Mutations in the genes responsible for the synthesis of furan fatty acids resolve the light-induced off-odor in soybean oil.

Soybean oil is the second most produced edible vegetable oil and is used for many edible and industrial materials. Unfortunately, it has the disadvantage of 'reversion flavor' under photooxidative conditions, which produces an off-odor and decreases the quality of edible oil. Reversion flavor and off-odor are caused by minor fatty acids in the triacylglycerol of soybean oil known as furan fatty acids, which produce 3-methyl-2,4-nonanedione (3-MND) upon photooxidation. As a solution to this problem, a reduction in furan fatty acids leads to a decrease in 3-MND, resulting in a reduction in the off-odor induced by light exposure. However, there are no reports on the genes related to the biosynthesis of furan fatty acids in soybean oil. In this study, four mutant lines showing low or no furan fatty acid levels in soybean seeds were isolated from a soybean mutant library. Positional cloning experiments and homology search analysis identified two genes responsible for furan fatty acid biosynthesis in soybean: Glyma.20G201400 and Glyma.04G054100. Ectopic expression of both genes produced furan fatty acids in transgenic soybean hairy roots. The structure of these genes is different from that of the furan fatty acid biosynthetic genes in photosynthetic bacteria. Homologs of these two group of genes are widely conserved in the plant kingdom. The purified oil from the furan fatty acid mutant lines had lower amounts of 3-MND and reduced off-odor after light exposure, compared with oil from the wild-type.

Rare case of exostosin 1/exostosin 2-related membranous lupus nephritis concomitant with dual ANCA- and anti-GBM antibody-associated crescentic glomerulonephritis effectively diagnosed by mass spectrometry: a case report.

BACKGROUND: Recent developments in mass spectrometry (MS) have revealed target antigens for membranous nephropathy (MN), including phospholipase A2 receptor and exostosin 1/exostosin 2 (EXT1/2). EXT1/2 are known antigens of autoimmune disease-related MN, especially membranous lupus nephritis. We describe the case of an elderly man who developed nephrotic syndrome followed by progressive renal dysfunction. CASE PRESENTATION: A 78-year-old man presented with rapidly progressive renal dysfunction with proteinuria and hematuria. Three years previously, he had developed leg edema but did not receive any treatment. Laboratory tests showed elevated anti-nuclear antibody (Ab), anti-dsDNA Ab titer, and hypocomplementemia, indicating systemic lupus erythematous. Myeloperoxidase anti-neutrophil cytoplasmic Ab (ANCA) and anti-glomerular basement membrane (GBM) Ab were also detected. The renal pathologic findings were compatible with crescentic glomerulonephritis (GN), whereas non-crescentic glomeruli exhibited MN without remarkable endocapillary or mesangial proliferative change. Immunofluorescence microscopy revealed glomerular IgG, C3, and C1q deposition. All IgG subclasses were positive in glomeruli. Anti-PLA2R Ab in serum was negative. MS analysis was performed to detect the antigens of MN, and EXT1/2 was detected in glomeruli. Therefore, we reached a diagnosis of membranous lupus nephritis concurrent with both ANCA-associated vasculitis and anti-GBM-GN. The simultaneous occurrence of these three diseases is extremely rare. CONCLUSIONS: This is the first report of EXT1/2-related membranous lupus nephritis concurrent with ANCA-associated vasculitis and anti-GBM-GN. This case demonstrates the usefulness of MS in diagnosing complicated cases of MN.

A younger and protracted emplacement of the Ontong Java Plateau.

The submarine volcanic emplacement of the Ontong Java Plateau (OJP) is the suggested cause of Ocean Anoxic Event 1a (OAE 1a). However, no precise timing and duration exists for the formation of OJP, and its connection to OAE1a relies mainly on proxies in the sedimentary record. We provide high-precision 40Ar/39Ar data from OJP drill and dredge sites that considerably improve OJP's eruptive history. The ages determined from this work are as much as 10 million years younger than previous dates and indicate a protracted formation over at least 6 million years. OJP now appears too young to have caused OAE1a, but we suggest that it may have had a role in the later OAE1b. The protracted eruptive sequence has implications for the emplacement dynamics of OJP and other large igneous provinces.

