| In this paper,Zanthoxylum armatum v.novemfolius seeds as raw materials,physical and chemical properties of protein were studied from both seed shell and seed kernel.The protein was extracted from the kernel by kernel and kernel protein isolate was preparated.The physical and chemical properties and processing properties of the protein isolated from Zanthoxylum armatum v.novenfolius seed kernel were further studied.So as to promote the development and utilization and increase the added value of Zanthoxylum armatum v.novenfolius seeds resources.The main contents and conclusions are as follows:(1)After Zanthoxylum armatum v.novemfolius seed being smashed into pieces,petroleum ether was used as the extraction agent,and the Soxhlet extraction method was used for degreasing treatment.The basic composition,isoelectric point,subunit composition and amino acid composition of protein in Zanthoxylum armatum v.novemfolius seed shell and kernel were compared.The results show that the components of Zanthoxylum armatum v.novemfolius seed shell to carbohydrate based,content is 62.92%,protein content is only 5.29%.Zanthoxylum armatum v.novemfolius seed contains not only 47.01%oil,also 30.90%protein,after degreasing the content of protein can reach 60.91%.The isoelectric point of protein pH value is 4.5 in shell,3.5 in kernel.The composition of amino acid of Zanthoxylum armatum v.novemfolius seed shell and kernel was complete,and the essential amino acids in kernel accounted for 29.43%of the total amino acids.Protein subunit distribution of Zanthoxylum armatum v.novenfolius seed shell and kernel are in the wide,both of them have 7 bands,and the molecular weight of each band of the two groups is quite different.(2)The salt extraction efficiency of protein from Zanthoxylum armatum v.novemfolius seed kernel was investigated with respect to five variables including extraction time,solid-liquid ratio,NaCl concentration,extraction temperature and pH value.And the extraction condition of protein from Zanthoxylum armatum v.novemfolius seed kernel by salt extraction was optimized by response surface methodology(RSM).The results showed that all investigated parameters had a notable effect on the extraction yield of protein and when pH value was 11 others could be ranked in decreasing order of importance in their effects as follows:extraction time,extraction temperature,solid-liquid ratio,NaCl concentration.The optimum conditions for extracting protein from Zanthoxylum armatum v.novemfolius seed kernel were determined as follows:extraction time 35 min,extraction temperature 50?,solid-liquid ratio(g/mL)1:21,the concentration of NaCl 1.2 mol/L,resulting in an extraction yield of 88.77%.(3)The purity of the protein of Zanthoxylum armatum v.novemfolius seed kernel is 93.17%after dialysis and freeze-drying,and the physicochemical parameters were characterized,Zanthoxylum armatum v.novemfolius seed kernel protein isolate nitrogen solubility index(NSI)is 92.47%,the dissolution rate is high,a good water soluble protein;pepper seed protein density is 147 mg/mL,and the kernel of Zanthoxylum armatum v.novemfolius seed defatted powder density changed significantly compared reduce;Zanthoxylum species rich amino acid,essential amino acid(EAA)proportion as high as 31.61%,according to the FAO/WHO recommended standard of essential amino acids,Zanthoxylum armatum v.novemfolius seed kernel protein isolate in 8 kinds of essential amino acid content were significantly higher than the recommended value for adults,in addition to glutamic acid and arginine content reached 24.58 g/100 g and 13.07 g/100 g.There are 6 bands in Zanthoxylum armatum v.novenfolius seed kernel protein isolate.Compared to the kernel of Zanthoylum armatum v.novemfolius seed defatted powder,a band with a molecular weight of about 19 KD is missing.The thermal stability of the heat separation protein was analyzed by differential scanning calorimetry,it begins to denaturalize at 46.0? and complete denaturalization at 95.9?.By scanning electron microscopy(SEM)observation showed that the lamellar microstructure of defatted kernel of Zanthoxylum armatum v.novenfolius seeds contain small inclusions and many small particles,and pepper seed protein showed a lamellar structure,sparse texture.(4)The effect of different factors on the solubility and foaming properties of Zanthoxylum armatum v.novenfolius seed kernel protein isolate The results showed that pH value,NaCl concentration,temperature and sucrose concentration had significant effects on the solubility and foaming properties of pepper kernel protein.The effect of pH value and NaCl concentration on properties of stabilized emulsions of Zanthoxylum armatum v.novenfolius seed kernel protein isolate were investigated by using emulsifying activity,emulsifying stability,droplet size,optical microscopy measurements and SDS-PAGE gel electrophores.The pH value and NaCl concentration have significant influence on the parameters mentioned above,with the increase of pH value,emulsifying activity and emulsion stability decreased firstly and then increased,with the lowest value at pH 3.In contrast,emulsion particle size(D4,3)increased firstly and then decreased,at pH 3,reached the maximum(D4,3=1.87?m).The addition of NaCl brought down the emulsifying activity and emulsifying stability,which promoted the flocculation of emulsified particles and increased the average particle size(D4.3).Optical microscopy clearly demonstrated that droplet aggregates formed at pH 3 and When the salt concentration was 1.2mol/L.In addition,SDS-PAGE gel electrophoresis showed that there are 3 kinds of proteins with emulsifying effect,respectively,about 5 KD,7 KD,20 KD. |
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