Browsing by Subject "whey"
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(2014)Thesis literature review deals with composition of cow´s milk, yogurt manufacturing, composition and process attributes affecting textural properties of yogurt and measuring textural properties of yogurt. Plain, stirred yogurts (kg) were manufactured at Valio Riihimäki and Oulu Dairies. The aim of the research was to find out attributes that affect yogurt quality. First milk base composition was determined and, yogurt textural properties were determined (viscosity, graininess, syneresis) using different techniques. Finally yogurt statistical relationships or Pearson correlations and statistical significance between yogurt textural properties and milk base composition and manufacturing process were determined. Additional objective was to determine common specification limits to yogurt textural properties. Statistical analysis; pearson correlation coefficients, p-value and specification limits were carried out using MINITAB®16 statistical software. Good yogurt texture is viscous, free from grains and syneresis. This study showed that yogurt textural properties (viscosity, graininess and syneresis) were affected significantly by yogurt manufacturing plant. There were a lot of fluctuations in yogurt textural properties. Consequently yogurt viscosity fluctuated over 50%, graininess approx. 25% and syneresis approx. 30%. According to this study, yogurts standing a long time before packaging, were less viscose or watery compared to those with shorter standing time prior to packaging. Graininess and evaporating process were found to correlate positively. Yogurts were with more grains when manufacturing process`s evaporating temperature and evaporating rate (l/h) were higher. The higher milk base fat and dry matter content (%) were found to correlate lesser whey separation in yogurt. In addition the higher evaporating rate was in the yogurt manufacturing process, the lesser whey separation was observed. Results from this research are useful for developing dairy processes concerning yogurt manufacturing.
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(2021)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.
Now showing items 1-2 of 2