| In recent years, deficiency of protein is a serious problem for our country. It is a matter of great urgency to find plant protein source with low price and excellent quality, but the proteins extracted from plants always have some disadvantages, such as low extraction rate of protein, lacking of the essential amino acids and having antinutritional factors (ANFs). Caragana korshinkii Kom. is a kind of econo-ecological tree species and not fully exploited. It with high content of crude protein, which has the possibility to be developed as a protein source. In order to optimize the content of the protein extracted from C. korshinkii Kom. by water and evaluate the potential application of this protein, it is necessary to study the mechanism of the extraction process and the quality of the protein.For the industry, the protein extracted from plant by using alkali solution and then by water. In this study, applying a empirical model, a one-site kinetic extraction model, a three-site kinetic extraction model and a second-order model to investigated the water extraction process of protein from C.korshinskii Kom.. The influence of different particle sizes, extraction temperature and alkali process on the water extraction process were studied. Al-CPI and A-CPI were the protein isolates extracted from C.korshinskii Kom. using alkaline extraction method and acetone precipitation method respectively. The nutritional factors and antinutritional factors of C.korshinskii Kom., Al-CPI and A-CPI was analyzed.The experimental data fit well with a three-site kinetic extraction model, which indicated that the water extraction process include washing, faster and slower stages. The protein content was raiseing with the decreasing of particle size of sample, and the increasing of the NaOH concentration or the extraction temperature. The maximum extraction rate of protein was 3.3 mg/g sample with the particle size of 60-80 mesh. The protein yield was dominated by the slower process. Under 0.1 M NaOH, the peak protein yield of water extraction process was 3.8 mg/g sample. When the concentration of NaOH ranging from 0.02M to 0.1 M, the protein content of the slower process was increased, and the faster process was not affected. Rising the temperature of extraction process is conducive to increase the protein yield of both the slower and the faster process. The maximum extraction rate of protein was 5.6 mg/g sample under extraction temperature at 313 K.In this study, the contents of nutritional ingredients and antinutritional factors of C.korshinskii Kom., Al-CPI and A-CPI were quantitatively investigated. It was shown that the crude protein contents of C. korshinskii Kom. and its protein isolates obtained by alkaline extraction method (Al-CPI) and acetone precipitation method (A-CPI) were 9.1, 50.1, and 42.6%, respectively. Amino acid contents for C. korshinskii Kom., Al-CPI, and A-CPI basically exceeded the FAO/WHO reference pattern for adults except ulfur-containing amino acids. The lysine levels in C. korshinskii Kom., Al-CPI, and A-CPI were 4.1,3.1, and 3.8 mg/100 mg crude protein respectively, which were higher than some other kinds of cereal grains. The antinutritional factors in C. korshinskii Kom. and Al-CPI were generally lower than those in some other kinds of legumes except total phenol and tannin. Total phenol and tannins in Al-CPI were 19.02 and 5.66 mg/g dry substance, respectively, but they were undetectable in A-CPI. This study provided a detailed analysis on nutritional and antinutritional factors in C. korshinskii Kom. and its protein isolates, indicating that they have a great potential on food and feed additives. |
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