【作者】 张鑫；

【导师】 张仁堂；

【作者基本信息】 山东农业大学 ， 食品科学与工程， 2025， 硕士

【摘要】 缺铁性贫血是全球普遍存在的一种营养性疾病,其发生不仅会影响机体免疫功能和生长发育,而且可能引起多种临床症状。传统补铁剂如硫酸亚铁虽具有较好的补铁效果,但往往伴随着胃肠道不适和过量铁离子诱发的氧化应激问题。因此,开发新型、作用温和且生物利用率高的补铁剂具有重要的理论意义和应用前景。本研究以红枣为原料,利用黑化工艺进行处理,旨在探讨黑化过程中其质构、微观结构及化学成分等方面的变化规律,并在此基础上提取、分离纯化黑化枣多糖,通过与铁离子形成复合物,构建一种新型的多糖铁复合物,进一步评估其在体外消化模拟条件下铁离子释放特性以及对缺铁性贫血小鼠的补铁作用。（1）红枣黑化过程中成分变化实验中通过质构分析发现,红枣黑化过程中,其硬度从初始的1607.85 g下降至黑化末期的1110.57 g,弹性与咀嚼性下降幅度分别为33.8%和41.5%,说明红枣质地因细胞降解而变软。SEM结果显示,黑化枣细胞壁逐渐变薄,内部孔隙明显增多,组织结构趋于疏松,这种变化有助于提高后续提取效率。通过GC-MS与电子鼻技术分析,发现黑化过程中红枣的挥发性成分发生显著改变,其中乙酸、苯乙醇、糠醛等含量显著上升,非靶组学和靶向组学分析发现,多糖含量上升、蔗糖、果糖含量下降,柠檬酸和乳酸则在黑化前期增加约32.7%和41.3%,至后期逐渐下降,黑化过程中可能伴随糖类降解、有机酸代谢及美拉德反应等多种化学过程。（2）黑枣多糖铁复合物的制备及表征经过提取分离纯化制得的黑枣多糖,与Fe Cl₃复合后,其铁结合率为27.83 mg/g,结构表征方面,BGJP-2-Fe在UV谱图中表现出280 nm处特征峰增强,FTIR光谱在1023cm?1处显示Fe-O伸缩振动峰,XRD图谱呈现出新晶型结构,CD分析显示空间构象由无序向部分螺旋转变,SEM-EDS结果证实铁元素均匀分布于复合物表面。结果表明,铁离子的加入使得多糖的分子量显著增加,同时在FTIR和XRD等测试中发现多糖与铁离子可能通过羟基、Fe-O键形成了稳定的配位结合结构,并改善了复合物的热稳定性和分子分布均一性。（3）黑枣多糖铁复合物对缺铁性贫血小鼠缓解作用机制探究体外消化模拟实验结果显示,BGJP-2-Fe在p H 2.0的胃液中2小时内铁释放率达到83.15%,而在p H 8.0的肠液中持续释放至5小时累计释放量达95.34%,表现出显著的缓释特性和潜在的肠道吸收优势。此外,BGJP-2-Fe在人工肠液中保持较好的稳定性和溶解性,说明其具备较强的生理适应能力和铁生物可利用性。缺铁性贫血小鼠模型实验结果显示,BGJP-2-Fe高剂量组（25 mg/kg）小鼠血红蛋白（HGB）浓度由建模后的78.53g/L升至112.36 g/L,红细胞计数（RBC）提升至8.12×10?/μL,血细胞比容（HCT）恢复至41.67%,明显优于等剂量的硫酸亚铁组。肝脏中铁储备提高35.7%,铁蛋白水平显著增加,表明铁代谢能力增强。同时,血清中丙二醛（MDA）含量下降19.5%,超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性分别升高18.2%和23.6%,表明BGJP-2-Fe在补铁同时具有抗氧化和组织保护作用。16S r RNA测序显示,BGJP-2-Fe干预显著提升肠道菌群多样性,增强拟杆菌门和厚壁菌门比例,益生菌如Bifidobacterium、Faecalibaculum相对丰度显著提高;功能预测表明其可增强能量代谢、氨基酸合成等关键通路。LC-MS代谢组学分析进一步揭示,BGJP-2-Fe主要氨基酸生物合成;鞘磷脂与甘油磷脂代谢;谷胱甘肽与泛醌合成等功能通路,激活免疫调节与抗氧化通路,为其缓解贫血作用提供代谢层面依据。综上所述,本研究通过对红枣黑化过程各项指标的系统检测和对黑化枣多糖铁复合物的深入制备及表征,证明了黑化工艺不仅能改善红枣的感官品质和营养成分,还能促进功能性多糖的提取,进而构建出一种新型补铁复合物。该复合物在体外消化和动物模型中均表现出良好的铁缓释和补铁效果,为开发作用温和、生物利用率高的新型补铁剂提供了坚实的实验依据和理论支持。未来研究可进一步优化制备工艺,深入探讨多糖与铁离子之间的相互作用机理,并在更大规模的动物实验及临床试验中验证其长期安全性和有效性。更多还原

