| Mousse is a popular type of low temperature dairy dessert.Adding probiotics and prebiotics in mousse not only increases the nutritional and functional properties of the product,but also gives the product a higher commercial value.Taking mousse as the research object,the fermentation characteristics of five strains of probiotics and their growth characteristics in the mousse matrix were studied,and the probiotic fermenters suitable for probiotic mousse production were screened.By adding inulin as a prebiotic,the effect of inulin on the probiotic mousse quality and probiotic activity was studied.The formulation of the product was optimized and the storage characteristics and functional properties of probiotics and inulin on mousse were studied.The results of the study are as follows:1.The fermentation properties of five lactic acid bacteria and their growth characteristics in mousse,as well as the sensory characteristics and storage stability of mousse were studied.The results showed that the curd time of 5 strains of lactic acid bacteria was 5.5?9.0 h,and the curd time of Streptococcus thermophilus grx02 and Lactobacillus fermentum V9 was shorter than that of 5.5 h and 6.0 h respectively.The pH of 5 probiotics was similar to that of fermented milk,but there was significant difference in the acidity of curd.The results showed that the acidity of L.fermentum V9 and S.thermophilus 937 was significantly higher than that of other lactic acid bacteria,which were 86.14 ° T and 80.19 ° T,respectively.The number of survivors of 5 strains exceeded 8.52 log cfu/mL.The probiotic mousse were prepared from the fermented milk prepared by the above five kinds of lactic acid bacteria,and the pH of the 5 mousse samples decreased slowly,titratable acidity slightly increased and the viable count remained above 7.0 log cfu/g during the 7 days storage at 4 ?.Among them,the decrease of the number of viable cells of mousse prepared by L.fermentum V9 and S.thermophilus grx02 was smaller.S.thermophilus grx02 were more stable and had higher sensory scores during storage.Based on the above results,S.thermophilus grx02,which has a short curd time,a stable pH and acidity during storage,a high viable cell counts,and a high sensory score,was selected as a starter for probiotic mousse.The best formula for probiotic mousse was studied.Based on the single factor test of the amount of fermented milk,whipping cream,maltose and milk added,the response surface methodology was used to optimize the technological parameters of fermented milk,whipping cream,maltose and milk.After analyzing the test results by Design-Expert 8.0 software,it was determined that the optimal formula for mousse was 40.5%for fermented milk,24%for whipping cream,5%for maltose,and 20%for milk,egg yolk 6.5%,white sugar 2.0%,and gelatin 2.0%.Under this condition,the probiotic mousse has a sensory score of 95.5,and a quadratic equation model of the sensory score of the probiotic mousse and various factors,the regression of this model is extremely significant,and is better fitting to the test.2.The effect of inulin instead of whipping cream on mousse quality was studied.Mousse was prepared in six different proportions of inulin instead of whipping cream,and changes in fat content,texture,rheological properties,and sensory quality were studied.The results showed that the addition of inulin reduced the fat content of mousse.When the ratio of inulin instead of whipping cream was 15%,the fat content was 10.9%.Using inulin instead of the cream in mousse will significantly increase the mousse's hardness,chewiness,and reduce mousse's elasticity;adding a certain amount of inulin will increase the initial apparent viscosity value of mousse,when the replacement ratio is 15%,the stability of mousse is relatively good,the hysteresis loop area is smallest,the fastest recovery,but adding too much inulin does not help the mousse's stability;Mousss sensory evaluation with the increase in the amount of inulin increased first rose then decreased,when the inulin instead of whipping cream at a rate of 15%,the sensory evaluation is highest.When it exceeds 15%,the tissue state and sensory evaluation of probiotic mousse are reduced.Through the correlation analysis between the results of texture characteristics and sensory evaluation,it was found that the flavor of mousse was significantly positively correlated with cohesiveness and chewiness,and was positively correlated with elasticity;in short,replacing 15%of the cream in the probiotic mousse with inulin does not affect the sensory quality and texture properties of the product and improves the stability and shape retention of the probiotic mousse.At this time,the fat content in mousse is 10.9%.3.The flavor,functional properties and stability during storage of mousse were studied.The main flavor components and relative content of mousse are known by SPME-GC-MS,by comparing the ability to scavenge hydroxyl radicals(· OH),scavenge DPPH · free radicals,scavenge superoxide(O2-·)and reducing activity to assess the antioxidant effect of mousse,in addition to study the stability of the mousse during storage by measuring physicochemical indicators,viable counts,and sensory evaluation.The results showed that six major volatile flavors was detected,including ketones,alcohols,acids,aldehydes,esters,and others.The three substances with higher contents in mousse are:3-hydroxy-2-butanone,2,3-butanedione and 2-heptanone;adding inulin can improve the formation of ketones and esters in mousse.In particular,the amount of 2,3-butanedione and acetoin is increased;the content of acids and aldehydes is reduced,especially the formation of acetic acid,indicating that the addition of inulin can improve the flavor of probiotic mousse.The effect of storage temperature on ketones and alcohols in mousse was not obvious,but the relative content of acids and aldehydes was reduced,and the formation of esters was increased.The effect on the content of volatile flavors was not obvious;The probiotic mousse has good anti-oxidation ability,and storage at-18? can better maintain the ability of the probiotic mousse to scavenge hydroxyl radicals,DPPH · radical,superoxide anion radicals and reducing power,which is more beneficial to maintain the antioxidant properties of probiotic mousse.The addition of inulin has little effect on the protection of hydroxyl free radicals,DPPH radicals,and superoxide anion radical scavenging ability of the strains,which contributes to improving the reducing power of mousse.Inulin has a certain increase in the antioxidant activity of mousse,but the effect is not significant;During the storage period,the pH of the mousse decreased,the acidity increased,and the number of viable cells remained at 7.0 log cfu/g or more;the inulin increased the pH of the mousse,reduced the titratable acidity of mousse,and protected the survival of S.thermophilus grx02;During the storage period,the hardness,absolute adhesion and chewiness of the four groups of mousse increased;the inulin increased the hardness and absolute adhesion of the mousse;the sensory scores decreased,and the frozen storage was compared with the cold storage.It is more conducive to the protection of the activity of S.thermophilus grx02,the quality is more stable,and it is beneficial to extend the storage period of the product.In short,adding inulin is beneficial to mousse's flavor and stability during storage.Frozen storage at-18? is more conducive to mousse's stability during storage.It is recommended that mousse be stored at-18?. |
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