Process development for continuous crystallization of fat under laminar shear

Maleky, Fatemeh; Marangoni, Alejandro G.

doi:10.1016/j.jfoodeng.2008.05.019

Cited by 44 publications

(56 citation statements)

References 21 publications

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“…The samples were then crystallized till reaching 20°C at a rate of 15°C min −1 during which shear ranging from shear rate of 0 (static sample), 50, 100, 200, 1,000 to 2,000s −1 were applied using a laminar shear crystallizer. 25 The crystallizer consisted of two concentric cylinders with a gap of 2 mm in between. The internal cylinder rotates at selected shear rates while the external cylinder remain stationary.…”

Section: Gel Preparationmentioning

confidence: 99%

Shear Nanostructuring of Monoglyceride Organogels

et al. 2010

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The aim of the present research was to study the effect of shear on the crystallization behavior of monoglyceride organogels. To this end, organogels were prepared by mixing cod liver oil and saturated monoglycerides at 80°C and then crystallizing them at 20°C under shear rates ranging from 0 to 2,000 s −1 . The organogels were characterized using polarized light microscopy, Cryo-SEM, and X-ray diffraction. The rheological properties and the oil binding capacity of the different systems were also evaluated. Results obtained in this study showed that the introduction of shear during organogel formation greatly affects structure at the nano, micro, and macro levels. Solidification of the organogel under static conditions led to the formation of a strong gel network, with a high oil binding capacity. On the contrary, shear processing during crystallization led to the formation of a weak gel network with a low oil binding capacity.

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Section: Gel Preparationmentioning

confidence: 99%

Shear Nanostructuring of Monoglyceride Organogels

et al. 2010

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“…20 The latter information has been recently used to design a prototype industrial laminar crystallizer to obtain anisotropic fat materials. 21,22 That the application of shear flow to cocoa butter increases the rate of transition from form II to form V has only recently been confirmed by using direct in situ X-ray diffraction. 16 This is in part due to the complexity of the shear systems compatible with X-ray diffraction (XRD) that need to be developed.…”

Section: Introductionmentioning

confidence: 99%

Rheo-NMR Measurements of Cocoa Butter Crystallized Under Shear Flow

Mudge

Mazzanti

2009

Crystal Growth & Design

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Modifications of a benchtop NMR instrument were made to apply temperature control to a shearing NMR cell. This has enabled the determination in situ of the solid fat content (SFC) of cocoa butter under shearing conditions. The cocoa butter was cooled at 3°C/min to three final temperatures of 17.5, 20.0, and 22.5°C with applied shear rates between 45 and 720 s -1 . Polymorphic transitions of the cocoa butter were determined using synchrotron X-ray diffraction with an identical shearing system constructed of Lexan. Sheared samples were shown to have accelerated phase transitions compared to static experiments. In experiments where form V was confirmed to be the dominant polymorph, the final SFC averaged around 50%. However, when other polymorphic forms were formed, a lower SFC was measured because the final temperature was within the melting range of that polymorph and only partial crystallization happened. A shear rate of 720 s -1 delayed phase transitions, likely due to viscous heating of the sample. Pulsed NMR is an invaluable tool for determining the crystalline fraction in hydrogen containing materials, yet its use for fundamental and industrial research on fat or alkanes crystallization under shear has only recently been developed.

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“…The effect of shear on secondary nucleation and crystal growth is proposed to be a result of alignment of triacylglycerol (TAG) molecules in the shear filed, increasing the possibility of TAG to come together and integrate onto nuclei crystal surfaces, 13,14 increased frequency of interparticle collisions, 1,15 and breakage of existing crystals increasing crystal surface. 13 In addition to its kinetic effect, shear results in the formation of higher stability polymorphs 9,10,16 and accelerated polymorphic transformations 14,17,18 in cocoa butter.It is hypothesized that processing conditions will impact the attachment of TAG molecules onto the growing seed crystals, consequently affecting different levels of structure in a cocoa butter crystal network. The effect of temperature and shear history on the kinetics and polymorphism of cocoa butter has been previously explored; however, very little information on the molecular dynamics of the process have been reported.…”

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Crystallization Dynamics of Shear Worked Cocoa Butter

Campos

Marangoni

2014

Crystal Growth & Design

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Control of heat and mass transfer conditions during chocolate manufacture is a critical factor influencing product quality and performance. The molecular basis for specific tempering protocols developed by the chocolatiers, and used widely by the food industry, is poorly understood. Here we show that cooling and shear rates applied during cocoa butter crystallization affect the incorporation of specific triacylglycerol (TAG) molecular species onto the surface of growing seed crystals, thus affecting the different structural levels in a cocoa butter crystal network. In this work, the effects of shear work on the different structural levels in cocoa butter are determined. Results from this research show different compositions during the early stages of static crystallization at different cooling rates. In other words, there is selective attachment of TAG species onto growing crystal surfaces, leading to fractional crystallization. With the application of shear, differences between cooling rates became negligible. Shear appears to enhance the formation of mixed crystal in the growing crystals, leading to faster crystallization kinetics, the formation of a higher number of smaller crystals, and a mechanically stronger crystal network. ■ INTRODUCTIONIn the manufacturing of chocolate products, the molten chocolate mass is processed under specific shear and cooling conditions with the aim of crystallizing cocoa butter into an ordered crystalline structure. Cocoa butter is chocolate's main fat component; therefore, its structure will directly affect the product's final physical properties such as contraction, snap, gloss, melting properties, and bloom resistance. This controlled crystallization is known as tempering. The purpose of tempering is to produce 1−3% of the desired highly ordered β V seed crystals, which will subsequently serve as nuclei for the rest of the mass to crystallize. 1−4 If molten chocolate mass were to be cooled directly at cooling tunnel or ambient temperatures, cocoa butter would crystallize in the metastable α II and β′ III−IV forms. 5−8 This results in a dull, soft, low melting point chocolate, prone to bloom.During tempering, the chocolate mass is cooled to 27−29°C to induce nucleation of both stable and unstable crystals. The temperature is then raised to 30−33°C to promote transformation of seed crystals to the stable β V form and melt unstable crystals. The temperature set points used vary by recipe. The tempered chocolate mass is then rapidly cooled to complete crystallization of the fat phase, yielding chocolate with desired quality attributes. 1−4 All methods of tempering, from small-hand tempering to large industrial scales, involve controlled cooling and some element of shear. Shear improves heat and mass transfer of molten cocoa butter, helping overcome kinetic barriers for nucleation and growth. 9 Shorter induction times for crystallization in cocoa butter 10 and chocolate 11,12 when processed under shear suggest that shear affects nucleation. The effect of shear on secondary nucleati...

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Process development for continuous crystallization of fat under laminar shear

Cited by 44 publications

References 21 publications

Shear Nanostructuring of Monoglyceride Organogels

Shear Nanostructuring of Monoglyceride Organogels

Rheo-NMR Measurements of Cocoa Butter Crystallized Under Shear Flow

Crystallization Dynamics of Shear Worked Cocoa Butter

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