including pectinase, cellulase (Cx), peroxidase (POD), polyphenol oxidase (PPO), and lipoxygenase (LOX), thereby reducing the degradation of chlorophyll and carotenoids and delaying the degradation of cell walls, thus jointly maintaining the structural integrity and sensory quality of postharvest fruits and vegetables. It is worth noting that the biological effects of magnetic fields are bidirectional and exhibit a distinct "window effect." The same magnetic field treatment may either inhibit or activate the same enzyme, depending on the magnetic field parameters, fruit variety, and storage conditions. Moreover, when the parameters exceed the effective window range, the effect may reverse. The mechanism of magnetic field-mediated preservation mainly involves the regulation of enzyme conformation, the maintenance of intracellular free radical homeostasis, and the guarantee of the stability of the structure and function of the cell membrane of horticultural products. However, several key bottleneck problems remain unsolved. For instance, the molecular mechanisms that lead to species-specific responses remain unclear, and the data supporting large-scale industrial applications are still insufficient. This review provides a reference basis for promoting and improving magnetic field preservation technology.