Ethyl acetate fraction of oregano seed protects non-alcoholic fatty liver in high-fat diet-induced obese mice through modulation of Srebp-1c.

Oregano (Origanum vulgare) seed is used as spices and is known to have anti-inflammatory, antibacterial, and antioxidant effects. The anti-fatty liver effects of oregano seed ethyl acetate (OSEA) were evaluated in high-fat diet (HFD)-induced obese mice. OSEA was orally administered with HFD for 10 weeks. The body weight, aspartate aminotransferase, alanine aminotransferase, cholesterol, triglyceride, and low-density lipoprotein levels in the HFD with 100 mg/kg of OSEA significantly decreased by approximately 1.21-, 1.44-, 2.12-, 1.12-, 1.05, and 1.59 times, respectively, while high-density lipoprotein levels increased by approximately 1.05 times compared to those in the HFD group (p < .05). In addition, the distribution of liver fat in the HFD with 100 mg/kg OSEA (OSEA 100) group decreased significantly (p < .05). Therefore, OSEA supplementation can ameliorate fatty liver disease and reduce the accumulation of triglycerides in adipose tissue. The expression of genes involved in liver fat accumulation, such as sterol regulatory element-binding protein-1c (Srebp-1c), fatty acid synthase (Fas), stearoyl-CoA desaturase-1 (Scd1), and acetyl-CoA carboxylase 1 (Acc1), significantly decreased in OSEA 100 by approximately 2.6-, 1.74-, 1.89-, and 1.56-times, respectively (p < .05). Therefore, OSEA may modify obesity and liver fat accumulation by regulating the expression of genes involved in lipid metabolism.

Correction to: Effects of association colloidal structures on the oxygen solubility in oil­in­water emulsion matrix.

[This corrects the article DOI: 10.1007/s10068-023-01338-6.].

Effects of association colloidal structures on the oxygen solubility in oil-in-water emulsion matrix.

Although association colloidal structures are believed as major oxidation places, relationship of oxygen molecules with association colloids have not been evaluated in oil-in-water (O/W) emulsion. Oxygen solubility was determined in O/W emulsion containing dispersed phases with different charges of emulsifiers, numbers of dispersed droplets, and surface areas of dispersed droplets. The rates of lipid oxidation were also examined. O/W emulsion made of positively charged emulsifier had higher oxygen solubility than negatively charged and neutral emulsifiers. As number and surface area of oil droplet in O/W emulsion increased, higher oxygen solubility was observed, implying that dispersed phases could be places for oxygen molecules. O/W emulsion made of positively charged emulsifier had higher lipid oxidation than neutral emulsifier. O/W emulsion with more interfaces had lower oxidative stability, implying interfaces of association colloids could affect rates of lipid oxidation. Dispersed phase in O/W emulsion can be places for oxygen molecules.

Generation of volatiles from heated enzymatic hydrolysates of perilla meal with coconut oil in Maillard reaction system.

Perilla meal hydrolysates (PMHs) were prepared by proteases; volatile profiles from heated mixtures of PMH and coconut oil (CO) were evaluated for their application as odor providers. Amino acids composition and degree of hydrolysis, and antioxidant activity in O/W emulsion of PMHs were assessed. PMHs were heated with different concentration of CO or with CO, xylose, and cysteine, which were non-Maillard and Maillard system, respectively. Among PMHs, double enzyme treatment using Alcalase and Flavourzyme showed higher degree of hydrolysis and antioxidant activity compared to PMHs from one type of enzymes. The presence of CO significantly increased oxygen, sulfur, and nitrogen-containing volatiles from PMHs in non-Maillard system. In case of Maillard system, PMHs with 10 % (w/w) CO contributed the formation of oxygen and nitrogen-containing volatiles such as furan and 2-methylpyrazine. PMHs might serve as an odor generator in the presence of edible oils like CO.

Approaches of lipid oxidation mechanisms in oil matrices using association colloids and analysis methods for the lipid oxidation.

