Browsing by Author "Jyry, Annika"

Whey is a significant side stream in the cheese making industry, and it can be utilized in several ways especially because whey proteins are nutritionally valuable. Whey cheeses are produced all around the world and mostly in small scale and traditional ways. The production of Ziger whey cheese has a long tradition in Switzerland, and it requires fresh whey derived from rennet-induced cheese making. The whey proteins are precipitated by high manufacturing temperature, the addition of acid and NaCl. The goal of this master’s thesis is to develop a Ziger whey cheese that can be applied in the Finnish dairy industry including optimization of the manufacturing process emphasizing the manufacturing temperature. The thesis also investigates and compares the effect of the temperature on the moisture, protein, and fat content and the yield of the Ziger whey cheese. Also, this thesis aims to examine the effect of the manufacturing temperature on the shelf life by monitoring microbial and physicochemical parameters of the Ziger whey cheese over 21 days of storage. The manufacturing temperatures examined in the production of Ziger were 88 oC and 93 oC, and the production was repeated three times for both temperatures which resulted in altogether six production series. The temperature had a significant effect on the yield which concluded, that the higher the temperature was during the manufacture, the higher the yield was. The microbiological quality was not affected by the manufacturing temperature. However, during the storage there was a significant correlation between the growth of lactic acid bacteria and the pH value i.e., the bacterial count increased as the pH value decreased. After 21 days of storage, every Ziger whey cheese sample crossed the threshold of spoilage for the total viable count which was set at 107 CFU/mL. The manufacturing temperature had no impact on the protein and fat contents. Instead of the manufacturing temperature, there was a strong correlation between the moisture and the fat content. Based on the fat content, the Ziger whey cheese can be categorized as creamy and soft whey cheese. For future reference of research, the quality and shelf life of Ziger whey cheese could be improved by modified atmosphere or vacuum packaging, high packaging temperatures, and shorter drainage time. Moreover, the production could be made more efficient by a continuous process in comparison to batch production.