The Study Of Extraction Process Of Papain In Papaya

Carica Papaya is also known as rock melon, pawpaw, Papaya, and young melon. It was native to Africa and tropical America, Then it was introduced to china. Papain is a kind of SH-protease, it widely exists in papaya roots, stems, leaves and fruits, the milk of immature fruit is the most abundant. The papain has strong protein hydrolysis and synthesis ability, and could be milk curd, lipolytic and bacteriolytic, it is not only used to improve the nutritional value or the function nature of plant proteins, but also widely applicated in food area. In order to get the best process condition to obtain the ideal enzyme about Papain,it used three kinds of extraction methods for comparation.And then the superiority and inferiority was also discussed between the aqueous two-phase extraction and the traditional process extraction.First of all, this topic tried to find out the most suitable extraction condition by using ethanol to extract papain of papaya.The experimental results showed that when the content of the volume of L-cys and EDTA was respectively 0.04mol/L and 0.002mol/L,it played a optimum protective effects.The concentration of ethanol 65%and the pH 6.0 could enable enzyme activity achieved 8.372×105u/mg.Secondly,this topic also tried to find out the most suitable extraction condition with ultrafiltration to extract papain form papaya.The results showed that when the content of the volume of L-cys and EDTA was respectively 0.04mol/L and 0.002mol/L,it played a optimum protective effects.The enzyme activity could achieved 9.398×105u/mg under the condition of the operate pressure 0.175Mpa,temperature 60℃and experiment time 5min.Moreover, we systematically study the most suitable extraction condition with aqueous two-phase extraction to extract papain form papaya. The results showed that different molecular of polyethylene glycol (PEG) had little effect to papain activity in concentration range of aqueous two-phase extraction. When the molecular of PEG 600, the enzyme activity of papain could achieved 10.376×105u/mg under the condition of the concentration of PEG 20%, phosphate 16%, the PH of aqueous two-phase extraction system 6.0.At the same time, we also investigated the impact by metal ions, such as NaCl,KB and CaCl2 in aqueous two-phase extraction system. Then optimized the aqueous two-phase extraction to obtain higher activity recovery that at selected experimental conditiony.The results showed that when PEG molecular 600, the concentration of phosphate 16%and the PH of system 6.0,the partition coefficient K of system could attained to 3.26 and the yield of papain could reached 92.4%at room temperature. While compared to three different extraction craf t from papain, the reaction time and temperature was tested to have effects with enzyme activity of papain.The results showed that the enzyme activity of papain could obtain when temperature in 30-90℃range, and at got the highest value 80℃. It certified that papain insensitivity with high temperature. Under the temperature 40℃, the most suitable reaction time was 20min.For the first time, this paper compared the traditional process with the aqueous two-phase extraction method on extraction of papain of papapay. The statistical results indicated that in three methods, the enzyme activity was the highest in the aqueous two-phase extraction and the worsest in organic solvent-ethanol extraction process. While in the extraction process of ethanol, it was difficult to grasp the point of solvent feeding, excessive adding will destroyed the hydrogen bond of protein, and easy to cause denatured and deactivation. It was more temperate between ultrafiltration extraction and organic solvent extraction, and more differ to occur changes on phenomena and deactivation, but it could produce concentration polarization phenomenon in the membrane surface, thus the extraction efficiency and effection were influenced. The process of aqueous two-phase extraction was relatively easy to extracted papain from papaya, and the phase splitting quickly and the operating condition temperate, so it could easily enlarged and continuous operated. And the aqueous two-phase extraction system could make protein member more steader. But the factors in the aqueous two-phase extraction system which was affected the assignment behavior were quite complex, and further study are in need with the rule. In summary, the aqueous two-phase extraction was better than tradition extraction methods.