Ali Sajid, Khan Ahmad Sattar, Nawaz Aamir, Naz Safina, Ejaz Shaghef, Shah Anis Ali, Haider Muhammad Wasim
Department of Horticulture, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan 60800, Punjab, Pakistan.
Institute of Horticultural Sciences, University of Agriculture, Faisalabad 38040, Pakistan.
Int J Biol Macromol. 2023 May 1;236:123966. doi: 10.1016/j.ijbiomac.2023.123966. Epub 2023 Mar 9.
Low temperature storage of citrus generally extends the storage potential but leads to chilling injury appearance on the rind of fruits. The said physiological disorder has been found associated with changes in the metabolism of cell walls and other attributes. In this work, the influence of Arabic gum [AG (10 %)] and γ-amminobutyric acid [GABA (10 mmol L)] either alone or in combined form was studied on fruits of 'Kinnow' mandarin during storage at 5 ± 1 °C for 60 days. The results exhibited that the combined AG + GABA treatment significantly suppressed weight loss (5.13 %), chilling injury (CI) symptoms (2.41 score), incidence of disease (13.33 %), respiration rate [(4.81 μmol kg h) RPR] and ethylene production [(0.86 nmol kg h) EPR]. In addition, AG + GABA application reduced relative electrolyte (37.89 %) leakage (REL), malondialdehyde [(25.99 nmol kg) MDA], superoxide anion [(15.23 nmol min kg) O] and hydrogen peroxide [(27.08 nmol kg) HO] along with lower lipoxygenase [(23.81 U mg protein) LOX] and phospholipase D [(14.07 U mg protein) PLD] enzyme activities compared with control. The AG + GABA treated 'Kinnow' group showed higher glutamate decarboxylase [(43.18 U mg protein) GAD] and lower GABA transaminase [(15.93 U mg protein) GABA-T] activity having higher endogenous GABA (42.02 mg kg) content. The fruits treated with AG + GABA exhibited higher cell walls (CW) components such as NaCO-soluble pectin [(6.55 g kg) NCSP], chelate-soluble pectin [(7.13 g kg) CSP] and protopectin [(11.03 g kg) PRP] concentrations along with lower water-soluble pectin [(10.64 g kg) WSP] compared to control. In addition, 'Kinnow' fruits treated with AG + GABA showed higher firmness (8.63 N) and lower activities of CW degrading such as cellulase [(11.23 U mg protein) CX], polygalacturonase [(22.59 U mg protein) PG], pectin methylesterase [(15.61 U mg protein) PME] and β-galactosidase [(20.64 U mg protein) β-Gal] enzymes. The activity of catalase [(41.56 U mg protein) CAT], ascorbate peroxidase [(55.57 U mg protein) APX], superoxide dismutase [(52.93 U mg protein) SOD] and peroxidase [(31.02 U mg protein) POD] was also higher in combined treatment. In addition, AG + GABA treated fruits showed better biochemical and sensory attributes than the control. So, combined AG + GABA could be used for CI mitigation and storage life prolongation of 'Kinnow' fruits.
柑橘的低温贮藏通常会延长其贮藏潜力，但会导致果实表皮出现冷害现象。已发现上述生理紊乱与细胞壁代谢及其他特性的变化有关。在本研究中，研究了阿拉伯胶[AG（10%）]和γ-氨基丁酸[GABA（10 mmol/L）]单独或组合使用对“金诺”柑桔果实的影响，果实于5±1℃贮藏60天。结果表明，AG + GABA组合处理显著抑制了失重（5.13%）、冷害（CI）症状（2.41分）、发病率（13.33%）、呼吸速率[（4.81 μmol/kg·h）RPR]和乙烯产量[（0.86 nmol/kg·h）EPR]。此外，与对照相比，AG + GABA处理降低了相对电解质（37.89%）渗漏（REL）、丙二醛[（25.99 nmol/kg）MDA]、超氧阴离子[（15.23 nmol/min·kg）O]和过氧化氢[（27.08 nmol/kg）H₂O]，同时降低了脂氧合酶[（23.81 U/mg蛋白质）LOX]和磷脂酶D[（14.07 U/mg蛋白质）PLD]的酶活性。AG + GABA处理的“金诺”组显示出较高的谷氨酸脱羧酶[（43.18 U/mg蛋白质）GAD]和较低的GABA转氨酶[（15.93 U/mg蛋白质）GABA-T]活性，内源性GABA（42.02 mg/kg）含量较高。与对照相比，AG + GABA处理的果实表现出较高的细胞壁（CW）成分，如碳酸钠可溶性果胶[（6.55 g/kg）NCSP]、螯合可溶性果胶[（7.13 g/kg）CSP]和原果胶[（11.03 g/kg）PRP]浓度，以及较低的水溶性果胶[（10.64 g/kg）WSP]。此外，AG + GABA处理的“金诺”果实表现出更高的硬度（8.63 N）和更低的CW降解活性，如纤维素酶[（11.23 U/mg蛋白质）CX]、多聚半乳糖醛酸酶[（22.59 U/mg蛋白质）PG]、果胶甲酯酶[（15.61 U/mg蛋白质）PME]和β-半乳糖苷酶[（20.64 U/mg蛋白质）β-Gal]。组合处理中过氧化氢酶[（41.56 U/mg蛋白质）CAT]、抗坏血酸过氧化物酶[（55.57 U/mg蛋白质）APX]、超氧化物歧化酶[（52.93 U/mg蛋白质）SOD]和过氧化物酶[（31.02 U/mg蛋白质）POD]的活性也更高。此外，AG + GABA处理的果实比对照表现出更好的生化和感官特性。因此，AG + GABA组合可用于减轻“金诺”果实的冷害并延长其贮藏寿命。
