不同干燥方式下菠菜粉理化性质的比较

Comparison of Physicochemical Properties of Spinach Powder Using Different Drying Methods

摘要:

以菠菜为原料，采用热风、太阳能、真空冷冻和喷雾干燥共4种干燥方式制备菠菜粉，考察不同干燥方式对菠菜粉色泽、抗氧化活性、微观结构等理化性质的影响。结果表明：喷雾干燥的L*值较高为33.28，a*值最小为-5.86，对菠菜粉色泽影响较小；与鲜样相比，4种干燥方式制备菠菜粉的色泽、叶绿素、抗坏血酸、总酚、总黄酮的含量及抗氧化活性均有所降低，而且4种干燥方式对菠菜粉抗氧化活性的影响较大，喷雾干燥的抗氧化活性最高，热风干燥的抗氧化活性最低；相关性分析显示，菠菜粉的总酚、总黄酮和抗坏血酸与其抗氧化活性显著正相关（p<0.05）；通过粒度分布仪和SEM分析，喷雾干燥制备的菠菜粉中位粒径Dx（50）减小至17.76 μm、比表面积增大到228.3 m2/kg、跨度值减小为2.87，菠菜粉呈短小的圆棒状或圆球状，颗粒小且分布均匀，部分表面较圆润，细胞结构保持较好，优于其它3种干燥方式。综合分析，喷雾干燥是制备菠菜粉的最佳干燥方式，较适于高抗氧化活性的菠菜粉的工业生产，为菠菜粉产品的精深加工提供科学依据。

Abstract:

Spinach powder was prepared by hot air drying, solar drying, vacuum freeze drying and spray drying. The effects of different drying methods on the color, antioxidant activity, microstructure and other physicochemical properties of spinach powder were investigated. The results showed that the L* value of spray drying was 33.28 and the a* value was -5.86, which had little effect on the color of spinach powder. Compared with the fresh control, the contents of chlorophyll ascorbic acid total phenols and total flavonoids and antioxidant activity of spinach powder prepared by four drying methods were decreased, and the four drying methods had a greater effect on the antioxidant activity of spinach powder, spray drying had the highest antioxidant activity, and hot air drying had the lowest antioxidant activity. Correlation analysis showed that the total phenols, flavonoids and ascorbic acid of spinach powder were significantly positively correlated with their antioxidant activity (p<0.05). Through particle size distribution analyzer and SEM analysis, the median particle size DX(50) of spinach powder prepared by spray drying decreased to 17.76 μm, the specific surface area increased to 228.3 m2/kg, and the span value decreased to 2.87. Spinach powder was a short round rod-shaped or spherical, the particles were small and evenly distributed, part of the surface was round, the cell structure was better maintained compared with the other three drying methods. Based on the comprehensive analysis, spray drying was the best drying method for preparing spinach powder, which was more suitable for industrial production of spinach powder with high antioxidant activity, and provided scientific basis for the deep processing of spinach powder products.