Analysis of lipidomics profile of rice and changes during storage by UPLC-Q-extractive orbitrap mass spectrometry

Effects of storage on the physicochemical characteristics of rice with different starch lysophospholipids contents

Whether paddy rice varieties with different starch lysophospholipids (LPLs) exhibit similar changes in the physicochemical characteristics during storage remain largely unknown. This study investigated the dynamic changes in the physicochemical properties of a japonica rice and its low- and high-LPLs mutants during storage at 24 and 37 °C for one year. During storage, resistant starch (RS), peak viscosity, breakdown viscosity, pasting temperature and enthalpy of gelatinization gradually increased, with higher values observed at 37 °C compared to 24 °C after one year of storage. In contrast, the contents of storage protein components and amino acids gradually decreased, with lower values observed at 37 °C than at 24 °C after one year of storage. It seems that these changes were independent of the starch LPLs. However, principal component analysis based on these physicochemical properties successfully distinguished the three genotypes with different LPLs, indicating that LPLs influence the physicochemical properties during storage.

Flavor formation and phospholipids degradation of crayfish meat treated by boiling combined air-frying during accelerated storage

Thermal treatment is an essential processing method in crayfish processing. This study analyzed the changes in lipids and volatile compounds in crayfish muscle subjected to three thermal processes: boiling (BO), air-frying (AF), and boiling combined air-frying (BO-AF). Aldehydes and heterocyclic compounds were found to be the predominant volatile compounds in crayfish muscle during thermal processing and storage. The intensity of lipid oxidation (POV, TBARS and p-AnV) was greatest in AF, and was notably lower in BO-AF. the total concentration of free fatty acids (FFAs) was highest in the AF group (4.14 mg/g) after processing, followed by BO (3.26 mg/g) and BO-AF (2.04 mg/g). During storage, the FFAs content gradually decreased, with generally lower levels observed at 65 °C compared to 45 °C. A total of 383 phospholipid species were identified, phosphatidylethanolamine being the primary difference lipid type in BO (26.7 %) and AF (36.7 %), while fatty acids were the main differential lipid types in BO-AF group, under the comparison between processed and stored. Overall, the BO-AF method improved the flavor sensory and decreased lipid oxidation, compared to the other two methods. These findings provide valuable insights into the effects of different thermal processing and storage methods on the quality and safety of crayfish muscle.

Critical overview of mass spectrometry-based lipidomics approach for evaluating lipid oxidation in foods

Mass spectrometry-based lipidomics, developed through rapid advancements in instruments and techniques, provides comprehensive analyses of individual lipidomes in diverse biological systems. This contribution summarizes the limitations of classical methods for measuring lipid oxidation in foods and presents current novel technologies for evaluating lipid oxidation. Notably, this study introduces the mass spectrometry-based lipidomics approach and its utility in assessing lipid oxidation through various analytical modes, supported by numerous examples. This overview offers significant insights into the use of mass spectrometry-based lipidomics for measuring lipid oxidation in foods, proposing lipidomics analysis as a promising method to address the limitations of classical approaches.

Effect of storage temperature on the quality of brown rice revealed by integrated GC-MS and lipidomics analysis

Brown rice is highly nutritious but more susceptible to deterioration without the rice husk's protection. In this study, the mechanism of storage temperature on brown rice quality was investigated based on GC-MS and lipidomics. The results showed that both 15 °C and 20 °C storage retarded the lipids oxidation of brown rice and maintained its texture properties. Moreover, 1-octanol, 1-octen-3-ol, octanal, fitone, 2, 3-dihydrobenzofuran, dodecane, and tridecane were key biomarkers in cooked brown rice flavor. Furthermore, significant correlations between lipid oxidation, texture, and flavor biomarkers were revealed. Notably, the quality of brown rice stored at 15 °C (Fatty acid value = 23.0 mg/100 g) was superior to that at 20 °C (Fatty acid value = 24.3 mg/100 g) due to more effective retardation of glycerophospholipid, glycerolipid, and phospholipid metabolism. This work provided a better understanding of temperature-controlled storage of brown rice and give recommendation for potential commercial applications.

Low temperature storage alleviates aging of paddy by reducing lipid degradation and peroxidation

The quality deterioration of paddy during storage is closely associated to lipid metabolism. To explore the effect of lipid metabolism on the texture of paddy, freshly harvested Nanjingxiangzhan (Indica rice) stored for 60 days at 15 °C and 25 °C for 60 days was investigated. Paddy stored at 15 °C showed higher contents of ATP, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, triacylglycerols, diacylglycerols, monogalactosyldiacylglycerol and digalactosyldiacylglycerol but lower levels of lysophosphatidylcholine, lysophosphatidylethanolamine, phosphatidic acid, ceramides and free fatty acids. Storage at 15 °C inhibited lipase, phospholipase D (PLD), lipoxygenase (LOX) activities and the corresponding gene expressions. Moreover, 15 °C storage retarded the rise of hardness, cohesiveness and chewiness, while delayed the reduction of gumminess and springiness. These findings suggested that maintenance in glycerophospholipids, glycerolipids and saccharolipids abundance, reduction in lysophospholipids, phosphatidic acid, ceramides and free fatty acids accumulation could contribute to enhanced internal resistance to aging in freshly harvested paddy at low temperature storage.