Elucidation of Olive Oil Oxidation Mechanisms by Analysis of Triacylglycerol Hydroperoxide Isomers Using LC-MS/MS.

Despite the importance of the insight about the oxidation mechanisms (i.e., radical and singlet oxygen (1O2) oxidation) in extra virgin olive oil (EVOO), the elucidation has been difficult due to its various triacylglycerol molecular species and complex matrix. This study tried to evaluate the mechanisms responsible for EVOO oxidation in our daily use by quantitative determination of triacylglycerol hydroperoxide (TGOOH) isomers using LC-MS/MS. The standards of dioleoyl-(hydroperoxy octadecadienoyl)-triacylglycerol and dioleoyl-(hydroperoxy octadecamonoenoyl)-triacylglycerol, which are the predominant TGOOHs contained in EVOO, were prepared. Subsequently, fresh, thermal-, and photo-oxidized EVOO were analyzed. The obtained results mostly agreed with the previously reported characteristics of the radical and 1O2 oxidation of linoleic acid and oleic acid. This suggests that the methods described in this paper should be valuable in understanding how different factors that determine the quality of EVOO (e.g., olive species, cultivation area, cultivation timing, and extraction methods) contribute to its oxidative stability.

Carboxylic acids derived from triacylglycerols that contribute to the increase in acid value during the thermal oxidation of oils.

Acid value (AV), is a widely used indicator of oil degradation that, by definition, measures the free fatty acids formed via the hydrolysis of triacyclglycerols. However, based on observations made in previous studies, we hypothesized that the oxidation of triacylglycerols leads to the formation of carboxylic acids with a glycerol backbone which are also calculated as AV. In this study, we aimed to identify such carboxylic acids and prove the above hypothesis. Heating a canola oil at 180 °C for 6 h without the addition of water resulted in an increase in AV from 0.054 to 0.241. However, the contribution of free fatty acids to this increase in AV was minimal; free fatty acid-derived AV before and after heating was 0.020 and 0.023, respectively. Then, via mass spectrometric analyses, we identified two 8-carboxy-octanoyl (azelaoyl) -triacylglycerols (i.e., dioleoyl-azelaoyl-glycerol and oleoyl-linoleoyl-azelaoyl-glycerol) in the heated oil. Azelaoyl-triacylglycerols-derived AV before and after heating the oil was 0.008 and 0.109, respectively, demonstrating that azelaoyl-triacylglycerols contribute to AV. Such an increase in AV by azelaoyl-triacylglycerols was also observed in an oil used to deep-fry potatoes (i.e., an oil with a relatively high water content). These results suggest that AV is also an indicator of the thermal oxidation of triacylglycerols.

Determination of acrolein generation pathways from linoleic acid and linolenic acid: increment by photo irradiation.

2-Propenal (acrolein) is a toxic aldehyde generated from the thermal degradation of edible oils. While previous studies have suggested that linolenic acid (LnA) is the origin of acrolein formation in edible oils, these studies were performed under thermal conditions where only the fatty acid hydroperoxide (FAOOH) isomers derived from radical oxidation were formed. In this study, we reinvestigated the acrolein generation pathway through another oxidation mechanism involving singlet oxygen (1O2) oxidation (type II photo-oxidation). Standards of the main FAOOH isomers (oleic acid hydroperoxide, linoleic acid hydroperoxide (HpODE), and linolenic acid hydroperoxide (HpOTE)) found in edible oils were prepared, and their decomposition products, including those derived from1O2 oxidation (i.e., 10- and 12-HpODE) were analyzed by GC-EI-MS. We found that 1O2 oxidation products of linoleic acid (LA) and LnA but not OA, are significant sources of acrolein formation. The amount of acrolein formed from edible oils high in LA (e.g., rice bran oil) increased by photo irradiation. Further investigation into the mechanism of acrolein generation demonstrated that the amount of acrolein derived from 1O2 oxidation-specific HpOTE isomers (i.e., 10- and 15-HpOTE) was two times greater than that of other HpOTE isomers (i.e., 9-, 12-, 13-, and 16-HpOTE). The results of the present study provide a new pathway of acrolein formation from type II photo-oxidation. This information can be used to inform on oil storage and processing conditions to reduce exposure and dietary intake of acrolein.

