Changes in volatile flavor compounds of Kimchi cabbage (Brassica rapa subsp. pekinensis) during salting and fermentation.

A main ingredient of Kimchi is Kimchi cabbage, which is soaked in brine to reduce its crispness. Volatile profile of raw Kimchi cabbage (RC) is changed during salting; however, characteristic aroma-active compounds of salted Kimchi cabbage (SC) have not been investigated. The objective of this study was to evaluate changes in aroma characteristics of Kimchi cabbage during salting and fermentation. Sulfur-containing compounds, such as sulfides and isothiocyanates, increased markedly by salting. (Z)-3-Hexen-1-ol, (Z)-3-hexenal, and hexanal decreased by salting. Hexanal was the most intense in RC, followed by 3-(methylthio)butanal, (Z)-3-hexen-1-ol, and benzenepropanenitrile. Dimethyl trisulfide had the highest log3FD in SC. Methyl (methylthio)methyl disulfide, allyl methyl trisulfide, and dimethyl tetrasulfide were detected only in SC. Dimethyl trisulfide, dimethyl tetrasulfide, methyl (methylthio) methyl disulfide, and allyl methyl trisulfide, decreased greatly in SC during fermentation. Our results demonstrated that characteristic odor of Kimchi cabbage could be significantly changed by salting and fermentation.

Major Sensory Attributes and Volatile Compounds of Korean Rice Liquor (yakju) Affecting Overall Acceptance by Young Consumers.

The sensory characteristics and volatile compounds that affect consumers' acceptance of rice liquors were investigated. A total of 80 consumers evaluated 12 yakju samples and descriptive analysis by 11 trained panelists was conducted. Solvent-assisted flavor evaporation-gas chromatography-mass spectrometry analysis also was conducted revealing 120 volatile compounds in the yakju samples. Sensory attributes (n = 31) except appearance attributes were used for principal component analysis (PCA). As results, fruit odor (apple, hawthorn, omija, and pineapple odor) and flower odor (chrysanthemum, pine, and peppermint odor) were placed on the positive side of PC1 whereas persimmon vinegar odor, bitter taste, alcohol flavor, stinging and coating mouthfeel were located on the negative side of PC1. The yakju samples were mainly characterized by their alcohol content and supplementary ingredients. Sensory descriptors (n = 31; except appearance attributes and p > 0.05) and volatile compounds (n = 30; p > 0.5 correlation coefficient with overall acceptance) were chosen for multiple factor analysis (MFA). The MFA correlation map showed that ethyl propanoate, ethyl-2-hydroxy-2-methylbutanoate, methyl 2-furoate, γ-butyrolactone, 4-ethoxycarbonyl-γ-butyrolactone, hawthorn odor, apple flavor, grape flavor, and sweet taste were positively correlated with young consumers' overall acceptance. Additionally, negative correlation with overall acceptance was found in 1,3-butanediol, 2,3-butanediol, and 1,1-diethoxy-3-methylbutane.

Characterization and Evaluation of Aroma Quality in Doubanjiang, a Chinese Traditional Fermented Red Pepper Paste, Using Aroma Extract Dilution Analysis and a Sensory Profile.

Doubanjiang, a Chinese traditional fermented red pepper paste, is eaten worldwide for its unique flavor. The objective of this study was to evaluate the aroma quality of doubanjiang using solvent-assisted flavor evaporation (SAFE) and headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-olfactometry (GC-O) and aroma extract dilution analysis (AEDA). A total of 165 volatile compounds, belonging to 13 chemical classes, were identified. Esters and hydrocarbons were the predominant groups. Thirteen aroma-active compounds were detected by AEDA of SAFE and HS-SPME, and their odor activity values (OAVs) were calculated by dividing their concentration by their odor threshold in water. Among them, ethyl isovalerate, ß-damascenone, 3-isobutyl-2-methoxypyrazine (IBMP), and sotolone had the highest OAVs (>1000). In addition, sotolone, methional, ß-damascenone, 3-isobutyl-2-methoxypyrazine, ethyl isovalerate, phenylethyl alcohol and linalool had high flavor dilution (FD) factors. Sotolone, ß-damascenone and 3-isobutyl-2-methoxypyrazine were identified for the first time in doubanjiang and played significant roles in its aroma quality.

Changes in antioxidant activities and volatile compounds of mixed berry juice through fermentation by lactic acid bacteria.

