Antimicrobial Activity of Kumazasa (Sasa albo-marginata)

The organic solvent extract of Kumazasa leaves (Sasa albo-marginata) showed antimicrobial activity against bacteria, fungi and yeast. Kumazasa at a concentration of 0.2-1.0% showed stronger antimicrobial activity than potassium sorbate or sodium benzoate at the same concentration. Both acidic and phenolic fractions of the extract showed strong antimicrobial activity. Thirty acidic and phenolic compounds were identified by GC and GC-MS analysis. Acetic, propionic, benzoic, phenylacetic, salicylic, 3-hydroxybenzoic and o-anisic acids, and guaiacol, phenol, 4-ethylphenol, xylenol and 4-vinylphenol were the main components. It was estimated that these components play an important role in the formation of the antimicrobial activity of Kumazasa extract.     

Volatile Flavor Components of Watermelon (Citrullus vulgaris)

Volatile flavor components of watermelon fruit (Citrullus vulgaris) were obtained by distilling juice under reduced pressure and extracting the resulting distillate with Freon-11. The volatiles were separated into acidic and neutral fractions and then analyzed by gas chromatography and gas chromatography-mass spectrometry.

Fifty-two compounds were found for the first time as flavor components of watermelon. Among them, the following compounds have not been previously reported as naturally occurring flavor components: 4-oxononanal and 2-hydroxy-, 2-pentyloxy-, 2-hexyloxy-, 2-octyloxy-, 2-nonyloxy-, 2-[(Z)-3-noneyloxy]-, 2-[(Z)-2-nonenyloxy]-, 2-[(Z,Z)-3,6-nonadienyloxy]-, 2-benzyl-oxy-, and 2-phenetyloxy-5-pentyltetrahydrofurans.     

Volatile Flavor Components of ZINGIBERIS RHIZOMA (Zingiber officinale Roscoe)

The toxicity of dimethyl sulfoxide (Me₂SO) was examined in HeLa cells cultured at 37°C for up to 72 hr. The growth of the cells was measured by a colorimetric method with the use of 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), which gave good correlation between the cell number and the color development from the reduction of MTT under suitable conditions. When the initial number of cells was 3 × 10⁴/ml, Me₂SO at 1% or less had no apparent effect on prolifiration for up to 48 hr of incubation, but in longer incubations, cell growth was repressed. When the initial number of cells was 3 × 10⁵/ml, the effect of Me₂SO was similar.     

Volatile Flavor Components of Dried Bonito (Katsuobushi) II. From Neutral Fraction

The aqueous extract of dried bonito (Katsuobushi) was distilled under reduced pressure. The resulting distillate with diethyl ether and the extract was separated into acidic, phenolic, basic and neutral fractions. The neutral fraction was further fractionated into ten sub-fractions by silica gel column chromatography. All these sub-fractions were analyzed by gas chromatography and gas chromatography-mass spectrometry.

One hundred and sixty-five compounds were identified and 12 compounds were tentatively identified from the neutral fraction. Among them, 111 compounds were newly identified as flavor components of Katsuobushi.     

Shoyu (Soy Sauce) Flavor Components: Neutral Fraction

From the vacuum distilled volatiles of shoyu, a neutral fraction was obtained. Shoyu was also directly extracted with dichloromethane and then the extract was separated into ten (A~J) fractions. The J fraction was a neutral one. The J fraction was further separated into twelve fractions by liquid column chromatography. All fractions obtained were analyzed by gas chromatography and combined gas chromatography-mass spectrometry. Consequently, 142 components were identified, 82 of which have not been reported previously as volatile constituents of shoyu. The identified compounds were 37 hydrocarbons, 22 alcohols, 22 carbonyls, 22 esters, 12 furans, 6 sulfurous compounds, 1 pyrone, 5 phenols, 1 furanone, 1 acid, 1 lactone and 12 other compounds. From the results of quantitative analysis and organoleptic evaluation, phenylacetal-dehyde is considered to be most important in the neutral fraction.     

Volatile Flavor of Black Tea

The volatile components extracted from fresh tea leaf, fermented leaf and black tea were analysed by gas chromatography.

Quantitative difference in the composition of essential oils was observed between fresh leaf and manufactured black tea; the former was rich in alcohols, whereas the latter in aldehydes and acids.

