不同樣式罐頭食品加熱殺菌受旋轉影響之研究

An Investigation of Deactivation of Bacteria in Various Shapes of Liquid Canned Food under Rotational and Stationary Conditions

楊智誠(Zhi-Cheng Yang)

指導教授 ： 鄧志浩

中原大學/工學院/生物環境工程研究所/碩士(2014年)

https://doi.org/10.6840/CYCU.2014.00015

摘要

本研究以數值計算流體動力學軟體( ANSYS Fluent )模擬罐頭在加熱過程中罐頭內部蘿蔔橘子湯溶液( Carrot-Orange soup )溫度的變化效應。將罐頭外部溫度設定為121℃，內部溶液溫度定為19℃，由於內外溫度差與重力影響，在罐頭內部的熱傳導與自然熱對流現象形成最慢加熱區 ( slowest heating zone, SHZ )，進而觀察SHZ在罐頭內部的分佈。
首先將圓柱罐頭以不同放置方式(水平、直立)模擬加熱，探討罐頭裡加熱溫度與時間經由靜止與三種不同旋轉速度( 5、10、20rpm )產生的變化量；接著針對不同樣式( 圓柱、漏斗、牛奶盒 )的罐頭容器，觀察不同樣式罐頭內部SHZ及加熱溫度之差異。
計算的結果我們發現靜止時，圓柱罐頭水平放置在加熱初期升溫速度較罐頭直立放置快；而當罐頭加入旋轉速度，罐頭放置方式對於升溫速度並沒有太大差異。而在探討不同樣式的罐頭容器中，保持各個類型罐頭具有相同體積不同表面積，我們發現在靜止與加入旋轉速度時，牛奶盒罐頭升溫效果最佳，因此改變罐頭的形狀後，表面積加大可以明顯減少需要加熱的時間，達到殺菌效果。

關鍵字

罐頭殺菌 ； 最慢加熱區 ； 自然對流 ； 計算流體力學

並列摘要

The effects of temperature change during the heating process of liquid canned food (carrot-orange soup) were investigated using numerical simulation, computational fluid dynamics software (ANSYS Fluent). The external wall temperature was set to 121 ℃ with an internal temperature of the solution at 19 ℃. Due to the internal and external temperature difference and the influence of gravity, heat conduction and natural convection phenomena occurs on the can’s internal solution which caused the movement of the slowest heating zone (SHZ). Thus, the distribution of the SHZ was observed on the liquid canned food internal solution.
First, cylindrical cans were placed vertically and horizontally during the heating process. The variation of liquid canned food internal temperature and time were observed with three different rotation speeds of 5, 10 and 20 rpm. Second, different shapes of liquid canned food such as cylindrical, funnel-type and milk-type cartons were investigated using the same external wall temperature and rotation speeds. The temperature and distribution of the SHZ were observed with different placement, rotation speed and shape of liquid canned food.
Based on the results of numerical simulation, cylindrical cans placed horizontally has a faster heating rate compared to the can placed vertically for both stationary and rotational conditions. Different liquid canned food containers having the same volume but different surface areas were examined and the results showed that milk-type cans exhibited the fastest heating rate. Thus, changing the shape of the liquid canned food to milk-type carton having the best surface area can accelerate the heating rate process significantly.

並列關鍵字

sterilization ； slowest heating zone ； Computational fluid dynamics ； natural convection

參考文獻

Datta, A. K. and Teixeira , A. A. (1988). Numerically predicted transient temperature and velocity profiles during natural convection heating of canned liquid foods. Journal of Food Science, 53, 191-195.

Dincer, I., Varlik, C. and Gun, H. (1993). Heat transfer rate variation in a canned food during sterilization. International Communications of Heat and Mass Transfer, 20, 301-309.

Farid, M. (2014). Response to the letter to the editor on Rotational effect on the sterilization of liquid food cans, 131, 61.

Farid, M. M. and Ghani, A. G. (2004). A new computational technique for the estimation of sterilization time in canned food. Chemical Engineering and Processing, 43, 523-531.

Ghani, A. G., Farid, M. M. and Chen, X. D. (1999). An investigation of deactivation of bacteria on a canned liquid food during sterilization using computational fluid dynamics (CFD). Journal of Food Engineering, 42, 207-214.