Prieto-Calvo María, Prieto Miguel, López Mercedes, Alvarez-Ordóñez Avelino
Institute of Food Science and Technology, University of León, León 24071, Spain.
Department of Food Hygiene and Technology, University of León, León 24071, Spain.
Molecules. 2014 Dec 18;19(12):21310-23. doi: 10.3390/molecules191221310.
High hydrostatic pressure (HHP) is a novel food processing technology that is considered as an attractive alternative to conventional heat treatments for the preservation of foods, due to its lethal effects on pathogenic and spoilage microorganisms, while causing minor effects on food quality and sensorial attributes. This study is aimed at investigating how HHP treatments at varying intensities in the range 50-900 MPa affect the viability, membrane integrity, ultrastructure and molecular composition of Escherichia coli. Results of membrane integrity tests (measurement of cellular leakage and monitoring of propidium iodide uptake through fluorescence microscopy) and ultrastructural observations by transmission electron microscopy demonstrated that HHP gave rise to cellular enlargement, membrane damage or detachment, DNA and protein denaturation and loss of intracellular contents. Fourier-transform infrared (FTIR) spectroscopy analyses evidenced minor changes in molecular composition in response to high pressures, which were mostly observed on the spectral region w4 (1200-900 cm-1), mainly informative of carbohydrates and polysaccharides of the cell wall. These findings suggest that exposure of E. coli cells to HHP causes alterations in their physical integrity while producing minor modifications in biochemical cellular composition. The current study increases the knowledge on the mechanisms of E. coli inactivation by HHP and provides valuable information for the design of more effective food preservation regimes based on the integration of mild HHP in combination with other food preservation strategies into a multi-target hurdle technology approach.
高静水压（HHP）是一种新型食品加工技术，由于其对致病和腐败微生物具有致死作用，同时对食品质量和感官特性影响较小，被认为是传统热处理用于食品保鲜的一种有吸引力的替代方法。本研究旨在探究50 - 900 MPa范围内不同强度的HHP处理如何影响大肠杆菌的活力、膜完整性、超微结构和分子组成。膜完整性测试结果（通过荧光显微镜测量细胞渗漏和监测碘化丙啶摄取）以及透射电子显微镜的超微结构观察表明，HHP导致细胞肿大、膜损伤或脱离、DNA和蛋白质变性以及细胞内物质流失。傅里叶变换红外（FTIR）光谱分析证明，高压处理后分子组成发生了微小变化，这些变化主要出现在光谱区域w4（1200 - 900 cm-1），该区域主要反映细胞壁的碳水化合物和多糖信息。这些发现表明，大肠杆菌细胞暴露于HHP会导致其物理完整性改变，同时细胞生化组成产生微小变化。本研究增加了对HHP使大肠杆菌失活机制的认识，并为基于温和HHP与其他食品保鲜策略相结合形成多靶点栅栏技术方法设计更有效的食品保鲜方案提供了有价值的信息。
