超音波應用於農產品與肉品之品質檢測

Quality Evaluation of Agricultural Products and Meat Using Ultrasonic Technology

洪滉祐(Huaang-Youh Houng)

指導教授 ： 盧福明

國立臺灣大學/生物資源暨農學院/生物產業機電工程學研究所/博士(2007年)

https://doi.org/10.6342/NTU.2007.03065

摘要

摘　　　要

本論文利用脈衝式超音波以及超音波聲射技術，分別針對數種農產品與肉品進行品質檢測之可行性評估與分析，包含：牛肉在凍結過程以超音波估測凍結率之技術建立、豬肉在不同凍結速率下波傳速度與凍結水份關係之建立、金煌芒果生理劣變之超音波檢測可行性評估、綠豆中豆象 (羽化前) 偵測技術評估以及其自動偵測系統建立等主題。
牛肉在凍結過程其質地隨凍結深度改變而改變，以超音波穿透法所得的回波時間響應可求得波傳速度。試驗結果顯示，牛肉在凍結過程的中心溫對應時間曲線中，凍結點附近潛熱特性明顯，在 0 ~ - 5 ℃ 之間則冰晶最大生成帶特性明顯。使肉品肌肉纖維方向與熱傳方向平行進行凍結時，凍結速率較高，在凍結前 (0 ~ 25 ℃)波傳速度約維持在定值，在冰晶最大生成帶期間，約有 72 % 的能量是耗用在潛熱的排除，波傳速度提高 63.64 %。由波傳速度預估肉品中心溫與凍結率具有可行性，其迴歸方程式的決定係數分別為 0.86 與 0.95。
豬肉在不同凍結速率下，其組織特性顯示差異，由組織切片觀察可推估，細胞或細胞間隙因水分凍結導致體積膨脹是重要原因。試驗結果顯示，慢速凍結比急速凍結豬肉的肌纖維斷裂情形嚴重，產生岑克氏變性的程度也高，肇因於慢速凍結的豬肉組織中含有較大的冰晶以及推擠較嚴重。利用脈衝穿透式超音波進行波傳速度測量得到，肉品凍結程度越高超音波穿透越容易，其波傳速度隨之增大，比較不同凍結速率下豬肉的波傳速度，慢速凍結豬肉顯示有較低的波傳速度，此結果可提供作為豬肉肉品凍結後，非破壞性的品質檢測參考應用。
利用浸置式超音波檢測技術，量化芒果的超音波檢測指標和生理特性間相關性的試驗中，係將芒果果肉浸入於水中並以反射式 (脈衝回波式) 超音波進行檢測，結果顯示，超音波的波型隨傳遞路徑上果肉質地的變化而變化。本試驗分析成熟芒果的超音波衰減與生理特性之間的相關性，利用 Fisher Z transformation 進行假設檢定，以瞭解樣本所得的皮爾森相關係數與母體相關係數間相關性的強度，以進行統計推論。由迴歸分析的結果顯示，生理劣變的芒果與健康的芒果比較，生理劣變的芒果具有較高的果肉密度與超音波衰減，由研究發現，超音波衰減係數與密度和楊氏模數之間分別具有線性 (linear) 與冪級數 (power function) 的關係，健康的果肉與生理劣變的果肉比較，則健康的果肉有較低的超音波衰減係數、低的糖酸比與高的楊氏模數。
以聲射超音波檢測豆象之偵測系統之研究係以超音波聲射為核心技術，建構一套自動偵測系統，用以觀察四紋豆象(Callosobruchus maculatus)的生活史週期及取食活動。豆象羽化前的咬食行為會使種子內部纖維斷裂，斷裂過程中會產生微弱超音波，藉由觀測斷裂聲便可以獲悉豆象的咬食頻度的變化，以辨別豆象幼蟲的齡期與估測其生活史週期。斷裂過程的超音波經由自製的電子電路進行放大、濾波與轉換，並由商用的資料擷取卡進行信號的擷取，所擷取的信號由電腦進行線上的信號處理、儲存以及資訊顯示。本系統已成功用於觀測四紋豆象寄宿於紅豆與綠豆的生活史。

