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Poster De Conférence Année : 2022

Deciphering the key parameters that influence the rheological properties of concentrated milk protein systems using a multifactorial approach

Résumé

Dairy ingredients with highly concentrated protein contents are nowadays high value-added products with increasing demand since their specific properties are well adapted for a multitude of applications (e.g. cheese, bakery, infant formulae, nutritional products for the elderly and athletes...). Milk protein concentrates are mainly found as dry ingredients but the use of liquid concentrates instead of powders have been of growing interest as it contributes to the reduction of energy costs of industrial processes. However, physical phenomena behind the ageing of liquid concentrates (e.g. during their transport...) are not fully understood. In the same way, in the powder manufacturing process, it is well established that rheological properties of protein concentrates before spray drying greatly modulate the final powder quality. In both cases, the control of rheological properties of protein concentrates is crucial to obtain a liquid or a dry product with the expected functional properties. Hence, identifying the parameters and understanding the molecular mechanisms that affect the viscosity of high protein concentrates during their manufacture and their ageing is a major challenge. In this study, we investigated the viscosity of unheated and heated milk protein concentrates (19–21% w/w total protein), at five casein micelles/whey protein ratios (92:8, 80:20, 50:50, 40:60 and 5:95) and in two physicochemical environments (high or low ionic strength/lactose content). The apparent viscosity of the 34 samples were monitored over a shear ramp from 1 to 500 s−1 at 40 °C. In order to evaluate the viscosity changes during storage, shear sweep tests were performed at periodic intervals for six hours. A multifactorial analysis was then carried out to identify the impact of the different parameters on the rheological properties of the concentrates. The casein/whey protein ratio greatly affected the rheological behaviour as well as the value of the apparent viscosity of the dispersions. In samples containing at least 80% of casein micelles, a shear-thinning behaviour was observed whereas samples containing less than 50% of caseins showed a Newtonian behaviour. Moreover, at 1 s-1, the apparent viscosity of the samples that had 92% of casein micelles was 150 times higher than the ones containing only 5% of caseins. At the boundaries of the sol-gel transition, a small increase in protein content induced a drastic increase in viscosity. An increase in whey protein denaturation led to an increase in viscosity. This phenomenon was enhanced at high casein/whey protein ratio. Finally, no changes in viscosity related to age-thickening was observed in this study.
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Dates et versions

hal-03841660 , version 1 (07-11-2022)

Identifiants

  • HAL Id : hal-03841660 , version 1

Citer

Francois Martin, Florence Rousseau, Jeehyun Lee, Gaëlle Tanguy, Emeline Gousse, et al.. Deciphering the key parameters that influence the rheological properties of concentrated milk protein systems using a multifactorial approach. 56ème Congrès du GFR, Oct 2022, Rennes, France. , 2022. ⟨hal-03841660⟩
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