Thermal processing of milk: Effects on nutrient content and physical properties
(2024)- Abstract
- Milk is a nutrient-dense fluid which is essential for a healthy balanced diet. Thermal processing is the dominating approach in the dairy industry to ensure food safety, however, heat treatment can alter both the composition and quality of the milk. The aim of this thesis has been to evaluate the effects of various processing technologies on the nutrient content and physical properties of milk and cream, mainly in the production of low- and high-pasteurised milk, milk with extended shelf-life (ESL) milk and ultra-high temperature (UHT) treated milk. The studies were performed in laboratory, pilot and dairy production scale to evaluate thermal processing effects on the milk system and to develop kinetic models for vitamin losses. The... (More)
- Milk is a nutrient-dense fluid which is essential for a healthy balanced diet. Thermal processing is the dominating approach in the dairy industry to ensure food safety, however, heat treatment can alter both the composition and quality of the milk. The aim of this thesis has been to evaluate the effects of various processing technologies on the nutrient content and physical properties of milk and cream, mainly in the production of low- and high-pasteurised milk, milk with extended shelf-life (ESL) milk and ultra-high temperature (UHT) treated milk. The studies were performed in laboratory, pilot and dairy production scale to evaluate thermal processing effects on the milk system and to develop kinetic models for vitamin losses. The results showed that the concentration of macro components in milk did not change due to heat treatment. However, vitamin degradation was observed in milk heat-treated at laboratory scale as well as at pilot scale for ESL/UHT treatment using both direct and indirect heating systems. The degradation increased with higher heating temperatures and longer holding times, although no differences were observed between heating systems. At dairy production scale, high pasteurisation caused the most significant vitamin degradation, while limited losses were observed for high-temperature-short-time (HTST) pasteurisation, ESL, and UHT processing. During storage, vitamin losses varied between 1-22% for different heat treatments, and more pronounced effects of vitamin degradation were observed with higher heat treatment and longer storage times. The concentration of vitamin B12 tended to decrease more over time than vitamins B1, B2, and E, and more losses of vitamins occurred during storage than after heat treatment. The total mineral concentration in milk and cream showed limited losses. Additionally, a decrease in ionic calcium concentration was observed after heat treatment, while no significant changes were observed during shorter storage times.An increase in fat globule size and aggregate formation were observed in milk heat-treated using direct heating at pilot scale, with more pronounced effects at higher temperatures. However, the physical stability of milk remained unaffected on the day of production. Heat treatments performed at dairy production scale resulted in an increase in casein micelle size but had no effect on the physical stability of milk. However, during storage of milk after heat treatment at both pilot and dairy production scale, physical stability of milk was affected. Further, during storage a decrease in pH was observed with longer storage times.
Minimal changes in milk colour were observed after heat treatment, whereas larger changes in colour were observed during prolonged storage. Laboratory scale experiments were used to fit kinetic models of vitamin degradation in milk (vitamins B1, B2 and E), which were validated with five different heat treatment processing lines at dairy production scale. Results showed that the predicted values obtained from laboratory scale experiments fit the validation data well. This means that simplified laboratory scale experiments can give valid predictions of thermal degradation of vitamins in milk during processing at dairies. The thesis has highlighted that heating systems for ESL/UHT treatment may influence milk quality, although no clear distinction between direct and indirect heating systems was observed at pilot scale for the investigated quality parameters. Furthermore, the thesis has shown that process techniques for heat treatment used in dairy production scale today are mild and have low effects on the nutrient content and physical properties of milk and cream, and that more pronounced changes primarily occur during longer storage times. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/5e3f3132-ec1e-4a5f-9ecd-d24203128172
- author
- Lalwani, Shruti LU
- supervisor
-
- Maria Glantz LU
- Marie Paulsson LU
- Andreas Håkansson LU
- Frida Lewerentz LU
- opponent
-
- Prof. Ahrné, Lilia, University of Copenhagen, Denmark.
- organization
- publishing date
- 2024
- type
- Thesis
- publication status
- published
- subject
- keywords
- Bovine milk, heat treatment, storage, nutrient, vitamin degradation, physical property, UHT milk, ESL milk, dairy production, kinetic modelling
- pages
- 92 pages
- publisher
- Food Technology, Lund University
- defense location
- Lecture Hall KC:A, Kemicentrum, Naturvetarvägen 14, Faculty of Engineering LTH, Lund University, Lund. The dissertation will be live streamed, but part of the premises is to be excluded from the live stream.
