Effect of Magnetic and Electrical Fields on Yield, Shelf Life and Quality of Fruits

Quality maintenance and metabolite changes of grape berry treated by high voltage alternating electric field during near-freezing temperature storage

High Voltage Alternating Electric Field (HVAEF), as an emerging postharvest preservation technology, is environmentally friendly and has garnered significant attention from scholars. This study investigated the effects of HVAEF on the postharvest quality and metabolite changes in 'Shine Muscat' grapes stored at near-freezing temperatures. The results demonstrated that HVAEF halved the weight loss and decay rate, inhibited browning by preserving polyphenol content, and reduced polyphenol oxidase and peroxidase activities, thereby extending the storage time by more than 20 days. Metabolomic analysis of the grape berries from the upper, middle, and bottom parts of the bunch revealed that the upper berries contained higher sugar levels and were more significantly influenced by HVAEF treatment. Additionally, HVAEF notably reduced the accumulation of amino acids, such as valine, leucine, and lysine, compared to the control. This study provides new insights into the enhancement of quality in fresh fruits and vegetables through HVAEF technology.

Optimizing Non-Thermal Magnetic Field to Minimize Weight Loss and Tissue Degradation: Identifying Possible Enzyme Inhibition Mechanisms

This research investigates potential mechanisms of novel magnetic field (MF) treatments in inhibiting cell-wall-degrading enzymes, aiming to reduce weight loss and preserve the post-harvest quality of tomatoes (Solanum lycopersicum L.) as a climacteric fruit. The optimization of the processing parameters, including MF intensity (1, 2, 3 mT), frequency (0, 50, 100 Hz), and duration (10, 20, 30 min), was accomplished by applying an orthogonal array design. In particular, the investigation delved into the underlying mechanisms by which MF impedes the activity of tissue-degrading enzymes, such as pectin esterase (PE), polygalacturonase (PG), and cellulase (Cx), during the storage period. The results showed that MF treatment delayed the increase in soluble solids by 1.5 times and reduced titratable acidity by 1.2 times. The optimal treatment conditions-2 mT, 50 Hz, and 10 min-achieved the most significant inhibition of weight loss (4.22%) and maintained tissue integrity for up to 21 days. Optimized MF significantly suppressed enzyme activity, with PE activity reduced by 1.5 times, PG by 2.8 times, and Cx by 2.5 times. Also, cross-sectional images and external appearance demonstrated that MF-treated tomatoes retained their internal tissue structure throughout the extended storage period. These findings suggest that MF treatments can effectively suppress the key enzymes responsible for tissue degradation, ultimately delaying weight loss and softening, preserving post-harvest quality, and contributing to sustainable food production and zero waste.

A Review of Electromagnetic Fields in Cellular Interactions and Cacao Bean Fermentation

The influence of magnetic fields on biological systems, including fermentation processes and cocoa bean fermentation, is an area of study that is under development. Mechanisms, such as magnetosensitivity, protein conformational changes, changes to cellular biophysical properties, ROS production, regulation of gene expression, and epigenetic modifications, have been identified to explain how magnetic fields affect microorganisms and cellular processes. These mechanisms can alter enzyme activity, protein stability, cell signaling, intercellular communication, and oxidative stress. In cacao fermentation, electromagnetic fields offer a potential means to enhance the sensory attributes of chocolate by modulating microbial metabolism and optimizing flavor and aroma development. This area of study offers possibilities for innovation and the creation of premium food products. In this review, these aspects will be explored systematically and illustratively.

Pulsed electric field-assisted drying: A review of its underlying mechanisms, applications, and role in fresh produce plant-based food preservation

Drying is a key processing step for plant-based foods. The quality of dried products, including the physical, nutritional, microbiological, and sensory attributes, is influenced by the drying method used. Conventional drying technologies have low efficiency and can negatively affect product quality. Recently, pulsed electric field (PEF)-assisted techniques are being explored as a novel pretreatment for drying. This review focuses on the application of PEF as pretreatment for drying plant-based products, the preservation effects of this pretreatment, and its underlying mechanisms. A literature search revealed that PEF-assisted drying is beneficial for maintaining the physicochemical properties of the dried products and preserving their color and constituent chemical compounds. PEF-assisted drying promotes rehydration and improves the kinetics of drying. Unlike conventional technologies, PEF-assisted drying enables selective cell disintegration while maintaining product quality. Before the drying process, PEF pretreatment inactivates microbes and enzymes and controls respiratory activity, which may further contribute to preservation. Despite numerous advantages, the efficiency and applicably of PEF-assisted drying can be improved in the future.

Method for Prolonging the Shelf Life of Apples after Storage

This study investigated the effects of the use of low magnetic fields as a potential method for improving the quality of apples after storage. The fruit were exposed to 100 μT magnetic fields for 8 h per day and kept for a period of two weeks in room conditions. The results showed that the samples that were treated with a magnetic field generally had a higher value ratio of total soluble solid and titratable acidity compared to the untreated samples, which indicated their higher quality. Continuous treatment with a magnetic field influenced the mechanical properties of apples, as demonstrated by the greater firmness, lower weight loss and suppressed CO2 production of the apples that were stored in room conditions. After the treatment of the apples, a new product was produced with greater firmness, higher quality potential (the ratio of total soluble solid and titratable acidity) and an extended shelf life/lower respiration rate. Therefore, treatment with a magnetic field can be used to extend the shelf life of apples and needs to be demonstrated by further investigations.