| Rich in cholesterol and various fatty acids,Chinese mitten crab(Eriocheir sinensis)has excellent nutritional value.Chinese mitten crab is heated before consumption to effectively kill pathogenic microorganisms,improve food safety,release odour-forming substances and improve flavour,but it also reduces nutritional value.Unsaturated fatty acids and cholesterol are chemically unstable and this instability is influenced by their chemical structure,oxygen,light and processing and storage factors.Among these,cholesterol is susceptible to thermal oxidation to form cholesterol oxides(COPs),which have been shown to be physiologically toxic and involved in the formation of fibrous and atherosclerotic plaques.Unsaturated fatty acids can also undergo oxidative breakdown,causing changes in the content of different types of fatty acids and resulting in a reduction in nutritional quality.There is no information on the effect of heat treatment on the changes in cholesterol and fatty acid content and the formation of COPs in Eriocheir sinensis.Therefore,in this paper,it is interesting to evaluate the effects of heat treatment on Eriocheir sinensis from the perspective of cholesterol and fatty acids.In this paper,the effects of steaming and boiling on the cholesterol and fatty acid contents of the three edible parts of E.sinensis were initially investigated.The study provides a reference for the selection of heating treatment methods for Eriocheir sinensis and the analytical method developed can also be applied to the determination of COPs in meat and meat products.The main findings are as follows.1.Analysis of the effects of steaming and boiling on the cholesterol and fatty acid content in Chinese mitten crab(Eriocheir sinensis)The cholesterol and fatty acid contents in the three edible parts of the crab yolk/paste,abdominal meat and leg meat of male and female Eriocheir sinensis crab were analysed after steaming and boiling.The results showed that the cholesterol content in the edible parts of the crab was similar in both sexes,and that the cholesterol content in each part was reduced by the steaming and boiling treatments,but the difference was not significant;the cholesterol loss in the edible parts was lower after steaming compared to boiling.The total fatty acid content(∑FA)was higher in the yolk of female crabs than in the paste of male crabs,while ∑FA was slightly higher in the belly and leg meat of male crabs than in female crabs;among the three edible parts,the highest percentage of total monounsaturated fatty acids(∑MUFA)was found in the yolk and paste,while the highest percentage of total polyunsaturated fatty acids(∑PUFA)was found in the belly and leg meat.After steaming and boiling,the main saturated fatty acids in Eriocheir sinensis were still palmitic acid and stearic acid,monounsaturated fatty acids were mainly oleic acid,and polyunsaturated fatty acids were mainly linoleic acid,EPA and DHA.2.Simultaneous determination of six cholesterol oxides in crab meat by solid-phase extraction-gas chromatography-triple quadrupole tandem mass spectrometryA method for the simultaneous determination of six cholesterol oxides(COPs)in crab meat by solid-phase extraction-gas chromatography-triple quadrupole tandem mass spectrometry was developed.The extraction was carried out on a methanolchloroform(1: 2,v/v)mixture.The clean-up effect of three solid phase extraction columns was investigated,and a Poly-Sery HLB solid phase extraction column was determined.The sample was derivatized with bis(trimethylsilyl)trifluoroacetamide,and the chromatographic conditions were set up to detect the major ions of the six COPs by single ion detection mass spectrometry.The results showed that the working concentrations of the six COPs were linear in the range of 0.2～10.0 μg/m L with their corresponding quantitative peak areas,the limits of detectionwere in the range of0.08～3.6 ng/g,the average recoveries were 77.64%～93.54%,and the relative standard deviations were 2.34%～8.25%.The method can satisfy the quantitative analysis of COPs in crab meat.3.Effect of heating time on the formation of cholesterol oxides and changes in fatty acid content in the Chinese mitten crab(Eriocheir sinensis)Different heating times were used to investigate the effects of different heating times on cholesterol oxides in three edible parts of male and female Eriocheir sinensis and to analyse the trends in key fatty acids.The results showed that the effects of heating treatment on cholesterol in both male and female E.sinensis showed similar trends.Cholesterol oxides such as 7α-hydroxycholesterol(7α-OH),7β-hydroxycholesterol(7β-OH),5α,6α-epoxycholesterol(5α,6α-EP),cholestane-3β,5α,6β-triol(triol),25-hydroxycholesterol(25-OH),and 7-ketocholesterol(7-keto)were produced during the heat treatment.The COPs of the three edible parts gradually increased with increasing heating time.The highest levels of COPs were found in the yellow and ointment parts of the crab,while the abdominal meat and leg meat contained relatively low levels of COPs,with the highest levels of 7-keto and the lowest levels of triol.During heating,the different types of key fatty acids in the three edible parts showed the same trend,with an increasing trend for saturated fatty acids,a decreasing trend for polyunsaturated fatty acids and a change in monounsaturated fatty acids depending on the specific edible part. |
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