Effect Of Flaxseed Gum On Thermal Gelling Properties Of Porcine Myofibrillar Protein At Different Physicochemical Conditions

In recent years,with the rapid development of the global food industry and the breakthrough technology of chemical synthesis,food additives have got more and more attention from consumers.Hydrocolloids or polysaccharides,derived from a variety of plants and microorganisms,are applied as the most effective fat substitutes for developing low-fat meat products.Flaxseed gum(FG)is one of the hydrocolloids,which has been extracted from flaxseed hull or flax seed.Owing to the features of thickening,gelling,emulsification,stability,FG has been used extensively as thickener,adhesive,stabilizer,emulsifier and foaming agent in the food industry to substitute pectin,agar,arabic gum,sodium alginate.FG has shown considerable potential in the meat product due to its good hydrophilicity and emulsibility and it can significantly ruduce oil extraction rate and enhance the stability of dispersed system and prevent the aging of starch.While myofibrillar protein(MP)gel thermal process affected by the outside world factors,such as heat temperature,pH value and ionic strength.To our knowledge,the effect of FG on MP gel properties under different physicochemical conditions is still unclear.In order to understanding of myofibrillar protein and flaxseed gum gel system,promoting the industrialized application of flaxseed gum in meat products,for the development and application of flaxseed gum in the gel in the low-temperature meat products provide theoretical basis.Hence,the objective of this study is to research the effects of FG(FG:MP=1:10)on the gel properties of heat-induced MP gel with different heat temperature,pH levels and NaCl concentration.The contents and results were as follows:1.Effects of flaxseed gum on thermal gelling properties of myofibrillar protein at different heating temperatureThe results revealed that increasing temperature value could significantly decrease the water holding capacity(WHC)of gels(P<0.05),and enhance the gel strength of gels(P<0.05).Addition of FG enhances WHC and decreases gel strength of gels as temperature higher than 50? significantly(P<0.05).Raman spectroscopic analysis reveals that increasing the heating temperature from 30? to 80? induces the partial transformation of ?-helices into ?-sheets.At the same heating temperature,addition of FG leads to the transformation of a-helices into ?-sheets,affecting the formation of gel.The rheological test showed that storage modulus(G')values during MP gelation were declined with addition of FG(P<0.05)when temperature higher than 50?.Gel holes of MP appears at 50?,and MP-FG forms a fine dense network at temperature of 70 and 80? as found by the scanning electron microscopy(SEM)images.2.Effects of flaxseed gum on thermal gelling properties of myofibrillar protein at different pH valuesIncreasing pH value from 5.5 to 7.5 could significantly enhance the WHC of MP gels(P<0.05).The gel strength increased first and then decreased with the increase of pH,and the highest gel strength was at pH 6.0.Addition of flaxseed gum has different effects on the gel strength of myofibrillar protein under different pH conditions.The addition of FG significantly decreases the gel strength(P<0.05)as pH lower than 6.5,and increased significantly.pH higher than 6.5.Raman spectroscopic analysis indicated that decreasing the pH from 7.5 to 5.5 caused the partial transformation of a-helices into(3-sheets,and when pH higher than 5.5,the addition of FG decreases significantly the content of a-helix(P<0.05),and ?-sheets increases significantly(P<0.05).From the SEM images,adding FG can make the MP microstructure more dense and homogeneous under different pH conditions.And same FG concentration,network structure is more compact as pH increased.3?Effects of flaxseed gum on thermal gelling properties of myofibrillar protein at different NaCl concentrationsThe results revealed that increasing NaCl concentration from 0.2 M to 0.4 M could significantly increase the WHC of gels(P<0.05),and increase the gel strength of gels(P<0.05).Addition of FG enhances WHC and decreases gel strength of gels at different NaCl concentration.Particle size distribution result showed that in low NaCl concentration(0.2 m)adding FG increased the particle size of MP,while decreased the particle size of MP at high salt concentration.We can found that when the concentration of NaCl 0.2 M conditions,adding FG of MP three-dimensional network structure is weak.With the increase of NaCl concentration,add flaxseed gum the myofibrillar protein network structure is more compact in SEM images.