NMR study of the lipid profile of mullet raw roe and bottarga

Abstract

Samples of mullet (Mugil cephalus) roes from two different fishing areas were studied by means of 1H, 13C and 31P NMR and GC techniques. The lipid fraction of unprocessed roes and that of the corresponding salted and dried commercial products “bottarga” were analyzed and the data compared. Roes of mullets from different origin showed different composition regarding mainly triacylglycerols, monounsaturated and n-3 polyunsaturated fatty acids. The NMR spectra of processed roes, compared to those of the corresponding raw materials, showed a release of free fatty acids and the formation of other minor molecular components, such as free fatty alcohols, lysophospholipids, and diacylglycerols, thus indicating that hydrolytic processes were the main consequence of manufacturing. An increase of cholesterol ester concentration after processing was also detected. Through the analysis of the 31P NMR spectra, it was possible to follow the fate of the phospholipids and the formation of lysophospholipids induced by the salting and drying procedures

Modifications of the 1H NMR metabolite profile of processed mullet (Mugil cephalus) roes under different storage conditions

“…In addition, as for Cho and P‐Cho, its presence can be linked to the complete hydrolysis of those lipid molecular components that have a glycerol backbone, such as triacylglycerol, diacylglycerol, monoacylglycerols, and phospholipids. Residuals of lipid hydrolysis can be found in the lipid fraction . Figure a and b shows the trends over time of the concentration of glycerol, Cho, and P‐Cho at 3 °C and at room temperature in the presence of light.…”

“…Residuals of lipid hydrolysis can be found in the lipid fraction. [15] Figure 3a and b shows the trends over time of the concentration of glycerol, Cho, and P-Cho at 3 C and at room temperature in the presence of light. Here, a considerable increase in the concentration of Cho and glycerol is shown, whereas P-Cho remains stable.…”

Multivariate fatty acid and fatty alcohol profile of mullet bottarga

“…From the analysis of data reported in the literature regarding the FA and FAL composition of the salted and dried mullet roes, several discrepancies can be seen. For example Bernasconi et al 9 reported the 16:1 FAL as the most abundant (66.2%) of the alcoholic fraction, while other works indicated the 16:0 FAL, with a concentration ranging 50–70% 3, 5–7. Furthermore, 18:1 n‐9 concentration detected by several authors ranges from 4.8–5.0% 4 to 16.7% 2; also our published data report different values: some samples exhibited values of approximately of 7.4, others 18.2% 7.…”

“…After the pioneering work of Lu et al 1, recently more interest has been devoted to the study of the lipid composition of the salted and dried product of mullet ( Mugil spp.) roe 2–8. This fish product, that in the western Mediterranean area is called ‘bottarga’, in Greece ‘avgotaracho’ and in Japan ‘Karasumi’, is regarded as a food delicacy.…”

“…The lipid fraction is composed of a high quantity of wax esters (WE) (approximately 60–80% of lipid classes), triacylglycerols, phospholipids and cholesterol in its free and esterified form 6. It has been shown that the salting and drying procedures do not change the FA and FAL (atty alcohol) composition of the raw material while they promote hydrolysis of the lipid components, with release of free FA and esterification of cholesterol 7. The oxidative susceptibility of mullet bottarga is very low 8 and its WE components have been proposed as a stable natural source of n‐3 PUFA 9.…”