Processing And Protein Of Selenium-rich Potato Powder

In 2015,China officially launched the potato staple food strategy,and it is estimated that more than 50%of potatoes will be consumed as the main grain by 2020.Selenium is an indispensable trace element in human and animal,which plays an important role in maintaining normal function and health.With the continuous development of selenium health industry and the promotion of national potato staple food strategy,researchers have carried out a lot of research work on the selenium absorption rules of potatoes and the influence of selenium on potato growth,yield,quality and other aspects.As the world capital of selenium,enshi prefecture of Hubei province has reached a new height in the development of selenium potato industry.This paper takes selenium-rich potato in enshi,Hubei province as the experimental material,aiming to develop the whole powder technology and selenium protein properties of selenium-rich potato.This is of great economic value and social significance for potato staple food and potato product upgrading.The research content of this paper mainly includes the following parts:1)The effects of slice thickness,blanching temperature,blanching time,steam temperature and hot air temperature on selenium content,protein content,starch content,reducing sugar and iodine blue value of potato were studied.The results showed that the changes of slice thickness and temperature had a significant effect on the selenium content,especially the thickness of slices,which may be caused by the loss of selenium binding substances in the process of slicing.According to the literature investigation,selenium is mainly divided into organic selenium and inorganic selenium in plants.Inorganic selenium content is small,mainly organic selenium,which accounts for about 80%of the total,and protein selenium is the main form of organic selenium.At the same time,the changes of slice thickness and temperature conditions also have significant effects on protein and starch.It can be inferred that selenium in potatoes has a lot of combination with protein and polysaccharide,and the loss of selenium is caused by the loss of starch and protein in the slicing process.Blanching time,blanching temperature and steam time had significant effects on reducing sugar and iodine blue value.This is related to the solubility of soluble sugar in water and the activity of starch decomposition enzyme.On the basis of single factor and multi-factor experimental design,through data analysis and considering the topic,the purpose of the selection of selenium is significantly influenced factors of slice thickness,blanching temperature and hot air temperature as the factor,multi-factor experiment of sensory evaluation of potato powder as indicators,finally it is concluded that the optimal potato flour production process conditions.The results showed that potato powder scored the highest sensory evaluation when slice thickness was 5mm,blanching temperature was 60?,hot air temperature was 70?,blanching time was 2min and steaming time was 10min.At this time,the selenium content of potato powder is 0.19?g/g,which is rich in selenium potato powder.2)The whole potato powder obtained by the optimal process was extracted with selenium protein of potato.Firstly,the extraction agent of potato protein was screened,and the relevant literature and the relevant experience of protein extraction in our laboratory were consulted.In the design of water,0.5mol/L of sodium chloride,0.1mol/L of hydrogen chloride and 0.1mol/L of sodium hydroxide were used as the extraction agent of potato protein,and the extraction rate of the protein was measured by coomas bright blue method.The results showed that the protein content of alkali extract was much higher than that of other extracts.According to the literature,potato contains 30%⁴0%storage proteins,50%protease inhibitors,10%²0%polyphenol oxidase and other proteins,while protease inhibitors are basic proteins,the experimental results may be related to the types of potato proteins.Therefore,0.1mol/L sodium hydroxide was selected as the extraction agent of potato protein.3)Potato protein was crude extracted by alkali extraction and acid precipitation,and then purified on anion exchange agarose gel column DEAE Sepharose Fast Flow?2.5cm×60cm?,and eluted with 0-1m NaCl tris-HCl buffer?pH 8.8,25 mmol/L?.The results showed that there was only one elution peak of potato protein and only one potato protein component was extracted.Eluent with absorbance greater than 0.1was collected and freeze-dried to obtain pure potato protein.The selenium content of crude protein and pure protein in potato was determined by 0.42?g/g and 1.78?g/g,respectively.The results showed that the selenium content was enriched when the protein content of potato increased,which proved that the selenium in potato was mainly bound to protein.4)The structural properties of potato protein were studied.Firstly,it can be obtained from the analysis of the amino acid composition of potatoes that the total amount of amino acids in selenium-rich potatoes is greater than that in keshan potatoes.The seven essential amino acids measured in selenium-rich potatoes account for 45.35%of the total amino acids.The seven essential amino acids measured in keshan potato account for 44.50%of the total amino acids.Moreover,the content of methionine in selenium-rich potatoes is higher than that of cysteine,so it is speculated that selenium mainly combines with methionine.According to the organic selenium morphology results of selenium protein in potato analyzed by HPLC-ICP-MS,selenium binds cysteine and methionine,and the content of selenium cysteine is higher than methionine selenide,which is inconsistent with the analysis results of amino acid composition,and it is speculated that the selenium methionine is destroyed during the enzymatic hydrolysis.The UV scanning results showed that the UV absorption peak of potato protein could be divided into two regions:the peptide bond absorption peak of 200²50nm and the aromatic amino acid absorption peak of250³00nm.The infrared results showed that the crude protein had two more absorption peaks of 1159cm^-11 and 1023cm^-1 than the pure protein,and some bond types of the protein were destroyed in the purification process.The structure difference of the two potato proteins was not significant.As can be seen from the electron microscope scanning spectrum,the morphology of se-rich potato protein and keshan potato protein are different to some extent.Se-rich potato protein is massive and relatively compact,while keshan potato protein is mostly rod-shaped and loose in structure.5)The activity properties of potato protein were studied.From the results of DPPH and ABTS free radical scavenging experiments,it can be concluded that the scavenging rate of pure protein is greater than that of crude protein,and that of enshi selenium-rich protein is greater than that of keshan potato protein,which may be caused by selenium.6)In order to respond to the potato staple food strategy and increase the use of potato powder,the maximum addition amount of potato powder in potato biscuits was studied.At last,through the research of potato biscuit texture and senses,the maximum addition amount of potato powder is 50%.