Lipidomics analysis reveals new insights into crisp grass carp associated with meat texture

Abstract

Feeding faba beans to grass carp could crisp its muscle texture to avoid softening, the relationship between texture formation throughout the crisping process and the critical lipids regulating the fish quality has not yet been clarified. Herein, an 60-day nutritional trial and untargeted lipidomic analysis was used to study the changes of lipids in crisp grass carp dorsal muscle. A total of 1036 lipids were remarkably different between ordinary and crisp grass carp. The concentrations of the LPC, LPE, PG, Cer, Hex2Cer, SM, MG and MGMG were positively correlated with hardness and springiness, and the CL, TG, PMe, WE, dMePE and AcCa were negative correlation. High content of lipids involved in storage in ordinary grass carp, such as glycerophospholipids, polyunsaturated and saturated fatty acid content. In contrast, high content of membrane components in crisp grass carp, such as monounsaturated fatty acid, sphingolipid and glycerolipids content, and the distribution of PUFA in lipid molecules was related to lipid biosynthesis. This study might provide some insights into improved knowledge of the association between meat texture and lipid molecules in fish fed with faba bean.

Keywords: Crisp grass carp; Faba bean; Lipidomics; Meat texture.

Fig. 1

The overall lipid composition and distribution in muscle of grass carp. (A) Lipid clustering heat map. The size of quantitative values is shown by the difference of colors. The more red the color, the higher the expression level, and the more blue the expression level, the lower. (B) Lipid subclasses and numbers of lipid molecules identified in muscle of crisp grass carp. (C) Lipid subclasses and numbers of lipid molecules identified in muscle of ordinary grass carp. Group A, crisp grass carp group; Group B, ordinary grass carp group. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 2

The multivariate statistical analysis. (A) The PCA analysis of lipids in muscle of grass carp group. (B) The OPLS-DA analysis of lipids in muscle of grass carp group. (C) The OPLS-DA analysis of lipids in muscle of grass carp group.

Fig. 3

The dfferential lipid classification violin diagram. Each subgraph shows the differential lipid outcomes under different lipid classifications. The horizontal coordinate is different group, and the vertical coordinate is the range of lipid signal values.

Fig. 4

The differential lipid analysis. (A) The differential lipid Class clustering heat map. The size of quantitative values in the figure is shown by the difference of colors. (B) The differential lipid class classification heat map. (C) The lipid volcano map. Each point in the figure represents a lipid, and the horizontal coordinate represents the Log2 value of the multiple of quantitative difference between the two groups of lipids; The ordinate represents the -log10 value of the p-value. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 5

The correlations of crucial lipids with meat quality. Red and blue represent positive and negative correlations, respectively. The deeper the color, the higher the correlation. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 6

The LION-PCA heatmap and LION enrichment analysis. A and B, LION-PCA heatmap analysis of lipidomics data. (A) Bar graphs showing the number of significant LION-terms (left) or the cumulative variance explained (right), per set number of principal components. (B) Heatmap generated by the LION-PCA heatmap module in LION/web with the number of principal components set to 6. Heatmap colors (from yellow to red) indicate the mean z-score for a given LION-signature per sample. (C) LION enrichment analysis. The gray vertical line indicates the cutoff value of significant enrichments. The size and color (from gray to red) of the horizontal bars (x-axis) are scaled with the enrichment. Ordinary grass carps were considered as the control condition and crisp grass carps as the condition of interest. "up" refers to an enrichment, and "down" refers to a depletion. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 7

The statistical heat map of differences in lipid structural characteristics. Each subgraph represents differences in lipid structural characteristics within a single group of a lipid classification. The X-axis represents the level of carbon saturation (number of double bonds) and the Y-axis represents the number of lipid carbon atoms. The rectangle represents different lipids of the same classification, the color represents the significance of the difference expression, the red represents the significant up-regulation, the blue represents the significant down-regulation, and the lipids with significant statistical differences between the comparison group are highlighted with different symbols. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)