Study On The Effect Of Stewing Time And Compound Polysaccharide On Quality Characteristics Of Meat Jelly

In recent years,with the improvement of the level of modernization,people are keen on the pursuit of food with high protein,low fat and low calorie.Pig skin jelly is a traditional cold-cut meat product in China.As a typical high-protein,low-fat food,it is favored by consumers because of its simple production technology,beautiful appearance,smooth and elastic mouthfeel,fresh and delicious taste,and high edible value.The main component of pig skin jelly is gelatin,which has a low melting point and is easy to melt at room temperature,which to some extent restricts its processing,transportation and preservation,and directly affects the sensory quality.Various polysaccharides have been added to pig skin jelly to improve the melting point and improve its texture and sensory quality.For example,Gellan gum is often used together with calcium chloride to improve pig skin jelly’s melting point and stability.However,the gel formed by Gellan gum is usually rigid and brittle,and excessive dosage will make the product too hard and taste worse,which it is difficult to improve the melting point of pig skin jelly and promote texture and sensory quality by using a single polysaccharide.Therefore,gellan gum is often used in combination with some other hydrophilic colloid to improve the gel properties.And a certain amount of inulin dissolved in water can provide a cream-like appearance,smooth texture and delicate mouthfeel.It is often used as a fat substitute in many studies.Therefore,inulin has the potential to combine with rigid and brittle gellan gum to improve sensory quality and melting point of pig skin jelly.However,the application of gellan gum and inulin mixed to improve the quality of pig skin jelly has not been reported,and the interaction mechanism between gelatin-gellan gum-inulin is not clear.Therefore,this research studied quality characteristic changes of the traditional meat jelly in different stewing time.And on this basis,the traditional meat jelly stewed in different stewing time under the quality characteristics of change,and on this basis,using of polysaccharides（gellan gum,inulin）optimized the quality of traditional pig skin jelly.Finally,with gelatin-gellan gum-inulin as pig skin jelly model,the properity and mechanism of protein-polysaccharide mixed gel were performed with adding different ratios of gellan gum-inulin.This study provides a theoretical basis for the further processing of pig skin jelly and the development of related gel products.The main research contents and results are as follows:1.Preliminary study on the quality characteristics of traditional meat jellyThe quality characteristics of meat jelly（pig skin and trotters）formed under the stewing time of 1,1.5,2,2.5 and 3 h were analyzed by measuring its proximate yield and composition,collagen solubility,gel strength,water binding capacity,texture,gelling and melting temperature,and sensory properties.The results showed that pig skin was easier to gel than trotters.Trotters were stewed for 3 h to gel,pig skin was stewed for 1 h to gel,and pig skin stewed for 1.5,2,2.5,3 h can form the edible solidification state.Stewing time significantly affected the quality of meat jelly.As the stewing time increasing,fat content,protein content and collagen solubility in meat jelly increased gradually,water binding capacity,hardness increased,and springness decreased.Combined with the sensory evaluation,it was determined that the hardness and springness of pig skin jelly with stewing for 2.5 h were the best,and the overall acceptability was the highest.However,the melting temperature of pig skin jelly didn’t change with the stewing time,and was always around 28.4℃,indicating that the pig skin jelly melts at room temperature.Therefore,pig skin jelly at 2.5 h was selected for the next experiment.2.Optimization of the addition of polysaccharide and calcium chloride in pig skin jelly by response surface methodologyPolysaccharides（gellan gum and inulin）and calcium chloride were added to optimize the gel property and edible quality of pig skin jelly with stewing 2.5 h.The hardness,springiness,melting point and sensory score were used as response value in the single factor experiment,then Box-Behnken response surface analysis was used to establish the regression equation of sensory score to get the optimal value.The results showed that the addition of gellan gum increased the melting point,hardness and springiness of pig skin jelly,the addition of Ca Cl₂ could promote gellan gum to increase the melting point of pig skin jelly,and the addition of inulin improved mouthfeel.The optimal addition conditions were 0.45 g/100g of gellan gum,0.06 g/100g of Ca Cl₂,and 3.77 g/100g of inulin.Under these conditions,the hardness,springiness,melting point and sensory score of the optimized pig skin jelly were 340.08 g,0.92,43.4℃and 8.85 respectively,and its microstructure was more compact.Therefore,it is feasible to improve the quality of pig skin jelly by adding gellan gum,inulin and Ca Cl₂.Moreover,the addition of gellan gum and inulin at the same time can make the sensory acceptability higher than that of gellan gum or inulin alone.3.Effects of gellan gum and inulin on the mixed-gel property and mechanism of gelatinThe optimized pig skin jelly system was simulated with gelatin-gellan gum-inulin in order to further explore the gel property and mechanism of the protein-polysaccharide mixed-gel system.The gelatin（6%）containing Na Cl and Ca Cl₂ was added with different ratios of gellan gum and inulin（0.4%）（10:0,8:2,6:4,5:5,4:6,2:8,0:10）.The texture profiles,rheological properties,water mobility,intermolecular forces,circular dichroism spectra,and microstructures were analyzed.The results showed that addition of gellan gum-inulin could improve the hardness,chewiness,and cohesiveness of mixed-gel,besides maintaining appropriate springiness.Water mobility of the mixed-gel decreased while viscoelasticity increased upon the addition gellan gum.At gellan gum:inulin=2:8,the melting temperature of mixed-gel was far higher than that of gelatin gel itself.The gelatin-gellan gum-inulin gel showed decrease in non-specific bonding and increase in hydrogen bonding compared to the gelatin gel.CD spectra indicated the promotion of gelatin unfolding by gellan gum,hence suggesting the binding of gellan gum to gelatin,and binding ability was better at gellan gum:inulin>5:5.Combined with Cryo-SEM,it was found that the chemical cross-linking between gellan gum and gelatin enhanced the network structure,and inulin was embedded into the network structure in the form of physical filling.Therefore,the presence of gelatin-gellan gum-inulin at the same time is propitious to form a excellent gel network structure and can improve the gel property.