The use of novel method for magnetic resonance instrument for quality assessment of chocolate confectionery

Date

2024-6

Author

Tuna, Umur İsmail

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In this study, the types of crystals present due to the polymorphic structure of cocoa butter in chocolate, which affect its textural properties, were measured. For this purpose, this study introduces a novel method using time-domain nuclear magnetic resonance (TD-NMR) to rapidly and non-invasively determine chocolate type III, IV, V, and VI crystal polymorph ratios without a need for post-processing fitting or calculation like traditional measurement techniques X-ray diffraction (XRD), temper meter or differential scanning calorimeter (DSC). In the first part of this study, a new NMR setup and measurement technique were developed to successfully measure present crystal types. As the first sample, only cocoa butter was studied. XRD measurements were also conducted on tempered cocoa butter samples by using a 45.0–29.5–31.5◦C temperature cycle complementary to NMR measurements as a control method for 8 weeks. Weekly statistical comparison of XRD and NMR measurements did not show a significant difference (p < 0.05) except on the 6th and 7th weeks measurements (p > 0.05) of type IV crystal over 32 measurements of type III, IV, V, and VI crystals for 8 weeks. In the second part of the study, NMR experiments were conducted on milk and dark chocolate tempered with a 45.0–29.5–31.5◦C temperature cycle, the same as cocoa butter samples stored at room temperature for 8 weeks, to observe crystal percentage change with time. Milk and dark chocolate results were statistically investigated for each measured crystal separately. The first week measurements showed that type V contents are 81%, 65%, and 63% for cocoa butter, milk, and dark chocolate, respectively. For both samples, while significant decrease (p < 0.05) was observed for type V crystal, significant increase was observed for type VI crystal content after 8 weeks. Also, linear fitting was performed to show the crystal type change over time. Although, a correlation cannot be found for type IV, and V change with time, it was found that there might be a linear model for increase in type VI crystal over time. The coefficient of determination (R2) is found as 0.96, 0.92, 0.89 for cocoa butter, dark chocolate, milk chocolate fitting respectively. The results showed that novel proposed method and TD NMR device for chocolate temper evaluation is a promising tool for chocolate quality control.

Subject Keywords

TD-NMR, NMR temper meter, Chocolate quality control, Chocolate temper measurement, Chocolate crystal types

URI

https://hdl.handle.net/11511/110394

Collections

Graduate School of Natural and Applied Sciences, Thesis