If a great number of rays are fished in the Tropical East Atlantic Ocean for their caudal fins, only a small amount of ray flesh is processed. Among them, three species of rays, Dasyatis marmorata, Rhinobatos cemiculus, and Rhinoptera marginata, from the Mauritanian coast have been investigated for the fatty acid composition of their lipids. Gas chromatography and gas chromatography-mass spectrometry allowed identification of 50 molecules from muscles, livers, and gonads of these fishes. Principal component analysis, starting from >50 samples, reveals significant differences in various fatty acid distributions, related to the species and sex of the sampled fish. Some of them are preferentially present in one sex or in both species, whereas the occurrence of others characterizes the male and female of one or two species. The results show that rays are potential resources of polyunsaturated fatty acids (PUFA) and should be used in the diet of local populations. The lipidic fractions contained a high amount of PUFA (up to 30% of the total), mainly composed of docosa-4,7,10,13,16,19-hexaenoic acid, eicosa-5,8,11,14-tetraenoic acid, and eicosa-5,8,11,14,17-pentaenoic acid.

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Scientific investigation of lipids in Elasmobranchs has been conducted mainly on shark species. Because rays seem to be neglected, this study was performed to examine the complete fatty acid (FA) composition with a particular interest for long-chain polyunsaturated FA (PUFA) content in different tissues of three ray species including parts usually discarded. The total FA and PUFA profiles of total lipids were determined in muscle, liver, and gonad of Rhinobatos cemiculus, Rhinoptera marginata, and Dasyatis marmorata, the most often caught ray species from the East Tropical Atlantic Ocean. Fifty FA were characterized as methyl esters and N-acyl pyrrolidides by gas chromatography/mass spectrometry, showing significant levels of 20:5n-3 (EPA) (up to 5.3%) and 22:5n-3 (DPA) (up to 7.3%), high levels of 20:4n-6 arachidonic (ARA) (4.8-8.6% of total FA) and 22:6n-3 (DHA) (up to 20.0%). The results show that muscle, liver and gonad of rays can provide high amounts of essential PUFA, specially DHA, for direct human nutrition or the food processing industry. High proportions of DHA were particularly found in all samples of R. cemiculus (11.6-20.0%), and in muscle and liver of D. marmorata (11.1-16.1%). Regarding the high amounts of (n-3) PUFA, this study shows that these rays deserve a better up-grading, including the normally discarded parts, and describes the occurrence of unusual NMID FA in all tissues studied. Five non-methylene-interrupted dienoic fatty acids (NMID FA) (0-3.4%) were reported, including previously known isomers, namely 20:2 Delta7,13, 20:2 Delta7,15, 22:2 Delta7,13, 22:2 Delta7,15, and new 22:2 Delta6,14. These acids are quite unusual in fish and unprecedented in rays. The 22:2 Delta6,14 acid occurred in gonads of male specimens of R. cemiculus at 2.9%.

Total determination of cinnamic acids (CA), including hydroxycinnamic acid derivatives is generally not accurate since, during hydrolysis, a possible degradation of dihydroxy CA such as caffeic acid could occur. Evaluations of CA (ferulic, p-coumaric, sinapic, cinnamic and caffeic acids) before and after hydrolysis have been undertaken using standards and either with or without addition of ascorbic acid and EDTA. The method was then applied to the determination of free and bound CA in five blond cultivars (Navelina, Washington navel, Pera, Salustiana and Valencia late) of sweet oranges [Citrus sinensis (L.) Osb.]. Four parts of the fruits (peel juice, flavedo, albedo and juice) have been investigated. Results show that CA are mainly bound (86% up to 92%) in the four fruit parts. The mean of total CA contents was found to be higher in peel juice (1.5 g kg-1) in comparison with flavedo (0.7 g kg-1), albedo (0.1 g kg-1) and juice (0.6 g kg-1). Free and bound ferulic acid represented 55-70% of CA in juices, followed by p-coumaric acid (20%), sinapic acid (10%) and caffeic acid (9%). Total contents of each CA in the four fruit parts are discussed and show the potential interest in orange peel wastes.