Validity and reliability of Raman spectroscopy for carotenoid assessment in cattle skin

Abstract

Carotenoids are powerful antioxidants capable of helping to protect the skin from the damaging effects of exposure to sun by reducing the free radicals in skin produced by exposure to ultraviolet radiation, and they may also have a physical protective effect in human skin. Since carotenoids are lipophilic molecules which can be ingested with the diet, they can accumulate in significant quantities in the skin. Several studies on humans have been conducted to evaluate the protective function of carotenoids against various diseases, but there is very limited published information available to understand the mechanism of carotenoid bioavailability in animals. The current study was conducted to investigate the skin carotenoid level (SCL) in two cattle skin sets – weaners with an unknown feeding regime and New Generation Beef (NGB) cattle with monitored feed at three different ages. Rapid analytical and sensitive Raman spectroscopy has been shown to be of interest as a powerful technique for the detection of carotenoids in cattle skin due to the strong resonance enhancement with 532 nm laser excitation. The spectral difference of both types of skin were measured and quantified using univariate and linear discriminant analysis. SCL was higher in NGB cattle than weaners and there is a perfect classification accuracy between weaners and NGB cattle skin using carotenoid markers as a basis. Further work carried out on carotenoid rich NGB cattle skin of 8, 12 and 24 months of age identified an increasing trend in SCL with age. The present work validated the ability of Raman spectroscopy to determine the skin carotenoid level in cattle by comparing it with established HPLC methods. There is an excellent correlation of R 2 = 0.96 between the two methods that could serve as a model for future application for larger population studies.

Identifying and locating carotenoids in supra‐orbital combs of male black grouse (Lyurus tetrix) using Raman and transmission electron microscopy: A histological study using rehydrated tissue samples

“…Despite both carbonyl and hydroxyl groups being present in the molecules, they do not offer a strong signal and are not reflected in the spectrum here. These results agree with exisiting literature on Raman analysis of carotenoids, as these peaks are not seen either (Lopez‐Sanchez et al, 2011; Mehta et al, 2020, 2021).…”

“…These results agree with exisiting literature on Raman analysis of carotenoids, as these peaks are not seen either (Lopez-Sanchez et al, 2011;Mehta et al, 2020Mehta et al, , 2021.…”

“…Representative spectra for the four reference carotenoids β‐carotene, astaxanthin, lutein and canthaxanthin are shown in Supporting Information: Figure . Characteristically of carotenoids, there are consistently three main bands seen due to their similar structures, notably C–CH 3 deformation and C–C and C═C stretching, assigned to the peaks labelled 1005–1008, 1155–1157 and 1514–1523 cm −1 , respectively (de Oliveira et al, 2010; Horiue et al, 2020; Mehta et al, 2021). Despite both carbonyl and hydroxyl groups being present in the molecules, they do not offer a strong signal and are not reflected in the spectrum here.…”

“…Despite the dermal spike tissue having been stored for a long period of time, the arrangement of the collagen bundles is well preserved (Figure 6). Horiue et al, 2020;Mehta et al, 2021). Despite both carbonyl and hydroxyl groups being present in the molecules, they do not offer a strong signal and are not reflected in the spectrum here.…”