Petrogenesis of isotopically enriched Quaternary magma with adakitic affinity associated with subduction of old lithosphere beneath central Myanmar.

We present a model for the petrogenesis of magma with adakitic affinity in an old subduction zone, which does not involve slab melting and is constrained by new geochronological and geochemical data for Mt. Popa, the largest of three Quaternary volcanoes in central Myanmar (Popa, Monywa and Singu). The edifice is composed of Popa Plateau (0.8-0.6 Ma) with high-K rocks and a stratovolcano (< 0.33 Ma) predominantly composed of medium-K rocks with adakitic affinity (Mg# 45-63, Sr/Y > 40). The distinct K contents indicate that the adakitic magmas cannot be derived from Popa high-K rocks, but they share trace-element signatures and Sr-Nd isotope ratios with medium-K basalts from Monywa volcano. Our estimation of water contents in Popa magma reveals that primary magma for medium-K basalts was generated by partial melting of wedge mantle with normal potential temperature (TP 1330-1340 °C) under wet conditions (H2O 0.25-0.54 wt%). Its melting was probably induced by asthenospheric upwelling that is recognized by tomographic images. Mafic adakitic magma (Mg# ~ 63, Sr/Y ~ 64) was derived from the medium-K basaltic magma in fractional crystallization of a garnet-bearing assemblage at high pressure, and felsic adakitic rocks (Mg# ~ 45, Sr/Y ~ 50) were produced by assimilation-fractional crystallization processes at mid-crustal depths.

Long-term clinical course of immunotactoid glomerulopathy complicated with diffuse large B-cell lymphoma.

We report a case of immunotactoid glomerulopathy (ITG) complicated with diffuse large B-cell lymphoma (DLBCL). A 68-year-old woman presented with leg edema and was diagnosed with nephrotic syndrome (NS). Renal biopsy revealed ITG. We treated the patient with prednisolone (20 mg/day) and she achieved complete remission of NS. Steroids were gradually reduced. After 1 year, the patient presented with a breast mass determined on biopsy to be DLBCL. She underwent six cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone) therapy. Follow-up revealed complete remission of both DLBCL and ITG. NS recurred after 5 years and she was simultaneously diagnosed with recurrence of DLBCL in bone marrow. She underwent four cycles of R-EPOCH (rituximab, etoposide, prednisolone, vincristine, cyclophosphamide, doxorubicin) therapy and entered remission for DLBCL. NS improved, but the treatment did not lead to remission. After 2 additional years, NS and DLBCL recurred again. She was administered rituximab and NS improved, although proteinuria tended to increase thereafter. One year later, we started prednisolone (10 mg/day), and proteinuria tended to decrease. She is currently undergoing outpatient follow-up. This case suggests that ITG with MGUS should be treated with the possibility of developing malignant hematological disease during the course.

Structural Analysis of Lipid Hydroperoxides Using Mass Spectrometry with Alkali Metals.

