ABSTRACT The crystal properties of fats are critical determinants of the rheological behavior of foods and cosmetics. Raman spectroscopy offers a nondestructive means of assessing crystal properties without requiring sample pretreatment; however, its application to predict rheological properties has not been established. In this study, the rheological attribute of “stickiness,” typically assessed by palpation, was investigated using Raman spectroscopy. Partial least squares‐discriminant analysis (PLS‐DA) was applied to the full spectral fingerprint region, and analysis of variance (ANOVA) was conducted on the degree of unsaturation ( α unsat ) and crystallinity ( α c ), calculated from the intensity ratio of two characteristic bands. The PLS‐DA results revealed that the two principal components were associated with crystallinity and unsaturation. Although no significant difference in α unsat was observed between samples with high and low stickiness, crystallinity differed significantly. Fats with lower crystallinity exhibited higher stickiness, likely due to the higher proportion of liquid phase, which increased the contact area with the finger. Conversely, when crystallinity was extremely low, fats were perceived as lowly sticky, presumably due to reduced cohesive forces within the system. These findings suggest that stickiness emerges within a specific crystallinity range. Thus, identifying this range could facilitate the development of a Raman spectroscopy‐based method for nondestructive evaluation of fat rheological properties.
Watanabe et al. (Sun,) studied this question.