Validation of an optical technology for the determination of ph in milk for the manufacture of yogurt
Current systems that allow online pH control in fermented dairy industry have drawbacks, such as protein adhesion on the pH electrode and measurement distortion. Therefore, the objective of this experiment was to validate the feasibility of estimating the pH of milk during the yogurt making process...
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| Tipo de recurso: | tesis de maestría |
| Fecha de publicación: | 2019 |
| País: | España |
| Institución: | Universitat Autònoma de Barcelona |
| Repositorio: | Dipòsit Digital de Documents de la UAB |
| Idioma: | inglés |
| OAI Identifier: | oai:ddd.uab.cat:215715 |
| Acceso en línea: | https://ddd.uab.cat/record/215715 |
| Access Level: | acceso abierto |
| Palabra clave: | Iogurt Tecnologia dels aliments Aliments i nutrició Enologia Olis Greixos |
| Sumario: | Current systems that allow online pH control in fermented dairy industry have drawbacks, such as protein adhesion on the pH electrode and measurement distortion. Therefore, the objective of this experiment was to validate the feasibility of estimating the pH of milk during the yogurt making process by a NIR light backscatter sensor measuring at a wavelength of 880 nm under different fermentation temperatures and milk protein concentrations, using a mathematical model that correlates the light scatter signal with pH, developed by Arango (2005). Three replications of the experiment with 2 protein concentrations (3.5, and 4.0%), and 2 fermentation temperatures (43 and 46 °C) were used to validate this inline pH prediction model. Prior to the beginning of each treatment, different adjustments were made in the initial voltage gain in the two vats of the light scatter device to evaluate which of the two procedures allowed a better calibration of the pH prediction model. The results showed that the optical sensor was suitable for inline monitoring of yogurt acidification. Temperature and initial voltage were the main factors affecting the fitting accuracy of the model. More concretely, the model adjustment at 43 ºC was better than at 46 ºC, the adjustment of the initial voltage gain is recommended, and the model with voltage gain adjustment has been successfully validated for both continuous and discontinuous measurements of pH, with SEP values < 0.09 pH units and CV < 1.82%. |
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