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马铃薯淀粉干法制备及高附加值利用

Dry method preparation of potato starch and its high value-added utilization

  • 摘要: 针对现有马铃薯淀粉提取技术中存在的淀粉得率低和加工废水多等不足,该研究构建了一种干法制备马铃薯淀粉的方法。具体工艺:将马铃薯洗净、去皮、切块,经压榨得到马铃薯压榨饼和压榨液,随后将马铃薯饼进行破碎与过筛处理,得到马铃薯淀粉。工艺研究结果显示,压榨饼的含水率对于淀粉是否能筛分至关重要,当压榨饼含水率低于38.5%时,可实现淀粉的干法分离。在破碎方式中,捶打破碎因能较好维持细胞壁之间的胞间连接,更有利于淀粉筛分,效果显著优于刀片破碎。较优工艺条件下,干法制备淀粉得率达到17.8%,含水率为13.6%,淀粉干基含量为88.7%。当压榨程度不足时,干燥处理可降低压榨饼含水率,但所得淀粉产品的淀粉含量和白度显著下降。将优化条件(55 MPa、5 min、捶打破碎)下的干法淀粉与市售产品进行对比,结果显示两者淀粉湿基含量相当,但干法淀粉干基含量与白度略低。为进一步明确干法淀粉的特性,该研究从淀粉得率、结晶结构、糊化特征与损伤率等方面,将其与水提法淀粉进行了比较,结果显示,干法的淀粉得率显著高于水提法(12.8%)。晶体结构分析表明,干法淀粉晶型未发生改变,仍为B型。在糊化特征方面,干法淀粉峰值黏度、谷值黏度与崩解值显著降低,而最终黏度与回生值升高,已不适合于常规用途。然而,显微观察发现干法淀粉中约70%的淀粉颗粒表面出现裂纹,这使其更容易被α-淀粉酶水解,较优条件(酶解12 h)下制备出的多孔淀粉有较好的吸附性能,吸水率可达156.6%,吸油率可达101.9%;扫描电子显微镜结果证实,干法淀粉颗粒表面存在裂纹,酶解12 h后出现明显孔洞。研究结果可为新型马铃薯淀粉加工方法以及高附加值利用提供参考。

     

    Abstract: Dry preparation of potato starch is one of the most important procedures in food processing. Existing potato starch extraction can be limited to the low starch yield and a large amount of wastewater. This study aimed to develop the dry preparation of potato starch for high yield in sustainable agriculture. The processing steps were as follows: Potatoes were washed, peeled, cut into cubes, and then pressed to obtain potato press cake and juice. The press cake was subsequently treated by hammer crushing and sieved to separate potato starch from potato residue. It was found that the moisture content of the press cake was crucial for the dry separation of starch. Dry separation of starch was achieved at a moisture content of the press cake below 38.5%. Hammer crushing better maintained the intercellular connections between cell walls, thereby facilitating starch sieving. The performance was significantly superior to that of blade crushing. The starch yield of 17.8% was achieved with a moisture content of 13.6%, a starch content of 88.7% (dry basis), a protein content of 1.94%, and an ash content of 0.60% under optimal conditions. When the pressing pressure was insufficient (20 MPa), drying treatment was used to reduce the moisture content of the press cake. But the starch content and whiteness of the starch product decreased significantly. A comparison was made of the commercial products of potato starch. The starch content (wet basis) was between those of the two commercial products. But the starch content (dry basis) of 88.7% was lower than that of the commercial products (92.0% and 92.4%), while the whiteness was slightly lower as well. The starch after water extraction was further clarified using starch yield, crystalline structure, gelatinization properties, and damage rate. The results indicated that the starch yield was significantly higher than that of the water extraction (12.8%). Crystalline structure analysis showed that the crystal type of potato starch remained unchanged, with the B-type. In terms of gelatinization characteristics, the peak viscosity, trough viscosity, and breakdown of potato starch decreased significantly, whereas the final viscosity and setback increased, indicating suitability for conventional applications. The damaged starch content increased significantly, as the cracks on the surface of starch granules accounted for approximately 70% of the total. These cracks made the starch more susceptible to hydrolysis by α-amylase. The porous starch shared the better adsorption properties under optimal conditions (enzymatic hydrolysis for 12 h), with a water and oil absorption capacity of 156.6% and 101.9%, respectively. The scanning electron microscopy confirmed that there were some cracks on the surface of starch granules. The outstanding pores appeared after 12 h of enzymatic hydrolysis.

     

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