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Preharvest blue diode laser irradiation enhances betalain biosynthesis, antioxidant responses, and postharvest quality of red amaranth microgreens during storage
(2026-12-01)
Supapvanich, Suriyan
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Sripumimas, Sookmas
;
Li, Man
;
Kang, Chuankai
;
Puisoongnoen, Nichaphat
In recent years, light-based technologies have attracted growing interest as a postharvest strategy for maintaining the quality of leafy vegetables and microgreens. This study investigated the effects of blue diode laser irradiation (450 nm, 3 h) on the postharvest quality, antioxidant system, and betalain biosynthesis of red amaranth (Amaranthus tricolor) microgreens during storage at 4 ± 1 °C for 9 d. Blue laser treatment effectively maintained visual quality and reduced weight loss compared with untreated samples. Treated microgreens exhibited significantly lower accumulation of hydrogen peroxide (H₂O₂), superoxide anion (O₂⁻), and lipoxygenase (LOX) activity during storage, indicating reduced oxidative stress and membrane lipid peroxidation. In addition, laser-treated samples maintained higher antioxidant capacity, including ferric reducing antioxidant power (FRAP) and DPPH radical scavenging activity, together with greater retention of total phenolics, flavonoids, vitamin C, and glutathione. Activities of antioxidant-related enzymes, including phenylalanine ammonia-lyase (PAL), superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), were also significantly enhanced by laser irradiation. Furthermore, blue laser treatment effectively delayed chlorophyll degradation and increased betacyanin accumulation during storage. Gene expression analysis revealed significant upregulation of betalain biosynthesis-related genes, including AtrWRKY42–2, AtrCYP76AD1, AtrMYB72, AtrDODA1–1, and AtrB5-GT, particularly during the early storage period. Principal component analysis clearly separated laser-treated and control samples, confirming the positive association between laser irradiation, antioxidant defense, pigment retention, and overall quality maintenance. These findings demonstrate that short-term blue laser irradiation is a promising postharvest technology for enhancing antioxidant defense, regulating betalain biosynthesis, and extending the shelf life of red amaranth microgreens.
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Laser light as a novel postharvest strategy to suppress chlorophyll degradation and oxidative stress in pakchoi (Brassica rapa subsp. Chinensis)
(2026-01-01)
Wen, Bo
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Kang, Chuankai
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Yang, Ting
;
Zhan, Qi
;
Chen, Tingyuan
Short-term diode laser light irradiation is an emerging physical treatment for preserving quality and enhancing oxidative stress resilience in postharvest commodities. Rapid deterioration, including leaf yellowing, is a major factor limiting the postharvest shelf life of pakchoi. This study investigated the effects of short-term exposure to blue (450 nm) and red (660 nm) diode laser light on quality maintenance, oxidative stress mitigation, and chlorophyll metabolism in pakchoi stored at 20 °C for 5 days. The results demonstrated that 660 nm red laser irradiation significantly maintained visual quality and green coloration while reducing weight loss more effectively than 450 nm blue laser light and the untreated control. Both laser treatments reduced respiration rates and ethylene production and induced partial stomatal closure. Additionally, both treatments regulated oxidative stress responses by lowering malondialdehyde (MDA) content, lipoxygenase (LOX) activity, and reactive oxygen species (ROS) accumulation (H₂O₂ and O₂⁻), while enhancing both enzymatic and non-enzymatic antioxidant systems. The red and blue laser treatments also preserved total chlorophyll content by suppressing the expression of chlorophyll degradation genes (BcPAO, BcNYC1, BcPPH1) and upregulating chlorophyll biosynthesis genes (BcCAO, BcCHLH). Among the treatments, the 660 nm red laser exhibited the strongest effects, as confirmed by higher maximum quantum efficiency of PSII photochemistry (Fv/Fm) values and principal component analysis (PCA). Overall, these findings demonstrate that 660 nm laser irradiation synergistically modulates chlorophyll metabolism and antioxidant defense, offering an effective and practical physical strategy to extend the postharvest shelf life of leafy vegetables.
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Protecting celtuce (Lactuca sativa L. var. augustana) slices against storage-induced oxidative stress and discoloration by using diode laser exposure
(2024-12-01)
Wen, Bo
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Xiao, Yinghui
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Zhang, Weiyan
;
Cui, Shijiang
;
Li, Junbing
Diode laser irradiation is a novel approach applied to preserve the quality of fresh commodities and minimise oxidative processes, including browning in fresh-cut products. The objective of this study was to investigate the efficacy of diode laser treatment in enhancing the quality of celtuce slices during refrigerated storage at 4 °C. The celtuce slices were subjected to a 660 or 450 nm diode laser for 5 min and then stored for 10 d. Both laser treatments hindered the progression of weight loss and firmness increase in the celtuce slices. The use of a 450 nm diode laser effectively prevented the development of browning and preserved the surface colour by inhibiting the increase in a* and overall colour difference values, as compared to other treatments, during storage for 10 d. The diode laser treatment suppressed the increase in oxidative stress by lowering the levels of MDA, H<inf>2</inf>O<inf>2</inf>, and O<sup>-</sup><inf>2</inf> while retaining a high level of DPPH scavenging activity, AsA, and antioxdant enzyme activities, including SOD, CAT, APX, and GR, in comparison to the untreated slices. The treatment enhanced chlorophylls content due to the up-regulation of LsHEMA1 gene and down-regulation of LsNYC1 gene. The treatment also inhibited factors involving enzymatic browning reaction by suppressing PAL activity, total phenols content, PPO activity and LsPPO gene expression. These suggest that the blue diode laser exposure at 450 nm for 5 min is an effective approach hindering oxidative stress and discoloration of celtuce slices during storage.
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Efficacy of blue-diode laser exposure on the postharvest quality maintenance of strawberries
(2024-12-01)
Cui, Shijiang
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Supapvanich, Suriyan
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Xiao, Yinghui
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Zhang, Weiyan
;
Li, Junbing
The purpose of this research was to evaluate the impact of postharvest laser irradiation on strawberry visual quality and texture. In preliminary studies, strawberries were exposed to diode laser radiation for 2.5 or 5 min at wavelengths of 405, 450 and 660 nm. The treatment at 450 nm for 2.5 or 5 min kept the visual appearance without deterioration after storage at 20 °C, 70% RH, for 4 d. The diode laser at 450 nm was selected to screen the exposure duration, and 2 min of exposure preserved a desirable visual appearance without decay during storage at 20 °C, 70% RH, for 6 d. Subsequently, the impacts of a diode laser at 450 nm for 2 min on the quality and softening of strawberries during storage at 4 °C for 14 d were observed. The laser treatment delayed strawberry softness and visual fungal development and maintained total acidity level, but had no effect on the total soluble solids content and BrimA value during storage. The membrane degradation of the laser-treated fruits was retarded, due to the inhibitions of the increases in malondialdehyde levels, phospholipase-D (PLD) activity and FaPLD gene expression. The activities of cell wall hydrolases such as polygalacturonase (PG) and β-galactosidase (β-Gal) activity and the expressions of FaPG1 and Faβ-Gal1genes were suppressed by the laser treatment. The laser treatment had no effect on the cellulase activity. These findings show that diode laser irradiation is a promising postharvest approach for efficiently preventing strawberry softness and deterioration.

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