Please inform the cause of fat bloom in chocolate and the prevention to avoid it.

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  1. Ricebowl Food Expert
    June 21, 2019 at 12:35 pm

    Fat bloom is a common occurrence when dealing with chocolate products. It is a physical defect that arises during storage and often appears as a whitish layer on the outer surface. Fat bloom can occur at different stages. There are various preventive methods that can help inhibit fat bloom formation (Tisoncik, 2013).

    Causes of Fat Bloom

    Dirty Molds

    • Fat bloom can be initiated by dirty mould from the residue left by previously deposited chocolate which serves as seed or site of crystal nucleation for the subsequent deposited chocolate.
    • Surface bloom is then formed by the newly deposited chocolate. Hence, proper cleaning of moulds is essential.
    Figure 1.1 The mould is dirty and contain residual chocolate
    Temper

    • Tempering chocolate can be in the form of the heating, stirring, and cooling steps that stabilise the cocoa butter (fat) crystals which assure the chocolate to dry shiny and hard and breaks with a snap instead of giving grey or streaky appearances with a soft cakey texture (Medrich & Lamotte, 2015).
    • Untempered chocolate will bloom after a short period of time because the cocoa butter has crystallised into less stable polymorphic forms which will recrystallize into more stable polymorphs. During the process, fat migrates to the surface and crystallises as a fine haze which lightens the chocolate colour and may also appear as visible, white or pale specks (Talbot, 2009).
    • Under-tempered chocolate: dull and blotchy, lacking its desired gloss (Talbot, 2009).
    • Over-tempered chocolate: poor gloss, since it often has fewer larger crystals and thus give rise to coarser structure in the chocolate, with the resulting dullness (Talbot, 2009).
    • The glossy nature of well-tempered chocolate is due to the fine crystals produced during cooling after tempering, when the cocoa butter is in the correct polymorph (Talbot, 2009).

    Figure 1.2 Improper temper leads to formation of multiple layers in cross-sectional view due to crystallization of chocolate deposited into the mold
    Cooling

    • Cooling capacity and temper prior to moulding are essential.

    Figure 1.3 Fat bloom found right after the cooling tunnel or on retail shelves due to improper cooling
    Formulation

    • After preclude all the possible environmental and production factors, formulation can be the reason causing extensive fat bloom.
    • There may be an inherit formulation issue that is causing the chocolate to bloom at a quicker rate when exposed to high heat temperatures. This type of bloom forms within 2 to 4 weeks after depositing and is caused by a mixture of incompatible fats.

    Figure 1.4 Extensive fat bloom
    Interaction with inclusions

    • Fat bloom will also take place when cocoa butter interacts with incompatible oils, such as peanut oil.
    • These liquid oils will migrate into the chocolate shell by dissolving cocoa butter liquid fractions, then migrate to the surface and form bloom.

    Figure 1.5 Fat bloom when cocoa butter meets with incompatible oils
    Extreme Temperature Fluctuations

    • This is caused during transportation or distribution, e.g., the shipping truck is at temperatures of 5° to 10° above the melting point of chocolate.

    Figure 1.6 Appearance of chocolate when environmental handling conditions were not ideal

    (Tisoncik, 2013).

    Preventative Methods

    Tempering
    • Practically, every chocolate mass, each production line, and each chocolate product has their own optimal temper, specific tempering conditions for different combinations of milk fat and cocoa butter must be determined to a larger extent, by trial and error (Garti & Widlak, 2012).
    • A quick great test method is to check temper is by using the temper meter instrument with easy readouts that are translated into a number indicating good, great or need to retemper.
    Knowledgeable Formulation
    • Other fats compound in the final formulation must be considered and evaluated of its risk of incompatibility.
    • For instance, combination of cocoa butter and lauric fat such as palm oil or coconut oil will promote blooming and exhibit softer texture due to their eutectic effect (melts and freezes at a single temperature that is lower than the melting point).
    • Creating a barrier between the two incompatible fats is another fundamental idea to consider, e.g. candy bar products, where sugar caramels build up a barrier between the nuts and the enrobed chocolate layer.
    • On the other hand, milk fat is a common ingredient added to chocolate products as it regulates the hardness of cocoa butter through its effect on phase behaviour and aids in preventing fat bloom during storage (Garti & Widlak, 2012).
    Proper Storage
    • Proper storage, whether it be postproduction, warehouse, distribution, customer end or retail shelving, is essential to prevent bloom from occurring before the shelf life expires as chocolates are susceptible to temperature fluctuations at this point.
    • The best condition for chocolate storage is in a controlled environment at room temperature with 40-60% relative humidity.

    (Tisoncik, 2013).

    References

    • Garti, N., & Widlak, N. (2012). Cocoa Butter and Related Compounds (p. 384). Champaign: AOCS Press.
    • Medrich, A., & Lamotte, M. (2015). Chocolate holidays: Unforgettable Desserts for Every Season (p. 112). United States: Artisan.
    • Talbot, G. (2009). Science and technology of enrobed and filled chocolate, confectionery and bakery products. Cambridge: Woodhead Publishing Ltd.
    • Tisoncik, M. (2013). Chocolate Fat Bloom. The Manufacturing Confectioner, 65-68.

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