School of Chemistry and Chemical Engineering,Qinghai Normal University,Qinghai Xining 810008
以裸藻蛋白液為原料，通過泡沫分離法提取裸藻蛋白，以回收率和富集比為指標，通過單因素和響應面設計探究pH、裝液量、溫度、稀釋倍數對裸藻蛋白的回收率和富集比的影響。同時研究了裸藻蛋白的功能特性，又采用傅里葉紅外光譜和雙光束紫外-可見分光光度計對蛋白進行結構分析，通過Peakfit Version軟件對蛋白的二級結構進行鑒定，并通過氨基酸分析儀測定了裸藻蛋白的氨基酸組成。結果表明：裸藻蛋白泡沫分離的最佳條件為： pH5.5，裝液量300 mL，溫度30 ℃，稀釋倍數15 倍，在此條件下的蛋白回收率為94.27%，富集比為4.18。蛋白的持水量在60 ℃最大，為7.27 g/g，持油量在40 ℃最大，為14.74 g/g。裸藻蛋白的乳化能力、乳化穩定性、起泡性、泡沫穩定性均隨著質量分數的增大呈現先增加后減小的趨勢。FT-IR和UV顯示裸藻蛋白有典型的蛋白峰，它的二級結構表示裸藻蛋白以β-折疊為主。蛋白中必需氨基酸含量和疏水性氨基酸含量為35.28%和50.81%。
In this study, euglena protein solution was used as raw material, and euglena protein was extracted by foam separation method. With the recovery and enrichment ratio as indexes, the effects of pH, liquid volume, temperature and dilution ratio on the recovery and enrichment ratio of euglena protein were investigated by single factor and response surface design. At the same time, the functional characteristics of euglena protein were studied, and the structure of the protein was analyzed by Fourier transform infrared spectroscopy and dual-beam ultraviolet-visible spectrophotometer. The secondary structure of the protein was identified by Peakfit Version software, and the amino acid composition of euglena protein was determined by amino acid analyzer. The results showed that the optimum conditions for foam separation of Euglena protein were as follows: pH5.5, liquid volume 300 mL, temperature 30 ℃, and 15 times of dilution. Under these conditions, the protein recovery rate was 94.27% and the enrichment ratio was 4.18. The maximum water holding capacity of protein was 7.27 g/g at 60 ℃, and the maximum oil holding capacity was 14.74 g/g at 40 ℃. The emulsifying ability, emulsifying stability, foaming property and foam stability of euglena protein increased at first and then decreased with the increase of mass fraction.. FT-IR and UV showed that euglena sp. protein had a typical protein peak, and its secondary structure indicated that euglena sp. protein was mainly β-folded. The contents of essential amino acids and hydrophobic amino acids in protein are 35.28% and 50.81%. The results provide experimental basis for the study of euglena protein.