3种蛋白膜包裹对核桃仁脂质过氧化作用的比较研究

Comparison of coating effects of three proteins films on the walnut lipid peroxidation

对于大豆蛋白、蛋清蛋白和乳清蛋白的成膜性及其膜特性研究已有一些报道,但对于这3种蛋白膜特性的分析和比较则未见报道。在3种蛋白最佳成膜条件下分别制备大豆蛋白膜、蛋清蛋白膜和乳清蛋白膜,分析比较其水蒸气透过率,来考察其膜特性;观察3种蛋白膜包裹对核桃仁在贮藏条件下的酸价、过氧化值和TBA值等的影响,来考察其对核桃仁脂质过氧化的影响。结果表明,在与大豆蛋白和蛋清蛋白相同蛋白浓度下,乳清蛋白需要较高甘油浓度才具有较好的成膜性,这使得乳清蛋白膜具有较高的水蒸气透过率。在贮藏过程中,核桃仁的酸价、过氧化值和TBA值均上升。但应用3种蛋白膜包裹均可使核桃仁的酸价显著降低,可降低约24.9%,3种蛋白膜包裹的核桃仁的酸价之间没有明显差异;3种蛋白膜包裹均可使核桃仁的过氧化值显著降低,其降低的程度依次为:大豆蛋白膜>蛋清蛋白膜>乳清蛋白膜,且3种蛋白膜包裹之间有明显差异;3种蛋白膜包裹均可使核桃仁的TBA值显著降低,其降低的程度依次为:大豆蛋白膜>蛋清蛋白膜>乳清蛋白膜,且3种蛋白膜包裹之间有明显差异。由上述结果可见,3种蛋白均能延缓核桃仁的脂质过氧化,其中效果最好的是大豆蛋白,其次是蛋清蛋白,最后是乳清蛋白。

Soybean protein isolate（SPI）, egg white protein（EWP）, and whey protein isolate（WPI） all are important matrixes for edible films because of their high nutritional value and good film-forming property. However, there is no evaluation on differences between film-forming and water barrier properties among the films of the three proteins. This study investigated the film-forming property and water vapour permeability（WVP） of three protein films prepared at their optimum conditions. Furthermore, walnuts were wrapped by three protein films, and their effects on walnut lipid peroxidation were assessed. The results showed that WPI required higher concentration of glycerol than SPI and EWP in film-forming process, which lead to higher WVP of WPI film than that of SPI and EWP films. During the 8-day storage period, the increases of rancidity value, peroxide value and TBA value of the walnuts were observed. The rancidity value of the film-coated walnuts was approximately 24.9% lower than that of the uncoated ones. While there were no significant differences among three film-coated walnuts. The film-coated walnuts were significantly lower than the uncoated ones in the peroxide value, and there were significant differences among three film-coated walnuts. The effect from high to low in the order： SPI film〉EWP film〉WPI film. The TBA value of the film-coated walnuts was significantly lower than that of the uncoated ones, and there were significant differences among three film-coated walnuts. The effect from high to low in the order： SPI film〉EWP film〉WPI film. In conclusion, the film-coated by three proteins are all able to effectively delay the walnut lipid peroxidation, and the effectiveness is in the order of SPI〉EWP〉WPI.