Crystallization and matrix formation - Oils and fats - crystallisation of triglycerides

9 important questions on Crystallization and matrix formation - Oils and fats - crystallisation of triglycerides

What is the complexity of oil and fat crystallisation?

Fats typically consist of a mixture of many different triacylglycerols. Each of those fats can crystallize in different crystal forms, or isomorphic.

What is the difference between alpha and beta crystals?

Beta crystals are formed at higher temperatures than alpha crystals. Alpha crystals crystallize faster, but are less stable. When you re-heat alpha crystals, they will met again and will re-crystallize into the beta' form. This form forms quicker than the beta form. The beta form forms only from a very slow cooling rate or from a solvent.

Which polymorph form of crystals is the best for chocolate?

Form V, glossy, firm, best snap, melts near body temperature (37C).

How is selective crystallisation also called?


At which temperature is all fat liquid?


Why is chocolate stored at 20C for some time after tempering?

  • Temperature too high --> crystals would disproportionate and form very large crystals, with a gritty texture as consequence
  • Temperature too low --> type V polymorph crystal may slowly convert into the lower polymorphs, which are also quite stable at low temperature

Temperature and moisture can have an influence on chocolate, how?

  • Temperature too high --> fat blooming (structural collapse by disproportionation). At higher temperatures, some of the fats in small crystals will melt, and are taken up by larger crystals. These show on the outside as whitish stains.
  • Moisture too high --> sugar crystals may be partially dissolved, re-crystallise into larger crystals, whitish stains on the outside.

What is a solution for the whitish crystals outside of chocolate?

To temper the chocolate such that the smallest crystals have already disappeared, and thus the driving force for recrystallization is reduced.

Spherulites contain non-crystallising fats. T/F


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