Analysis of lipidomics profile of Brassica napus hybrid 'Fangyou 777' and its parents during ripening stages based on UPLC-MS/MS

BACKGROUND

Lipids in rapeseed is of great significance to human health, and 'Fangyou 777' (No. GPD-2019-510073) has been identified as an excellent cultivar with high oil content. However, the change of lipid profile at different ripening stages remain unclear. Herein, UPLC-MS/MS was utilized for comprehensive lipidomics analysis of 'Fangyou 777' and its parents at four ripening stages.

RESULTS

778 lipids components across 25 subclasses were identified, and triglycerides (TGs), diglycerides (DGs), phosphatidylserines (PSs), phosphatidylinositols (PIs), phosphatidylglycerols (PGs), phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), and free fatty acids (FFAs) were identified as the dominant lipid subclass. Due to heterotic vigor, the total lipids, TGs, FFAs, lysophosphatidylglycerol (LPGs) and PSs contents in 'Fangyou 777' were significantly higher than its parents. The PCA and OPLS-DA results elucidated that lipids in 'Fangyou 777' differed obviously from its parents at S1 (17 April, 2023; 28 days before ripening, 28 DBR), S2 (1 May, 2023; 14 DBR), and S3 (15 May, 2023; ripening day). TG(18:1_18:3_22:1), TG(18:1_22:1_18:2), TG(16:0_18:1_20:1), TG(16:0_18:1_22:1), TG(20:1_18:2_20:2), TG(18:1_18:1_20:1), and FFA(24:4) were recognized as key differential lipids. The glycerolipid metabolism and unsaturated fatty acid biosynthesis were the differential metabolic pathways at S1 and S3, while glycosylphosphatidylinositol (GPI)-anchor biosynthesis and glycerophospholipid metabolism were the differential metabolic pathways at S2 and S4 (7 days after ripening/physiologically ripened for one week).

CONCLUSION

This study provided a comprehensive profile to facilitate the understanding lipids accumulation in 'Fangyou 777' and its parents during ripening stages, and offered a foundation to comprehend lipid metabolism.

A Comprehensive Investigation of Lipid Profile During the Solid-State Fermentation of Rice by Monascus purpureus

Red yeast rice is a nutraceutical fermented product used worldwide for the symptomatic relief of dyslipidemia and cardiovascular disease. However, the fermentation-induced lipid transformation from rice to red yeast rice remains unclear. Herein, an ultra-high performance liquid chromatography coupled with hybrid quadrupole-orbitrap mass spectrometry method was developed for the comprehensive lipid analysis during fermentation. A total of 246 lipids fall in 21 subclasses were annotated in rice and red yeast rice, including 37 lysophospholipids, 14 phospholipids, 29 diglycerides, 114 triglycerides and fatty acid (15 species), ceramide (12 species), hexosylceramide (3 species), sitosterol ester (2 species), monogalactosyldiacylglycerol (2 species), digalactosyldiacylglycerol (2 species), monogalactosylmonoacylglycerol (8 species), digalactosylmonoacylglycerol (5 species), coenzyme Q (1 species), acyl hexosyl campesterol ester (1 species), and acylcarnitine (1 species). Results showed that lipid profiles changed, and new lipid species emerged. Notably, 18 medium- and long-chain triacylglycerols and triacylglycerols with short-chains were tentatively identified. These triacylglycerols also show the effects of body fat accumulation reduction, and hypolipidemic and hypoglycemic activities. Furthermore, lipid species that were profoundly changed were quantified, and the dynamic changes were investigated. This study clarified the molecular species and compositional changes in fermented rice from lipid aspect.

Integrated lipidomics and microbiomics reveal the quality changes of fresh yak tenderloin during storage

The changes in lipid and microbial during beef storage exert a substantial impact on the overall quality of beef. In this study, lipidomics and microbiomics were used to evaluate the effects of chilled storage (at 4 °C, CS) and superchilled storage (at -2 °C, SS) on the quality of yak tenderloin. The data revealed that TG, PS, PI, PE, and Car are the key factors contributing to the generation of undesirable odor during the storage of tenderloin. Macrococcus, Lactobacillus, Myroides, and Proteobacteria directly affect the storage quality of yak tenderloin. Integrated analysis revealed that microbial metabolites interact with lipids, resulting in a deterioration of meat quality. These changes are mediated by Myroides, Pseudomonas, and Lactobacillus, which regulate fatty oxidation and metabolism of PE, PI, PS, Cer, and SM. These findings have important implications for understanding the changes in quality and microbial activity of refrigerated meat and meat products.

Lipidomics combined with random forest machine learning algorithms to reveal freshness markers for duck eggs during storage in different rearing systems

The differences in lipids in duck eggs between the 2 rearing systems during storage have not been fully studied. Herein, we propose untargeted lipidomics combined with a random forest (RF) algorithm to identify potential marker lipids based on ultra-performance liquid chromatography‒mass spectrometry (UPLPC-MS/MS). A total of 106 and 16 differential lipids (DL) were screened in egg yolk and white, respectively. In yolk, metabolic pathway analysis of DLs revealed that glycerophospholipid metabolism and sphingolipid metabolism were the key metabolic pathways in the traditional free-range system (TFS) during storage, glycosylphosphatidylinositol-anchored biosynthesis and glyceride metabolism were the key pathways in the floor-rearing system (FRS). In egg white, the key pathway in both systems is the biosynthesis of unsaturated fatty acids. Combined with RF algorithm, 12 marker lipids were screened during storage. Therefore, this study elucidates the changes in lipids in duck eggs during storage in 2 rearing systems and provides new ideas for screening marker lipids during storage. This approach is highly important for evaluating the quality of egg and egg products and provides guidance for duck egg production.