Lipid oxidation is involved in various biological phenomena (e.g., oxylipin generation and oxidative stress). Of oxidized lipid structures, the hydroperoxyl group position of lipid hydroperoxides (LOOHs) is a critical factor in determining their biological roles. Despite such interest, current methods to determine hydroperoxyl group positions possess some drawbacks such as selectivity. While we previously reported mass spectrometric methods using Na+ for the highly selective determination of hydroperoxyl group positions, nothing was known except for the fact that sodiated LOOHs (mainly linoleate) provide specific fragment ions. Thus, this study was aimed to investigate the effects of different alkali metals on the fragmentation of LOOHs, assuming its further application to analysis of other complex LOOHs. From the analysis of PC 16:0/18:2;OOH (phosphatidylcholine) and FA 18:2;OOH (fatty acid), we found that fragmentation pathways and ion intensities largely depend on the binding position and type of alkali metals (i.e., Li+, Hock fragmentation; Na+ and K+, α-cleavage (Na+ > K+); Rb+ and Cs+, no fragmentation). Furthermore, we proved that this method can be applied to determine the hydroperoxyl group position of esterified lipids (e.g., phospholipids and cholesterol esters) as well as polyunsaturated fatty acids (PUFAs) including n-3, n-6, and n-9 FA. We anticipate that the insights described in this study provide additional unique insights to conventional lipid oxidation research.

Heated Corn Oil and 2,4-Decadienal Suppress Gastric Emptying and Energy Intake in Humans.

Consumption of 2,4-decadienal (2,4-DD) delays gastric emptying (GE) rate in animals. Oil heating produces 2,4-DD and other aldehydes. Here we examined whether heated oil affects GE rate and food intake in humans, and whether it is mediated by 2,4-DD. In the first experiment, 10 healthy volunteers consumed 240-g pumpkin soup with 9.2 g of heated (HO) or non-heated corn oil (CO). Subsequently, 17 participants consumed pumpkin soup containing 3.1 g of either heated corn oil (HO), 1 mg 2,4-DD + non-heated corn oil (2,4-DD), or non-heated corn oil (CO). Sixty minutes following pumpkin soup, cod roe spaghetti was provided, and then energy intake was determined. To evaluate GE rate, 13C breath test (Experiment 1) and ultrasonography (Experiments 1 and 2) were used. The results from the Experiment 1 confirmed that consumption of heated corn oil reduced GE rate. Experiment 2 showed a delayed GE rate in HO and 2,4-DD trials compared with CO trial (p < 0.05). Energy intake was approximately 600-650 kJ lower in HO and 2,4-DD trials compared with CO trial (p < 0.05). These findings suggest that 2,4-DD, either formed by oil heating or added to food, contributes to suppressing GE rate and energy intake.

Initiation of peritoneal dialysis in a patient with chronic renal failure associated with tetralogy of Fallot: a case report.

BACKGROUND: Tetralogy of Fallot is the most common cyanotic congenital heart disease. Patients with the condition have a high risk of developing chronic kidney disease. Treatment of kidney disease in patients with complex hemodynamics presents unique challenges. However, there are very few reports on the treatment of end-stage renal failure in patients with tetralogy of Fallot. CASE PRESENTATION: We present a rare case of peritoneal dialysis in a 47-year-old man with tetralogy of Fallot who had not undergone intracardiac repair. Peritoneal dialysis successfully removed fluids and solutes without adversely affecting the patient's hemodynamics. Our patient was managed with peritoneal dialysis for 5 years before he succumbed to sepsis secondary to digestive tract perforation. CONCLUSIONS: In this paper, we discuss the importance of monitoring acid-base balance, changes in cyanosis, and hyperviscosity syndrome during peritoneal dialysis in patients with tetralogy of Fallot. Lower leg edema and B-type natriuretic peptide level were useful monitoring parameters in this case. This case illustrates that with attention to the patient's unique requirements, peritoneal dialysis can provide successful renal replacement therapy without compromising hemodynamics in patients with tetralogy of Fallot.

Analysis of oxidation products of α-tocopherol in extra virgin olive oil using liquid chromatography-tandem mass spectrometry.

