No abstract

Raman spectroscopy was used to characterize the polymorphs and liquid state of cocoa butter, with emphasis placed on the evolution of the ester carbonyl stretching region (1800–1700 cm−1), along with complementary analysis and comparison of the Raman‐active CC (1200–1000 cm−1), CC (1660 cm−1), CH (3000–2700 cm−1) and CH2 (1500–1250 cm−1) vibrational modes. Unique Raman signatures were obtained for all cocoa butter polymorphs, with their identity confirmed using DSC and XRD. The ester carbonyl region permitted polymorph discrimination due to differences in the number of modes, their relative frequencies and their full‐widths at half‐maximum. The CC stretching modes, which provided insight into the trans/gauche content, were polymorph‐independent. CH stretching generally increased with polymorph stability, indicating the dominance of antisymmetric CH methylene vibrations as the cocoa butter crystal lattice became more ordered. The change in the intensities of the CH stretching bands used to probe the order–disorder transition of forms IV, V and VI hinted at pre‐melt structural changes mostly in forms IV and V. Overall, Raman spectroscopy clearly demonstrated that the different functional groups studied could be characterized independently, allowing for the understanding of their role in cocoa butter polymorphism.Practical applications: Fat bloom is the unwanted, uncontrolled re‐crystallization or polymorphic transition of CB form V crystals into form VI normally caused by the migration of lower‐melting fats (e.g. in centre‐filled products) and/or temperature fluctuations during storage. In its mildest form, it appears as an overall dulling of the chocolate surface. In its extreme form, the appearance of the chocolate deteriorates significantly with the development of distinct white patches. Though forms V and VI can be clearly distinguished via XRD, we present evidence that Raman spectral characterization of the ester carbonyl stretching (1800–1700 cm−1), CC (1200–1000 cm−1), CC (1660 cm−1), CH (3000–2700 cm−1) and CH2 (1500–1250 cm−1) vibrational modes yields distinct liquid–solid and polymorph‐dependent differences in CB. From a practical standpoint, the unique signatures associated with forms V and VI offer novel possibilities in the study of fat bloom formation, such as the development of predictive tools.

No abstract

No abstract

No abstract

No abstract

No abstract

In materials research, polymer nanocomposites have attracted great attention worldwide from both academic and industrial points of view. The material properties of polymers can be enhanced dramatically by incorporating nanoelements from renewable resources depending on their biological origin (e.g., cellulose, starch, and chitin). We have used as the reinforcing phase, in this work, cellulose nanowhiskers (CNWs) and nanofibrillated cellulose (NFC) to prepare nanocomposite films by casting/evaporation using natural rubber (NR) latex as the matrix. Our interest is focused, in this work, especially on the investigation of the chemical bonds of the NR matrix and the chemical links of nanowhiskers added to the matrix and therefore the physical and chemical interactions which could happen between the reinforcement and the matrix. Many techniques have been used to explore the interface. Among these techniques, attenuated total reflectance/Fourier transform infrared spectroscopy (ATR/FTIR), which is employed in this work. It is exhibited that some differences are observed in FTIR spectra of nanocomposite films when adding cellulose nanoparticles into NR matrix. Overall IR spectroscopy clearly demonstrated that the interfacial adhesion in the case of NR‐NFC nanocomposite is higher than that of NR‐CNW one which was explained by the presence of residual lignin at the NFC surface that play the role of “compatibilizing” agent that enhance the adhesion between the NFC and the NR. POLYM. COMPOS., 2018. © 2018 Society of Plastics Engineers