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The stabilization mechanism of soil organic matter (SOM) has received considerable attention. It is widely accepted that mineral sorption/protection is important for SOM stabilization. However, it remains unclear which organic carbon component is beneficial for mineral protection. We collected soil samples from a paddy field (TP) to compare with natural soil (NS). To illustrate the behavior of different SOM pools and their protection by particles, we separated the soils into different particle-size fractions and then removed the active minerals using an acid mixture (1 M HCl/10% HF). The different carbon pools were analyzed using stable carbon isotopes and lipid biomarkers. Our study showed that acid treatment evidently increased the extractability of free lipids, usually over 60%, which confirmed the predominant role of minerals in SOM protection. For NS, the δ13C values increased with decreasing soil particle sizes and soil depths, indicating that 13C-enriched SOM was selectively preserved. However, this trend disappeared after cultivation, which was mainly attributed to the combined effects of the input of 13C-depleted fresh SOM and decomposition of the preserved 13C-enriched SOM. Meanwhile, based on the degradation parameters of the overall lipid biomarkers, SOM showed higher degradation states in clay and silt fractions than in the sand fraction before cultivation. It is possible that the small particle-size fractions could selectively absorb highly degraded SOM. The clay-associated SOM showed a low degradation state, but its carbon content was low after cultivation. We propose that the previously protected SOM was degraded after cultivation and was replaced by relatively fresh SOM, which should be carefully monitored during SOM management. [ABSTRACT FROM AUTHOR]

Four varieties in Northeast China rice were used as research materials, and starch bound lipids and free lipids in the rice were detected based on high-resolution mass spectrometry. A total of 371 types of free lipids (including glycerol phospholipids, glycerol esters, ceramides, and fatty acids) and 14 types of starch bound lipids (phospholipids) were detected from the four varieties of rice. The partial least squares discriminant analysis (PLS-DA) results showed that the four different varieties of rice grains can be distinguished by starch bound lipids and free lipids. The results of this study provide technical support for revealing the lipid composition and lipid analysis of rice.

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Purpose: The transformation of extractable plant compounds after their incorporation into soil was qualitatively and quantitatively studied in two forests under Juniperus communis L. and Pinus sylvestris L. Methods: Leaf, litter and soil samples were taken from representative pine and juniper forests in central Spain. The lipid fraction was extracted with dichloromethane, while methanol was used for polar compounds, which were then derivatized (silylation-oximation). Extracts were analyzed by gas chromatography-mass spectrometry. van Krevelen's graphical-statistical method, enhanced as surface density maps, was used to study changes in molecular assemblages during their transformation from plant to soil. Shannon Wiener diversity indices were also determined for the main groups of molecules to quantify the progressive removal or the appearance of new compounds throughout the transformation. Results: In the lipid fraction up to 126 compounds were identified, mainly alkanes (C10–C30 in pine forest and C10–C36 in juniper forest), fatty acids and cyclic compounds. In the polar extracts, up to 22 compounds were found, mainly sugars, polyols, cyclic acids and fatty acids. Conclusion: Comparing the successive stages of evolution of leaf extractive compounds, alkanoic acids and disaccharides tend to accumulate in the soil. On the other hand, the greatest molecular complexity was found in the intermediate stage (litter), and attributed to the coexistence of biogenic compounds with their transformation products, while the molecular complexity was simpler in soil extracts. This preliminary investigation could be extended to specific studies on the factors that determine the quality of soil organic matter under different environmental scenarios. [ABSTRACT FROM AUTHOR]

