Study On The Extraction And Purification Technology And Functional Characteristics Of Protein From Pecan Cake

There is a kind of pecan nut which riches in oil content, nutritional value anda variety of mineral elements. Specially, the content of pecan protein is higher. It’s including18kinds of amino acid. The content of eight kinds of essential aminoacids that the human body need is reasonable. If you eat for a long time, it couldprevent cardiovascular and cerebrovascular diseases and reduce blood fat,. It has apreventive effect on cancer. It’s the nutrient-rich and pollution-free food. At presentin addition to direct edible, one part of pecans has been used for oil squeeze. However, the research report about making comprehensive use of pecan cake after crushing is too little. In order to make full use of the materials and promote the value of pecan cake, the paper as raw material of NingGuo pecan cake researches theextraction, purification, discoloration and functional characteristics of pecan protein.The results can provide a technology reference about pecan cake comprehensive utilization and the development of new products. The main results of this paper are asfollows:1. We determined the optimum technology parameters of extracting pecan protein.We mainly researched the effect of extraction methods, time, solid-liquid ratio, alkali pH,alkali temperature and acid precipitation pH to the extraction rate of the pecan protein. Wetook each of them to study on single factor test. According to the results of single factortest, we obtained the largely effect element of pecan protein’s the extraction rate are alkalipH, solid-liquid ratio and alkali temperature. Then we designed the quadratic orthogonalrotation combination design experiment of three factors and three levels to optimize theextraction condition of pecans protein. At last, we determined the zero level of alkali pH,solid-liquid ratio and alkali temperature respectively was8.5,1:25and55℃.2. According to the quadratic orthogonal rotation combination design experiment, weestablished the mathematical model which took the pecan protein’s extraction rate as targetfunction. With the interactive analysis, we obtained the most significant to leaching rate isalkali pH, followed by alkali temperature and solid-liquid ratio. According to theforecasting model, we got the best extraction technology condition of pecan protein waswhen pH was9.0, solid-liquid ratio was1:25and alkali temperature was57℃.On thiscondition, we could even have the extraction rate of56.88%.The correlation regressionmodel for the responding values and influencing factors was as follows: Y=52.39425+3.25832X₁²+0.84180X₂+1.56694X₃-0.36754X₁-0.93853X₂²-1.82772X₃²-0.38875X₁X₂-0.11375X₁X₃-0.36625X₂X₃3. We studied the condition of pecan protein’s purification and discoloration.We used different technology which including removing impurity by enzyme and washing to purify the protein. Then we made sure that the influence of enzyme added, bathing temperature and bathing ratio on purity of pecan protein. The results showed the protein purity was improved when α-amylase was added and the protein was washed at40℃twice. Then we respectively added the activated carbon, kaolin,ascorbic acid and H202to discoloring the protein. The results showed that it’s bestof kaolin to discoloring and the discoloration rate reached above70%. After bleaching the color became obviously shallow and the solution was much clearer. And theprotein loss controlled at about10%. So we have to choose the low amount of kaolin to discolor the pecan protein.4. We researched the functional characteristics of pecan protein including the aminoacid content, solubility, water-holding capacity, oil absorption, emulsifiability, foamabilityand viscosity. The results showed that the protein extracted from pecan cake have a fullrange of amino acids. The amino acids content and sorting of protein from pecan cake hada consistency of the protein from the pecan nut. At the same time, the protein from pecancake also has good features. The solubility reached the lowest value near the isoelectricpoint. In the acid and alkaline condition deviating from isoelectric point, the solubilityincreased gradually. The water-holding capacity was influenced by the temperature and pHvalue. It reached the maximum value at50℃. When pH is5it reached the lowest value.Deviating from isoelectric point, the water-holding capacity increased gradually. The oilabsorption reached the lowest value at50℃.Deviating from50℃, the oil absorptionincreased gradually. The emulsifiability and emulsion stability reached the lowest valuenear the isoelectric point. In the acid and alkaline condition deviating from isoelectric point,theemulsifiability and emulsion stability increased gradually. The foamability reached thelowest value near the isoelectric point. At the same time, the foam stability was best. Withtemperature increasing, viscosity presented a downward trend.