Lipidomic Profiling and Storage-Induced Changes in Cassava Flour Using LC-MS/MS

Cassava serves as a primary staple food for over one billion people worldwide. The quality of cassava flour is markedly affected by the oxidation and deterioration of lipids during storage. Despite its significance, the lipid composition of cassava flour and its alterations throughout storage periods have not been extensively studied. This study offers a comprehensive lipidomic analysis of cassava flour over storage periods using liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). The results showed that 545 lipids from five classes and 27 subclasses were identified in cassava flour, including key substances such as free fatty acids (36 species), diglycerides (DGs) (31 species), and triglycerides (TGs) (259 species). Using Metware Cloud for statistical analysis, significant variations were observed in 50 lipid species over long-term storage, reflecting changes in lipid profiles due to storage. These lipids correlate with seven metabolic pathways, among which glycerolipid metabolism is the most affected. The metabolites associated with these pathways can differentiate cassava flour based on the length of storage. This study provides a theoretical basis and storage technology parameters for lipid changes during cassava flour storage.

Effects of Artificial Aging on Rice Lysophospholipids

Lysophospholipids (LPLs) represent a major class of polar lipids crucial for rice's nutritional and functional properties. This study investigates the impact of varying storage temperatures (20, 30, and 40 °C) and humidity (50 and 95%) on the nonstarch and starch LPLs of paddy and milled rice. The findings revealed that the average nonstarch LPL content in paddy rice aged at 20 °C (82.6 μg/g) and 40 °C (83.6 μg/g) was significantly lower than that at 30 °C (95.0 μg/g). The nonstarch LPL content of milled rice aged at 20 °C (78.0 μg/g) was significantly higher than that at 30 and 40 °C. High storage temperature (40 °C) and humidity (95%) resulted in a significant reduction in rice total starch LPC and LPE content when compared to low humidity (50%). The ratio of rice starch/nonstarch LPL components such as LPC16:0 and LPC18:2 remarkably increased with increased storage temperature and humidity.

Lipidomics analysis of rice bran during storage unveils mechanisms behind dynamic changes in functional lipid molecular species

Rice bran, recognized for its rich lipids and health-beneficial bioactive compounds, holds considerable promise in applications such as rice bran oil production. However, its susceptibility to lipid hydrolysis and oxidation during storage presents a significant challenge. In response, we conducted an in-depth metabolic profiling of rice bran over a storage period of 14 days. We focused on the identification of bioactive compounds and functional lipid species (25 acylglycerols and 53 phospholipids), closely tracking their dynamic changes over time. Our findings revealed significant reductions in these lipid molecular species, highlighting the impact of rancidity processes. Furthermore, we identified 19 characteristic lipid markers and elucidated that phospholipid and glycerolipid metabolism were key metabolic pathways involved. By shedding light on the mechanisms driving lipid degradation in stored rice bran, our study significantly advanced the understanding of lipid stability. These information provided valuable insights for countering rancidity and optimizing rice bran preservation strategies.

Exploring the oxidative rancidity mechanism and changes in volatile flavors of watermelon seed kernels based on lipidomics

Watermelon seed kernels (WSK) are prone to oxidative rancidity, while their evaluation biomarkers and changes in volatile flavor are still unknown. The research tracked the changes in volatile compounds and lipid components before and after rancidity using HS-SPME-GC-O-MS and lipidomic techniques. The results showed the flavor of watermelon seed kernels changed significantly before and after rancidity, from mild aroma to rancidity. A total of 42 volatile compounds were detected via GC-O-MS, and a total of 220 lipid molecules were detected via lipidomic technology. 55 lipids with significant differences were screened via multivariate statistical analysis. Combining the above analysis, it found that glycerol phospholipid and glyceride pathways were the most important metabolic pathways and 1-Pentanol and styrene could be used as potential biomarkers to judge the rancidity process of watermelon seed kernels. The research could provide powerful technical support for the storage, transportation and freshness preservation of watermelon seed kernels.

The Chemical Reactivity of Membrane Lipids

It is well-known that aqueous dispersions of phospholipids spontaneously assemble into bilayer structures. These structures have numerous applications across chemistry and materials science and form the fundamental structural unit of the biological membrane. The particular environment of the lipid bilayer, with a water-poor low dielectric core surrounded by a more polar and better hydrated interfacial region, gives the membrane particular biophysical and physicochemical properties and presents a unique environment for chemical reactions to occur. Many different types of molecule spanning a range of sizes, from dissolved gases through small organics to proteins, are able to interact with membranes and promote chemical changes to lipids that subsequently affect the physicochemical properties of the bilayer. This Review describes the chemical reactivity exhibited by lipids in their membrane form, with an emphasis on conditions where the lipids are well hydrated in the form of bilayers. Key topics include the following: lytic reactions of glyceryl esters, including hydrolysis, aminolysis, and transesterification; oxidation reactions of alkenes in unsaturated fatty acids and sterols, including autoxidation and oxidation by singlet oxygen; reactivity of headgroups, particularly with reactive carbonyl species; and E/Z isomerization of alkenes. The consequences of reactivity for biological activity and biophysical properties are also discussed.

