农业工程学报
農業工程學報
농업공정학보
2014年
7期
250-257
,共8页
李伟明%王鹏%陈天浩%徐幸莲%周光宏
李偉明%王鵬%陳天浩%徐倖蓮%週光宏
리위명%왕붕%진천호%서행련%주광굉
神经网络%介电特性%品质控制%冻融%阻抗%鸡胸肉
神經網絡%介電特性%品質控製%凍融%阻抗%鷄胸肉
신경망락%개전특성%품질공제%동융%조항%계흉육
neural networks%dielectric properties%quality control%freezing-thawing%electric impedance%chicken breasts
为了探究利用肉的介电特性检测冷冻肉品质的可能性，研究了新鲜鸡胸肉和不同冻融次数的鸡胸肉的品质以及阻抗的幅值和相位角变化状况。在0.05～200 kHz频率范围内，选择了16个不同的频率点进行阻抗特性分析。试验结果表明：鸡胸肉阻抗的幅值会随着频率上升而下降，相位角则相反。冷鲜肉与冷冻肉高频段相位角相差一个数量级，低频段阻抗的幅值差异也极显著（P＜0.01）。多次冻融处理后，解冻损失、丙二醛含量上升显著（P＜0.05），pH值变化不明显（P＞0.05）。反复冻融后低频段阻抗幅值降低（P＜0.05），大于50 kHz时，相位角有增大的趋势（P＜0.05），这与正常1次冻结-解冻肉的相位角变化趋势相反。利用径向基函数（radial basis function， RBF）神经网络提取阻抗和幅值信息建立判别模型可以对不同冻融次数的肉进行较为准确的分类。研究结果表明，阻抗测量作为一种冷冻肉快速无损检测方法具有很大的发展潜力。
為瞭探究利用肉的介電特性檢測冷凍肉品質的可能性，研究瞭新鮮鷄胸肉和不同凍融次數的鷄胸肉的品質以及阻抗的幅值和相位角變化狀況。在0.05～200 kHz頻率範圍內，選擇瞭16箇不同的頻率點進行阻抗特性分析。試驗結果錶明：鷄胸肉阻抗的幅值會隨著頻率上升而下降，相位角則相反。冷鮮肉與冷凍肉高頻段相位角相差一箇數量級，低頻段阻抗的幅值差異也極顯著（P＜0.01）。多次凍融處理後，解凍損失、丙二醛含量上升顯著（P＜0.05），pH值變化不明顯（P＞0.05）。反複凍融後低頻段阻抗幅值降低（P＜0.05），大于50 kHz時，相位角有增大的趨勢（P＜0.05），這與正常1次凍結-解凍肉的相位角變化趨勢相反。利用徑嚮基函數（radial basis function， RBF）神經網絡提取阻抗和幅值信息建立判彆模型可以對不同凍融次數的肉進行較為準確的分類。研究結果錶明，阻抗測量作為一種冷凍肉快速無損檢測方法具有很大的髮展潛力。
위료탐구이용육적개전특성검측냉동육품질적가능성，연구료신선계흉육화불동동융차수적계흉육적품질이급조항적폭치화상위각변화상황。재0.05～200 kHz빈솔범위내，선택료16개불동적빈솔점진행조항특성분석。시험결과표명：계흉육조항적폭치회수착빈솔상승이하강，상위각칙상반。랭선육여냉동육고빈단상위각상차일개수량급，저빈단조항적폭치차이야겁현저（P＜0.01）。다차동융처리후，해동손실、병이철함량상승현저（P＜0.05），pH치변화불명현（P＞0.05）。반복동융후저빈단조항폭치강저（P＜0.05），대우50 kHz시，상위각유증대적추세（P＜0.05），저여정상1차동결-해동육적상위각변화추세상반。이용경향기함수（radial basis function， RBF）신경망락제취조항화폭치신식건립판별모형가이대불동동융차수적육진행교위준학적분류。연구결과표명，조항측량작위일충냉동육쾌속무손검측방법구유흔대적발전잠력。
Electric impedance properties of biological tissue closely relate with their tissue structure. A few published investigations have shown that electric impedance has a rapid detection capability to meat quality. To explore the impedance detection ability for frozen-thawed meat, electric impedance magnitude and phase properties of unfrozen and frozen-thawed chicken breasts subjected to different thawing times were studied. The maximum freezing-thawing circle was three times. Sixteen different frequencies from 50 Hz to 200 kHz and quality parameters like thawing loss, cooking loss, pH value, and TBARS (Thiobarbituric acid reactive substances) of 20 samples of each group were investigated. <br> The impedance of the samples was measured by an LCR electronic bridge at the voltage of 3 V. Copper needle electrodes with a length up to 15 mm and a distance of 15 mm between two electrodes were used. The temperature of the meat was kept within 0-4℃during the measurement. The location of each test was the same and measurement time was 1-2 sec at every frequency. <br> The experimental results showed that changes in the tissue structure caused by freezing and thawing could be reflected by the impedance magnitude and phase. The impedance magnitude of both fresh and frozen-thawed meat would decrease as the frequencies increased and the impedance magnitude of fresh meat was significantly higher (P<0.01) than frozen-thawed meat in the low-frequency range, while the opposite trend was found in the high-frequency range. Those changing trends of impedance are indicators for capacitance characteristics of cell remembrance. Biological tissues are composed of cells that are surrounded by extracellular liquid. The main current flows through the extracellular fluid and the cells are bypassed when low-frequency current is applied to the tissue. The cell membrane acts as an insulator at low frequencies. With the current frequency increases, a part of the current will flow through intracellular fluid through the cell membrane. So, low-frequency impedance of biological tissue is larger than high-frequency impedance. <br> The impedance phase angle of both fresh and frozen-thawed meat would increase as the frequencies increase. Compared with frozen-thawed meat, fresh meat had a higher (P<0.05) impedance phase angle in the low-frequency range but a lower (P<0.05) value in the high-frequency range. So, the significant difference (P<0.05) of high-frequency phase angle and low-frequency impedance magnitude between fresh and frozen-thawed meat would be an ideal index to distinguish those two kinds of meat. <br> After freezing-thawing cycles, low-frequency impedance magnitude would decrease significantly (P<0.05), but the difference between two and three times freezing-thawing cycle was not significant (P>0.05). High-frequency phase angle would increase (P<0.05) which is different with normal frozen processing groups, especially at levels higher than 50 kHz. This impedance phase property of meat with more than one freezing-thawing cycle gives a clear distinction between them and meat with one freezing-thawing cycle. These changes of impedance properties demonstrate that freezing-thawing cycles have a remarkable influence on the structure of cell membrane and lead to a decline of cell membrane capacitance. <br> From the quality aspect, the increasing of freezing-thawing cycles lead to inevitable decline in meat quality. More thawing loss, cooking loss and higher TBARS value are found after freezing-thawing cycles. The precise calculation of the quality by impedance measurement could not be obtained for no accordant significant correlation (P>0.05) was found between impedance properties and quality parameters in different groups. <br> Radial Basis Function (RBF) Neural Networks that are built up based on impedance magnitude and phase angle of specific frequencies from 50 Hz to 200 kHz (Total 12 frequencies) could give a solution to estimate the freezing-thawing cycles of meat without complex mathematics modeling, and the prediction accuracy satisfies the requirement. Accuracy of the testing samples of fresh chicken meat was up to 100 percent, one time freezing-thawing cycle samples also had a high degree of distinction from two and three times. These results reflect that electrical impedance measurement is a simple innocuous tool for frozen meat characterization. For improving the measurement accuracy, a dadatabase with a big enough data volume needs to be built in future work.