關鍵字

超音波 ； 非破壞檢測 ； 冷凍 ； 肉品 ； 芒果 ； 四紋豆象

並列摘要

Abstract

This study utilized the ultrasonic pulse-echo method and acoustic emission technology to evaluate the internal qualities of agricultural products and meat. Those researches covered the areas of freezing rate evaluation of beef and pork, physiological properties evaluation of mango fruit, and life history monitoring of the Callosobruchus maculatus inhabiting in beans.
The beef texture is influenced by the depth of freezing front during freezing process. The ultrasound speed in frozen beef was obtained by measuring echo response time and transmitting distance of the ultrasound. The ultrasound velocity is constant above freezing point. The latent heat effect is obvious at the freezing point. The zone of maximum ice crystal formation occurs between 0 °C and -5 °C. The maximum freezing rate was observed as the meat fiber direction paralleled the heat flow during meat freezing process. The amount of energy for latent heat released and ultrasound speed measured at the zone of maximum ice crystal formation were respectively about 72% of total input energy and 63.64% of ultrasound speed range during the freezing process. The coefficients of determination for the regression of meat thermal center temperature against ultrasound velocity and the regression of freezing ratio against ultrasound velocity were 0.86 and 0.95 respectively. It is feasible to estimate the meat thermal center temperature and freezing ratio from the ultrasound velocity.
Due to expansion of frozen water contained in the cell or intercellular space, the texture of frozen pork meat will be influenced by different freezing rates. The experimental results show that the meat muscle fiber fragmentation situation is serious in slow-freezing as compared to rapid-freezing. It means that the degree of Zenker’s degeneration increases at low freezing rate. The ultrasound speed in pulse-transmission system increases as freezing degree increases. Therefore the ultrasonic technology can be adopted to evaluate pork meat quality during freezing process.
The immersion ultrasonic testing technology was used to establish quantitative relations between ultrasonic diagnostic indices and physiological properties of mango fruits. Pulse-echo ultrasonic testing of submerged mango fleshes indicated that the ultrasound waveforms changed as it propagating through the different fruit texture. The relationship between ultrasound attenuation and physiological properties of ripening mango was analyzed in this study. The Fisher Z transformation procedure was used to estimate the characteristics of a population with ultrasound attenuation and physiological parameters. Ultrasound attenuation subject to other parameters is analyzed with regression analysis. As validated by experiments, disordered fruits usually have a higher density and attenuate ultrasound more than healthy fruits. This work found that the correlations of ultrasound attenuation with the density and Young’s modulus of fruit exhibit linear and power relationships, respectively. Experimental results show that a healthy flesh has less ultrasound attenuation, less SSC (soluble solids content)/acid ratio, and higher Young’s modulus in comparison with a disordered one.
An ultrasonic monitoring system was developed for exploring the life history of Callosobruchus maculatus inhabiting in beans. Callosobruchus maculatus only feeds before eclosion and the demand for food is different in every life stage. The feeding process cracks bean texture fibres and produces feeble ultrasound. Hence the life history of an inhabitant can be explored through spying the feeding cracks. The developed ultrasonic monitoring system consists of a delicate electronic signal conditioning module which amplifies, filters, and transforms a biting crack into a square pulse. A computer equipped with software developed in house acquires biting pulses and displays the life history on line. Acquired data are stored for subsequently off-line analysis. The system has been successfully applied to exploration of the life histories of Callosobruchus maculatus inhabiting in Azuki beans and mung beans.

並列關鍵字

ultrasonic ； nondestructive technology ； freezing ； mea ； mango ； Callosobruchus maculatus

參考文獻

38. Goral, D. and F. Kluza. 2002. Experimental and analytical determination of freezing point depression. Electronic Journal of Polish Agricultural Universities, Agricultural Engineering 5(2).

12. 黃清旺、連振昌、郭鳳瑞、洪滉祐。1995。連霧之黏彈性質(一)負荷鬆弛特性之研究。農業機械學刊 4(2)：47-57。

24. Ay, C. 1992. Measuring changes in physical properties of milk during coagulation by ultrasonic analysis. PhD dissertation. Wisconsin-Madison University, Department of Agricultural Engineering, U.S.A

7. 林達德。1992。生物細胞內凍結現象之機率模式與分析。農業機械學刊 1(4)：278-289。

15. 楊秀珠、吳育郎、黃裕銘、鄭慶生。1999。芒果綜合管理。25-53。臺灣：臺灣省農業藥物毒物試驗所。