A method to assess industrial paraffin contamination levels in rice and its transferability analysis based on transfer component analysis

Accurate assessment of industrial paraffin contamination levels (IPCLs) in rice is critical for food safety. However, time-consuming and labor-intensive experiments to produce labels for targeted adulterated rice have hindered the development of IPCL estimation methods. In this paper, a transfer learning method (TCA-LSSVR) has been developed. The algorithm integrates transfer component analysis (TCA) with domain adaptive capabilities to produce accurate estimates. Rice from 7 different regions and 3 industrial paraffins were used to generate 4,680 samples from 9 datasets for benchmarking. The test results showed that the established algorithm achieved good estimation performance in various modelling strategies, and only 20 % of off-site samples were needed to supplement the source dataset, the average determination coefficient R2 reached 0.7045, the average RMSE reached 0.140 %, and the average RPD reached 2.023. This work highlights the prospect of rapidly developing a new generation of adulteration detection algorithms using only previous trial data.

Oxidative Stability and Pasting Properties of High-Moisture Japonica Brown Rice following Different Storage Temperatures and Its Cooked Brown Rice Flavor

The study proposed to investigate the impacts of storage temperatures (15, 20, 25 °C) on the oxidative stability (peroxide value, carbonyl value, malondialdehyde content) and sensory attributes (pasting properties, cooked brown rice flavor) of high-moisture japonica brown rice. According to the findings, the peroxide value, the carbonyl value, and the malondialdehyde content of high-moisture japonica brown rice stored at a temperature of 15 °C exhibited consistently low levels, and the pasting properties were favorable. In addition, 22 out of 51 flavor volatiles were screened as key differential volatile flavor compounds in cooked brown rice via a combination of ANOVA and orthogonal projections to latent structures-discriminant analysis (OPLS-DA). Among them, 3-heptylacrolein had an aroma of fat and mushroom, and its contents were higher at 15 °C and 20 °C. These findings could serve as a valuable reference for storing high-moisture japonica brown rice under low temperature conditions as well as for investigating the flavor characteristics of cooked brown rice derived from this variety.

Evaluation of Lipidomics Profile of Quinoa Flour and Changes during Storage Based on Ultra Performance Liquid Chromatography Coupled with Quadrupole Exactive Orbitrap Mass Spectrometry

Although quinoa is nutritious, its high fat content and lipase activity make it easily oxidized during storage. Meanwhile, quinoa's lipid composition and changes during storage are still unknown. Therefore, we stored fresh quinoa flour at low temperature and low humidity (LL), normal temperature and normal humidity (NN), and high temperature and high humidity (HH) conditions for 120 days to assess its oxidative stability and to monitor the changes in lipid composition. Herein, the contents of fatty acids, the peroxide values, the malondialdehyde values, and the lipase activity in quinoa flour during storage are determined to evaluate its oxidation stability. At LL and NN conditions, the contents of fatty acids, the peroxide values, the malondialdehyde values, and the lipase activity changed slowly. They were 3 (LL) and 5 times (NN), 2.7 (LL) and 4.7 times (NN), 1.4 (LL) and 2.3 times (NN), and 1.5 (LL) and 1.6 times (NN) the initial content at storage up to 120 d. However, with the prolongation of storage time under HH conditions, they all increased significantly to 8, 6.6, 3, and 2 times the original content. Moreover, during the storage of quinoa under LL, NN, and HH conditions for 120 days, we continuously monitored the lipid composition of quinoa grains with UPLC-Q-Exactive Orbitrap MS/MS. We identified a total of 14 subclasses of 229 lipids, including 90 significantly different lipid species. PCA and PLS-DA showed that quinoa lipids in HH conditions changed significantly with prolonged storage; among these, the TG and DG classes were the most susceptible to oxidation, which could distinguish fresh quinoa from oxidized quinoa. Simultaneously, we also found that lipase activity has a significant impact on lipid metabolism through correlation analysis, which also indicates that enzyme inactivation treatment can slow down lipid hydrolysis and oxidation during storage. To explore the mechanism of these changes, we also identified twelve important lipid metabolism pathways during quinoa storage. In conclusion, our study advances knowledge of the storage stability and lipid oxidation mechanisms of quinoa and provides a theoretical basis for setting the shelf life of quinoa.

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.

An overview of food lipids toward food lipidomics

Increasing evidence regarding lipids' beneficial effects on human health has changed the common perception of consumers and dietary officials about the role(s) of food lipids in a healthy diet. However, lipids are a wide group of molecules with specific nutritional and bioactive properties. To understand their true nutritional and functional value, robust methods are needed for accurate identification and quantification. Specific analytical strategies are crucial to target specific classes, especially the ones present in trace amounts. Finding a unique and comprehensive methodology to cover the full lipidome of each foodstuff is still a challenge. This review presents an overview of the lipids nutritionally relevant in foods and new trends in food lipid analysis for each type/class of lipids. Food lipid classes are described following the LipidMaps classification, fatty acids, endocannabinoids, waxes, C8 compounds, glycerophospholipids, glycerolipids (i.e., glycolipids, betaine lipids, and triglycerides), sphingolipids, sterols, sercosterols (vitamin D), isoprenoids (i.e., carotenoids and retinoids (vitamin A)), quinones (i.e., coenzyme Q, vitamin K, and vitamin E), terpenes, oxidized lipids, and oxylipin are highlighted. The uniqueness of each food group: oil-, protein-, and starch-rich, as well as marine foods, fruits, and vegetables (water-rich) regarding its lipid composition, is included. The effect of cooking, food processing, and storage, in addition to the importance of lipidomics in food quality and authenticity, are also discussed. A critical review of challenges and future trends of the analytical approaches and computational methods in global food lipidomics as the basis to increase consumer awareness of the significant role of lipids in food quality and food security worldwide is presented.

