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首页> 外文学位 >Proteins as emulsifiers in retarding oil oxidation in an oil/water emulsion.
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Proteins as emulsifiers in retarding oil oxidation in an oil/water emulsion.

机译：蛋白质作为乳化剂，可延迟油/水乳液中的油氧化。

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摘要

Food proteins form a class of natural emulsifiers. Also, due to their high nutritional value and generally-recognized-as-safe (GRAS) status, they make a popular choice as encapsulating agents for bioactive lipids. However, their efficacy in the ability to confer emulsion oxidative stability is scarcely reported in literature. The main objective of this investigation was to study the influence of processing on the structural characteristics of interfacial food proteins in Menhaden oil-in-water emulsion systems, and relate these characteristics to emulsion oxidative stability. Being the foremost immediate physical barrier around the oil drop, the interfacial protein layer might confer effective protection of the oil from oxidative deterioration if strategically designed.;Three different food proteins with distinct characteristics were experimentally studied: (i) sodium caseinate (∼24 kDa)---which has a random-coiled structure; (ii) bovine beta-lactoglobulin (∼18.4 kDa)---which is globular and encompasses a beta-barrel in its native state; and (iii) soy beta-conglycinin (7S) (∼180 kDa in trimeric form), which is globular, much larger in size, and has a predominant beta-sheet structure. A number of ways were identified which improved the efficacy of these proteins in protecting the encapsulated Menhaden oil against oxidation, depending on the conformation of the protein. In the case of sodium caseinate, homogenization at higher pressure levels, the use and subsequent vaporization of a food-grade volatile solvent to induce drop shrinkage, and limited transglutaminase treatment of the interfacial layer were all found to be useful in promoting oxidative stability. For the globular beta-lactoglobulin, momentary preheating to the molten globule state, before homogenization at ambient temperature, had a noteworthy impact on improving oxidative stability due to increased surface aggregation while retaining the original protein stiffness. As for soy 7S, trypsinization was successful in improving the functionality of the native control at neutral and alkaline pH; it was likely due to the induced formation of beta-sheets oriented close to the oil surface which reinforced the protection of oil, in addition to protein unfolding that promoted protein-oil hydrophobic interaction. Based on mathematical modeling, the aforementioned successful methods caused a similar effect, i.e. a decrease in the diffusion coefficient of oxygen in the interfacial protein layer.
机译：食物蛋白形成一类天然乳化剂。而且，由于它们的高营养价值和公认的安全（GRAS）状态，它们作为生物活性脂质的包囊剂是一种流行的选择。然而，文献中几乎没有报道它们在赋予乳液氧化稳定性方面的功效。这项研究的主要目的是研究加工过程对Menhaden水包油乳液系统中界面食品蛋白质结构特征的影响，并将这些特征与乳液的氧化稳定性相关联。作为油滴周围最重要的直接物理屏障，如果进行战略性设计，界面蛋白层可能会有效保护油免受氧化变质的影响；；对三种具有不同特征的食物蛋白进行了实验研究：（i）酪蛋白酸钠（〜24 kDa ）-具有无规螺旋结构； （ii）牛β-乳球蛋白（〜18.4 kDa）---球形，在其天然状态下包含一个β-桶； （iii）大豆β-伴大豆球蛋白（7S）（三聚体形式约为180 kDa），呈球形，大小更大，具有主要的β-折叠结构。根据蛋白质的构象，已鉴定出多种方法来改善这些蛋白质在保护被包封的Menhaden油中免受氧化的功效。在酪蛋白酸钠的情况下，发现在较高的压力水平下均质化，使用和随后蒸发食品级挥发性溶剂以引起液滴收缩以及对界面层进行有限的转谷氨酰胺酶处理均有助于提高氧化稳定性。对于球状β-乳球蛋白，在环境温度下均质化之前，瞬间预热至熔融球状状态对氧化稳定性的改善有显着影响，这是因为表面聚集增加，同时保留了原始蛋白质的硬度。对于大豆7S，胰蛋白酶消化成功地改善了天然对照在中性和碱性pH下的功能；这可能是由于诱导形成的β-片层靠近油表面而形成的，这种层增强了对油的保护作用，此外还促进了蛋白-油疏水相互作用的蛋白解折叠。基于数学模型，上述成功的方法产生了相似的效果，即界面蛋白层中氧的扩散系数降低。

著录项

  • 作者

    Phoon, Pui Yeu.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Agriculture Food Science and Technology.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 199 p.
  • 总页数 199
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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