| Cantaloupe is a kind of fruit with beautiful color and sweet taste, which also contains many body essential nutrients; it has many certain health functions, such as playing a clear fanner to anxiety, dieresis and other kinds of effects. But when concerned to the concentrated maturity melon harvest, it is easy for cantaloupe to decay because of bacterial infection or long-time storage, therefore, how to extend the shelf life of cantaloupe and maintain its commodity value becomes an urgent problem to be solved in cantaloupe development. Cantaloupe powder, as a new processed product, has benefits of convenience and rich-nutrient, which not only provide consumers a new product, enriches melon series type, improves the added value of cantaloupe, but also plays a balancing role in cantaloupe sales peak, and thus melon powder processing has good economic effects and broad application prospects.In this thesis, different drying agents were used to help get the melon powder, and quality degradation regularity was studied. We preliminary developed a cantaloupe powder spray drying process, discussed the effect of accessory added ratio on cantaloupe powder properties, and optimized operating parameters using response surface methodology, the optimal set of quality cantaloupe powder were studied. The main findings are as follows:1. HDE maltodextrin, LDE maltodextrin and gum arabic were used as drying agent to obtain dry powder samples, three batches of samples were tested for adsorption isotherm model fitting, the results showed that:sample based on LDE were less hygroscopic, while powder based on HDE were the most hygroscopic, the water adsorption data of batches of samples fitted BET model well; tests of the samples were measured for Tg values (glass transition temperature) after adsorption equilibrium, and Gordon-Taylor equation seemed to fit the data well; hygroscopic tests and Tg measurement both validated the plasticizing effects of water on amorphous materials.2. Test analyzed effects of several materials like LDE maltodextrin, P-cyclodextrin and gum Arabic on liquid viscosity, sensory scores, moisture contents and solubility of cantaloupe powder products. For the sake of improving the powder quality, the consolidated balance analyses through orthogonal test were conducted for spray-dried powder, and the optimal amounts of accessory were:maltodextrin50%,β-cyclodextrin3%,0.5%gum Arabic.3. Based on the single-factor tests, we selected three factors inlet air temperature (A), hot air flow rate(B) and feeding rate (C) for BBD optimization design, and product yield was the main response index, the corresponding quadratic response surface regression model was as follows:Y (%)=45.75-1.08A+2.67B-0.36C+0.52AB-1.33AC+1.37BC-6.96A2-3.81B2-4.29C2, R2=0.9587. Via response surface optimization analysis, spray-dried powder cantaloupe optimum conditions were obtained:cantaloupe juice concentration11Brix, maltodextrin dosage50%, inlet air temperature149℃, hot air flow37.5m3/h, feeding rate10r/min. Proving experiments data of melon powder obtained under this process were:product yield51.07%, moisture content3.56%, which were close to the theoretical values.4. Sensory evaluation and determination tests were carried out under the optimal conditions to determine its sensory quality and nutrition contents, the results showed that:the powder obtained under preferred accessory ratio have a color of pale yellow, with no impurities or powder caking, the moisture, solubility are all in good levels, the redissolved solutions are of good dispersibiliry and stability. Physicochemical indicators of cantaloupe powder measured were as follows:32.38%of total sugar content,29.45%of revertose content, Vc content was67mg/100g, powder products overall have a good level of nutritional quality. However, the product is still strong hygroscopic, how to control its hygroscopicity with methods like adding anti-caking agent still need further study. |
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