Determination of Moisture Content and Crystallinity of Hard Candies by TD-NMR

Date

2023-8-28

Author

Kuzu, Sena

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

726
views

183
downloads

Cite This

Hard candies are perfect amorphous food materials prepared by minimal ingredients. Crystallization process in a hard candy is not desirable since it has a negative effect on the quality of the product. Crystallization of a hard candy can be determined by different techniques such as Differential Scanning Calorimetry (DSC) and X-ray Diffraction (XRD). Another quality parameter of the hard candies is the moisture content which should normally be around 2-3% and determined by highly chemical intensive method of Karl-Fischer titration. Low field Time Domain Nuclear Magnetic Resonance (TD-NMR) technique is widely employed in assessing changes in foods, commonly relying on T1 (spin-lattice) and T2 (spin-spin) relaxation times. Recently, it has been shown that TD-NMR can also be used to assess the crystallinity of different products through the use of Solid Echo (SE) pulse sequence. TD-NMR can also be a great tool to determine the moisture content of candies as well. In this thesis, two types of hard candies were studied for assessing crystallinity and moisture content by TD-NMR. The first one is the regular hard candies made of sucrose, glucose syrup, and water. The second one is the traditional akide candy which is made of sucrose, water, and citric acid. In the first part of the study, hard candies were cooked and stored at different temperatures. Moisture content, total soluble solids, and XRD analysis were also made as complementary methods to TD-NMR experiments of T1 and Solid Echo. T1 relaxation times and SE results significantly changed at different cooking and storage temperatures (p≤0.05). In the 2nd part of the study, akide candies were formulated, and T1 and SE experiments were conducted. Akide candies were prepared by using different citric acid concentrations and cooked different temperatures. Likely, moisture content, total soluble solids, and XRD analysis were made as complementary methods to TD-NMR. T1 results showed significant differences at different citric acid concentrations and cooking temperatures (p≤0.05) corroborated by SE outcomes (p≤0.05). Overall, it can be seen that TD-NMR method is an appropriate and easy method for determination of moisture content and crystallinity in hard candies.

Subject Keywords

Hard candy, Akide candy, TD-NMR, Crystallinity, Moisture Content

URI

https://hdl.handle.net/11511/105164

Collections

Graduate School of Natural and Applied Sciences, Thesis