Publicação
Pasteurization of whey by pulsed electric fields and ultrasound technologies
| Resumo: | In recent years the importance of sustainability has increased, and as such the food industry decided to leverage byproducts in a manner that produces more sustainable products. Whey is a nutrient filled byproduct of the dairy industry, and for years it has been used as animal feed or disposed as waste. Whey is quickly degraded by lactic acid bacteria, leading to the necessity of whey preservation or rapid transformation in stable products. Heat is the most commonly used treatment to inactivate microorganisms, however, this procedure reduces the nutritional quality of whey. Alternative non-thermal technologies, such as pulse electric fields (PEF) and ultrasound (US), are a potential alternative that can reduce input cost and improve nutritional quality. The objective of this research was to evaluate the effectiveness of PEF and US technologies for the conservation of whey. For this effect, whey samples were processed at different conditions of PEF and US to evaluate microbial inactivation. The PEF conditions comprised of 5 passages with 16 kV/cm electric field intensity and 55 kJ/kg of specific energy. Between each passage the whey was cooled to 3-4 °C. The US conditions were conducted at constant temperature (thermosonication) with a power output of 70 W, corresponding to an acoustic power density of 8.75 W/mL. Using PEF system no significant reductions in microorganism were detected, proving that the stand-alone PEF treatment applied is ineffective to inactivate Lactococcus lactis in whey. On the contrary, utilizing PEF as a pre-treatment it was possible to detect a reduction in D-value compared with thermal treatment, implying a possible use of PEF to improve whey pasteurization. The thermosonication treatment studied in this work also demonstrated a significant decrease in inactivation time, however this technology has a limitation of 3.5 to 4 log reductions, afterwards the inactivation kinetics follow a normal thermal inactivation. |
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| Autores principais: | Marques, Bruno Alexandre Galego |
| Assunto: | cheese whey preservation Lactococcus lactis US PEF queijo conservação de soro |
| Ano: | 2024 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso embargado |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | In recent years the importance of sustainability has increased, and as such the food industry decided to leverage byproducts in a manner that produces more sustainable products. Whey is a nutrient filled byproduct of the dairy industry, and for years it has been used as animal feed or disposed as waste. Whey is quickly degraded by lactic acid bacteria, leading to the necessity of whey preservation or rapid transformation in stable products. Heat is the most commonly used treatment to inactivate microorganisms, however, this procedure reduces the nutritional quality of whey. Alternative non-thermal technologies, such as pulse electric fields (PEF) and ultrasound (US), are a potential alternative that can reduce input cost and improve nutritional quality. The objective of this research was to evaluate the effectiveness of PEF and US technologies for the conservation of whey. For this effect, whey samples were processed at different conditions of PEF and US to evaluate microbial inactivation. The PEF conditions comprised of 5 passages with 16 kV/cm electric field intensity and 55 kJ/kg of specific energy. Between each passage the whey was cooled to 3-4 °C. The US conditions were conducted at constant temperature (thermosonication) with a power output of 70 W, corresponding to an acoustic power density of 8.75 W/mL. Using PEF system no significant reductions in microorganism were detected, proving that the stand-alone PEF treatment applied is ineffective to inactivate Lactococcus lactis in whey. On the contrary, utilizing PEF as a pre-treatment it was possible to detect a reduction in D-value compared with thermal treatment, implying a possible use of PEF to improve whey pasteurization. The thermosonication treatment studied in this work also demonstrated a significant decrease in inactivation time, however this technology has a limitation of 3.5 to 4 log reductions, afterwards the inactivation kinetics follow a normal thermal inactivation. |
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