Soil water repellency (SWR) is a physical phenomenon whereby water cannot penetrate or has difficulty penetrating the soil surface. There are many factors involved in its occurrence, but the main factors controlling its emergence in loess remain unclear. In this work, we have studied numerous physicochemical and biological factors functioning in different dominant vegetations (Pinus tabulaeformis Carr., Robinia pseudoacacia L., and Hippophae rhamnoides L.) in a loess hilly region by gas chromatography--mass spectrometry (GC-MS) and high-throughput sequencing techniques. We observed that more than 75% of the soils under Robinia and Hippophae are categorized as slightly or strongly water repellent, while nearly 50% of the soils under Pinus are categorized as severely to extremely water repellent. The relative concentrations of total free lipids in the soil in the same water-repellency class were Pinus > Robinia > Hippophae, where fatty acids, alkanols, and sterols were positively correlated with SWR, whereas alkanes were not. For the abundance and diversity index of bacterial and fungal communities, the three species ranked in the following order: Robinia ≈ Hippophae > Pinus. Thus, solvent-extractable polar waxes were indicated to be better preserved in water-repellent soils under Pinus due to lower microbial diversity than Robinia and Hippophae. Here, we demonstrate polar waxes to be the principal factor controlling SWR. Moreover, the dominant phyla of fungi varied greatly than those of bacteria under three vegetation types. Correlation analysis showed that the abundance of Actinobacteria in dominant bacteria increased with SWR. Nonmetric multidimensional scaling suggested the fungal community in different waterrepellent soils under Pinus to vary more than those under Robinia and Hippophae. The indicator species mainly belonged to Actinobacteria in bacteria and Basidiomycota in fungi at the phylum level; this finding was further supported by the linear discriminant analysis (LDA) effect size (LEfSe). Additionally, GC-MS identified a small amount of ergosterol, a specific biomarker of fungi under Pinus. These pieces of evidence collectively reveal that severe to extreme SWR occurs under Pinus and appears to be the most influenced by fungi and actinomycetes when the topsoil is close to air drying. However, there is a need for further testing on different plant species or land use. [ABSTRACT FROM AUTHOR]

Lipids are a minor nutritional component of barley (Hordeum vulgare L.) grain and have not been as widely explored as the major components. The aim of this study was to investigate the effect of genotype and environment, including conventional farming system with three crop management regimes, differing in agrochemical input, and organic farming system, on oil content and fatty acid composition in grain of two covered and four hulless spring barley genotypes during two growing seasons. Genotype significantly affected oil content and it was on average 4.26% and ranged in individual barley samples from 2.87 to 5.53%. We found linoleic, oleic, palmitic, α-linolenic, stearic and capric fatty acids in average proportions of 55.6; 21.3; 18.6; 3.7; 0.6 and 0.4%, respectively. Higher average oil content and proportion of α-linolenic acid was found in covered barley. Crop management regime did not significantly affect oil content but had some effect on the proportion of linoleic, α-linolenic, oleic and stearic acid. Decrease of chemical inputs was in favour of oil content and proportion of α-linolenic, oleic and stearic acids but did not promote linoleic acid. Waxy hulless barley line with high oil content and a very high proportion of linoleic acid was identified. [ABSTRACT FROM AUTHOR]

Highlights • Chlorination impacts free and bound wheat flour lipids. • It improves the cake batter solvent phase holding capacity of wheat flour. • It improves interaction between the flour components and the batter solvent phase. • Starch and protein networks in chlorinated flour-sucrose gels are well organized. Abstract Chlorine treatment increases the surface hydrophobicity of starch granules of soft wheat flour and reduces its gluten network forming capacity and apparent content of the flour lipids, the latter presumably by forming chlorinated derivatives. It also increases its solvent holding capacity as shown by proton nuclear magnetic resonance (1H NMR) experiments in presence of sucrose. The exchanging protons in the extra-granular space are present in an environment with restricted mobility, indicating strong interactions between chlorinated soft wheat flour (CSWF) components and solvent. Chlorination reduced the capability of free flour lipids to shield starch granules during rapid visco analysis (RVA). The higher viscosity reached in RVA with CSWF was attributed to not only its lipids having different properties but also its protein, resulting in improved starch swelling and amylose leaching. Finally, 1H NMR indicated that starch and protein networks in CSWF-sucrose gels were better structured than in gels prepared from non-chlorinated flour. [ABSTRACT FROM AUTHOR]

Lipids from various anatomical parts of Costaria costata were characterized. Differences were found in the contents of individual lipid constituents. Free lipids were isolated from stipe (0.084% of moist mass) and rhizoids (0.079% of moist mass). Thallus typically had lower contents (0.068% of moist mass). A large part of the bound lipids consisted of polar lipids, primarily glyceroglycolipids. A total of 19 fatty acids, i.e., five saturated, three monounsaturated, and 11 polyunsaturated, were detected. [ABSTRACT FROM AUTHOR]

