【作者】 王伟；

【导师】 刘亚平；

【作者基本信息】 山西农业大学 ， 食品科学与工程， 2024， 硕士

【摘要】 红地球葡萄营养丰富、皮薄多汁,深受消费者喜爱,但在贮藏过程中,易受灰霉菌侵染而导致腐烂,造成损失。目前国内外提高葡萄贮藏效果的常用方法是SO₂处理,但SO₂易造成残留和漂白问题。壳聚糖和硒分别以其保护和抗氧化特性已被用于果蔬采后贮藏,基于此,本文研究了亚硒酸钠(25 mg·L^-1,Se)、壳聚糖（1.0%,CS）以及硒-壳聚糖(25 mg·L^-1亚硒酸钠和1.0%壳聚糖,CS+Se)处理对红地球葡萄贮藏品质和抗病性的影响,并基于气相色谱-离子迁移谱（GC-IMS）研究了果实贮藏中风味物质的变化,运用实时荧光定量PCR（RT-q PCR）技术进行了硒-壳聚糖保鲜机理研究,以期为葡萄保鲜新方法和抗病性提供依据。主要研究结果如下:（1）硒-壳聚糖处理可有效降低葡萄贮藏中的腐烂率,保持了葡萄中可溶性固形物、可滴定酸和还原糖的含量,保持了葡萄的硬度、破裂力和粘附性,有效保持了葡萄的贮藏品质和质地。（2）硒-壳聚糖处理可提高葡萄在贮藏过程中的抗病性。硒-壳聚糖通过提高POD、CAT以及苯丙烷代谢途径相关酶（PAL、C4H、4CL）的活性,降低PPO的活性,以促进酚类化合物的积累。基因表达分析表明,硒-壳聚糖处理阻止了VvPAL、VvC4H、Vv4CL的上调,进一步证明硒-壳聚糖对葡萄抗性的提升。（3）硒-壳聚糖处理能有效保持葡萄的颜色,明显抑制褐变过程,并抑制总酚、类黄酮和花色苷在贮藏过程中的下降。基因表达分析表明,硒-壳聚糖处理不仅增加了VvCHS、VvF3H、VvF’3’H、VvLDOX和Vv5GT的表达,而且在整个贮藏过程中稳定了VvCHI、VvF3’H和VvDFR的表达,从而促进了花色苷的积累和稳定。总之,与CS或Se处理相比,硒-壳聚糖处理能有效地保持葡萄贮藏中的颜色。（4）各处理葡萄的挥发性物质含量差异显著。在GC-IMS检测出的62个信号中,筛选出VIP>1的信号有16个,VIP>1.2的信号有11个,其中已知的挥发性物质包括苯乙烯、丙酮、2-丁醇、己醛、2-戊酮、乙酸乙酯、乙酸甲酯、2,3-戊二酮、叔丁醇。硒-壳聚糖对苯乙烯和C6化合物的保留具有显著效果,抑制了部分醇类和酮类等不愉快气味的产生,同时也抑制了酯类等香气物质的合成。基因表达分析表明,CS+Se处理抑制了脂氧合酶途径相关酶基因的表达。硒-壳聚糖处理使一些挥发性化合物得以保留,减缓了酯类、醛类和酮类等挥发性化合物的合成。综上所述,硒-壳聚糖处理可保持葡萄在贮藏过程中的品质和质地,可提高葡萄在贮藏过程中的抗病性,保持果皮颜色,维持挥原有的挥发性化合物含量。更多还原

【Abstract】 Red Globe grapes are rich in nutrients,thin-skinned and juicy,which are popular among consumers,but they are susceptible to grey mold infestation during storage,leading to rot and loss.A common method used at home and abroad to improve the storage effect of grapes is SO2 treatment,but the residue and bleaching problems brought by SO2 are worried by consumers.Chitosan and selenium have been used for postharvest storage of fruits and vegetables for their protective and antioxidant properties,respectively.Based on this,this paper investigated the effects of sodium selenite(25 mg·L-1,Se),chitosan(1.0%,CS),and selenium-chitosan(25 mg·L-1 sodium selenite and 1.0%chitosan,CS+Se)solution treatments on the storage quality and resistance of Red Globe grapes to disease,and based on gas chromatography-ion mobility spectrometry(GC-IMS)to study the changes of flavor substances in fruit storage,and selenium-chitosan preservation mechanism using real-time fluorescence quantitative PCR(RT-q PCR)technology,with a view to providing a basis for new methods of grape preservation and disease resistance.The main research results are as follows:(1)Selenium-chitosan treatment effectively reduced the decay rate of grapes,maintained the content of soluble solids,titratable acid and reducing sugar in grapes,maintained the hardness,breaking force,and adhesion of grapes,and effectively maintained the storage quality and texture of grapes.(2)Selenium-chitosan treatment improves the disease resistance of grapes during storage.Selenium-chitosan reduced the activity of PPO by increasing the activities of POD,CAT,and enzymes related to the phenylpropane metabolic pathway(PAL,C4H,4CL)to promote the accumulation of phenolic compounds.In the gene expression analysis,selenium-chitosan prevented the up-regulation of VvPAL,VvC4H,and Vv4CL,indicating that the grapes under this treatment still did not have obvious stress response at the late storage stage,which further proved the enhancement of selenium-chitosan on the resistance of grapes.(3)Selenium-chitosan treatment can effectively maintain the native color of grapes.In addition,this treatment significantly inhibited the browning process and suppressed the decline of total phenols,flavonoids and anthocyanins during storage.These effects can be attributed to the antioxidant properties of selenium and the protective barrier formed by chitosan,which effectively reduced pigment oxidation and water loss.Gene expression analysis showed that CS+Se treatment not only increased the expression of VvCHS,VvF3H,VvF’3’H,VvLDOX,and Vv5GT,but also stabilized the expression of VvCHI,VvF3’H,and VvDFR throughout the storage process,which contributed to the accumulation and stabilization of anthocyanins.In conclusion,selenium-chitosan treatment proved to be effective in maintaining grape color during storage compared to CS or Se treatments alone.(4)The volatile matter compositions of the grapes were essentially similar among the treatments,with significant differences in content.PCA analysis and PLS-DA analysis enabled effective separation of the treatment groups.Among the 62 signals,16 signals with VIP>1 and 11 signals with VIP>1.2 were screened to distinguish grape samples from different treatments,in which the known volatiles included styrene,acetone,2-butanol,hexanal,2-pentanone,ethyl acetate,methyl acetate,2,3-pentanedione,and tertiary butanol.CS+Se had a significant effect on the retention of styrene and C6 compounds,inhibited the production of unpleasant odors such as some alcohols and ketones,and also inhibited the synthesis of aroma substances such as esters.Specific gene,expression analysis showed that CS+Se treatment inhibited the expression of lipoxygenase pathway related enzyme genes.Overall,CS+Se treatment resulted in the retention of some volatile compounds and slowed down the synthesis of volatile compounds such as esters,aldehydes and ketones.In summary,selenium and chitosan have a synergistic effect on grape preservation.Selenium-chitosan treatment can maintain the quality and texture of grapes during storage,can improve the disease resistance of grapes during storage,maintain the normal skin color,maintain the volatile compounds content of volatile original,and reduce the rate of their synthesis.更多还原