Shotgun lipidomics reveals the changes in phospholipids of brown rice during accelerated aging

Brown rice exhibits higher nutritional value and attracts more and more attentions; however, the change in phospholipid molecular species in brown rice during aging is poorly understood. In this study, shotgun lipidomics was employed to investigate the changes in phospholipid molecular species in four brown rice varieties (two japonica rice and two indica rice) during accelerated aging. A total of 64 phospholipid molecular species were identified, and most of them were rich in polyunsaturated fatty acids. For japonica rice, phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylglycerol (PG) gradually decreased during accelerated aging. However, the content of PC, PE, and PG in indica rice showed no difference during accelerated aging. Significantly different phospholipid molecular species from four brown rice were screened during accelerated aging. Based on these significantly different phospholipids, the metabolic pathways including glycerophospholipid metabolism and linoleic acid metabolism during accelerated aging were depicted. The findings from this study could be helpful in explaining the impact of accelerated aging on phospholipids of brown rice, and offer an understanding on relationships between phospholipids degradation and brown rice deterioration.

Development and application of lipidomics for food research

Lipidomics is an emerging and promising omics derived from metabolomics to comprehensively analyze all of lipid molecules in biological matrices. The purpose of this chapter is to introduce the development and application of lipidomics for food research. First, three aspects of sample preparation are introduced: food sampling, lipid extraction, and transportation and storage. Second, five types of instruments for data acquisition are summarized: direct infusion-mass spectrometry (MS), chromatographic separation-MS, ion mobility-MS, MS imaging, and nuclear magnetic resonance spectroscopy. Third, data acquisition and analysis software are described for the lipidomics software development. Fourth, the application of lipidomics for food research is discussed such as food origin and adulteration analysis, food processing research, food preservation research, and food nutrition and health research. All the contents suggest that lipidomics is a powerful tool for food research based on its ability of lipid component profile analysis.

Lipidomics and volatilomics reveal the changes in lipids and their volatile oxidative degradation products of brown rice during accelerated aging

Brown rice exhibits higher nutritional value and attracts more and more attentions; however, lipid alteration in brown rice during aging is poorly understood. In this study, lipidomics and volatilomics were employed to investigate free fatty acids, triglycerides, and volatile oxidative degradation products of lipids in brown rice during accelerated aging for 70 days. The results showed that the total free fatty acids in brown rice increased significantly (2.90-4.14 times) while triglycerides decreased remarkably at the initial stage of aging. Monounsaturated and polyunsaturated aldehydes, ketones, and acids increased obviously in brown rice during accelerated aging for 70 days. The screening of significantly different compounds indicated that the enzymatic hydrolysis of triglycerides (EHT) and enzymatic oxidation of lipids (EOL) were the main biochemical behaviors at the initial stage of aging (0-28 day) while automatic oxidation of lipids (AOL) was the primary chemical reaction for 28-70 days aging.

Accumulation and metabolism of pyroxasulfone in tomato seedlings

Pyroxasulfone (PYS) is an isoxazole herbicide favored for its high activity. However, the metabolic mechanism of PYS in tomato plants and the response mechanism of tomato to PYS are still lacking. In this study, it was found that tomato seedlings had a strong ability to absorb and translocate PYS from roots to shoots. The highest accumulation of PYS was in the apex tissue of the tomato shoots. Using UPLC-MS/MS, five metabolites of PYS were detected and identified in tomato plants, and their relative contents in different parts of tomato plants varied greatly. The serine conjugate, DMIT [5, 5-dimethyl-4, 5-dihydroisoxazole-3-thiol (DMIT)] &Ser, was the most abundant metabolites of PYS in tomato plants. In tomato plants, the conjugation of thiol-containing metabolic intermediates of PYS to serine may mimic the cystathionine β-synthase-catalyzed condensation of serine and homocysteine (in the pathway sly00260 sourced from KEGG database). This study ground breakingly proposed that serine may play an important role in plant metabolism of PYS and fluensulfone (whose molecular structure is similar to PYS). PYS and atrazine (whose toxicity profile is similar to PYS but not conjugate with serine) produced different regulatory outcomes for endogenous compounds in the pathway sly00260. Differential metabolites in tomato leaves exposed to PYS compared with the control, including amino acids, phosphates, and flavonoids, may play important roles in tomato response to PYS stress. This study provides inspiration for the biotransformation of sulfonyl-containing pesticides, antibiotics and other compounds in plants.

Understanding fatty acid composition and lipid profile of rapeseed oil in response to nitrogen management strategies

The fatty acid composition of rapeseed seeds plays an important role in oil quality for human nutrition and a healthy diet. A deeper understanding of fatty acid composition and lipid profiles in response to different nitrogen managements is critical for producing healthier rapeseed oil for the human diet. The fatty acid composition and lipid profiles were characterized through targeted GC-MS and lipidomics analysis (UPLC-MS) in this study. The results showed that nitrogen management significantly altered the fatty acid composition, thereby influencing oil quality when it is used to maximize the seed yield of rapeseed. Several fatty acid components (particularly oleic acid, linoleic acid, and linolenic acid) decreased significantly with increasing N application rate. A total of 1212 differential lipids in response to different N levels in the two varieties were clearly identified, that can be categorized into five classes, including 815 glycerolipids (GLs), 195 glycerophospholipids (GPs), 155 sphingolipids (SPs), 32 sterols (STs), and 15 fatty acyls (FAs). These differential lipids are likely to participate in lipid metabolism and signal transduction. Co-expression lipid modules were determined, and the key lipids, such as triglyceride (20:0/16:0/16:0; 18:0/18:1/18:3; 8:0/11:3/18:1), were found to be strongly related to several predominant fatty acids such as oleic acid and linoleic acid. The results further imply that some identified lipids are involved with lipid metabolism and could affect the fatty acid composition, which provide a theoretical guidance for increasing seed oil in Brassica napus.