The objectives of this study were to analyze antioxidant activities and identify volatile compounds in mixed berry juice after fermentation by lactic acid bacteria (LAB). Antioxidant activity of the mixed berry juice increased significantly from 209.57±2.93 to 268.30±1.75 µmol TE/g after 24 h of fermentation. After LAB fermentation, 34 volatile compounds were identified. Among them, three compounds-benzoic acid, benzaldehyde, and vitispirane-showed significant changes in their concentrations. Peak areas of benzoic acid and benzaldehyde, which are known to possess antioxidant activities, increased by 64 and 188%, respectively, after fermentation. However, the peak area of vitispirane, which is the most abundant terpene compound in berry juices, decreased by 92% after fermentation.

Solid self-nanoemulsifying drug delivery system (SNEDDS) for enhanced oral bioavailability of poorly water-soluble tacrolimus: physicochemical characterisation and pharmacokinetics.

To develop a novel self-nanoemulsifying drug delivery system (solid SNEDDS) with better oral bioavailability of tacrolimus, the solid SNEDDS was obtained by spray-drying the solutions containing the liquid SNEDDS and colloidal silica. Its reconstitution properties were determined and correlated to solid state characterisation of the powder. Moreover, the dissolution and pharmacokinetics in rats was done in comparison to the commercial product. Among the liquid SNEDDS formulations tested, the liquid SNEDDS comprised of Capryol PGMC, Transcutol HP and Labrasol (10:15:75, v/v/v) presented the highest dissolution rate. In the solid SNEDDS, this liquid SNEDDS was absorbed in the pores and attached onto the surface of the colloidal silica. Drug was present in the amorphous state in it. The solid SNEDDS with 5% w/v tacrolimus produced the nanoemulsions and improved the oral bioavailability of tacrolimus in rats. Therefore, this solid SNEDDS would be a potential candidate for enhancing the oral bioavailability of tacrolimus.

Aroma quality assessment of Korean fermented red pepper paste (gochujang) by aroma extract dilution analysis and headspace solid-phase microextraction-gas chromatography-olfactometry.

The objective of this study was to assess aroma quality of gochujang using purge and trap, simultaneous steam distillation and solvent extraction (SDE), and headspace solid-phase microextraction (HS-SPME), followed by gas chromatography-olfactometry (GC-O). Nineteen and 28 aroma-active compounds were detected by aroma extract dilution analysis of purge and trap and SDE, respectively. Diallyl disulfide and 3-isobutyl-2-methoxypyrazine played a significant role in the aroma quality of gochujang. Twelve aroma-active compounds were detected by HS-SPME-GC-O based on sample dilution analysis. Methional, diallyl disulfide, and 3-isobutyl-2-methoxypyrazine were the most intense aroma-active compounds. 3-Isobutyl-2-methoxypyrazine was identified for the first time in gochujang.

Determination of trimethylamine in spinach, cabbage, and lettuce at alkaline pH by headspace solid-phase microextraction.

UNLABELLED: Trimethylamine (TMA) found in some leafy vegetables, such as spinach, cabbage, and lettuce, at alkaline pH was identified and quantified using headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME and GC-MS). HS-SPME conditions were optimized at an adsorption temperature of 50 °C, equilibration time of 5 min, and adsorption time of 5 min with 65 µm of polydimethylsiloxane/divinylbenzene fiber. The TMA that was formed from spinach, cabbage, and lettuce was assayed at pH 7 to 11 for 0 to 4 h at 50 °C using HS-SPME. The results showed that the amount of TMA formed was dependent on pH. The amount of TMA formed increased dramatically at a pH greater than 9. TMA was not formed at a pH lower than 7. Spinach produced a higher amount of TMA than cabbage or lettuce. TMA was formed at alkaline pH from choline, betaine, and carnitine, which are TMA precursors. To confirm the SPME results, TMA was quantitated using the AOAC official method. Data obtained from chemical analysis were in good agreement with the SPME data. The formation mechanism of TMA is thought to be the Hofmann elimination reaction, which generates amine compounds at alkaline pH. PRACTICAL APPLICATION: Fishy off-flavor in foods is associated with trimethylamine (TMA), which is frequently found in fish and seafood. In this study, TMA was identified for the first time in some leafy vegetables, such as spinach, cabbage, and lettuce, at alkaline pH. The presence of TMA in leafy vegetables under certain circumstances such as high pH and temperature may affect the sensory properties of foods containing these vegetables.

Development of novel ibuprofen-loaded solid dispersion with enhanced bioavailability using cycloamylose.

