Impact of Ultrasound Emulsification on the Physicochemical Properties of Emulsions Stabilised by Quinoa Protein Isolates at Different pHs

IF 2.8 4区农林科学 Q2 FOOD SCIENCE & TECHNOLOGY Food Biophysics Pub Date : 2023-10-13 DOI:10.1007/s11483-023-09812-8

Zhi Yang, Lirong Cheng

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Abstract

Ultrasonication (20 kHz, 19.9 W/10 mL sample) was used to form O/W emulsions stabilised by quinoa protein isolate (QPI) particles at 3 wt%. Effects of pH (3, 5, 7, 9) and oil volume fractions (20%, 40%, and 60%) on rheological properties and microstructural characteristics of emulsions were investigated. All emulsions show viscoelastic behaviours and form a network structure comprising aggregated oil droplets and QPI particles. Emulsions stabilised by QPI at pH 5 showed largest droplet sizes and lowest gel strength due to extensive aggregation of proteins around the isoelectric point (pI ~ 4.5). The gel strength (G´(1 Hz)) were enhanced when the oil volume fraction increased and reached ~ 1100–1350 Pa at 60% oil volume fraction at different pH. This could be attributed to a tighter packing of oil droplets at 60% oil. Confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM) revealed that interdroplets bridging and voids filling of QPI particles between oil droplets are critical in formation of aggregated emulsions network. Emulsions stabilised by QPI at pH 7 and 9 possessed thinner interfacial layers compared to those at pH 3 and 5. Finally, this study shows a potential of using ultrasonication to prepare gel-like emulsions stabilised by QPI, broadening applications of quinoa proteins in making dairy substitutes with semi-solid textural characteristics.

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不同 pH 值下超声乳化对藜麦蛋白分离物稳定乳液理化性质的影响

使用超声波（20 kHz，19.9 W/10 mL 样品）形成由 3 wt% 的藜麦蛋白分离物 (QPI) 颗粒稳定的 O/W 型乳液。研究了 pH 值（3、5、7、9）和油体积分数（20%、40% 和 60%）对乳液流变特性和微观结构特征的影响。所有乳液都表现出粘弹性行为，并形成由聚集的油滴和 QPI 颗粒组成的网络结构。由于蛋白质在等电点（pI ~ 4.5）附近广泛聚集，在 pH 值为 5 时由 QPI 稳定的乳液显示出最大的油滴尺寸和最低的凝胶强度。当油的体积分数增加时，凝胶强度（G´(1 Hz)）增强，在不同 pH 值下，当油的体积分数为 60% 时，凝胶强度达到约 1100-1350 Pa。这可能是由于当油的体积分数为 60% 时，油滴的堆积更为紧密。共焦激光扫描显微镜（CLSM）和透射电子显微镜（TEM）显示，油滴间的 QPI 颗粒桥接和空隙填充是形成聚合乳液网络的关键。与 pH 值为 3 和 5 的乳液相比，pH 值为 7 和 9 的 QPI 稳定乳液具有更薄的界面层。最后，这项研究显示了使用超声波来制备由 QPI 稳定的凝胶状乳剂的潜力，从而拓宽了藜麦蛋白在制造具有半固体质地特性的乳制品替代品方面的应用。

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来源期刊

Food Biophysics 工程技术-食品科技

CiteScore

5.80

自引率

3.30%

发文量

审稿时长

1 months

期刊介绍： Biophysical studies of foods and agricultural products involve research at the interface of chemistry, biology, and engineering, as well as the new interdisciplinary areas of materials science and nanotechnology. Such studies include but are certainly not limited to research in the following areas: the structure of food molecules, biopolymers, and biomaterials on the molecular, microscopic, and mesoscopic scales; the molecular basis of structure generation and maintenance in specific foods, feeds, food processing operations, and agricultural products; the mechanisms of microbial growth, death and antimicrobial action; structure/function relationships in food and agricultural biopolymers; novel biophysical techniques (spectroscopic, microscopic, thermal, rheological, etc.) for structural and dynamical characterization of food and agricultural materials and products; the properties of amorphous biomaterials and their influence on chemical reaction rate, microbial growth, or sensory properties; and molecular mechanisms of taste and smell. A hallmark of such research is a dependence on various methods of instrumental analysis that provide information on the molecular level, on various physical and chemical theories used to understand the interrelations among biological molecules, and an attempt to relate macroscopic chemical and physical properties and biological functions to the molecular structure and microscopic organization of the biological material.