Study On The Mechanism And Functionality Of Protein-Starch Mixed Gels Processed By HIPEF

In this paper, myofibrillar protein and pueraria were choosed as the object ofstudy. Under the processing of high-voltage pulsed electric field, the influence onrheological property, microstructure, texture property and water-retaining property ofmixed gel of myofibrillar protein and pueraria starch was analyzed based on thedifferent experimental condition of electric field intensity, pulse count, pH, salt, andinternal exchange reaction between SH and S-S molecule is analyzed. Besides, theformation mechanism of the mixed gel was discussed. In addition, functionalcharacteristics of various gel products were investigated by taking the digestibility andoxidation resistance as the main indexes.In this paper, various factors which influence the gel formation were fullyconsidered. True and reliable data are obtained from experiments, and the processingtechnological parameters are screened. A technology platform for the gel mixingproduction from myofibrillar protein and pueraria starch using high-voltage pulsedelectric field processing was established. The research contents are as follows:(1) The effect of concentration, pH, ionic strength, and metal ions on gelhardness of pueraria starch were studied using the L8(27) orthogonal testes. Moreover,the effect of pueraria starch proportion, pH and ionic strength on the hardness andwater holding capacity (WHC) of protein-starch mixed gel were also studied. Theresults showed that the order of the factors which affect the hardness of puerariastarch is: K+>ionic strength>Ca2+>pueraria starch content>Mg2+. The hardness ofmixed gels of myofibrils and pueraria starch are higher than that of pure myofibrilsand pure pueraria starch case while the WHC is lower than that of the pueraria starchcase.The order of factors which effect the hardness of myofibrillar protein andpueraria starch mixed gels is: pueraria starch ratios> ionic strength>pH.(2) The influence of the treating conditions on the hardness, elasticity and water holding capacity of the myofibrillar protein gels were investigated by the single-factorexperiments, in which the ranges of the electric field strength, pulse numbers andheating temperature are15to55kV/cm,2to8and50to90℃, respectively. Theresearches results showed that the treatment of the high intensity pulsed electric fieldcan lead a significant change in the properties of the formed gel. Compared with theuntreated myofibrillar protein, the hardness, elasticity and water holding capacity ofthe HIPEF treated gels decrease when the electric field strength varied from15to25kV/cm, increase significantly when the electric field strength was35kV/cm, anddecrease again when the electric field strength is reached to45kV/cm. Under theelectric field strength of35kV/cm, the hardness, elasticity and water holding capacityof gel increase with the increase of pulse number, but the gradient is graduallydecreased. The gel has the optimal performances of hardness and elasticity, and thewater holding capacity at the heating temperature of80℃and70℃, respectively.(3) In order to produce the protein-starch gel, the mixed solution with variouspueraria starch content was firstly treated by HIPEF, and then processed by water bathtreatment. The gelling properties of the myofibril protein-pueraria starch mixed gelwere tested using single factor experiments and orthogonal analysis experiments, inwhich the different factors of pueraria starch content, electric intensity, and pulsenumber were studied. The results indicated that the mixed gels have favorable gellingproperties under the conditions of mix solutions with myofibril protein (5%) andpueraria starch (5%),30kv/cm HIPEF pretreatment, pulse number of6and water bathof80℃for30min. Effects degree of factors on the gelling properties of the mixedgels is electric intensity, pulse number and mass fraction of pueraria starch in theorder of decreasing evolutionary.(4) The effects of the HIPEF-assisted extraction of total flavonoids from puerariawere preliminary investigated, in which the technical parameters were optimized.Four factors including ethanol concentration (35%,45%,55%,65%,75%,85%, and95%), electric field intensity (10,20,30,40,50,60kV/cm), electric pulse number (0,2,4,6,8,10and12) and ratio of material-solvent (1:20,1:30,1:40,1:50,1:60and1:70) were investigated using the L9(34) orthogonal test. The results indicated that theratio of material-solvent is the main factor, followed by electric field intensity, pulsenumber and ethanol concentration. The optimal conditions were as follows:material-solvent ratio of1:40, electric field intensity of20kV/cm, pulse number of8 and ethanol concentration of75%. Under these conditions, the extraction yield of totalflavonoids can reach to5.12%which is higher then that of conventional extractionmethod for1.56%, and the microwave assisted extraction for1.92%. The resultssuggested that the HIPEF-assisted extraction process is feasible, and the extractionyield of total flavonoids from pueraria leaves was higher than that of the conventionalmethod.(5) The D-galactose induced aging mice were chose as the model and fed withdifferent gels that have the same content of pueraria lobata flavone to study theefficacy of the different gel on the antioxidant capacity in induced aging mice. The gelsamples contain three types of gel (Group A, B, C). The Group A is HIPEF processedmyofibrillar protein and pueraria starch mixed gel; Group B is heating processedmyofibrillar protein and pueraria starch mixed thermal gel; and Group C is myofibrillarprotein gel. The results show that by comparing with the control group, the activitiesof SOD, GSH-Px, CAT, and T-AOC in the serum, liver and brain tissues of the micefed by the gel contents flavone extract are significantly increased as well as thecontent of MDA is dramatically decreased. This result indicates that the flavonoidscontained in pueraria starch have the great effect of improving the activity ofantioxidase in subacute senile mice. Considering the changes among the groups, theantioxidant effect in a descending order is: Group A> Goup B> Group C> controlgroup, i.e. feeding the myofibrillar proteins and pueraria starch mixed gel whichproceeded by HIPEF can obtain the best antioxidant effect in mice.This study disscussed the mechanisms of the high-voltage pulse electric fieldtreatment on the formation and property of the protein gel and protein-starch mixedgel. The results of this study provide a basis for the further researches in this field.The results of this study indicated the mechanism of the high-voltage pulseelectric field that plays the role on protein gels and protein gels and protein-starchmixed gel to some extent, which provides an important reference value in theacademic for further research.