To develop a novel ibuprofen-loaded solid dispersion with enhanced bioavailability using cycloamylose, it was prepared using spray-drying techniques with cycloamylose at a weight ratio of 1:1. The effect of cycloamylose on aqueous solubility of ibuprofen was investigated. The physicochemical properties of solid dispersions were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction. The dissolution and bioavailability in rats were evaluated compared with ibuprofen powder. This ibuprofen-loaded solid dispersion improved about 14-fold drug solubility. Ibuprofen was present in an unchanged crystalline state, and cycloamylose played the simple role of a solubilizing agent in this solid dispersion. Moreover, the dispersion gave 2-fold higher AUC (area under the drug concentration-time curve) value compared with a ibuprofen powder, indicating that it improved the oral bioavailability of ibuprofen in rats. Thus, the solid dispersion may be useful to deliver ibuprofen with enhanced bioavailability without crystalline change.

Enhanced solubility and bioavailability of flurbiprofen by cycloamylose.

The effect of cycloamylose on the aqueous solubility of flurbiprofen was investigated. To improve the solubility and bioavailability of flurbiprofen (poor water solubility), a solid dispersion was spray dried with a solution of flurbiprofen and cycloamylose at a weight ratio of 1:1. The physicochemical properties of solid dispersions were investigated using SEM, DSC, and X-ray diffraction. The dissolution and bioavailability in rats were evaluated compared with a commercial product. Cycloamylose increased solubility of flurbiprofen approximately 12-fold and dissolution of it by 2-fold. Flurbiprofen was present in an unchanged crystalline state, and cycloamylose was a solubilizing agent for flurbiprofen in this solid dispersion. Furthermore, the dispersion gave higher AUC and C(max) values compared with the commercial product, indicating that it improved the oral bioavailability of flurbiprofen in rats. Thus, the solid dispersion may be useful to deliver flurbiprofen with enhanced bioavailability without changes in crystalline structure.

Characteristic aroma-active compounds of Korean perilla (Perilla frutescens Britton) leaf.

Aroma-active compounds from Korean perilla (Perilla frutescens Britton) leaf were extracted by solvent-assisted flavor evaporation (SAFE), liquid-liquid continuous extraction (LLCE), and hydrodistillation (HD) and analyzed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O). Thirty-three volatile compounds were identified by GC-MS. 1-(3-Furyl)-4-methyl-1-pentanone (perilla ketone) was found to be the most abundant volatile compound, followed in order by (Z)-3-hexenol and 1-octen-3-ol. Perilla ketone comprised 81% (93 ppm), 84% (120 ppm), and 95% (490 ppm) of the volatile compounds obtained from SAFE, LLCE, and HD, respectively. Thirteen aroma-active compounds were detected by GC-O. Perilla ketone, 1-(3-furyl)-4-methyl-3-penten-1-one (egoma ketone), and 1-(3-furyl)-4-methyl-2-penten-1-one (isoegoma ketone) were considered to be the characteristic aroma-active compounds of Korean perilla leaf. Perilla ketone, (Z)-3-hexenal (green), egoma ketone, and isoegoma ketone were the most intense aroma-active compounds in Korean perilla leaf. Other relatively intense odorants included (Z)-3-hexenol (green), (E)-2-hexenal (green), benzaldehyde (almond), 1-octen-3-one (metallic), 1-octen-3-ol (mushroom), phenylacetaldehyde (honeysuckle), linalool (lemon), and beta-caryophyllene (woody).

Identification of characteristic aroma-active compounds from water dropwort (Oenanthe javanica DC.).

Characteristic aroma components of water dropwort (Oenanthe javanica DC.) were evaluated by aroma extract dilution analysis and solid-phase microextraction-gas chromatography-olfactometry. Alpha-Terpinolene (plastic/cucumber-like) was the most intense aroma-active compound in water dropwort. Other potent aroma-active compounds included p-cymene (kerosene-like), alpha-terpinene (lemon), (E)-caryophyllene (woody), (Z,E)-alpha-farnesene (woody), hexanal (green), (Z)-3-hexenol (green), phenylacetaldehyde (honey), (E)-2-nonenal (cucumber), bornyl acetate (cooked vegetable), and gamma-terpinene (lemon). Of these, p-cymene was believed to be primarily responsible for the distinct kerosene-like aroma note of water dropwort. The aroma property of p-cymene was dependent on its concentration and was described as kerosene-like at relatively high concentrations but changed to citrus and green aroma notes at low concentrations.