- defense date
- 2024-05-15 09:15:00
- ISBN
- 978-91-8096-025-0
- 978-91-8096-024-3
- language
- English
- LU publication?
- yes
- id
- 5e3f3132-ec1e-4a5f-9ecd-d24203128172
- date added to LUP
- 2024-04-16 11:14:37
- date last changed
- 2024-04-18 10:34:17
@phdthesis{5e3f3132-ec1e-4a5f-9ecd-d24203128172,
abstract = {{Milk is a nutrient-dense fluid which is essential for a healthy balanced diet. Thermal processing is the dominating approach in the dairy industry to ensure food safety, however, heat treatment can alter both the composition and quality of the milk. The aim of this thesis has been to evaluate the effects of various processing technologies on the nutrient content and physical properties of milk and cream, mainly in the production of low- and high-pasteurised milk, milk with extended shelf-life (ESL) milk and ultra-high temperature (UHT) treated milk. The studies were performed in laboratory, pilot and dairy production scale to evaluate thermal processing effects on the milk system and to develop kinetic models for vitamin losses. The results showed that the concentration of macro components in milk did not change due to heat treatment. However, vitamin degradation was observed in milk heat-treated at laboratory scale as well as at pilot scale for ESL/UHT treatment using both direct and indirect heating systems. The degradation increased with higher heating temperatures and longer holding times, although no differences were observed between heating systems. At dairy production scale, high pasteurisation caused the most significant vitamin degradation, while limited losses were observed for high-temperature-short-time (HTST) pasteurisation, ESL, and UHT processing. During storage, vitamin losses varied between 1-22% for different heat treatments, and more pronounced effects of vitamin degradation were observed with higher heat treatment and longer storage times. The concentration of vitamin B12 tended to decrease more over time than vitamins B1, B2, and E, and more losses of vitamins occurred during storage than after heat treatment. The total mineral concentration in milk and cream showed limited losses. Additionally, a decrease in ionic calcium concentration was observed after heat treatment, while no significant changes were observed during shorter storage times.An increase in fat globule size and aggregate formation were observed in milk heat-treated using direct heating at pilot scale, with more pronounced effects at higher temperatures. However, the physical stability of milk remained unaffected on the day of production. Heat treatments performed at dairy production scale resulted in an increase in casein micelle size but had no effect on the physical stability of milk. However, during storage of milk after heat treatment at both pilot and dairy production scale, physical stability of milk was affected. Further, during storage a decrease in pH was observed with longer storage times. <br/>Minimal changes in milk colour were observed after heat treatment, whereas larger changes in colour were observed during prolonged storage. Laboratory scale experiments were used to fit kinetic models of vitamin degradation in milk (vitamins B1, B2 and E), which were validated with five different heat treatment processing lines at dairy production scale. Results showed that the predicted values obtained from laboratory scale experiments fit the validation data well. This means that simplified laboratory scale experiments can give valid predictions of thermal degradation of vitamins in milk during processing at dairies. The thesis has highlighted that heating systems for ESL/UHT treatment may influence milk quality, although no clear distinction between direct and indirect heating systems was observed at pilot scale for the investigated quality parameters. Furthermore, the thesis has shown that process techniques for heat treatment used in dairy production scale today are mild and have low effects on the nutrient content and physical properties of milk and cream, and that more pronounced changes primarily occur during longer storage times.}},
author = {{Lalwani, Shruti}},
isbn = {{978-91-8096-025-0}},
keywords = {{Bovine milk, heat treatment, storage, nutrient, vitamin degradation, physical property, UHT milk, ESL milk, dairy production, kinetic modelling}},
language = {{eng}},
publisher = {{Food Technology, Lund University}},
school = {{Lund University}},
title = {{Thermal processing of milk: Effects on nutrient content and physical properties}},
url = {{https://lup.lub.lu.se/search/files/180133694/Thesis_Shruti_Lalwani_without_papers_Lucris.pdf}},
year = {{2024}},
}