Effects Of Strong Alkaline Electrolyzed Water On Properties Of Konjac Sol And Gel

Konjac glucomannan（KGM）is the main functional component of konjac concentrate,with good water absorption,gelation,film formation and emulsification functional propertie.Glucomannan molecules of konjac sol were deacetylated by heat treatment under certain alkaline conditions to form konjac gel.The commonly used konjac gel basic coagulants are calcium hydroxide,sodium carbonate,etc.Alkaline electrolyzed water（AEW）is obtained by electrolyzing salt solution.It has strong permeability and high p H value,and oxidation-reduction potential（ORP）can sterilize and inhibit bacteria,with low cost and high safety.In this paper,konjac refined powder was taken as the research object,and AEW was used to swell konjac refined powder to explore the effect of AEW on the properties of konjac sol.And prepared konjac gel to explore the influence of AEW on the properties and quality of gel,in order to provide a preliminary reference for the application of AEW in konjac gel processing.In addition,through AEW sterilization and storage of konjac gel,the effect of non-heated sterilisation of AEW on the gel storage effect was explored,which provided the basic research theory in the preservation of konjac gel,and accumulated the basic data of AEW in the preservation of konjac gel.To sum up,in order to speed up the transformation and upgrading of the konjac industry in my country,it provides some technical support.The main research methods and results of this topic are as follows:（1）Swelling properties of konjac sol prepared with AEW（H_A）and pure water（H_W）.The swelling speed and viscosity of the refined powder particles were measured,the effect of AEW on the swelling behavior was explored,and the transparency of the sol after the konjac refined powder was completely swollen and the effects of time and temperature on the stability of the sol were further studied.And to explore the influence of the fluid properties of the sol,the steady-state scan and the frequency scan were carried out respectively.The results showed that the swelling rate of the two konjac sols was the same,the maximum viscosity was reached in 2h,H_Wwas 25017 m Pa·s,and H_Awas 25650 m Pa·s,with no significant effect（P>0.05）.After slow swelling at room temperature,the transmittance of H_Adecreased,and the H_Wremained basically unchanged.However,the transparency of the two konjac sols had no significant effect within 2 h（P>0.05）.As the scanning time increases,the stability of H_Wincreases,and it gradually changes to solid-like properties during the gelation process.For H_A,the storage modulus（G′）and loss modulus（G″）have been in a flat trend,and the stability is better.The temperature scan found that the G′and G″of H_Wbefore 60℃decreased with the increase of temperature,after the intersection at 60°C,with the increase of temperature,it rises slowly,and gradually tends to be flat at 80°C.The G′and G″of H_Adecreased slowly before 80℃,and then increased rapidly with the increase of temperature,and the increase of G′was larger than that of G″.The viscosities of H_Wand H_Agradually decreased with increasing shear rate,and showed obvious shear-thinning properties at low shear rates.The viscosity eventually tends to be constant at higher shear rates.（2）Konjac gel was prepared by using AEW(G_AEW),calcium hydroxide(G_Ca)and sodium carbonate(G_Na).By comparing the color,water holding capacity,gel strength,freeze-thaw stability,texture properties and rheological properties of gel samples,the physical properties of AEW on konjac gel were explored.The results show that G_AEWhas the best whiteness and the lowest yellowness value,and its L*value of77.27 is much larger than that of G_Caand G_Na（P<0.05）.The water evolution rate after5 freeze-thaw cycles was measured and found that the water evolution rates of G_AEW,G_Caand G_Nawere 72.29%,72.05%and 72.00%,respectively,with no significant difference（P>0.05）.G_AEWhas a solid internal structure and the highest gel strength（562.29 g）,showing a significant difference（P<0.05）.In addition,the water holding capacity of the gel sample reached 95.93%,which was not significantly different from that of G_Ca（96.59%）（P>0.05）.Through the determination of rheological properties,G_Ca,G_Naand G_AEWhave strong gel structures in the frequency range.（3）AEW affects the konjac gel properties was investigated by using deacetylation determination,infrared,X-ray diffraction,thermogravimetric and scanning electron microscopy.The gel deacetylation degree measurement showed that all the prepared konjac gels had a certain degree of deacetylation reaction,and the deacetylation degrees of G_Ca,G_Naand G_AEWwere 87.06%,75.90%and 63.57%,respectively.FT-IR spectrum confirmed that the characteristic peak of acetyl group at 1724 cm^-1in the prepared konjac gel KGM molecular structure disappeared.X-ray diffraction shows that G_AEWhas diffraction peaks at 2θ=10^oand 20^o,and the molecular microstructure is ordered compared with natural KGM.It was found by scanning electron microscope that the wall layer of G_AEWwas thin,but there were few micropores on the wall,and the network structure was orderly,flat and dense.（4）The chromaticity,weight loss rate,texture properties,total number of colonies of gel and p H of storage solution were measured to reflect the changes in physical properties of the gel during storage,and the effects of non-heated sterilisation of AEW and pasteurization on the storage stability of konjac gel were compared and analyzed.sexual influence.The results showed that the L*,a*,b*values of konjac gel treated by AEW-nonheated sterilisation were significantly different from pasteurization（P<0.05）,and the G_AEW-nonheated sterilization group had the best color performance.With the increase of storage time,the L*value of it showed an upward trend,and the a*and b*values gradually decreased.The weight loss rate of the samples increased with time,but decreased more slowly for non-heated sterilization than for pasteurization.The p H of the storage solution decreased with time,and the p H value of the non-heated sterilization group decreased significantly compared with the pasteurization group.Among them,the p H of G_Na-nonheated sterilization group decreased from 12.65 to10.79.However,the difference in p H drop in pasteurization group was less than 1,and the difference was not significant（P>0.05）.The increase in gel hardness in the pasteurized group was greater than that in the non-heated sterilized group.G_Ca-pasteurized hardness increased the most,G_AEW-nonheated sterilization increased the least.On 28d,G_AEW-nonheated sterilization had the smallest hardness.On 7d and 14d,the elasticity difference of the samples were close to 1,and the product elasticity was good.But at 21d and 28d,the difference in elasticity between the samples increased.On28d,the chewability of the G_Ca-pasteurized group reached 4800,and the G_AEW-pasteurized and G_AEW-nonheated sterilized groups were 3900 and 2897,respectively.By regularly measuring the total number of microbial colonies,it was found that within 28 days,the total number of sample colonies was lower than the standard limit（1000 cfu/g）.The total number of colonies in the G_AEW-nonheated sterilization group was the lowest.