Lipidomic Profiling of Rice Bran after Green Solid-Liquid Extractions for the Development of Circular Economy Approaches

Rice bran is a rather underutilized by-product of the rice industry that nowadays is far from being valorized. In this study, the lipidomic profile of bran of the Italian rice variety, Roma, has been evaluated through ultra performance liquid chromatography-tandem mass spectrometry. Crude lipid extracts were obtained from rice bran treated with different green solvents (1-butanol, ethanol and methyl tert-butyl ether/methanol mixture) in combination with an ultrasonic pre-treatment, and then compared with extracts obtained with standard solvents (chloroform/methanol mixture). Lipid yield, number and type of lipids and composition of prevalent lipid classes extracted were evaluated in order to provide an exhaustive lipid profile of the rice bran and to identify the most efficient green solvent for solid-liquid extractions. Twelve different lipid classes and a maximum of 276 lipids were identified. Ethanol and methyl tert-butyl ether/methanol solvents provided higher lipid extraction yields, the former being the most effective solvent for the extraction of triglycerides and N-acylethanolamines and the latter the most effective for the extraction of diglycerides, phospholipids and ceramides at 4 °C. Moreover, extraction with ethanol at 20 °C gave similar results as at 4 °C in terms of lipid yield and for most of the classes of lipids extracted. Taken together, our results indicate ethanol and methyl tert-butyl ether/methanol as excellent solvents for lipid extraction from rice bran, with the aim to further valorize this food by-product in the perspective of a circular economy.

Nutritional lipidomics for the characterization of lipids in food

Lipids represent one out of three major macronutrient classes in the human diet. It is estimated to account for about 15-20% of the total dietary intake. Triacylglycerides comprise the majority of them, estimated 90-95%. Other lipid classes include free fatty acids, phospholipids, cholesterol, and plant sterols as minor components. Various methods are used for the characterization of nutritional lipids, however, lipidomics approaches become increasingly attractive for this purpose due to their wide coverage, comprehensiveness and holistic view on composition. In this chapter, analytical methodologies and workflows utilized for lipidomics profiling of food samples are outlined with focus on mass spectrometry-based assays. The chapter describes common lipid extraction protocols, the distinct instrumental mass-spectrometry based analytical platforms for data acquisition, chromatographic and ion-mobility spectrometry methods for lipid separation, briefly mentions alternative methods such as gas chromatography for fatty acid profiling and mass spectrometry imaging. Critical issues of important steps of lipidomics workflows such as structural annotation and identification, quantification and quality assurance are discussed as well. Applications reported over the period of the last 5years are summarized covering the discovery of new lipids in foodstuff, differential profiling approaches for comparing samples from different origin, species, varieties, cultivars and breeds, and for food processing quality control. Lipidomics as a powerful tool for personalized nutrition and nutritional intervention studies is briefly discussed as well. It is expected that this field is significantly growing in the near future and this chapter gives a short insight into the power of nutritional lipidomics approaches.

Storage Drives Alterations of Proteomic and Protein Structural Properties in Rice (Oryza sativa L.)

Rice quality changes during storage. However, few studies have reported the difference in protein structure between the indica and japonica varieties of rice during storage. The current research characterized the structural properties of the rice protein, and further investigated the proteomic profiles of Jianzhen 2 (indica rice) and Nanjing 9108 (japonica rice) during storage using the TMT labeling method. A significant reduction in free sulfhydryl content and an increase in disulfide bonds content and surface hydrophobicity were observed in both varieties after storage. The results of FTIR indicated that the changes in the protein’s secondary structure of Nanjing 9108 (japonica rice) were more significant than in Jianzhen 2 (indica rice). A total of 4039 proteins in Nanjing 9108 and 4301 proteins in Jianzhen 2 were identified by TMT-labeled proteomics analysis in this study. Significantly, changes were detected in 831 proteins in Nanjing 9108, while only in 60 proteins in Jianzhen 2. Protein processing in endoplasmic reticulum, starch, and sucrose metabolism were both accelerated in both varieties, while oxidative phosphorylation in mitochondria, glycolysis, fatty acid metabolism, and glutathione metabolism were enhanced in Nanjing 9108 (japonica rice). This study provides insight into the proteomic changes and protein structure in rice induced by storage.

