Heat-Induced Conformational Changes in Whey Protein Isolate and Its Relation to Foaming Properties

Zhu, Haiming; Damodaran, Srinivasan

doi:10.1021/jf00040a002

Cited by 173 publications

(154 citation statements)

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“…The control WPI is characterised by the possibility of stabilising a greater interface area per unit weight of protein compared with WPC, which can be quantified with a higher value of EAI (148.21 ± 1.56 m 2 ·g -1 vs. 117.81 ± 3.21 m 2 ·g -1 ). The presence of lactose and lipids in WPC prevent protein propagation at the interface surface, resulting in decreased values of the emulsion activity index [50]. The higher value for EAI of WPI is also related to its protein composition.…”

Section: Influence Of High Pressure On Emulsifying Properties Of Wpc mentioning

confidence: 99%

Effects of high pressure on functionality of whey protein concentrate and whey protein isolate

Krešić

Lelas

Herceg

et al. 2006

Lait

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-The objective of this study was to evaluate the influence of high-pressure treatments on the solubility, surface hydrophobicity, foaming and emulsifying ability of whey protein concentrate (WPC) and whey protein isolate (WPI). Dispersions of WPC and WPI powders (10% (w/w)) were processed at 300 MPa and 600 MPa, for 5 and 10 min at 40 ± 2°C. Changes in protein solubility were determined as solubility at pH 7.0 and at pH 4.6. Assessment of foaming properties was based on the foam expansion during prolonged whipping, and foam stability. Emulsifying properties were characterised by emulsion stability and emulsifying activity indices. The results show significant (P < 0.05) modification of solubility and surface hydrophobicity with increasing intensity and duration of applied pressure, indicating partial denaturation and aggregation of proteins. It was found that high-pressure treatments significantly (P < 0.05) improved the foaming behaviour of WPI, while the foaming ability of WPC was diminished. However, foams formed with high-pressuretreated WPC and WPI exhibited significantly prolonged stability (P < 0.05) compared with control samples. There was a significant trend of decreasing emulsifying efficiency and emulsifying stability related to the intensity of applied pressure and treatment time for both WPC and WPI. emulsifying properties / foaming properties / high pressure / whey protein concentrate / whey protein isolate / solubility / surface hydrophobicity 摘要 -高压处理对乳清浓缩蛋白和乳清分离蛋白的影响。本文研究了高压处理对乳清浓缩蛋白 (WPC) 和乳清分离蛋白 (WPI) 的溶解性、表面疏水性、发泡性和乳化性的影响。在 40°C 下，乳清浓缩蛋白 (10 %, w/w) 和乳清分离蛋白 (10 %, w/w) 的分散液分别在 300 MPa 和 600 Mpa 下高压处理 5 min 和 10 min。在 pH 7.0 和 pH 4.6 测定了两种蛋白质溶解性的变化。以长时间搅打后形成的泡沫膨胀度和泡沫稳定性来评价蛋白质的发泡性能；根据测定乳液稳定性指数和乳化活性指数评价两种蛋白质的乳化特性。试验结果表明，经过高压长时间的处理后，由于蛋白质发生了部分变性和凝聚作用，使得蛋白质的溶解性和表面疏水性发生了显著的改变 (P < 0.05)。高压处理能够显著地改善 WPI 的发泡性 (P < 0.05)，而 WPC 的泡沫形成能力则降低。然而与对照样品相比，经过高压处理后的 WPC 和 WPI 形成的泡沫稳定性有显著提高 (P < 0.05)。随着处理压力和作用时间的增加，两种蛋白质的乳化性和乳化稳定性均呈下降的趋势。乳化性 / 发泡性 / 高压 / 乳清浓缩蛋白 / 乳清分离蛋白 / 溶解性 / 表面疏水性 * Corresponding author (通讯作者): Greta.Kresic@fthm.hrArticle published by EDP Sciences and available at http://www.edpsciences.org/lait or http://dx

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Section: Influence Of High Pressure On Emulsifying Properties Of Wpc mentioning

confidence: 99%

Effects of high pressure on functionality of whey protein concentrate and whey protein isolate

Krešić

Lelas

Herceg

et al. 2006

Lait

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“…These whey proteins have excellent nutritional value, due to their high content in cystein, and to the high content of α-lactalbumin in tryptophan residues [91]. They also have very good foaming and emulsion properties in their native state, or when partially denatured [34,79,167], and high water retention and gelation properties in their denatured state [32,33,79,155,160].…”

Section: Introductionmentioning

confidence: 99%

Formation of heat-induced protein aggregates in milk as a means to recover the whey protein fraction in cheese manufacture, and potential of heat-treating milk at alkaline pH values in order to keep its rennet coagulation properties. A review

