生乳乳樣防腐劑添加量對檢測影響之研究

Study on the Effect of Detection of Preservative Doses in Raw Milk Samples

連振昌(Cheng-Chang Lien) ； 楊朝旺(Chao-Wang Young) ； 張心怡(Hsin-I Chang) ； 萬一怒(Ye-Nu Wan)

《台灣農學會報》 12卷3期 (2011/06) Pp. 287-302

https://doi.org/10.6730/JAAT.201106_12(3).0006

摘要

生乳中體細胞數(somatic cell count, SCC)多寡及導電度(electrical conductivity, EC)高低可作為檢測生乳品質的指標，牧場乳牛擠乳後因設備不足無法及時檢測生乳其品質，因此一般是採樣乳樣後添加防腐劑再寄送做檢測，本研究目的是在乳樣中添加重鉻酸鉀作為防腐劑，探討在未冷藏及有冷藏情況下，不同防腐劑添加量的乳樣檢測其貯放天數對體細胞數及導電度的影響。由實驗結果得到不論在未冷藏及有冷藏情況下，乳樣體細胞數均隨貯放天數的增加而逐漸遞減，而防腐劑的添加會提高乳樣導電度，乳樣導電度對防腐劑添加量的線性迴歸方程式如下：EC=0.279(上標 *)[K2Cr2O7]＋4.890 (R^2＝0.991)。在未冷藏條件下，乳樣導電度隨貯放天數的增加而提高，當添加0.3 mg/ml防腐劑時，在第2天的乳樣體細胞數比第1天減少14.1%，而乳樣導電度比第1天提高了10.2%，由脈衝高度分析圖可知乳樣在第6天時已變質酸敗。在冷藏條件下，當添加0.3 mg/ml防腐劑時，在第2天的乳樣體細胞數比第1天減少了1.3%，而乳樣導電度減少了0.9%，由脈衝高度分析圖可知乳樣在第6天時未變質酸敗。

關鍵字

防腐劑 ； 重鉻酸鉀 ； 牛乳 ； 體細胞數 ； 導電度

並列摘要

In raw milk analysis, the somatic cell count (SCC) and electrical conductivity (EC) are used as indicators for the quality of milk. Due to the lack of facilities, the samples of raw milk cannot generally be tested immediately after milking at the farm. Therefore, preservatives will be added to the samples of raw milk before the tests. The aim of this research is to measure the effect of using potassium dichromate as a preservative to modify the preservative dose in raw milk in terms of the somatic cell count and electrical conductivity with time under the refrigeration and non-refrigeration conditions. The results show the SCC in raw milk decreases with storage time in refrigeration or non-refrigeration conditions. However, adding preservatives to raw milk increases the value of EC and the linear equation between K2Cr2O7 dose and EC is as follows: EC＝0.279(superscript *) [K2Cr2O7]＋4.890 (R^2＝0.991). Under the non-refrigeration condition, EC increased with the storage time. With the addition of 0.3 mg/ml K2Cr2O7 to the milk sample, SCC at day 2 was reduced by 14.1% but EC increased by 10.2% in comparison with day 1. The pulse height analysis of the Fossmatic SCC detector indicates the milk samples had gone bad. Under the refrigeration condition, SCC at day 2 was reduced by 1.3% with the addition of 0.3 mg/ml K2Cr2O7 to the milk sample and EC decreased by 0.9% compared with day 1. However, the pulse height analysis of the Fossmatic SCC detector indicates the milk samples had not gone bad by day 6.

並列關鍵字

Preservative ； K2Cr2O7 ； Milk ； Somatic sell counts ； Electrical conductivity