Exopolysaccharides producing strains to control yogurt functionality

加拿大的酸奶产量在过去十年中增长了60%，部分原因是希腊酸奶进入市场，以及许多创新，如调味料、零食选择和酸奶饮料。多年来，消费者一直要求更多的“天然”食品。这一需求转化为需要一个更简单的配料表，不含食品防腐剂、着色剂和其他添加剂。然而，如果不使用一些质构成分(如淀粉、果胶、明胶等)，酸奶的质构和口感就很难控制。不再受到消费者欢迎的产品。最有希望的策略是引入具有内在能力的细菌菌株来调节发酵牛奶的质地。这些菌株产生胞外多糖(EPS)，这是由细菌自然释放的糖基聚合物(不同菌株不同)，它增加了产品的粘度，降低了产品的脱水(将乳清从凝胶中排出)。许多菌株已经被鉴定为产生EPS的菌株，并在多年来成功地用于酸奶生产。然而，在该行业中，产生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产生菌。菌株的选择将基于它们在实验室中参与EPS生产的特定基因的基因组含量。随后，将在实验室规模上研究一组菌株的酸化速度和功能特性。最后，最有希望的候选人将在试点处理设施中接受评估。该项目为博士和硕士学生提供了一个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.