NaCl胁迫与超声处理对发芽小麦淀粉结构及功能特性的影响

    Effect of NaCl stress and ultrasonic treatment on starch structure and functional properties of germinating wheat

    • 摘要: 发芽处理可显著富集小麦中的γ-氨基丁酸、多酚类及阿拉伯木聚糖等活性成分,同时改变其淀粉结构与理化特性,从而有效提升小麦的生物利用率与营养价值。为探究发芽小麦的最佳处理条件,首先对小麦进行超声处理,然后使用60 mmol/L NaCl溶液浸泡不同发芽时间(24、48、72 h)的小麦,模拟盐胁迫环境,最后对发芽小麦进行均质匀浆提取淀粉,并测定空白组(未发芽)、NaCl处理组(超声与NaCl协同)和对照组(仅超声)小麦淀粉的理化特性、结构及功能特性。结果表明:超声协同NaCl处理48 h为最佳条件,NaCl胁迫显著影响淀粉的表面结构、粒径分布、结晶结构及分支度等特性;超声协同NaCl处理48 h,淀粉的功能特性达到最佳,酚类物质含量最高(1.50 mg/g),淀粉粒径增大,结晶度降低,片层结构被破坏,分形维数由2.25降至1.96,内部无序性增加,峰值黏度降低至2 098.50 mPa·s,热焓值升高至11.25 J/g。综上所述,经48 h的NaCl超声协同处理后,所得淀粉具有良好的热稳定性、低黏度及高溶解度。

       

      Abstract: Germination, as a natural bioprocessing technique, has been demonstrated to effectively enrich bioactive components in wheat, such as γ-aminobutyric acid (GABA), polyphenols, and arabinoxylan, while simultaneously modifying the structural and physicochemical properties of wheat starch. These modifications significantly enhanced the bioavailability and nutritional quality of wheat-based products. To optimize germination conditions, this study employed a synergistic strategy combining ultrasonic pretreatment with NaCl-induced salt stress. Wheat grains were treated with a 60 mmol/L NaCl solution under varying germination durations (24, 48, and 72 h) following ultrasonic processing. Starch was subsequently extracted from germinated wheat through homogenization, and its characteristics were systematically compared among three groups: the blank group (non-germinated), NaCl treatment group (ultrasonic combined with NaCl), and control group (ultrasonic only). The results indicated that the optimal condition for improving starch functionality was ultrasonic-assisted NaCl treatment for 48 h. NaCl stress significantly affected starch properties, including surface morphology, particle size distribution, crystalline structure, and degree of branching. Specifically, after 48 hours of ultrasonic treatment combined with NaCl, the functional properties of starch reached the best level: the phenolic content reached a peak of 1.50 mg gallic acid equivalents/g dry weight; the starch particle size increased substantially, indicating structural loosening; the lamellar structure was destroyed; the fractal dimension decreased from 2.25 to 1.96, indicating increased internal disorder and reduced molecular compactness. Rheological analysis demonstrated a notable decline in peak viscosity (2 098.50 mPa·s vs. 2 450 mPa·s in controls), suggesting weakened starch granule integrity. Conversely, differential scanning calorimetry (DSC) indicated an elevated gelatinization enthalpy (11.25 J/g), attributed to modified amylopectin double-helix alignment. These multi-scale modifications in starch structure-function relationships highlight the synergistic potential of ultrasonic and NaCl treatments in modulating germination dynamics. The optimized protocol not only enhances the synthesis of bioactive compounds but also tailors starch properties for specific food applications, such as low-viscosity or high-digestibility formulations, thereby promoting the development of nutritionally fortified wheat-based products. In conclusion, 48 hours of NaCl-ultrasound combined treatment is the optimal condition, and the corresponding starch has good thermal stability, low viscosity, and high solubility. This study provides experimental evidence for further investigating the structural and functional changes of starch in sprouted wheat under salt stress.

       

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