Lipid oxidation is one of the key chemical reactions in foods containing fats and oils during production and storage. For several decades, many researchers have tried to understand the mechanisms of lipid oxidation and ways to control the rates of lipid oxidation. Theories of autoxidation or free radical chain reaction have been developed to successfully explain the phenomenon observed in oxidized lipids. Many studies have been conducted to explain the other factors that can affect the lipid oxidation such as food matrix, oxidation time and temperature, transition metal ions, pigments with sensitizing abilities, and surface-active compounds such as phospholipids, free fatty acids, monoacylglycerols, and diacylglycerols. Several strategies were developed to evaluate the degree of oxidation and oxidative stability. This review provides crucial information on the mechanism of lipid oxidation affected amphiphilic compounds and association colloids. This review article will extensively discuss about the methods for determining the oxidative stability.

Antioxidant effects and reaction volatiles from heated mixture of soy protein hydrolysates and coconut oil.

Soy protein hydrolysates (SPHs) are prepared from soybean meal using commercially available protease enzymes and acid/alkali treatment. The antioxidant properties of SPHs were evaluated by measuring headspace oxygen consumption and conjugated diene formation in oil-in-water (O/W) emulsions. In addition, volatile profiles were analyzed for the heated mixture of SPHs and the coconut oil (SPHCO). Total amino acid content was the highest in double proteases. SPHs prepared from enzymes acted as better antioxidants than those prepared from acid/alkali treatments in O/W emulsions. SPHs prepared from double proteases generated the highest amounts of total volatiles and nitrogen-containing compounds in SPHCO. 2,3-Dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, 2-methyl-butanal, benzeneacetaldehyde, and 2,6-dimethylpyrazine were the major volatiles in SPHCO. Enzymatic SPHs act as natural antioxidants in the O/W emulsion matrix, and thermal reaction products from SPHCO may contribute to the production of a unique volatile flavor in plant protein-based foods. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-022-01189-7.

Evaluation of deodorization techniques using cyclodextrins on the headspace volatiles and antioxidant properties of onion.

Sulphur-containing volatiles in onion produce unpleasant odors and this limit their usage in foods. To expand its application, several additives including α-cyclodextrin (α-CD), ß-cyclodextrin (ß-CD), 2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD), and chitosan were added to onion solution and evaluated for their effect on sulphur-containing volatiles. Also, antioxidant property using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and oxidative stabilities in an oil-in-water (O/W) emulsion were carried out. The total volatile contents were decreased in the order of α-CD (50.1%), ß-CD (49.3%), HP-ß-CD (46.2%), and chitosan (7%). Meanwhile, HP-ß-CD showed the highest DPPH radical scavenging ability followed by ß-CD, α-CD, and chitosan with decreasing order. The ß-CD significantly enhanced the oxidative stability of the O/W emulsion, whereas α-CD and ß-HP-CD showed prooxidative behavior. Overall, ß-CD might be used as a sulphur-containing volatile decreasing agent, which could keep the antioxidant properties of onion in the O/W emulsion.

Changes of molecular mobility of ascorbyl palmitate and α-tocopherol by phospholipid and their effects on antioxidant properties in bulk oil.

Molecular mobility of ascorbyl palmitate and α-tocopherol in the presence of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) were determined by NMR relaxation technique. Synergistic effects of DOPC on the antioxidative capacities of ascorbyl palmitate were evaluated in DPPH radical scavenging assay and bulk oil matrix. NMR relaxation technique can provide information on the mobility of protons. Molecular mobility of two protons in hydroxyl group of ascorbyl palmitate decreased by 85 and 78% in the presence of DOPC compared to those without DOPC. However, proton mobility of α-tocopherol increased by 41% when DOPC was present. DOPC significantly enhanced the DPPH reactivity in medium chain triacylglycerol, while this effect was not observed in α-tocopherol. Mixture of ascorbyl palmitate with DOPC showed synergistic antioxidant properties in corn oil at 60 °C. DOPC may make protons of ascorbyl palmitate in more rigid state, which can enhance hydrogen donating ability and antioxidant properties of ascorbyl palmitate in bulk oils.

Physicochemical properties and oxidative stability of corn oil in infrared-based and hot air-circulating cookers.

