An overview of food lipids toward food lipidomics

Dissecting new lipids and their composition in herbal tea using untargeted LC/MS

Herbal teas and beverages have gained global attention because they are rich in natural bioactive compounds, which are known to have diverse biological effects, including antioxidant and anticarcinogenic properties. However, the lipidomic profiles of herbal teas remain unclear. In this study, we applied an untargeted lipidomics approach using high-performance liquid chromatography coupled with linear ion trap-Orbitrap mass spectrometry to comprehensively profile, compare, and identify unknown lipids in four herbal teas: dokudami, kumazasa, sugina, and yomogi. A total of 341 molecular species from five major classes of lipids were identified. Multivariate principal component analysis revealed distinct lipid compositions for each of the herbs. The fatty acid α-linolenic acid (FA 18:3) was found to be abundant in kumazasa, whereas arachidonic acid (FA 20:4) was the most abundant in sugina. Interestingly, novel lipids were discovered for the first time in plants; specifically, short-chain fatty acid esters of hydroxy fatty acids (SFAHFAs) with 4-hydroxy phenyl nonanoic acid as the structural core. This study provides insight into the lipidomic diversity and potential bioactive lipid components of herbal teas, offering a foundation for further research into their health-promoting properties and biological significance.

From Oxidized Fatty Acids to Dimeric Species: In Vivo Relevance, Generation and Methods of Analysis

The occurrence of free fatty acids (FFAs) and the generation of reactive oxygen species (ROS) such as hydroxyl radicals (HO●) or hypochlorous acid (HOCl) is characteristic of inflammatory diseases, for instance, rheumatoid arthritis. Unsaturated fatty acids react with ROS yielding a variety of important products such as peroxides and chlorohydrins as primary and chain-shortened compounds (e.g., aldehydes and carboxylic acids) as secondary products. These modified fatty acids are either released from phospholipids by phospholipases or oxidatively modified subsequent to their release. There is increasing evidence that oligomeric products are also generated upon these processes. Fatty acid esters of hydroxy fatty acids (FAHFAs) are considered as very important products, but chlorinated compounds may be converted into dimeric and (with smaller yields) oligomeric products, as well. Our review is structured as follows: first, the different types of FFA oligomers known so far and the mechanisms of their putative generation are explained. Industrially relevant products as well as compounds generated from the frying of vegetable oils are also discussed. Second, the different opinions on whether dimeric fatty acids are considered as "friends" or "foes" are discussed.

Untargeted Lipidomics Reveal Quality Changes in High-Moisture Japonica Brown Rice at Different Storage Temperatures

Low temperatures are an effective way of delaying grain rancidity and deterioration. However, little is known about the difference in quality changes in high-moisture japonica brown rice at different storage temperatures. In this study, the storage quality changes in japonica brown rice with a 15.50% moisture content stored at 15 °C, 20 °C, and 25 °C were investigated. In addition, an untargeted lipidomics analysis coupled with gas chromatography and mass spectrometry (GC-MS) was applied to analyze the volatile compounds and metabolite changes in the high-moisture japonica brown rice. The results showed that storage at 15 °C could well maintain the color and aroma stability of the brown rice and delay the increase in fatty acid value (FAV). The lipidomics results showed that storage at 15 °C delayed glycerolipid and sphingolipid metabolism and reduced glycerophospholipid catabolism in the brown rice. The low-temperature environment regulated these three metabolic pathways to maintain higher contents of triglycerides (TG), phosphatidylserine (PS), abd phosphatidylethanolamine (PE), and lower contents of diglycerides (DG), OAcyl-(gamma-hydroxy) FA (OAHFA), ceramides (Cer), and glycosylceramides (Hex1Cer) in the high-moisture japonica brown rice, which maintained the storage stability of the brown rice. Our results proposed the cryoprotection mechanism of postharvest brown rice from the perspective of volatile compounds and metabolite changes, providing a foothold for the further exploration of low-temperature storage as a safe and efficient cryoprotectant in the grain storage field.