When α-tocopherol (α-Toc) exerts its antioxidative effect, a portion of α-Toc is converted to certain oxidation products. Although accumulation of such oxidation products is considered to cause a deterioration in the quality of foods, their distribution and generation in food samples have been still unknown. In this study, we tried to analyze α-Toc hydroperoxide (Toc-OOH) stereoisomers and tocopherylquinone (TQ) in extra virgin olive oil (EVOO) using liquid chromatography-tandem mass spectrometry. Photo-irradiation (5000 lx) to EVOO increased Toc-OOH stereoisomers but not TQ. In contrast, thermal oxidation (150 °C) of EVOO increased TQ but not Toc-OOH. We considered that the generation of Toc-OOH and TQ were due to the [4+2]-cycloaddition reaction and proton donation from the phenolic hydrogen, respectively. Our data and method would be helpful for understanding of α-Toc oxidation mechanisms in edible oil samples or the estimation of food quality.

An autopsy case of TAFRO syndrome with membranoproliferative glomerulonephritis-like lesions.

TAFRO syndrome (thrombocytopenia, anasarca, myelofibrosis, renal dysfunction, and organomegaly) is an atypical manifestation of multicentric Castleman's disease. Although overproduction of interleukin-6, vascular endothelial growth factor, and other cytokines may partially explain the pathophysiology of this rare syndrome, the precise mechanisms underlying the renal dysfunction associated with the condition remain unclear. Here, we describe a case of a 69-year-old male with TAFRO syndrome. He was treated with immunosuppressive agents and his renal function improved. Tapering of immunosuppressive agents resulted in a deterioration of renal function and an elevation of C-reactive protein. After 20 months of treatment, the patient died from tuberculous peritonitis and gastrointestinal bleeding. An autopsy revealed miliary tuberculosis, mediastinal lymphadenopathy, and gastric ulcers. Renal histopathology showed a membranoproliferative glomerulonephritis-like appearance. Almost all glomeruli showed lobular formations with mesangial proliferation and duplication of glomerular capillary walls on light microscopy. Immunofluorescence showed deposition of C1q and IgM along the glomerular capillary walls. Electron microscopy showed mesangial expansion and widening of the subendothelial space with a large number of electron-dense deposits. The glomerular lesions might be characteristic of TAFRO syndrome, and were regarded as the main cause of the patient's renal dysfunction.

Epidemiological observations of Kawasaki disease in Japan, 2013-2014.

BACKGROUND: The etiology of Kawasaki disease (KD) is unknown. In Japan, the number of patients and incidence rate of KD has increased continuously since its discovery. The aim of this report was to analyze the latest nationwide epidemiological survey of KD in Japan. METHODS: The 23rd nationwide survey of KD was conducted in 2015. To report on all patients diagnosed with KD in 2013 and 2014, a questionnaire was sent to hospitals with ≥100 beds containing pediatric departments, as well as specialized pediatric hospitals. RESULTS: The number of KD patients reported was 15 696 in 2013 and 15 979 in 2014, resulting in an annual incidence rate of 302.5 and 308.0 per 100 000 population aged 0-4 years, respectively. The number of patients and incidence rate of KD in 2014 were the highest ever recorded in Japan. The number of patients diagnosed per month peaked in January, and a gradual increase in summer was also observed. Eight patients died of KD in 2013 and 2014. CONCLUSIONS: The number of patients and incidence rate of KD in Japan continue to increase. Continued surveillance of epidemiological trends of KD is therefore required.

An 18-Year Follow-up Survey of Dioxin Levels in Human Milk in Japan.

