Process validation and efficacy of antimicrobial systems used in foods; understanding the bacterial stress response

虽然加拿大被公认为拥有相当安全的食品供应，但加拿大公共卫生署估计，每年有400万人（八分之一的加拿大人）因国内获得的食源性疾病而患病。肉类是最常见的犯罪食品，每年的经济负担为5亿美元，另外还有2亿美元的腐败。消费者对易于制备、加工程度最低、添加剂较少的食品的需求，促使食品科学家寻找创新方法来保持食品供应的安全和质量。传统上，在挑战研究期间，通过固体生长培养基上的细胞计数来评价抗菌系统的有效性。然而，过于应激或损伤的活生物体不会立即生长以在固体培养基上形成独特的菌落。活的但不可培养的生物体可以在储存期间恢复，以便稍后在食品中恢复生长。因此，如果仅基于细胞计数，则可能高估抗菌治疗的功效。为了开发有效和实用的微生物控制手段，我们必须在分子水平上了解它们的微生物生理反应。因此，使用细胞对数减少，在许可和工业储存条件下的恢复时间和功效，细胞对抗微生物应激反应能力的下降，以及严重处理后残留代谢活性的水平和类型作为阈值限制，我们将优化抗微生物系统的严重性，以确保安全的食品/肉类，而不影响产品质量。使用这种方法，我们已经证明鸭肝酱可以在F°为1而不是3的情况下灭菌，从而使最终产品符合国际市场的高标准。此外，通过跟踪细菌应激标志物（如DnaK和GroEL）的下降，我们确定了抗菌系统开始有效的条件。在这项资助中，我们将研究烹饪和温和的热处理应用于不同的速度，以控制腐败和致病生物的功效。我们对控制微生物腐败和病原体的新替代品的研究使我们研究了来自各种来源的天然抗菌剂的功效（例如，植物源精油、乳酸链球菌素、蟹水解物中的肽）。它们在肉类系统中的功效也将被研究。仅在魁北克，每年就有15，000吨洋葱因各种原因被拒绝并被发现不适合人类食用。在食品或饲料中有效利用从植物生产副产品中提取的多酚，符合可持续农业和经济效率的全球愿景。为了在肉类等复杂的食品基质中充分发挥这些新型抗菌剂的潜力，我们必须确定它们的功效并了解它们引起的生理应激，正如本申请中所提出的那样。

Although Canada is recognized to have a fairly safe food supply, the Public Health Agency of Canada estimates that four million people (one in eight Canadians) get sick every year due to domestically acquired food-borne illnesses. Meat is the most commonly incriminated food with a financial burden of $500 million a year and another $200 million for spoilage. Consumer demand for easily prepared, minimally processed foods with fewer additives, challenges food scientists to find innovative ways to maintain the safety and the quality of our food supply. The efficacy of antimicrobial systems is traditionally evaluated by cell enumeration on solid growth medium during challenge studies. However, viable organisms that are too stressed or injured do not grow immediately to form distinct colonies on solid media. Viable but non-culturable organisms may recover during storage to later resume growth in foods. Hence, the efficacy of an antimicrobial treatment can be overestimated if solely based on cell counts. To develop effective and practical means of microbial control, we must understand their microbial physiological response at the molecular level. So, using cell log number reduction, recovery time and efficacy in permissive and industrial storage conditions, the decline of cellular ability to response to antimicrobial stresses, and the level and type of residual metabolic activity upon severe treatment as threshold limits, we will optimize the severity of antimicrobial systems to secure safe foods/meats without compromising product quality. Using this approach, we have demonstrated that duck liver pate can be sterilised at an F° of 1 instead of 3, resulting in a final product that now meets the high standard of international markets. Also, by following the decline of bacterial stress markers, such as DnaK and GroEL, we determined the conditions under which antimicrobial systems start to be effective. In this grant, we will investigate the efficacy of cooking and milder heat treatments applied at different rates to control spoilage and pathogenic organisms. Our search for new alternatives to control microbial spoilage and pathogens has led us to study the efficacy of natural antimicrobials from various sources (e.g., essential oils of plant origins, nisin, peptides from crab hydrolysate) in meat products. Their efficacy in meat systems will be investigated as well. In Quebec alone, 15,000 tonnes of onion per year are rejected and found unfit for human consumption for various reasons. Effective use of polyphenols extracted from by-products of plant production in food or feed aligns with a global vision for sustainable agriculture and economic efficiency. To use these novel antimicrobials to their full potential in a complex food matrix such as meat, we must determine their efficacy and understand the physiological stress they elicit, as proposed in this grant application.