Nuclear Magnetic Resonance (NMR) study of Palm Kernel Stearin: Effects of cooling rate on crystallization behaviour

OKUR İ., ÖZEL B., UCBAŞ D., Grunin L., Okur P. S., ALPAS H., ...More

LWT-FOOD SCIENCE AND TECHNOLOGY, vol.155, 2022 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 155
  • Publication Date: 2022
  • Doi Number: 10.1016/j.lwt.2021.113001
  • Journal Name: LWT-FOOD SCIENCE AND TECHNOLOGY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aquatic Science & Fisheries Abstracts (ASFA), BIOSIS, Biotechnology Research Abstracts, CAB Abstracts, Compendex, Food Science & Technology Abstracts, Veterinary Science Database
  • Keywords: 1 H NMR, Palm kernel stearin, Crystal polymorph, X-ray scattering, Wide angle X-ray scattering (WAXS), ISOTHERMAL CRYSTALLIZATION, MILK-FAT, STRUCTURAL BEHAVIOR, POLYMORPHISM, MODEL, OIL, KINETICS, MICROSTRUCTURE, FORMULATION
  • Middle East Technical University Affiliated: Yes

Abstract

In this study, effects of different cooling rates (0.5,3.3,4.7 and 6.9 degrees C/min) on the crystallization behavior of palm-kernel-stearin (PKS) were studied by low-field NMR relaxometry. According to results, solid fat content (SFC), longitudinal relaxation time (T1), second moment (M2) and degree of crystallinity (%) of the samples increased with increase in cooling rate from 0.5 to 6.9 degrees C/min. In contrast, transverse relaxation time (T2) demonstrated an opposite behavior with respect to T1 and decreased when the cooling rate increased. Additionally, effects of cooling rate on the changes of polymorph structures were detected by X-ray measurements. Degree of crystallinity showed high Pearson correlation values (alpha <= 0.05) with SFC (r = 0.771) and T1(r = 0.932). Changes in the crystal polymorphs could also be explained by NMR parameters to some extent as can be observed by the strong correlation between the 13 crystal content and T2 (r = 0.927). At the highest cooling rate, 13 ' crystals were the dominant polymorphic form and constituted 75(%) of the total crystals present. Results of this study suggested that NMR relaxometry could be used as a complementary tool to interpret the crystallization behavior of PKS.