pH和固体含量对牛奶中蛋白质结构变化的影响

IF 1.1 4区农林科学 Q3 AGRICULTURE, DAIRY & ANIMAL SCIENCE

Mljekarstvo Pub Date : 2021-03-16 DOI:10.15567/MLJEKARSTVO.2021.0202

Tatijana Markoska, Melbourne Vic Australia Biomedicine

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引用次数: 2

摘要

浓缩牛奶系统在热处理过程中可能不稳定。本研究采用傅立叶变换红外光谱(FTIR)和SDS-PAGE技术，研究了脱脂牛奶(固体含量为9、17和25%)在pH值调整至7.5以及在75、85、95、100、110和121°C加热后蛋白质的结构变化。pH值调整到7.5导致酪蛋白与血清分离，主要是在总固体含量为9%的样品中。此外，由于蛋白质展开，pH调节导致所有浓度水平下随机结构的增加。热处理对血清相蛋白质组成影响较大，并引起结构改变。所有牛奶样品在加热到110°C时，由于热诱导聚集，血清β-LG， α-LA和酪蛋白(主要是κ-酪蛋白)的损失。随着浓度的增加，聚集强度增大。121℃时的趋势相似，但团聚体更大。随着浓度因子的增加，新形成的结构之间的共价键似乎占上风。

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Influence of pH and solids content on heat-induced changes in structural arrangements of proteins in milk

Concentrated milk systems can be unstable during heat treatment. In this work, we studied the structural changes in the proteins in skim milk (9, 17 and 25 % solids) as a result of pH adjustment to pH 7.5 and heating at 75, 85, 95 100, 110 and 121 °C by Fourier transform infrared spectroscopy (FTIR) and SDS-PAGE. The pH adjustment to 7.5 resulted in some dissociation of caseins to serum, predominately in the 9 % total solids samples. Furthermore, pH adjustment resulted in an increase in random structures at all concentration levels, due to protein unfolding. Heat treatment affected greatly the protein composition in the serum phase and induced structural modifications. All milk samples when heated to 110°C exhibited loss of serum β-LG, α-LA and caseins (mainly κ-casein) as a result of heat induced aggregation. The intensity of aggregation increased with concentration factor. The trend appeared similar at 121 °C but with larger aggregates. As a concentration factor increased, covalent bonds among newly formed structures appeared to prevail.

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来源期刊

Mljekarstvo Agricultural and Biological Sciences-Animal Science and Zoology

CiteScore

1.90

自引率

41.70%

发文量

审稿时长

12 weeks

期刊介绍： Mljekarstvo is an open access, peer-reviewed international quarterly scientific journal. The first issue was published in 1951, by the Croatian Dairy Operators'' Association (today: Croatian Dairy Union, publisher). In a paper at a Union conference held 28 October 1951 in Zagreb it was said: "Our desire is that this magazine does not meet the fate of its predecessors, but that it continues to reflect the creative efforts and to provide guidelines for the producers as well as all other operators employed in the dairy industry." It is our pleasure today to say that wishes of the enthusiasts who attended the conference have come true, and the magazine Mljekarstvo during the last six decades was a reflection of the creative efforts of numerous dairy scientists and experts, and through its texts it served as a guideline in improving production and processing of milk and dairy products. Mljekarstvo has been following all the achievements of the dairy profession in Croatia, and it also gives the short surveys of world achievements. The result of the research of local and foreign scientists and experts always find their place in the magazine Mljekarstvo. It has been edited by our outstanding dairy experts employed at colleges, research institutions and dairy companies.