Corn oil was heated using an infrared cooker, an air fryer, and a cooking oven at similar temperatures, and oxidative stability and physicochemical properties including moisture content, temperature change, the profile of headspace volatiles, formaldehyde and acetaldehyde of the heated oils were compared. Corn oil heated using the air fryer showed the lowest degree of oxidation, followed by that heated using the infrared cooker and the cooking oven. However, the content of headspace volatiles in 120 min heated oil using the infrared cooker was higher by 2.57 and 5.37 times than that in oil heated using the cooking oven and the air fryer, respectively. The profiles of formaldehyde and acetaldehyde in oils showed patterns inconsistent with those of headspace volatile and oxidation parameters. Generally, the air fryer-treated oil underwent slow lipid oxidation, whereas oil from the infrared cooker had more volatiles and imparted odor to foods.

Antioxidant and anti-obesity effects of in vitro digesta of germinated buckwheat.

Buckwheat germinated on days of 3, 5, and 7 was digested in vitro, and the antioxidant and anti-obesity effects of the digesta were evaluated. In vitro digesta of 5 days germinated buckwheat (GBD5) showed significantly higher antioxidant activity in DPPH, ABTS, total phenolic content, total flavonoid content, and ferric reducing antioxidant power by 5.3, 1.3, 2.0, 3.2, and 2.8-fold, respectively than in vitro digesta of non-germinated buckwheat. GBD5 exerted inhibitory effect on total lipid accumulation in 3T3-L1 adipocyte in a dose-dependent manner, with over 25% reduction at 400 µg/mL. Additionally, GBD5 significantly downregulated genes related to adipocyte differentiation and fat accumulation. GBD5 possessed different metabolite profiles compared to others such as higher content of γ-aminobutyric acid and succinic acid. Therefore, GBD5 has potent antioxidant effects and suppresses fat accumulation-related genes and proteins expression, which could act as a new functional substance.

Metabolites of oregano (Origanum vulgare) seed and their anti-obesity effects on 3T3-L1 adipocytes through down-regulated adipogenesis.

Metabolites of the 80% ethanol extract (OSE) and ethyl acetate fraction (OSEA) of oregano seed were analyzed by GC-MS, and anti-obesity effects of OSE and OSEA were evaluated in 3T3-L1 adipocyte. OSE possessed high content of glucose, fructofuranose, and sucrose while OSEA had high content of phenolic chemicals. OSEA contained higher levels of gallic acid, syringic acid, protocatechuic acid, and catechin than OSE. OSEA inhibited lipid droplet accumulation with concentration dependent manner in 3T3-L1 preadipocytes during differentiation. OSEA showed more inhibition ability than OSE by 13.7-fold at the level of 125 µg/mL. Additionally, relative mRNA and protein expression levels of pparγ, c/ebpα, fas, and srebp-1c which are related to adipogenesis were significantly lower in OSEA treatment group than in OSE treatment group (p < 0.05). Therefore, OSEA could be used as anti-obesity functional ingredient.

Physicochemical properties and volatile formation mechanism of medium-chain triacylglycerols during heating.

Medium-chain triacylglycerols (MCTs), including caprylic acid (C8), a mixture of caprylic acid and capric acid (C8+C10), and high-MCT coconut oil (HMCO), were heated at 180°C. Their volatile profiles were analyzed to determine the MCT degradation mechanisms. As heating time increased to 10 h, secondary oxidation products and acid value of all samples increased continuously. Ketones, alkanes, fatty acid anions, fatty acid esters, and lactones were found in all heated MCTs. 2-Hexanone and heptane were detected in C8 after 2 h of heating, and 2-heptanone, heptanal, methyl octanoate, γ-octalactone, and δ-octalactone were detected after 4 h. For the C8+C10, ketones, alkanes, and aldehydes were first observed. Hydrolysis and decarboxylation seem to occur first for ketone and alkane formation. Cracking and cyclization may occur later for fatty acid esters and lactones in heated MCTs. This result can help to understand thermal decomposition mechanisms of saturated fatty acids like MCTs. PRACTICAL APPLICATION: Medium-chain triacylglycerols (MCTs) have been used in cosmetic and fragrance industries due to their high oxidative stability, relatively high polarity, and smooth textures. In addition, MCTs have gained popularity among consumers for their health beneficial effects. MCTs could be used as major continuous phases for many food ingredients receiving high thermal energy for cooking. The results of this study can provide basic and useful information on the physicochemical properties and thermally decomposed volatile profiles from MCTs, which can help to produce stable processed products with lengthy shelf-lives in the food industry.

