| Gel candy is a popular casual snack.There are many kinds of gel candy in the market,but they taste similarly and lack of creativity.Therefore,this research developed a new type of coated gel soft candy with gelatin and gellan gum.The experimental design methods of this research are orthogonal test and response surface test and so on.This paper studied the optimum dissolution conditions of gellan gum,the gel properties and rheological properties of gelatin-gellan gum compound system,the best formula of new gel jelly and the characteristics of coated jelly gum.The main conclusions are showed as follows:(1)The research of dissolution conditions of colloidGellan gum is insoluble in water at normal temperature,which make it inconvenient to use.The influence factors of the dissolution of gellan gum include sodium citrate concentration,sugar concentration and dissolution temperature.And its effects on dissolution characteristics were researched in this paper.The single factor experiment obtains the dissolve optimum condition of gellan gum is: Sodium citrate concentration 1%,white sugar concentration 10%,temperature 90 ?.This research select the appropriate three-factor and three-level orthogonal test based on single-factor experiments,and the conclusion of preferred gellan gum dissolution process conditions is: Sodium citrate concentration 0.75%,white sugar concentration 9%,temperature 100 ?,under which,the turbidity of solution is 45.33±0.57 NTU and the best dissolution of gellan gum was obtained.(2)The research of gel properties of gelatin-gellan gum compound systemThe hardness and elasticity of colloid are the most important factors that affect the taste of gel soft candy.The effect of colloidal amount,metal ions,sugar and acid on gel properties were studied.According to the research data: The hardness and elasticity of the system both increased significantly with increase of gelatin concentration.When the concentration of gellan gum increased,the hardness of the system increased gradually,and the elasticity changed little.When the concentration of calcium chloride,sugarconcentration or acid concentration increased,the hardness of the system rose first and then decreased,and the elasticity changed little.The single factor experiment obtains the optimum condition is: Gelatin concentration 4.5%,gellan gum concentration 0.5%,calcium chloride concentration 0.1%,sugar concentration 40%,proportion of white sugar and fructose syrup 1:1,acid concentration 0.75%;citric acid and malic acid ratio 1:1,under which,the taste of system was more close to commercial jelly.(3)The research of rheological properties of gelatin-gellan gum compound systemBy temperature scanning of gelatin-gellan gum compound system,it was shown that pure gelatin system only has one gelation temperature of 20.9 ?,and it means that the thermal stability of its gel is poor and it's easy to melt at normal temperature.However,three gelatin-gellan gum compound systems that adding different concentrations of gellan gum have two sharp increases in the elastic modulus during the cooling process.In this process,two gels occur,corresponding to two gelation temperatures.The first gelation temperature lies between 31.8 ?-42.1 ?,and it is determined by the characteristic of gellan gum and is positively correlated with its concentration.The higher the gellan gum concentration,the higher the gelation temperature at the first time.The second gelation temperature is determined by the characteristic of gelatin in system,and three of them are basically maintained at around 21 °C.The rheological properties of the compounded gel show that gellan gum can increase significantly the gelation temperature of gelatin-gellan gum compound system and improve the thermal instability of the single gelatin gel system by compounding,and then increase the shelf life and high temperature tolerance of the soft candy.The shear scan showed that the gellan gum solution is pseudoplastic fluid,and the system apparent viscosity decreases sharply under the high sugar solution.So the amount of sugar in soft candy production should not be too high.(4)The optimization process research of gel jelly process based on response surface methodThree are three factors(gelatin concentration,gellan gum concentration,calcium chloride concentration)and two indicators(hardness and sense scores of gel jelly).The optimum process condition in a certain ratio of sugar to acid analyzed by response surfaceis: gelatin concentration 4.48%,gellan gum concentration 0.49%,calcium chloride concentration 0.08%,under which,the taste of system was more close to commercial jelly and the sensory value was the highest.Adding juices based on the best process can improve the flavor of gel jelly.When the concentration of concentrated grape juice is 10%,the gel jelly texture was best.(5)The characteristics research of coated gel soft candyThe effects of heating temperature and heating time on the tensile strength of collagen casing were researched.The tensile strength value and toughness of collagen casing that without pretreatment are too high,so it is poor taste.The tensile strength value of collagen casing was too low when the heating time was more than 1.5 h or the heating temperature was above 90°C.Therefore,the heating temperature of collagen casing should be controlled below 90°C,and the heating temperature should be controlled within 1.5 h.Too high or too low tensile strength was unfavourable to the texture properties of casing.Due to the high moisture content of the coated gel soft candy,sterilization can guarantee shelf life safety.The effect of bactericidal conditions on the texture of coated gel soft candy was explored.Both the sterilization time and the sterilization temperature increased would make the hardness and elasticity of the coated gel candies decreased,which the hardness decreased significantly and the elasticity decreased slowly.Considering the palatability of commercially available soft candy,the sterilization temperature of 80°C and the sterilization time of 0.5h were selected.The coated gel soft candy obtained at this condition is closest to the commercial candy,and the palatability is best.The microbiological content of coated gel soft candy was determined according to the national standard GB17399-2016.The results showed that the total number of colonies and the number of coliforms were all within the limits specified by the national standard. |
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