Impact de la technologie et des conditions du foisonnement sur l’élaboration de mousses laitières de type « topping »

Abstract

Impact of technology and whipping conditions on dairy topping fabricationThe continuous manufacturing of dairy toppings has been studied using first the conventional industrial technology, the axial rotor-stator mixer. The influence of process parameters including operating pressure, residence time and rotational speed has been investigated in terms of overrun, bubble size distribution, as well as foam texture and stability using a model dairy emulsion. The performance of the rotor-stator mixer has then been confronted to that of alternative technologies, such as narrow gap annular columns and scraped surface heat exchangers. Experimental results have highlighted the significant role of operating pressure, the ambiguous role of high residence times that make easier the achievement of desired overrun values, but provide larger bubble sizes, and also the negative interaction between high rotational speed and high residence times. Scale effects have been quantified using a generalized Reynolds number that takes into account the shearthinning behaviour of the emulsion, the increase in viscosity due to the gas phase and all the geometrical characteristics of a rotor-stator unit. The results have also shown that scraped surface heat exchangers constitute an attractive alternative to other foaming devices: they behave globally as a rotor-stator unit with long residence time, but provide foams with smaller bubble sizes than other types of units.

Influence of protein heat treatment on the continuous production of food foams

“…Vinckier, Moldenaers, Terracciano, & Grizzuti, 1998). For s = 40 s, Eff was 100%, mainly because the increase of the actual residence time due to pressurised conditions is counterbalanced by the decrease of the apparent residence time s from 120 s to 40 s. This result is in perfect agreement with data already reported by Labbafi et al (2005) on aerated dairy desserts: under pressure, gas dispersion in the RS unit is easier, but must be achieved at a lower apparent residence time in order to avoid overwhipping.…”

“…Djelveh & Gros, 1995;Hanselmann & Windhab, 1999;Thakur, Vial, & Djelveh, 2003;Müller-Fischer & Windhab, 2005;Indrawati, Wang, & Narsimhan, 2008b;Indrawati, Wang, Narsimhan, & Gonzalez, 2008a;Narchi, Vial, & Djelveh, 2007). In the food industry, aeration is typically carried out in axial rotor-stator mixers, using rotor and stator fitted with rows of pins (Hanselmann & Windhab, 1999;Labbafi et al, 2005;Müller-Fischer & Windhab, 2005), except for ice cream for which scraped surface heat exchangers prevail. From a practical point of view, rotor-stator devices are usually operated at high speed under pressure in the industry, although there is no proof that such a high shear and an energy input are required for aeration.…”

CFD simulation of flow and mixing in‐inline rotor‐stator mixers with complex fluids

“…The present work is devoted to the analysis of a rotor‐stator geometry dedicated to this application. Only a dozen of papers can be found in the literature on this topic, although it covers different fields within the industry, such as textile treatments, but also the production of aerated food (e.g., whipped cream, ice cream or chocolate mousse) or cosmetic products . Another application of foam generation involves the manufacture of aerated building material, but most data remain confined to the industry and can be found in patent applications (see, e.g., Demanet and Valenti) .…”

“…This stems probably from the differences in density, viscosity and interfacial properties between liquid‐liquid and gas‐liquid systems. As a result, there is a particular lack of information on the rotor‐stator devices specifically devoted to foam generation, although the power draw curves obtained in single‐phase flows are known to be useful for designing foam generation process . Among them, a simple design has been shown to be quite effective for in‐line aeration for various non‐Newtonian continuous phases and operating conditions, whereas it is reported to be poorly efficient for emulsion preparation.…”

“…It constitutes, therefore, a useful tool that could also be used quantitatively for design purpose, but remains time‐consuming and requires experienced users. A possible alternative approach, developed by Thakur et al and Labbafi et al for in‐line flat‐blade and pin mixers, respectively, is based on the virtual Couette analogy . This approximation enables the estimation of the generalized power draw curves from a limited databank using Newtonian fluids only; it constitutes an intermediate way between CFD based on first principles and phenomenological correlations.…”