Integrated Metabolome and Lipidome Strategy to Reveal the Action Pattern of Paclobutrazol, a Plant Growth Retardant, in Varying the Chemical Constituents of Platycodon Root

Platycodon root, a medicinal food homology species which has been used in Asian countries for hundreds of years, is now widely cultivated in China. Treatment with paclobutrazol, a typical plant growth retardant, has raised uncertainties regarding the quality of Platycodon root, which have been rarely investigated. In the present study, metabolomic and lipidomic differences were revealed by ultra-high performance liquid chromatography coupled to ion mobility-quadrupole time of flight mass spectrometry (UPLC-IM-QTOF-MS). A significant decrease of platycodigenin-type saponins was observed in the paclobutrazol-treated sample. Carrying out a comprehensive quantitative analysis, the contents of total saponins and saccharides were determined to illustrate the mode of action of paclobutrazol on Platycodon root. This study demonstrated an exemplary research model in explaining how the exogenous matter influences the chemical properties of medicinal plants, and therefore might provide insights into the reasonable application of plant growth regulators.

UHPLC-Q-Orbitrap-based untargeted lipidomics reveals the variation of yolk lipids during egg storage

BACKGROUND

Egg yolk is recognized for its excellent nutritional benefit and economic value; however, egg is a perishable food, potentially losing quality if not handled properly between the time from farm production to consumption. Knowledge of the changes of yolk lipid composition under an extreme storage condition close to vitelline membrane breaking, which results in an inedible condition for shelf-eggs, remains incomplete. Considering the complexity of yolk lipids, the architectural features of yolk lipids at high-temperature storage (30°C for 10 days versus fresh) were classified through lipidomics.

RESULTS

This strategy yielded 1508 features within the lipid database coupled with 74 significantly different lipids (P < 0.05, fold change > 1.2 or < 0.83), mainly triglycerides, phospholipids, and sphingolipids. Most of them were decreased after storage; for example, triglycerides were assumed to play a role as a 'buffer' to maintain the system stability during storage by balancing fatty acid saturation, which strongly reduces the egg edible value for humans. Furthermore, phospholipids, especially the highly unsaturated phosphatidylcholine, decreased significantly and were suggested to be the primary cause for the variation in yolk emulsifying properties and flavor.

CONCLUSION

Altogether, these results deriving from oxidation and lipolysis reactions enhance our understanding of lipid transformation and the biochemical mechanisms, at the molecular level, of the deteriorative process of the egg yolk. These findings may lay the foundation for identifying processes, including some modifications of the lipid composition of rations fed to laying hens, aiming to improve the long-term shelf-stability of shell eggs and egg products. © 2022 Society of Chemical Industry.

Comprehensive lipidomics analysis reveals the changes in lipid profile of camellia oil affected by insect damage

Information on changes in lipid composition of seed oils under biotic stresses is scare. The camellia weevil, Curculio chinensis (Coleoptera: Curculionidae) as a notorious seed predator of Camellia species, has caused huge economic losses in China. Lipidomics is used in this study to reveal the lipid composition of camellia oil and its changes after insect damage. 278 lipids including glycerolipids (GL) (221), glycerophospholipids (GP) (34), fatty acyls (FA) (13), sphingolipids (SP) (8), prenol lipids (PR) (1) and sterol lipids (ST) (1) were determined in camellia oils. Insect damage had a significant impact on lipids, particularly FA and GL. Ten significantly different lipids [FFA(18:2), FFA(24:6), TG(14:1/18:2/18:2), TG(16:0/23:0/18:2), TG(20:1/24:1/18:2), TG(18:2/24:0/18:2), TG(16:3/18:2/22:5), PI(16:1/18:1), PE(16:0/18:1), PE(18:1/18:2)] were identified as potential biomarkers for distinguishing oil extracted from non-infested oilseeds and oil from infested oilseeds. We also detected four most important metabolic pathways by bioinformatics analysis to explore the mechanisms underlying changes. Our findings may be useful for future camellia oil production and may provide new insight into improving of nutritional quality of camellia oil.

Metabolomic Analysis Reveals Insights into Deterioration of Rice Quality during Storage

To determine the changes in the quality of rice during storage, this study investigated the comprehensive metabolomic profiles of Nanjing 9108 (typical japonica rice) and Jianzhen 2 (typical indica rice) varieties in China, using metabolomics. A total of 13 categories of 593 metabolites including lipids (134 species), phenolic acids (78 species), flavonoids (70 species), alkaloids (67 species), organic acids (64 species), amino acids and derivatives (64 species), saccharides and alcohols (44 species), nucleotides and derivatives (37 species), vitamins (14 species), lignans and coumarins (9 species), tannins (2 species), terpenoids (2 species), and others (8 species) were identified in both varieties. The result showed significant changes in 204 metabolites in Nanjing 9108, while only 26 were altered in Jianzhen 2 during storage. These metabolites involved 46 metabolic pathways. The TCA cycle, linoleic, and α-linolenic acid metabolic pathways were unique in Nanjing 9108. Finally, the results of quantitative mass spectrometry of 11 metabolites provided insight into biomarkers associated with quality deterioration of rice. This study provides insights into the mechanism of deterioration in the quality of rice during storage.