BACKGROUND: Globally, few published studies have tracked the temporal trend of dioxin levels in the human body since 2000. This study describes the annual trend of dioxin levels in human breast milk in Japanese mothers from 1998 through 2015. METHODS: An observational study was conducted from 1998 through 2015. Participants were 1,194 healthy mothers following their first delivery who were recruited annually in Japan. Breast milk samples obtained from participants were analyzed using gas chromatography and mass spectrometry for dioxins, including polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (PCBs). RESULTS: Mean age was 29.5 years, and 53% of participants were 20-25 years old. A declining trend in total dioxin levels was found, from a peak of 20.8 pg toxic equivalence (TEQ)/g fat in 1998 to 7.2 pg TEQ/g fat in 2014. Data from the last 5 years of the study indicated a plateau at minimal levels. In contrast, an increasing trend was found in the mean age of participants during the last 5 years. Although significantly higher dioxin levels were observed in samples from older participants, an upward trend in dioxin levels was not observed, indicating that dietary and environmental exposure to dioxins had greatly diminished in recent years. CONCLUSIONS: Dioxin levels in human breast milk may be approaching a minimum in recent years in Japan. The findings may contribute to global reference levels for environmental pollution of dioxins, which remains a problem for many developing countries.

Determination of triacylglycerol oxidation mechanisms in canola oil using liquid chromatography-tandem mass spectrometry.

Triacylglycerol (TG), the main component of edible oil, is oxidized by thermal- or photo- oxidation to form TG hydroperoxide (TGOOH) as the primary oxidation product. Since TGOOH and its subsequent oxidation products cause not only the deterioration of oil quality but also various toxicities, preventing the oxidation of edible oils is essential. Therefore understanding oxidation mechanisms that cause the formation of TGOOH is necessary. Since isomeric information of lipid hydroperoxide provides insights about oil oxidation mechanisms, we focused on dioleoyl-(hydroperoxy octadecadienoyl)-TG (OO-HpODE-TG) isomers, which are the primary oxidation products of the most abundant TG molecular species (dioleoyl-linoleoyl-TG) in canola oil. To secure highly selective and sensitive analysis, authentic OO-HpODE-TG isomer references (i.e., hydroperoxide positional/geometrical isomers) were synthesized and analyzed with HPLC-MS/MS. With the use of the method, photo- or thermal- oxidized edible oils were analyzed. While dioleoyl-(10-hydroperoxy-8E,12Z-octadecadienoyl)-TG (OO-(10-HpODE)-TG) and dioleoyl-(12-hydroperoxy-9Z,13E-octadecadienoyl)-TG (OO-(12-HpODE)-TG) were characteristically detected in photo-oxidized oils, dioleoyl-(9-hydroperoxy-10E,12E-octadecadienoyl)-TG and dioleoyl-(13-hydroperoxy-9E,11E-octadecadienoyl)-TG were found to increase depending on temperature in thermal-oxidized oils. These results prove that our methods not only evaluate oil oxidation in levels that are unquantifiable with peroxide value, but also allows for the determination of oil oxidation mechanisms. From the analysis of marketed canola oils, photo-oxidized products (i.e., OO-(10-HpODE)-TG and OO-(12-HpODE)-TG) were characteristically accumulated compared to the oil analyzed immediately after production. The method described in this paper is valuable in the understanding of oil and food oxidation mechanisms, and may be applied to the development of preventive methods against food deterioration.

Cumulative incidence of Kawasaki disease in Japan.

BACKGROUND: Although the incidence rates of Kawasaki disease (KD) in Japan have been determined in nationwide surveys, the cumulative incidence, that is, the proportion of those with a history of KD in the general population of 10-year-olds, is currently unknown. The aim of this study was therefore to assess the cumulative incidence of KD in Japan. METHODS: Using the age- and sex-specific incidence rate of KD in Japan from the results of the nationwide surveys, incidence probabilities, that is, the age-specific number of KD patients divided by the population used in the vital statistics, and cumulative proportions of those not affected by KD up to the end of 9 years of age, were calculated. The cumulative incidence was then defined as 1 minus the cumulative proportion. The observed age classes were 0, 1, 2, 3, 4, and 5-9 years. All data were calculated by sex. RESULTS: The cumulative incidence was 0.004833 for boys and 0.003474 for girls in 1991, but was 0.015284 and 0.012145 in 2014, respectively. According to these figures, 15.284 per 1,000 boys and 12.145 per 1,000 girls have been affected by KD by the age of 10 years. The birth-cohort cumulative incidences had similar trends. CONCLUSIONS: More than 10 persons in 1,000 have a history of KD at age 10 years in Japan.