【Abstract】 Iron deficiency anemia is a widespread nutritional disorder globally.Its occurrence not only affects immune function and growth development but may also lead to a variety of clinical symptoms.Although traditional iron supplements such as ferrous sulfate are effective,they are often accompanied by gastrointestinal discomfort and oxidative stress caused by excess free iron ions.Therefore,the development of novel iron supplements with mild effects and high bioavailability holds significant theoretical and practical value.In this study,jujubes were used as raw materials and subjected to a blackening process to investigate the changes in texture,microstructure,and chemical composition during the transformation.On this basis,polysaccharides were extracted,isolated,and purified from blackened jujubes to form polysaccharide-iron complexes.A new type of polysaccharide-iron complex was constructed and its iron release characteristics under in vitro digestion conditions,as well as its iron supplementation effects in iron-deficiency anemia mice,were evaluated.(1)Changes in composition during the blackening of jujubeTexture analysis showed that the hardness of jujube decreased from 1607.85 g at the initial stage to 1110.57 g at the end of the blackening process.Elasticity and chewiness decreased by33.8%and 41.5%,respectively,indicating that the fruit’s texture became softer due to cellular degradation.SEM results revealed that cell walls of blackened jujube gradually thinned,internal pores increased significantly,and the tissue structure became looser,which is conducive to improving subsequent extraction efficiency.GC-MS and electronic nose analyses demonstrated significant changes in the volatile components of jujube during blackening,with increased levels of acetic acid,phenylethanol,and furfural.Non-targeted and targeted metabolomics analyses revealed increased polysaccharide content,decreased sucrose and fructose content,and an approximate 32.7%and 41.3%increase in citric acid and lactic acid,respectively,in the early stages,followed by a gradual decrease.These changes suggest the occurrence of sugar degradation,organic acid metabolism,and Maillard reactions during the blackening process.(2)Preparation and characterization of the black jujube polysaccharide-iron complexThe purified black jujube polysaccharide was complexed with Fe Cl?,resulting in an iron-binding capacity of 27.83 mg/g.Structural characterization showed that the BGJP-2-Fe complex had enhanced absorption at 280 nm in the UV spectrum.FTIR spectra exhibited a Fe–O stretching vibration peak at 1023 cm?1.XRD analysis revealed the emergence of a new crystalline structure.CD spectroscopy indicated a conformational shift from disordered to partially helical structure.SEM-EDS confirmed that iron was uniformly distributed on the surface of the complex.These results suggest that the addition of iron ions significantly increased the molecular weight of the polysaccharides and that stable coordination bonds were likely formed between hydroxyl groups and iron via Fe–O bonds,thereby enhancing thermal stability and uniform molecular distribution.(3)Mechanistic study of the black jujube polysaccharide-iron complex in alleviating iron deficiency anemia in miceIn vitro digestion experiments showed that BGJP-2-Fe released 83.15%of iron within 2hours in gastric fluid at p H 2.0,and continued to release up to 95.34%over 5 hours in intestinal fluid at p H 8.0,demonstrating sustained-release properties and potential intestinal absorption advantages.BGJP-2-Fe maintained good stability and solubility in simulated intestinal fluid,indicating strong physiological adaptability and iron bioavailability.In iron-deficient anemia mice,the high-dose BGJP-2-Fe group(25 mg/kg)showed an increase in hemoglobin(HGB)concentration from 78.53 g/L to 112.36 g/L,red blood cell(RBC)count increased to8.12×10?/μL,and hematocrit(HCT)recovered to 41.67%,significantly outperforming the equivalent dose of ferrous sulfate.Liver iron storage increased by 35.7%,and ferritin levels rose significantly,indicating enhanced iron metabolism.Additionally,serum malondialdehyde(MDA)levels decreased by 19.5%,while superoxide dismutase(SOD)and catalase(CAT)activities increased by 18.2%and 23.6%,respectively,suggesting that BGJP-2-Fe possesses antioxidant and tissue-protective effects during iron supplementation.16S rRNA sequencing revealed that BGJP-2-Fe significantly increased gut microbiota diversity and enhanced the proportions of Bacteroidetes and Firmicutes.The relative abundance of beneficial bacteria such as Bifidobacterium and Faecalibaculum also increased significantly.Functional predictions indicated enhanced pathways related to energy metabolism and amino acid synthesis.Furthermore,LC-MS-based metabolomics analysis revealed that BGJP-2-Fe mainly affected pathways including amino acid biosynthesis,sphingolipid and glycerophospholipid metabolism,as well as glutathione and ubiquinone synthesis,thereby activating immune regulatory and antioxidant pathways and providing metabolic evidence for its anemia-relieving effects.In conclusion,this study systematically analyzed various parameters during the jujube blackening process and thoroughly characterized the black jujube polysaccharide-iron complex.The results demonstrate that the blackening process not only improves the sensory quality and nutritional content of jujube but also promotes the extraction of functional polysaccharides,leading to the development of a novel iron supplement.This compound exhibited excellent iron release and supplementation effects both in vitro and in vivo,providing strong experimental and theoretical support for the development of mild,high-bioavailability iron supplements.Future studies should focus on optimizing the preparation process,further exploring the interaction mechanisms between polysaccharides and iron ions,and validating long-term safety and efficacy through larger-scale animal and clinical trials.更多还原