Relationship between Crystallization Behavior and Structure in Cocoa Butter
Bibliographic record
Abstract
Cocoa butter was crystallized statically from the melt to various temperatures in the range of −20 to 26 °C and annealed for up to 45 days. During this period, the polymorphism of the solid state was monitored using differential scanning calorimetry and powder X-ray diffraction. Moreover, the microstructure of the materials was imaged using polarized light microscopy. Below −15 °C, a mixture of the transient metastable γ and α phases was observed. Between −15 and 20 °C, the material nucleated initially into an α form and then gradually transformed into more stable phases. The lifetime of the α phase was at least 7 days at and below 0 °C and decreased gradually above 0 °C to 30 min at 15 and 20 °C. The α phase transformed into the β‘ phase, which was stable for 28 days between 0 and 15 °C. Above 15 °C, the lifetime of the β‘ phase decreased gradually to 10 h at 24 °C. The β‘ form could be formed directly from the melt above 20 °C. Above 15 °C, the β‘ phase could transform into the β phase. Interestingly, cocoa butter crystals did not nucleate directly from the melt into the β phase and did not form under any conditions below 20 °C. The β polymorph could only be formed via the β‘ form. Microstructural studies indicated that cocoa butter initially nucleated as metastable γ or α phases below 15 °C remained granular in appearance, irrespective of further phase transformations into other more stable forms. The microstructures of the β‘ form could thus appear granular, clustered, and needlelike, depending on whether they were formed through the α form or directly from the melt. The microstructure of the β form was complex and varied, from granular to needlelike to featherlike. Crystallization kinetics was quantified from solid fat content−time curves at the different crystallization temperatures using the Avrami model. Changes in the Avrami exponent and the induction time of crystallization were correlated with certain polymorphic transformations, particularly the β‘ to β transition. Microstructure was quantified using a box-counting fractal dimension. Changes in microstructure as a function of time at 20, 22, and 26 °C correlated with changes in the fractal dimension. A particularly interesting finding in this work was the fact that the fractal dimension was directly related to the rate of nucleation as well as inversely related to the Avrami exponent.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".