本文選題：速凍技術(shù) + 三溫段食品速凍機��； 參考：《天津商業(yè)大學》2014年碩士論文

【摘要】：速凍技術(shù)應用十分廣泛，其中食品的速凍過程是一個非常復雜的動態(tài)過程，涉及的學科包括傳熱學、食品學、冷凍冷藏學等方面。因此，研究食品的速凍過程及速凍特性，對選取食品最佳速凍工藝條件、改進優(yōu)化速凍裝置結(jié)構(gòu)、降低裝置整體制冷系統(tǒng)的能耗以及在復雜條件下對速凍過程進行建模優(yōu)化具有重要的意義。 本文通過實驗和模擬研究了饅頭在三溫段食品速凍機中的變溫速凍過程，分析了速凍特性以及不同速凍工藝對凍結(jié)速度和饅頭品質(zhì)的影響。 實驗過程中，通過調(diào)節(jié)節(jié)流閥改變進入蒸發(fā)器的制冷劑流量，從而改變空氣溫度，研究各階段溫度對饅頭凍結(jié)速度的影響；進行一組正交試驗，研究預冷段、結(jié)晶段、深冷段的風速以及即速凍時間四個因素對凍結(jié)速度和饅頭品質(zhì)的影響，同時，通過SPSS軟件分析了饅頭質(zhì)構(gòu)品質(zhì)與感官品質(zhì)的相關(guān)性。采用Fluent軟件，選取k-epsilon中的RNG模型模擬計算了饅頭在三溫段食品速凍機內(nèi)速凍時的溫度變化，并與實驗結(jié)果進行對比，得到結(jié)論如下： (1)速凍過程中，饅頭的表面溫度下降最快，中心溫度下降最慢；在同一時間內(nèi)，越接近饅頭中心的溫度越高；測點的溫度梯度在凍結(jié)前先逐漸變大，然后逐漸變小，在凍結(jié)完成后又逐漸變大，最后逐漸變��；在速凍過程中-3℃左右饅頭會出現(xiàn)過冷現(xiàn)象；速凍時間越長，，饅頭中心溫度越低；速凍時間在4000s以上，饅頭中心溫度能達到貯藏溫度所需的-18℃。 (2)結(jié)晶段溫度與凍結(jié)速度呈高度相關(guān)，當結(jié)晶段溫度越低，凍結(jié)速度越快，但是隨著溫度的降低，凍結(jié)速度逐漸趨于平緩；預冷段溫度與凍結(jié)速度呈高度相關(guān)；深冷段溫度對凍結(jié)速度沒有明顯影響。 (3)在預冷段、結(jié)晶段、深冷段的風速以及速凍時間四個因素中，對饅頭品質(zhì)影響最大的因素是結(jié)晶段風速，對凍結(jié)速度影響最大的也是結(jié)晶段風速，其次是速凍時間。得出的饅頭最佳速凍工藝是預冷段、深冷段風速為4m/s，結(jié)晶段風速為5m/s，速凍時間為4000s。 (4)饅頭比容與硬度、膠著性和咀嚼性呈顯著負相關(guān)；表面結(jié)構(gòu)與回復力呈顯著負相關(guān)；饅頭的彈性與通過質(zhì)構(gòu)儀檢測的彈性存在顯著性相關(guān)，表示質(zhì)構(gòu)儀檢測的彈性可代替感官評價中的彈性；韌性與硬度呈顯著負相關(guān)。
[Abstract]:The frozen process of food is a very complicated dynamic process, including heat transfer, food science, refrigeration and so on. Therefore, this paper studies the fast freezing process and characteristics of food, and improves the structure of the fast freezing device by selecting the best technology conditions of food freezing. It is of great significance to reduce the energy consumption of the whole refrigeration system of the unit and to model and optimize the rapid freezing process under complex conditions. In this paper, the variable temperature freezing process of steamed bread in the three-temperature food quick-freezing machine is studied by experiment and simulation. The effects of different freezing processes on the freezing speed and steamed bread quality were analyzed. In the experiment, the air temperature was changed by adjusting the refrigerant flow into the evaporator by adjusting the throttle valve. The effects of temperature at different stages on the freezing speed of steamed bread were studied, and a group of orthogonal experiments were carried out to study the effects of four factors on the freezing speed and the quality of steamed bread, such as the wind speed of the precooling section, the crystallization section, the cryogenic stage and the quick freezing time, at the same time, The correlation between texture quality and sensory quality of steamed bread was analyzed by SPSS software. Using fluent software, the RNG model in k-epsilon was selected to simulate and calculate the temperature change of steamed bread during the rapid freezing of food in the three-temperature section, and the results were compared with the experimental results. The conclusions were as follows: during the rapid freezing, the surface temperature of steamed bread decreased fastest. At the same time, the temperature gradient of the measuring point gradually increased before freezing, then gradually decreased, and then increased gradually after the freezing, and finally became smaller. In the process of quick freezing, the steamed bread will appear undercooling at about -3 鈩

本文編號：1987046