Smoothing temperature and ratio of casein to whey protein: Two tools to improve nonfat stirred yogurt properties.

Autor:	Gilbert A; Department of Food Sciences, Université Laval, Quebec City, QC, Canada, G1V 0A6; STELA Dairy Research Centre and Institute of Nutrition and Functional Foods, Université Laval, Quebec City, QC, Canada, G1V 0A6., Rioux LE; Department of Food Sciences, Université Laval, Quebec City, QC, Canada, G1V 0A6; STELA Dairy Research Centre and Institute of Nutrition and Functional Foods, Université Laval, Quebec City, QC, Canada, G1V 0A6., St-Gelais D; Department of Food Sciences, Université Laval, Quebec City, QC, Canada, G1V 0A6; Saint-Hyacinthe Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Hyacinthe, QC, Canada, J2S 8E3., Turgeon SL; Department of Food Sciences, Université Laval, Quebec City, QC, Canada, G1V 0A6; STELA Dairy Research Centre and Institute of Nutrition and Functional Foods, Université Laval, Quebec City, QC, Canada, G1V 0A6. Electronic address: Sylvie.Turgeon@fsaa.ulaval.ca.
Jazyk:	angličtina
Zdroj:	Journal of dairy science [J Dairy Sci] 2021 Oct; Vol. 104 (10), pp. 10485-10499. Date of Electronic Publication: 2021 Jul 16.
DOI:	10.3168/jds.2020-20040
Abstrakt:	Consumers are not always ready to compromise on the loss of texture and increased syneresis that nonfat stirred yogurts display compared with yogurts that contain fat. In this study, we investigated milk protein composition and smoothing temperature as a means to control nonfat yogurt microstructure, textural properties, and syneresis. Yogurts were prepared with different ratios of casein to whey protein (R1.5, R2.8, and R3.9). Yogurts were pumped through a smoothing pilot system comprising a plate heat exchanger set at 15, 20, or 25°C and then stored at 4°C until analysis (d 1, 9, and 23). Yogurt particle size and firmness were measured. Yogurt syneresis and water mobility were determined, respectively, by centrifugation and time domain low-frequency proton nuclear magnetic resonance ( 1 H-LF-NMR). Increasing the smoothing temperature increased gel firmness and microgel (dense protein aggregates) sizes independently of the whey protein content. Also, yogurt microgel sizes changed with storage time, but the evolution pattern depended on protein ratio. Yogurt R1.5 showed the largest particles, and their sizes increased with storage, whereas R2.8 and R3.9 had smaller microgels, and R3.9 did not show any increase in microgel size during storage. Micrographs showed a heterogeneous gel with the empty area occupied by serum for R1.5, whereas R2.8 and R3.9 showed fewer serum zones and a more disrupted gel embedding microgels. Induced syneresis reduced with greater whey protein content and time of storage. This is in agreement with 1 H-LF-NMR showing less bulk water mobility with increasing whey protein content during storage. However, 1 H-LF-RMN revealed higher values of spontaneous serum separation during storage for R1.5 and R3.9 yogurts, whereas these were lower and stable for R2.8 yogurt. Microgels play an important structural role in yogurt textural attributes, and their characteristics are modulated by whey protein content and smoothing temperature. Optimization of these parameters may help improve nonfat stirred dairy gel. (© 2021, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).)
Databáze:	MEDLINE
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