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Pulsed Air-impingement Drying Characteristics And Quality Of Jujube Slices

Posted on:2017-04-09Degree:MasterType:Thesis
Country:ChinaCandidate:G WangFull Text:PDF
GTID:2271330503989407Subject:Engineering
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Jujube is rich in Vc, sugar, acid and other nutrients, and replenishing spleen, nourishing the heart, soothe the nerves, ease the effects of the medicine and other medicinal value. Jujube production increased year after year, but every year because of poor sales led to a serious waste of date. Now, most of the dates are dried and then further processing into finished products. Furthermore, jujube drying methods are limited, longer drying time, low efficiency, high power consumption, serious and quality loss during the drying process. This study presents Pulsed air-impingement drying dried jujube slices, study on drying characteristics, establish drying model. By the 0 order kinetics model of color change, and a first-order fractional model to fit the establishment date slices at different temperatures. Analysis of jujube slice quality changes in different drying parameters under the condition. Provide technical support and theoretical basis for the control and pulsating air impingement drying process prediction of jujube slices.Through the experimental study on winter jujube slices drying curve and water content in the different temperature(55, 60, 65, 70, 75, 80℃), wind speed(6, 7, 8, 9, 10 m/s) and fluctuating ratio(rotation speed of the disc material: 4, 5.5, 7 r/min) effective diffusion coefficient and drying and activation energy. Study shows that: the winter jujube slices of the drying process of the falling rate drying, moisture diffusion coefficient in the range of 1.52~4.93×10-9 m2/s with the increase of drying temperature and wind speed increased, the Arrhenius equation calculated winter jujube slices drying activation energy for 43.90kJ/mol.Will winter jujube slices pulsation type gas jet impingement drying process fitting commonly used six thin layer drying model, the coefficient of determination(R2), root mean square error(RMSE) and squared error and(SSE) goodness degree evaluation index of six kinds of drying model was evaluated, regression analys is was used to establish the model parameters and drying parameters, different drying parameters on optimal drying model is established. The model fitting optimization index show that the modified page model can better reflect and predict the variation of winter jujube slices pulsation type gas jet impingement drying process water.In order to study on winter jujube slices pulsation type gas jet impingement drying process color change dynamics and color brightness L*(lightness), green/red value a*(Greeness/Redness) b*(Blueness/Yellowness) and △E* describe winter jujube s lices in pulsed gas jet impact the dynamic changes of drying process in color,fitting zero order, first-order and a fractional model, establish dynamic model of color change. Research shows that: the winter jujube slices in different dry temperat ure, the lightness L*, green/red-a* are is increased with the increase of drying time lower; blue/yellow value b* and △E* values are rises with the increase of drying time. A dynamic model of L* were established, a*, b* and △E* with drying temperature and drying time.To study on winter jujube slices pulsation type gas jet impingement drying quality characteristics, in different drying temperature, wind speed and pulsation ratio conditions were winter jujube slices drying experiment, of winter jujube slices in post drying of the VC, total acid and reducing sugar content were detected. The results show that the drying temperature and wind speed are of significant effects on VC and total acid and reducing sugar, the effect of drying pulsation ratio of VC, total acid and reducing sugar was not significant, the influence order: temperature > wind speed > pulsation ratio.
Keywords/Search Tags:winter jujube slices, pulsed, air-impingement drying, drying model, color change dynamics
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