Exopolysaccharides producing strains to control yogurt functionality

加拿大酸奶产量在过去十年中增长了60%，部分原因是希腊酸奶在市场上的引入，以及许多创新，如口味混合、零食选择和酸奶饮料。多年来，消费者要求更多的“天然”食品。这一需求转化为需要一个更简单的成分表，不含食品防腐剂、着色剂和其他添加剂。然而，如果不使用一些不受消费者欢迎的增质成分（如淀粉、果胶、明胶等），酸奶的质地和口感的控制是很难实现的。最有希望的策略是结合具有内在能力的细菌菌株来调节发酵乳的质地。这些菌株产生外多糖（EPS），这是由细菌自然释放的葡萄糖聚合物（因菌株而异），它增加了产品的粘度，减少了产品的协同作用（从凝胶中排出乳清）。许多菌株已被确定为eps生产者，并在多年来成功地进行了酸奶生产测试。然而，在工业上，生产eps的菌株的使用主要是在过去十年中通过经验实验引入的。本项目旨在从一组乳酸菌（LAB）中筛选出新的EPS生产菌株。菌株选择将基于它们在已知的与LAB中EPS产生有关的特定基因中的基因组含量。随后，将在实验室规模上研究一组菌株的酸化速率和功能特性。最后，最有希望的候选人将在试点加工设施中进行评估。该项目为博士和硕士学生提供了在工业合作伙伴研究团队实习的独特机会。在这个项目结束时，我们希望扩大发酵乳制品的功能，并提供多样化和开发新的创新产品的机会。

The Canadian yogurt production showed a 60% increase during the last ten years partly due to the introduction of Greek yogurt in the market, and of many innovations such as flavor mash-ups, snacking options and yogurt drink. For many years, consumers have requested more "natural" food products. This demand is translated by the need of a simpler ingredient list with the absence of food preservative, colorants and other additives. However, the control of yogurt texture and mouthfeel is difficult to achieve without the use of some texturizing ingredients (e.g. starch, pectin, gelatin, etc.) that are no longer welcomed by consumers. The most promising strategy is the incorporation of bacterial strains that have intrinsic capabilities to modulate the texture of fermented milk. These strains produce exopolysaccharides (EPS) which are glucidic polymers (which differs from strain to strain) naturally released by the bacteria which increase the viscosity and decrease the syneresis (the expulsion of whey from the gel) of the product. Many strains have been identified as EPS-producers and were successfully tested for yogurt production over the years. However, in the industry, the use of EPS-producing strains was introduced mainly through empiric experimentation during the last decade. This project aims to select new EPS producing strains from a set of lactic acid bacteria (LAB). Strain selection will be based on their genomic content in specific genes known to be involved in EPS production in LAB. Subsequently, a set of strains will be studied at laboratory scale for their acidification rate and functional properties. Finally, the most promising candidate will be evaluated in pilot processing facilities. This project offers a unique opportunity for a PhD and a MSc student to have an internship in the industrial partner research team. At the end of this project, we expect to widen the functionality of the fermented dairy products and offer diversification and opportunities to develop new innovative products.