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標題: | 高壓加工技術與香蜂草精油對於病原性大腸桿菌在牛絞肉中的殺菌模型建構 Modeling the Inactivation of Pathogenic Escherichia coli in Ground Beef by High Pressure Processing and Melissa Officinalis L. Essential Oil |
作者: | Shih-Yung Chien 簡世勇 |
指導教授: | 沈立言(Lee-Yan Sheen) |
關鍵字: | 高壓加工技術,香蜂草,病原性大腸桿菌,牛絞肉,模型建構, High hydrostatic pressure,Melissa officinalis L.,Pathogenic E. coli,Ground beef,Model construction, |
出版年 : | 2019 |
學位: | 博士 |
摘要: | 高靜水壓技術(High hydrostatic pressure)是一項非加熱的加工技術,能夠減少食品中病原菌及造成腐敗的微生物數量,進而達到食品加工、保存及殺菌的目的。近年來高靜水壓技術已大量應用於食品工業上。香蜂草(Melissa officinalis L.)為歐美廣泛使用之天然芳香與藥用保健植物,廣泛使用於傳統治療,其活性成分主要來自於精油(essential oil)與酚類化合物(phenolic compound),有抗憂鬱、鎮靜、抗痙攣、抗發炎等效果。腸致病性大腸桿菌,例如大腸桿菌O157:H7在美國是爆發許多食品中毒事件的元凶之一。最近,致腎盂腎炎大腸桿菌(Uropathogenic E. coli, UPEC)也成為一個食源性風險,藉由食用肉品而引起人們的尿道感染。本研究將新鮮牛絞肉利用高壓(300-400 MPa)與0.5%,1.0%和2.0%的香蜂草精油或其相似的化學成分(Citral、Geraniol,Caryophyllene,化學成分混合:各1/3 Citral、Geraniol,Caryophyllene)共同處理後,將樣品保存於4 ℃,並連續七天偵測病原性大腸桿菌數目。此外,再以新鮮牛絞肉接種大腸桿菌O157:H7或UPEC在不同的加壓條件(250-350 MPa; 10-20分鐘)和檸檬醛濃度(0.75-1.25%)處理,來建構數學方程式,以預測不同條件下,可殺滅的致病性大腸桿菌數目。結果顯示,病原性大腸桿菌計數減少的程度取決於壓力和香蜂草精油或相似的化學成分的濃度與加壓時間。並且發現在低溫貯藏過程中,牛絞肉中的大腸桿菌數目會隨著儲存時間的推移而減少。而二次線性迴歸方程式與非線性模型的建構可用來描述和預測大腸桿菌O157與UPEC的減少,其數學預測模型的準確度皆高於85 %,經由這些模型實驗驗證,可以幫助食品行業和監管機構在大腸桿菌O157:H7與UPEC的風險管理。 High hydrostatic pressure (High Pressure Processing, HPP) is an emerging non-thermal technology that can inactivate pathogenic and spoilage microorganisms in food, and extend the shelf life of foods and becomes more popular in food operation nowadays. Melissa officinalis L., widely used in conventional treatment, the bioactive ingredients mainly from essential oil and phenolic compounds to possess antidepressant, sedative, antispasmodic, anti-inflammatory effects. The essential oils (EOs) from aromatic and medicinal plants have attracted attention and interest as potential natural antimicrobials in food preservation. This work addresses the inactivation achieved with pathogenic Escherichia coli by combined applications of high pressure processing (HPP) and Melissa officinalis leaf essential oils (natural EOs) or their similar chemical constituents (CCs, natural and artificial) in fresh ground beef stored at 4 °C for 7 days. Ground meat pressurized from 250 to 400 MPa for 15min were combined with 0.5%, 1.0% and 2.0% of EOs (Melissa officinalis leaf essential oils) and CCs (Citral, Geraniol, Caryophyllene, Mixture: 1/3 w/w of Citral, Geraniol, and Caryophyllene). In E. coli, the extent of inactivation or cell count reduction depended on the pressure (at 15 min) and the concentrations of the EOs or CCs. However, Caryophyllene alone was found almost not lethal to E. coli under HPP. For 24 h under refrigeration, 1% of citral with 250MPa caused a reduction of 2.5 log10 CFU/g. Further, 1% of citral, mixture, and EOs with 300 - 350 MPa could reduce ca. 3-6 log CFU/g of E. coli. And then, to reduce and/or eliminate the risk of E. coli O157: H7 and UPEC, the impact (lethality as log CFU/g reduction) of combined HPP and antimicrobial (e.g. citral) was studied using a hurdle concept. Ground beef inoculated with E. coli O157: H7 or UPEC were treated at different HPP conditions (250-350 MPa; 10-20 min) and citral concentration (0.75-1.25 %) following a central composite experimental design. Quadratic linear regression equations were developed to describe and predict the reductions of E. coli O157: H7 (R2 = 0.93, p < 0.001) and UPEC (R2 = 0.92, p < 0.001). Dimensionless nonlinear models consisting of three impact factors were also developed and compared with the linear models. These models were experimentally validated. Antimicrobial citral showed positively enhancing the HPP inactivation which may reduce the high pressure level applied on meats and therefore, reduce the operation cost and quality damages. The models may assist the food industry and regulatory agencies in risk assessment of E. coli O157: H7 and UPEC on ground meats. The inactivation potential continues its impact during the low temperature storage, i.e. showing cell counts reduction as time progresses. Similar results were observed for Salmonella survival in ground chicken meats. The High Pressure level imposed on foods (meats) during HPP, therefore, can be reduced (≤ 350 MPa) with the addition of antimicrobials to much reduce the pressure damage on food texture/quality without scarifying the microbial food safety concerns. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/73648 |
DOI: | 10.6342/NTU201903790 |
全文授權: | 有償授權 |
顯示於系所單位: | 食品科技研究所 |
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