Comprehensive analysis of phospholipids and glycerol glycolipids in green pepper by ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry.

RATIONALE

As important components of plant cells, lipids are involved in various biological functions. However, the composition and content of lipids in cell membranes changes at low temperature resulting in chilling injury and affecting the commercial value of green peppers. Detecting the changes in lipids helps to understand the mechanism of low-temperature stress in green peppers; however, a comprehensive study of lipid profiles in green pepper has not been well documented.

METHODS

Herein, we report an ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/QTOF MS) method to determine phospholipids and glycolipids in green peppers and compare five extraction methods among which the isopropanol/chloroform/water (ICW) method demonstrated the best extraction efficiency. The established method was used to determine the membrane lipids of fresh samples, chilled samples(4°C-20d), and control samples (10°C-20d).

RESULTS

A total of 98 lipids, including 77 phospholipids and 21 glycolipids, were extracted from green peppers using ICW extraction. The content and profile of phosphatidylcholine (PC) among phospholipids were found to be the highest, accounting for 58.58% of all the phospholipids. The monogalactosyldiacylglycerol (MGDG) content among the glycolipids was the highest, accounting for 1.43%. The samples stored at low temperature (4°C, 20d) had a significantly higher PC content and a higher content of lipids containing unsaturated fatty acid residues as compared with the control samples (10°C, 20d). The recovery ranged from 75.55% to 96.64% while the limit of quantification ranged from 10 to 1000 ng mL .

CONCLUSIONS

The results indicated that the established method provided a reliable platform to study the changes in membrane lipids of a green pepper under low-temperature conditions.