The presence and potential role of adiponectin- and resistin-like peptides in mobilizing free lipids of hemolymph during over-wintering was studied in females of the European solitary red mason bee Osmia bicornis L. (Hymenoptera: Megachilidae). The levels of both peptides (as demonstrated both by RIA/ELISA and Western blots) were highest in fat body tissue homogenates during early pre-wintering (September) followed by a gradual and significant decline during wintering and post-wintering months (November-March). There was a gradual reduction of the lipid levels in hemolymph and adiponectin-like and resistin-like peptide content in fat body. Thus, the total lipid content in hemolymph and the adiponectin-like and resistin-like peptides in fat body homogenates was positively correlated. Our experiments also demonstrated that injections of various concentrations of fat body extracts as well as various doses of adiponectin and resistin increased the lipid levels in hemolymph in O. bicornis females at the three different periods of over-wintering time. In particular, injections of fat body extract and adiponectin resulted in the strongest mobilization of lipids especially in the first two periods of over-wintering: pre-wintering and wintering. Resistin also elicited an increase of lipid levels in hemolymph, but its effectiveness was lower compared to fat body extract and adiponectin. Taken together, our results strongly suggest the presence of adiponectin-like and resistin-like peptides in the fat body of O. bicornis and postulate a dynamic physiological role for these peptides during the process of over-wintering. [ABSTRACT FROM AUTHOR]

Both warming and nitrogen (N) addition affect the chemistry and characteristics of soil organic matter (SOM). However, their interactive impacts on molecular compositions and origins (plant- or microbial-derived) in agroecosystems are indeterminate. A nine-year field trial study in Northern China was undertaken to quantify the effects of warming (+2 °C), N addition (315 kg N ha−1 yr−1), and their interaction on SOM content and its composition, using biomarkers (i.e., free lipids, lignin phenols and amino sugars) and 13C NMR. Despite insignificant changes in bulk SOM content, the characteristics (i.e., molecular constituents, lability and source origin) were significantly influenced by warming and/or N addition in surface soil (0–10 cm), but not in the subsurface soil (10–20 cm). The SOM was composed of approximately 18–27% microbial residues with the bulk derived from fungi (up to 4–fold higher than bacteria). Warming alone reduced total free lipids (mainly short-chain lipids,

For whole grains, the most sensitive components to the environmental changes are the lipids. In the current study, the effects of drying temperature (27 and 93 °C) and storage temperature (4 and 27 °C) on the fatty acid (FA) levels and lipid classes of endosperm lipids on four selected corn genotypes were investigated during a 12-month storage period. Storage temperature indicated greater impact on the FA composition than did the drying temperature. The ratio of saturated to unsaturated fatty acids, which was around 0.20-0.22 levels in the free lipid (FL) fractions of all corn types studied here, did not change significantly due to the drying and storage temperatures. However, in the bound lipid (BL) fractions, it was changed by a change in the drying and storage temperature in some of the corn types. Some changes were also found in the lipid classes within the FL and BL fractions of the studied corn samples. No lysophosphatidylcholine (LPC) was found in the FL fractions. In the BL fractions of two of the corn samples, the level of free fatty acids (FFA) increased more likely due to the deterioration of LPC. The results of the current study indicated a possible migration of triglycerides and FFA between the FL and BL fractions due to drying and storage at higher temperatures. [ABSTRACT FROM AUTHOR]

In order to investigate the natural ecosystem of Lake Dianchi and to assess its anthropogenic impacts, a stratigraphic study of bulk and molecular compositions of organic matter was conducted using a 63-cm long sediment core. The results show that two apparent environmental changes occurred during the evolution of Lake Dianchi: (1) the first change occurred in the 43–63 cm sediment depth, and was revealed by the amount and the composition of organic matter in the stage. Natural changes were possibly major factors responsible for triggering the environmental change, but the influence of human activities could not be excluded. Subsequently, the lake entered into a relatively stable and oligotrophic stage, which maintained until 20-cm sediment depth. (2) Eutrophication started in the upper 20 cm depth. Human activities became a major factor influencing environmental changes in this stage. Vertical profiles of various organic geochemical variables in the upper 20-cm sediments show evidence that primary productivity of the lake increased progressively and that the lake started eutrophic. Especially in the uppermost 10 cm, notable excursions to less negative δ13Corg and δ15Ntotal and high TOC concentrations have recorded an abrupt change in the lacustrine environment, suggesting that the lake entered a hypereutrophic stage. In addition, enhancement of αβ-hopanes reflects the contribution of fossil fuels to the lake sediments. [ABSTRACT FROM AUTHOR]

