Compare the melting profiles of the dark chocolate and white chocolate and explain differences. Please see the ingredients of the dark and white chocolates used in the DSC melting study.
Dear Xingfa Ma
Your DSC curves are not highly resolved but the following aspects can be identified. The melting pattern of the White Chocolate (WCH) is shifted to lower temperatures which is expected due to the most probably included fraction of some milk fat, which mixes well with the cocoa butter and generates (a) some eutectic effects as well as (b) some hindrance in forming the most stable beta-VI cocoa butter crystal polymorphs. The offset of the melting curve at ca. 32.5°C indicates only beta-V.
In contrast in your dark chocolate (DCH) sample you seem to have some beta-VI polymorphs included, which increases the melting peak offset to ca. 35°C. At ca 32°C you get an additional peak shoulder and inflection point which can be interpreted as the beta-V / beta-VI polymorph overlap domain.
Both of your chocolates (WCH & DCH) seem to have been well tempered and/or stored over a longer time period, because lower melting cocoa butter polymorphs (e.g. alpha or beta III / IV seem to be only marginally represented in the DCH sample. The support of beta-VI polymorph formation in the DCH may indicate some seed tempering with tailored polymorph seeding suspension.
My comments are certainly based on the assumption that cocoa butter is the main fat fraction in your products..
Another assumption is that your DSC measurements were carried out with not too large sample mass (ca. ≤ 10 mg) and your meting temperature gradient was not above ca. 5 °C/min, because both would shift your curves towards a higher temperature range as a consequence of some "thermal inertia" effects.
Kind regards
Erich Windhab
- Badges
- Science topic
- Similar topics
- Biological Science
- Botany
- Pharmaceutical Botany
- Plant Extracts