Investigating the crystallinity of hard candies prepared and stored at different temperatures with low field-NMR relaxometry

Date

2024-01-01

Author

Kuzu, Sena
Özel, Barış
Uguz, Sirvan Sultan
Dogdu, Sarper
Marangoz, Mehmet Ali
Grunin, Leonid
Öztop, Halil Mecit

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Background: In this study, hard candies were produced by using sucrose, glucose syrup and water. They were cooked at different temperatures, changing from 135 to 145 °C with an interval of 2.5 °C. They were stored at different storage temperatures, which were 25, 4, −18 and −80 °C. Hard candies placed at room temperature were stored for 2 months. In order to understand the crystallization characteristics of the hard candies, time domain (TD) proton nuclear magnetic resonance (1H-NMR) parameters of longitudinal relaxation time (T1) and second moment (M2) measurements were conducted. Moisture contents of the hard candies were determined by Karl–Fischer titration. X-ray diffraction experiments were also conducted as the complementary analysis. Results: Increasing cooking temperature increased the crystallinity and decreased the moisture content of the hard candies significantly (P ≤0.05). Furthermore, storage temperature and storage time had significant effects on the crystallinity of the hard candies (P ≤0.05). The results of T1 and M2 correlated with each other (r > 0.8, P ≤ 0.5) and both produced the highest value at the cooking temperature of 145 °C and storage temperature of 4 °C (P ≤ 0.05). The values of T1 and M2 were obtained as 245.9 ms and 13.0 × 10−8 Hz2, respectively, for the cooking temperature of 145 °C and storage temperature of 4 °C. Conclusion: This study demonstrated that the crystallinity of hard candies can be observed and examined by TD-NMR relaxometry, as an alternative to commonly used methods. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Subject Keywords

1H-NMR, crystallinity, hard candy, moisture content, second moment, T1

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https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85202538961&origin=inward
https://hdl.handle.net/11511/111091

Collections

Department of Food Engineering, Article