Effects of heat treatment on conformation and cell growth activity of alpha- lactalbumin and beta-lactoglobulin from market milk

Heat processes, low temperature for long time (LTLT) pasteurization and ultra-heat treatment (UHT) sterilization, are essential for commercial market milk to improve the shelf life of raw milk and ensure microbial safety. We evaluated the effects of heat experience on the molecular properties of α-l...

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Bibliographic Details
Published in:Biomedical Research 2017/02/01, Vol.38(1), pp.53-59
Main Authors: INAGAKI, Mizuho, KAWAI, Shuji, IJIER, X, FUKUOKA, Mayuko, YABE, Tomio, IWAMOTO, Satoshi, KANAMARU, Yoshihiro
Format: Article
Language:English
Subjects:
Animals
Cell growth
Cell Line
Cell Proliferation
Circular Dichroism
Conformation
Cytotoxicity
Dichroism
Epithelium
Food Handling
Heat treatment
Hot Temperature
Intestine
Lactalbumin
Lactalbumin - chemistry
Lactoglobulin
Low temperature
Microorganisms
Milk
Milk - chemistry
Molecular Conformation
Molecular properties
Pasteurization
Proteins
Rats
Shelf life
Sterilization
Temperature effects
Ultrahigh temperature
Whey protein
β-Lactoglobulin
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Summary:Heat processes, low temperature for long time (LTLT) pasteurization and ultra-heat treatment (UHT) sterilization, are essential for commercial market milk to improve the shelf life of raw milk and ensure microbial safety. We evaluated the effects of heat experience on the molecular properties of α-lactalbumin (α-LA) and β-lactoglobulin (β-LG) isolated from four types of market milk such as LTLT-A (66°C for 30 min), LTLT-B (65°C for 30 min), UHT-I (130°C for 2 s, indirect heating) and UHT-D (135°C for 2 s, direct heating) samples. We examined molecular conformations using circular dichroism spectrum measurement and cell growth activity using the WST-1 method for the proteins. α-LA isolated from each of these four types of market milk displayed no significant structural difference as compared to raw milk α-LA, while α-LA of UHT-I only inhibited cell growth of an intestinal epithelial cell line more potently than raw milk α-LA. In the case of β-LG, only the UHT-I sample demonstrated a drastic change in structure, while it did not exhibit any cytotoxicity. We found that cell viability effects of α-LA and β-LG are attributable to the type of UHT; indirect and direct. These findings indicate that the effect of heat treatment on whey proteins should carefully be investigated further.
ISSN:0388-6107
1880-313X
DOI:10.2220/biomedres.38.53