The effects of sour doughs produced by using waste whey water on quality and shelf life properties of the bread

Whey is a by-product resulting from cheese production, partially used in the production of whey powder, but generally considered as waste. The last waste water obtained as a result of separating the curd obtained as a result of adding calcium to whey and re-boiling is called whey waste water (PAAS). Within the scope of this thesis, it is aimed to determine the nutritional and chemical content of PAAS, which is released into the environment as waste, and to regain its current nutritional content to production by using it in sourdough production. For this purpose, sourdoughs were prepared by using traditional spontaneous fermentation method with water, whey (PAAS) and enzyme hydrolyzed whey (PAASEH). Prepared sourdoughs were incorporat in the bread dough formulation at 6 different rates. The effects of the obtained breads on the product quality and shelf life qualities were investigated. For this purpose, some physicochemical and bioactive properties of breads such as crust and crumb colour, volume, specific volume, crust thickness, pH, phytic acid, antioxidant activity, total phenolic content, ash and digestible ash were investigated. In addition, the effects of the sourdoughs used on the shelf life of the bread and their preference were investigated by subjecting them to sensory tests. Obtained results were evaluated statistically. As a result of the thesis, it was determined that lactose in PAAS content can be reduced to glucose and galactose by the hydrolysis of the enzyme galoctosidase. While more acidity development occurred in the same period of sourdough prepared with PAAS and PAASEH, LAB and yeast counts were found to be the same in the final sourdough samples. The use of different sourdoughs affected the bread qualities, the use of PAAS reduced the bread volume, while the use of PAASEH gave similar results to traditional sourdough. The use of PAAS and PAASEH increased the total mineral content and digestible ash ratio of the breads, while the use of PAASEH in particular provided a high level of browny color formation on the crust surface. The bioactive qualities of breads were also affected by both sourdough types and usage rates. The use of PAAS and PAASEH sourdoughs increased the antioxidant activity and total phenolic content of the bread samples, while a decrease was observed in the content of phytic acid, an antinutrient, with increasing rates of sourdough. As a result of the study, it has been determined that it is appropriate to use in sourdough production for the bakery products sector in order to reduce the release of PAAS, which has a negative effect, to the environment and to provide its use in an alternative field in its nutritional content.