Journal
JOURNAL OF FOOD ENGINEERING
Volume 223, Issue -, Pages 189-196Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.jfoodeng.2017.10.020
Keywords
Whey protein isolate; Nanofibrils; Denaturation; Microfluidization; pH; Viscosity
Categories
Funding
- PepsiCo (Valhalla, NY)
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The functional attributes of globular proteins can be extended by controlling the nature of the aggregates they form. In this study, the effect of thermal treatment (85 degrees C/20 min) and high pressure micro fluidization (20,000 psi, 1 pass) on the physical properties of whey protein isolate solutions (5-9%; pH 2) was investigated. Heating solutions of native whey protein isolate (8 wt%) under these acidic conditions led to the formation of highly viscous solutions (eta = 306 mPa s) with low turbidity (tau = 0.04 cm(-1)), which was attributed to the formation of protein fibrils (effective d = 310 nm). Microfluidization of these protein fibrils decreased their length (effective d = 97 nm) leading to a substantial reduction in solution viscosity (eta = 3.8 mPa s), and a slight reduction in turbidity (tau < 0.03 cm(-1)). The impact of solution pH (2 - 7) on the appearance and rheology of native, heated, and heated-microfluidized whey protein isolate solutions was then examined. For all systems, highly turbid solutions (tau > 1 cm(-1)) were formed at pH values close to the isoelectric point of the whey proteins (pH 4.5) due to protein self-association caused by reduction of the electrostatic repulsion between the protein molecules. Highly viscous or gelled solutions were formed for the heated and heated-microfluidized proteins across a wide pH range, which was attributed to the presence of fibrils. The study showed that the functional attributes of whey proteins can be modulated by thermal and high-pressure homogenization treatment. (C) 2017 Elsevier Ltd. All rights reserved.
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