New Anti-Nephrin Antibody Mediated Podocyte Injury Model Using a C57BL/6 Mouse Strain.

BACKGROUND: Focal segmental glomerulosclerosis (FSGS) is considered a subset of the podocytopathies. The molecular pathogenesis of podocytopathy is still unknown. There has not been an experimental animal model of isolated podocytopathy induced by antibody in C57BL/6 strain, which is widely used as the genetic background. Nephrin is closely associated with the slit diaphragm of the glomerular podocyte, and has recently received attention as a potential therapeutic target. The function of nephrin, especially its role in FSGS development via podocytopathy, is being elucidated. We report our experience with a C57BL/6 FSGS model induced by polyclonal rabbit anti-mouse nephrin antibody (α-mNep Ab). METHODS: α-mNep Ab, which was generated by genetic immunization, was administered into C57BL/6 mice at once, intravenously. Urinary protein excretion, the development of glomerulosclerosis and the number of podocyte in mouse kidney were evaluated. RESULTS: The α-mNep Ab-induced FSGS was associated with massive proteinuria and nephrotic syndrome. In periodic acid-Schiff staining, FSGS was observed from day 7 after antibody injection. Podocyte numbers and podocyte marker (anti-Wilms tumor 1 and anti-synaptopodin)-positive areas were clearly decreased. These results suggest that this FSGS mouse model reliably reproduces the human nephrotic syndrome and FSGS. CONCLUSION: We succeeded in making the nephrotic syndrome model mice induced by α-mNep Ab using C57BL/6. This model may be useful for studying the mechanisms of podocytopathy.

Alternative Internal Standard Calibration of an Indirect Enzymatic Analytical Method for 2-MCPD Fatty Acid Esters.

An indirect enzymatic analysis method for the quantification of fatty acid esters of 2-/3-monochloro-1,2-propanediol (2/3-MCPD) and glycidol was developed, using the deuterated internal standard of each free-form component. A statistical method for calibration and quantification of 2-MCPD-d5, which is difficult to obtain, is substituted by 3-MCPD-d5 used for calculation of 3-MCPD. Using data from a previous collaborative study, the current method for the determination of 2-MCPD content using 2-MCPD-d5 was compared to three alternative new methods using 3-MCPD-d5. The regression analysis showed that the alternative methods were unbiased compared to the current method. The relative standard deviation (RSDR) among the testing laboratories was ≤ 15% and the Horwitz ratio was ≤ 1.0, a satisfactory value.

Effect of Furan Fatty Acids and 3-Methyl-2,4-nonanedione on Light-Induced Off-Odor in Soybean Oil.

Soybean oil is one of the most widely consumed vegetable oils. However, under photooxidative conditions, this oil develops a beany and green off-odor through a mechanism that has not yet been elucidated. Upon photooxidation, 3-methyl-2,4-nonanedione (3-MND) produces a strong aroma. In this study, the effect of furan fatty acids and 3-MND on odor reversion in soybean oil was investigated. Our findings suggest that the observed light-induced off-odor was likely attributable to the furan fatty acids present in the oil through the generation of 3-MND. While 3-MND may not be directly responsible for the development of light-induced off-odor, this compound appears to be involved because off-odor was detected in canola oil samples containing added 3-MND. In addition, in the present work, 3-hydroxy-3-methyl-2,4-nonanedione, which is derived from 3-MND, was identified for the first time in light-exposed soybean oil and shown to be one of the compounds responsible for odor reversion.