A mixture of poly-γ-glutamic acid and levan ameliorates obesity in high fat diet-induced mice.

Anti-obesity effects of a mixture of poly-γ-glutamic acid (γ-PGA) and levan (PL, 6:4 w/w) were evaluated using C57BL/6 mouse models including normal diet (G1), normal diet containing 5% of PL (G2), high-fat diet (HFD) (G3), HFD with 3% of PL (G4), and HFD with 5% of PL (G5) and followed by breeding 12 weeks. After 12 weeks, the content of epididymal fat and the size of fat cell for test animals were significantly decreased by comparing G3 (p < 0.05). Similarily, contents of serum triglyceride, total cholesterol, LDL cholesterol, insulin and leptin in G5 were significantly decreased than G3. Fat accumulations and inflammatory degrees within liver and fat cells were also decreased in the G5 than G3. In addition 5% PL diet might not have any problems causing liver damages. Conclusively, a mixture of γ-PGA and levan could help to improve obesity and dyslipidemia due to high-fat meals.

Microwave resonator can help to predict oxidative stability in C18-based vegetable oils.

Effects of moisture content, degree of oxidation, degree of unsaturation of fatty acid compositions in C18-based edible oils were determined by a microwave resonator in the range of 0-4.4 GHz. Moisture content and degree of oxidation in corn oil made difference in signal intensity at 1.7-1.9 GHz and 1.0-1.2 GHz, respectively without uniform trend in signal intensity. Degree of unsaturation of C18-based edible oils including corn, sesame, soybean, olive, perilla, and flaxseed oils provided difference in 3.0-3.1 GHz with a dependent manner of degree of unsaturation. Average of signal intensity (ASI) in 3.0-3.1 GHz had high correlation (R2 > 0.93) to the degree of unsaturation in edible oils. Oils with high oleic acid had relatively low ASI while those with high linolenic acid had high ASI value. Oxidative stability of C18-based edible oils can be categorized successfully without fatty acid analysis using a microwave resonator.

Distribution of aldehydes compared to other oxidation parameters in oil matrices during autoxidation.

Distribution of aldehydes between headspace (HS) and inner matrix (IM) of bulk oil or oil-in-water (O/W) emulsion was determined and contents of aldehydes were compared with other oxidation parameters in soybean oil or O/W emulsion during 50 °C autoxidation. Bulk oil matrix had higher portion of IM aldehydes than O/W emulsion. HS aldehydes in O/W emulsion reflected aldehyde content better than in bulk oil. Moisture content in soybean oil increased distinctively before the generation of oxidation products including hydroperoxides and volatiles. HS aldehydes and other oxidation parameters were simultaneously increased in soybean oil. In case of O/W emulsion, HS aldehydes had a sudden increase point while lipid hydroperoxides and conjugated did not show such increase during autoxidation. HS aldehydes reflected oxidation stage better in O/W emulsion than in bulk oil based on partition distribution and linear changes during autoxidation.

Evaluation of solvent effects on the DPPH reactivity for determining the antioxidant activity in oil matrix.

Reactivity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical in methanol, ethanol, isopropanol, isooctane, and ethyl acetate, was evaluated to assess the antioxidant capabilities in medium chain triacylglycerol. DPPH loss values were obtained over 30 min, with sampling every 5 min. Even the same concentration of antioxidants showed different DPPH reactivity depending on solvent. In methanol, 5 min was enough for α-tocopherol to react with DPPH, whereas BHT did not react with DPPH even after 30 min. Gallate series showed higher DPPH reactivity than TBHQ, sesamol, or BHA in methanol, while lower reactivity in isooctane. Antioxidants in ethanol and isopropanol reacted with DPPH less efficiently compared to those in methanol, the exception being sesamol. DPPH reactivity of gallate series in isooctane was lower than that of sesamol, TBHQ, and α-tocopherol. Combinatorial usage of methanol and isooctane for DPPH reactivity could provide reliable information on the antioxidant capacities of chemicals in edible oils. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10068-020-00874-9.

Metabolite analysis and anti-obesity effects of celery seed in 3T3-L1 adipocytes.