Abstract: Protein–lipid interactions in dough have an important impact on the quality of bakery products. Understanding of protein–lipid interactions in gluten can enhance the development of technological solutions to improve the breadmaking quality of flour as well as the functional properties of gluten. In this study, acetic acid at two different concentrations was used for treating and fractionating gluten. The impact of these procedures on the distribution of lipid components was measured. Acetic acid was able to dissociate non-polar lipids from the gluten protein matrix. Upon fractionation monomeric proteins (predominantly gliadins) and phospholipids were high in the 0.01M acetic acid soluble fraction. The subsequent fractionation step using 0.1M acetic acid resulted in an increased amount of high-molecular-weight glutenin subunits (HMW-GS) in the soluble fraction, along with more non-polar lipids and glycolipids in both the free and bound lipid extracts. The distribution of lipid classes demonstrates that non-polar lipids are either associated with the glutenin polymeric network through hydrophobic interactions or entrapped within the gluten matrix. The results also indicate that in gluten, glycolipids are likely to be associated with glutenins through both hydrophobic interactions and hydrogen bonds whilst phospholipids preferentially interact with gliadins and lipid binding proteins. [Copyright &y& Elsevier]

Abstract: The relationships between textural and cooking qualities of Chinese noodles and flour lipids were investigated. Removal of free lipids (FL) or excess FL caused significant decreases in hardness and cohesiveness of noodles. The highest hardness and cohesiveness of noodles were obtained at certain FL levels (1.84 and 1.24g/100g flour, respectively). Tensile strength and breaking length of noodles both reached the highest values when FL content in the flour was adjusted to about half of the original level. A good correlation was found between cohesiveness and cooking loss of noodles (r =−0.967). Hardness and cohesiveness of cooked noodles increased linearly with the increase of polar lipids (PL) relative proportion of FL (r =0.939 and 0.900, respectively). Entire replacement of PL with nonpolar lipids in flour led to a significant decrease in springiness of noodles. These results suggest that PL play an important role in obtaining strong noodle texture. [Copyright &y& Elsevier]

Abstract: Soil organic matter (SOM) biomarker methods were utilized in this study to investigate the responses of fungi and bacteria to freeze–thaw cycles (FTCs) and to examine freeze–thaw-induced changes in SOM composition and substrate availability. Unamended, grass-amended, and lignin-amended soil samples were subject to 10 laboratory FTCs. Three SOM fractions (free lipids, bound lipids, and lignin-derived phenols) with distinct composition, stability and source were examined with chemolysis and biomarker Gas Chromatography/Mass Spectrometry methods and the soil microbial community composition was monitored by phospholipid fatty acid (PLFA) analysis. Soil microbial respiration was also measured before and during freezing and thawing, which was not closely related to microbial biomass in the soil but more strongly controlled by substrate availability and quality. Enhanced microbial mineralization (CO2 flush), considered to be derived from the freeze–thaw-induced release of easily decomposable organic matter from microbial cell lyses, was detected but quickly diminished with successive FTCs. The biomarker distribution demonstrated that free lipids underwent a considerable size of decrease after repeated FTCs, while bound lipids and lignin compounds remained stable. This observation indicates that labile SOM may be most influenced by increased FTCs and that free lipids may contribute indirectly to the freeze–thaw-induced CO2 flush from the soil. PLFA analysis revealed that fungal biomass was greatly reduced while bacteria were unaffected through the lab-simulated FTCs. Microbial community shifts may be caused by freezing stress and competition for freeze–thaw-induced substrate release. This novel finding may have an impact on carbon and nutrient turnover with predicted increases in FTCs in certain areas, because fungi and bacteria have different degradation patterns of SOM and the fungi-dominated soil community is considered to have a higher carbon storage capacity than a bacteria-dominated community. [Copyright &y& Elsevier]

Abstract: The work presents the content and composition of free lipids and carotenoids in spring and winter classes of wheat flour. It discusses genetical and physiological aspects of their synthesis and accumulation in wheat kernels and also indicates how methodological differences explain differences in results presented in the literature. It has been reported that spring wheat flours are richer in free lipids, especially in the non-polar fraction. The content of glycolipids ranged from 134 to 215 mg/100 g flour and was more stable within the winter wheat class. The percentages of the two main fractions, namely DGDG and MGDG, were similar in both wheat classes and reached ca. 77%. Phospholipids constituted the smallest fraction of the flour free lipids in both wheat classes; however, spring wheat flours were richer in these compounds, which is likely associated with a greater content of spherosomes in the endosperm of this wheat class. The free lipids of spring wheat flour contained more oleic and slightly less linoleic and linolenic acids. Spring wheat flour was also richer in carotenoids, although there were varieties in both classes that deviated from this. The main carotenoid was lutein, whose total percentage in the form of different isomers ranged from 71.3% to 83.3% and was slightly lower for spring wheat flour. Lutein, in the form of a trans-isomer, constituted about 62% and 70% of all carotenoids in spring and winter wheat flours, respectively. [Copyright &y& Elsevier]