Guyomarc’H

2006

Lait

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-The heat-treatment of cheese milk, or whey, to denature the whey proteins has long been the most applied means of recovering these proteins, either directly in the cheese curd, or as added to the cheese milk prior to renneting. In heat-treated milk, the interaction of the denatured whey proteins with the casein micelles, however, limits the primary phase of the enzymatic reaction, and prevents fusion of the casein micelles. Cheeses containing heat-denatured whey proteins also exhibit excessive moisture, a crumbly and soft texture, and poor meltability. Various technological means to reduce these drawbacks are reviewed. Especially, it is generally accepted that the heat-treatment of skim milk at alkaline pH generates aggregates of denatured whey proteins and κ-casein in the serum phase of milk, rather than on the surface of the casein micelles. As a consequence, the casein micelles are depleted in κ-casein, and free of denatured whey proteins. However, the attempts made to exploit this interesting protein distribution in cheese-making remain scarce, despite their promising results. Résumé -Récupération des protéines sériques du lait dans le caillé fromager au moyen de la formation d'agrégats thermo-induits, et intérêt de chauffer le lait à pH alcalin dans le but de conserver son aptitude à la coagulation présure. Revue. Le traitement thermique du lait ou de lactosérum est un des moyens les plus utilisés pour incorporer les protéines sériques ainsi dénatu-rées, soit directement dans le caillé, soit sous forme d'ingrédient ajouté au lait fromager. Cependant, l'interaction entre les protéines sériques dénaturées et les micelles de caséines, due au chauffage du lait, a pour effet de limiter la phase primaire de la coagulation par la présure, ainsi que la fusion des micelles déstabilisées. Les fromages obtenus à partir de lait chauffé sont aussi plus humides, plus mous, plus granuleux et moins aptes à la fonte que les fromages standards. Les moyens technologiques de pallier ces inconvénients sont rappelés. En particulier, il est connu que le traitement thermique du lait à pH alcalin favorise la formation d'agrégats de protéines sériques dénaturées et de caséine κ dans la phase soluble du lait, plutôt qu'en surface des micelles de caséines. En consé-quence, la teneur en caséine κ des micelles est réduite et celles-ci ne sont pas recouvertes de protéi-nes sériques dénaturées. Cependant, peu d'études ont tenté d'exploiter ces caractéristiques du lait chauffé à pH alcalin en technologie fromagère, malgré des résultats prometteurs. coagulation présure / traitement thermique / protéine sérique / fromage

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“…The heat July 2011 inactivation of trypsin inhibitors and the heat denaturation of SB globulins, makes them more susceptible to proteolysis, thereby improving soy protein bioavailability for human foodstuffs or animal feeding [16]. Also, heat denaturation improves the foaming and emulsifying properties of soy proteins [21]. However, if the heating is excessive, e.g., autoclaving at 130 o C for 24 hr or even heating at 90-100 o C for prolonged periods even at neutral pH, the nutritive value is impaired and one mechanism is believed to be cross-linking of peptide bonds by acylation of free amino groups [17,22].…”

Section: Effects Of Heat On Soybean Proteinmentioning

confidence: 99%

Effects of processing on soybean nutrients and potential impact on consumer health: An overview

Lokuruka¹

2011

African Journal of Food, Agriculture, Nutrition and Development

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Production of soybeans and consumption of soy products is increasing worldwide mainly due to acclaimed health benefits. Processing can alter soybean sensory appeal, nutritive value and potentially affect consumer health. This review of the literature examines these issues. Despite potential changes in nutritive value during processing, soy foods processing below 100 o C for short periods, may not adversely affect nutritive value. However, heat inactivation of trypsin inhibitors, denaturation of soybean globulins and haemagglutenins, increases soy protein bioavailability. Excessive heating can impair nutritive value by making lysine unavailable, as serine, cystine and cysteine are converted to a dehydroprotein intermediate that reacts with lysine to form lysinoalanine. Tryptophan and methionine are also lost during excessive heating. The acylation reaction catalyzed by alkali, generates lysinoalanine, an unavailable and potentially toxic compound. In rats, ingestion of lysinoalanine results in diarrhoea, pancreatic hyperplasia, and loss of hair. At levels present in foods, protein-bound lysinoalanine does not cause nephrotoxicity in humans. Heat treatments at alkaline pH result in destruction of arginine, which is converted to ornithine, urea, citrulline and ammonia, while cysteine is converted into dehydroalanine. Serine, threonine and lysine are also reduced at alkaline pH. These conditions may be present during alkali refining of soy oil. Carbohydrates with free reducing groups react with carbonyl groups on proteins as part of the Maillard reaction. Heat treatments at alkaline pH and above 200 o C cause isomerization of amino acids, leading to formation of racemic mixtures of L and D forms. Since D isomers have reduced bioavailability and some including D-proline are reported to be toxic, racemization of an essential amino acid reduces its nutritional value. Changes in lipids include oxidation, loss of lipid-soluble vitamins and change of fatty acids from cis to trans isomers. Autoxidation of unsaturated fatty acids initiates free radical formation leading to destruction of unsaturated fatty acids, with potential reduction of essential fatty acid content. Oxidized lipid-protein interaction products are important precursors of atherosclerotic plaques in vivo. Carotenoids are lost on bleaching, thereby reducing Vitamin A potential. Vitamin E is lost during oil refining. Roasting and toasting have no effect on soy isoflavones, but organic solvents remove them, while fermentation increases their bioavailability. Dehulling reduces total mineral content but most soy minerals follow protein or meal, while sodium and potassium are lost in wash water. To minimize adverse changes, minimal washing, fermentation, reduction of hydrogenation temperature and thermal processing below 100 o C for short periods, are recommended.

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Heat-Induced Conformational Changes in Whey Protein Isolate and Its Relation to Foaming Properties

Cited by 173 publications

References 12 publications

Effects of high pressure on functionality of whey protein concentrate and whey protein isolate

Effects of high pressure on functionality of whey protein concentrate and whey protein isolate

Formation of heat-induced protein aggregates in milk as a means to recover the whey protein fraction in cheese manufacture, and potential of heat-treating milk at alkaline pH values in order to keep its rennet coagulation properties. A review

Effects of processing on soybean nutrients and potential impact on consumer health: An overview

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