Celery seeds were fractioned successively by organic solvents, and fractions were screened for their antioxidant properties. Metabolites of high antioxidative fractions were analyzed, and then anti-obesity properties and mechanisms of selected fractions were evaluated in 3T3-L1 adipocytes. Celery seed ethanol extract (CSE) and celery seed ethyl acetate fraction (CSEA) possessed higher in vitro antioxidant properties, including radical scavenging and total phenolic content, than that of hexane, butanol, and water fractions. Total of 43 and 19 metabolites were identified from CSE and CSEA, respectively, by gas chromatography-mass selective detector. Isoferulic acid and p-coumaric acid were only found in CSEA. CSEA possessed higher anti-adipogenesis in the 3T3-L1 cells than CSE by decreasing adipogenic hormones, including leptin and adiponectin. Expression levels of adipocyte-related transcription factors and genes such as C/EBPα, PPARγ, aP2, and FAS decreased to comparable levels of control. CSEA could be used as a natural ingredient with antioxidant and anti-obesity functionality.

Dioleylphosphatidylcholine increases the antioxidant properties of ascorbyl palmitate in bulk oils compared to other hydrophilic and lipophilic antioxidants.

Effects of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and moisture on the solubility of hydrophilic and lipophilic antioxidants were evaluated in medium-chain triacylglycerol (MCT) by 2,2-diphenyl-1-picrylhydrazyl (DPPH) reactivity. Next, we assessed the oxidative stability of antioxidant-containing corn oil depending on the presence of DOPC. The critical micelle concentration (CMC) of DOPC decreased when the moisture content was increased from 300 to 495 mg/kg oil and gradually increased when the moisture was further increased to 2122 mg/kg oil. As the DOPC concentration increased, the DPPH reactivity of ascorbyl palmitate in the control MCT increased by 10.23-fold, whereas that of the ascorbic acid and α-tocopherol was slightly affected both by the DOPC and moisture content. Presence of DOPC significantly increased the oxidative stability of ascorbyl palmitate-containing corn oil (p < 0.05), whereas these synergistic antioxidant effects were not observed in ascorbic acid-or α-tocopherol-containing corn oil. In conclusion, DOPC displays a synergistic antioxidant effect with ascorbyl palmitate in bulk oil.

Improvement of viscous substance production during Cheonggukjang fermentation added with glycine.

When Bacillus subtilis NB-NUC1 associated with Cheonggukjang fermentation was aerobically grown in a synthetic medium containing 1 to 2% glycine (w/v), cell growth was inhibited in a dose-dependent manner. Subsequently, different concentrations of glycine (0, 1, and 2%) were used in Cheonggukjang fermentation for 96 h at 40 °C. Supplementation of 1% glycine increased extracellular γ-glutamyl transpeptidase (γ-GTPase), responsible for the production of viscous substance. Based on correlation studies, we conclude that the production of viscous substance is correlated with viscous extension (r = 0.867), extracellular proteins contents (r = 0.821), and γ-GTPase activity (r = 0.807). The molecular weight of the viscous substance obtained during Cheonggukjang fermentation by B. subtilis NB-NUC1 was also affected by glycine supplementation. Our results demonstrate that glycine supplementation before solid-state fermentation may increase the mass production of mucilage in food industry.

Effects of 1,2-dioleoyl-sn-glycero-3-phosphocholine on moisture content and oxidative stability in soybean oil-water system at different interfaces.

Effects of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) on the oxidative stability were determined in soybean oil-water system at different locations including at the interface of air-oil, in the middle of oil, and at the interface of oil-water. Also, profile changes of tocopherols were determined during UV irradiation for 18 days. Although no significant changes in tocopherol profiles were observed at three different locations irrespective of DOPC from 0 to 1250 µmol/kg oil, addition of DOPC increased total tocopherols, α-tocopherol, and δ-tocopherol whereas content of ß + γ tocopherols did not increase at any locations. Moisture content in water-oil interface was higher than other locations while those were not consistent at different DOPC concentration. Added DOPC significantly decreased oxidative stability from 250 to 830 µmol/kg oil compared to controls (p < 0.05) whereas 1250 µmol/kg oil DOPC increased oxidative stability. Stabilities of tocopherols especially α-tocopherol were lower in oil-water system than those in bulk oil at UV irradiation.