Protective Mechanism of Polygonum perfoliatum L. Extract on Chronic Alcoholic Liver Injury Based on UHPLC-QExactive Plus Mass Spectrometry Lipidomics and MALDI-TOF/TOF Mass Spectrometry Imaging

Polygonum perfoliatum L. has a long history of medicinal and edible applications. Studies have shown that it can significantly protect liver injury, but the mechanism is unclear. The purpose of this study was to explore the protective mechanism of P. perfoliatum on chronic alcoholic liver injury from the perspective of lipid metabolism. After 8 weeks of alcohol exposure in male Wister mice, the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) in serum were significantly increased, and the activities of alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) in liver were significantly decreased. Meanwhile, pathological changes of liver tissue in mice were observed by histopathology. Then, Ultra-High Performance Liquid Chromatography (UHPLC) QExactive Plus Mass Spectrometer lipidomics and matrix-assisted laser desorption/ionization time-of-flight/time -of-flight (MALDI-TOF/TOF) mass spectrometry imaging methods were established to analyze lipid metabolism in mice. Ten different lipids were identified by statistical analysis, including Fatty Acyls, Glycerophospholipids, Prenol lipids and Sphingomyelins. After intervention with P. perfoliatum extracts at different doses (25 to 100 mg/kg), levels of AST, ALT, ALP in serum, and activities of ADH and ALDH in liver were significantly corrected. The hepatic cord structure was clear, and the liver cells were closely arranged without other obvious abnormalities. Non-target lipidomics analysis showed that P. perfoliatum extract could regulate the metabolic disorders of the 10 different lipids caused by continuous alcohol exposure. Pathway analysis suggested that the mechanism of P. perfoliatum extract on chronic alcoholic liver injury may be related to the regulation of linoleic acid and α-linolenic acid.

Lipidomic, Transcriptomic, and BSA-660K Single Nucleotide Polymorphisms Profiling Reveal Characteristics of the Cuticular Wax in Wheat

Plant epidermal wax helps protect plants from adverse environmental conditions, maintains the function of tissues and organs, and ensures normal plant development. However, the constituents of epidermal wax and the regulatory mechanism of their biosynthesis in wheat have not been fully understood. Wheat varieties with different wax content, Jinmai47 and Jinmai84, were selected to comparatively analyze their waxy components and genetic characteristics, using a combination of lipidomic, transcriptomic, and BSA-Wheat 660K chip analysis. Through lipidomic analysis, 1287 lipid molecules were identified representing 31 lipid subclasses. Among these, Diacylglycerols (DG), (O-acyl)-ω-hydroxy fatty acids (OAHFA), wax ester (WE), Triacylglycerols (TG), and Monoradylglycerols (MG) accounted for 96.4% of the total lipids in Jinmai84 and 94.5% in Jinmai47. DG, OAHFA, and WE were higher in Jinmai84 than in Jinmai47 with the content of OAHFA 2.88-fold greater and DG 1.66-fold greater. Transcriptome sequence and bioinformatics analysis revealed 63 differentially expressed genes related to wax biosynthesis. Differentially expressed genes (DEGs) were found to be involved with the OAHFA, DG, and MG of synthesis pathways, which enriched the wax metabolism pathway. Non-glaucous and glaucous bulks from a mapping population were used to identify single nucleotide polymorphisms (SNP) via 660K chip analysis. Two loci centered on chromosomes 2D and 4B were detected and the locus on 4B is likely novel. These data improve understanding of complex lipid metabolism for cuticular wax biosynthesis in wheat and lay the foundation for future detailed investigation of mechanisms regulating wax metabolism.

Significantly Different Lipid Profile Analysis of Litopenaeus vannamei under Low-Temperature Storage by UPLC-Q-Exactive Orbitrap/MS

Low-temperature storage is one of the most important preservation methods for aquatic product storage. However, the effects of low-temperature storage on the lipid profiles of shrimp are unclear. Herein, UPLC-Q-Exactive Orbitrap/MS combined with LipidSearch software was applied to analyze the effect of three low storage temperatures (4 °C, -2 °C, and -18 °C) on the lipidomics of Litopenaeus vannamei. A total of 15 lipid classes were analyzed, and PC, PE, DG, and TG accounted for vast majority of peak areas. Furthermore, 531 individual lipid variables enriched in 12 metabolic pathways were identified via bioinformatics analysis methods. A total of 56 significantly different lipid molecular species (55 belonging to PC, PE, DG, and TG) were selected as potential biomarkers of lipid oxidation via correlational analysis between physical properties (texture and color) and individual lipid variables. The results indicated that the three low storage temperatures caused different effects on the lipidomics profile of L. vannamei, and PC, PE, DG, and TG could become potential focuses in further studies of lipid oxidation in L. vannamei.

Research advance in gas detection of volatile organic compounds released in rice quality deterioration process

Rice quality deterioration will cause grievous waste of stored grain and various food safety problems. Gas detection of volatile organic compounds (VOCs) produced by deterioration is a nondestructive detection method to judge rice quality and alleviate rice spoilage. This review discussed the research advance of VOCs detection in terms of nondestructive detection methods of rice quality deterioration, applications of VOCs in grain detection, inspection of characteristic gas produced during rice spoilage, rice deterioration prevention and control, and detection of VOCs released by rice mildew and insect attack. According to the main causes of rice quality deterioration and major sources of VOCs with off-odor generated during rice storage, deterioration can be divided into mold and insect infection. The results of literature manifested that researches mainly focused on the infection of Aspergillus in the mildew process and the attack of certain pests in recent years, thus the research scope was limited. In this paper, the gas detection methods combined with the chemometrics to qualitatively analyze the VOCs, as well as the correlation with the number of colonies and insects were further studied based on the common dominant strains during rice mildew, that is, Aspergillus and Penicillium fungi, and the common pests during storage, that is, Sitophilus oryzae and Rhyzopertha dominica. Furthermore, this paper pointed out that the quantitative determination of characteristic VOCs, the numeration relationship between VOCs and the degree of mildew and insect infestation, the further expansion of detection range, and the application of degraded rice should be the spotlight of future research.