During fermentation process the following components mainly brought about changes: n-capronaldehyde (4.1 times after fermentation for 3hrs.), trans-2-hexen-l-al (13.2 times) and cis-3-hexenoic acid (1.2 times) increased, but n-hexylalcohol (0.7 time), cis-3-hexen-l-ol (0.7 time) and methylsalicylate (0.8 time) decreased.

These changes during fermentation were scarcely carried out in nitrogen atmosphere.     

Volatile Flavor of Black Tea

The first effluent of essential oil of black tea in the gas chromatographic analysis is important for characterizing black tea flavor. The isolation and identification of main unknown components were conducted by means of gas chromatography, and also by infrared spectra and ultraviolet spectra. Ethylacetate, ethylalcohol and β-myrcene were identified as the increasing compounds during fermentation. cis-β-Ocimene and trans-β-ocimene were also identified only in completely manufactured black tea. These three terpenoid hydrocarbons are newly found constituents of essential oil of black tea and are supposed to contribute considerably to the black tea flavor.     

Volatile Flavor Components of Dried Bonito (Katsuobushi). I. On Basic,Acidic and Weak Acidic Fractions

The aqueous extract of dried bonito (Katsuobushi) was distilled by using a thin film evaporator. The resulting distillate was extracted with diethyl ether, and the extract was separated into basic, acidic, weak acidic, and neutral fractions.

The basic, acidic, and weak acidic fractions were analyzed by gas chromatography and gas chromatography-mass spectrometry.

Seventy-four compounds, including 24 acids, 24 phenols, 8 pyridines, 12 pyrazines, 3 thiazoles, and 3 other compounds were identified. Thirty-six of these compounds were newly identified as volatile flavor compounds of Katsuobushi.     

Flavor Components of Roasted Almond

Roasted almond volatiles were separated into basic, carbonyl and non-carbonyl fractions. Each fraction was analyzed by combination gas chromatography-mass spectrometry. Twenty-five compounds, in addition to eighteen known components, were identified. Many of the components identified were considered to contribute to the overall flavor. 2,5-Dimethyl-4- hydroxy-3(2H)-furanone, which was identified from methanol extract of roasted almond, seemed to make the largest contribution to the sweet aroma of roasted almond.     

Volatile Flavor Compounds of Boiled Buckwheat Flour

Volatile flavor compounds of boiled buckwheat flour were collected using a Likens and Nickerson apparatus type and were fractionated into acidic, weak acidic, basic and neutral fractions. The neutral fraction was further fractionated by silica gel column chromatography. All fractions were analyzed by gas chromatography and gas chromatography-mass spectrometry.

Two hundred and nine compounds were thus identified. Among them, 168 were newly identified as volatile flavor compounds of buckwheat flour; special note is made of 2-(1′-ethoxyethyl)pyrazine and 2-(1′-ethoxyethyl)-5-methylpyrazine being found which are compounds previously unreported in any literature.     

新疆野苹果挥发性化合物组分的遗传多样性研究

以中国新疆伊犁地区巩留县莫合镇的新疆野苹果(Malussieversii(Lebed.)Roem.)30个实生株系及国光、元帅、富士、金冠等苹果(MaluspumilaMill.)品种的成熟果实为试材,采用顶空固相微萃取和气相色谱质谱联用技术,分析香气成分,旨在为探讨新疆野苹果与栽培苹果的亲缘关系及为新疆野苹果资源保护利用提供基本资料。结果表明,①根据新疆野苹果与栽培苹果共有挥发性化合物种类数计算相似系数,其大小与苹果品种(类型)的演化历史相吻合;②新疆野苹果各实生株系挥发性化合物总含量、各类挥发性化合物种类数及其含量以及主要挥发性化合物分离比率与含量等存在广泛的遗传变异,参试的30个实生株系间差异明显,遗传多样性极为丰富;进一步与4个栽培苹果品种挥发性化合物组分进行比较,结果发现,新疆野苹果与栽培苹果品种化合物种类数在5以上、含量在0.04mg/L的化合物均属于酯类、醇类、醛类和酮类,说明新疆野苹果与栽培苹果的主要挥发性化合物组分基本一致,上述研究结果支持“新疆野苹果可能是栽培苹果的祖先种”的结论,但有48种成分为栽培苹果特有的挥发性化合物成分,在新疆野苹果检测不到,其中乙酸丙酯及苯乙醛等6种成分为特征香气成分。因此,栽培苹果可能是杂种起源;③从新疆野苹果30个实生株系中共检测到包括酯类、醇类、酮类、醛类、酸类、苯衍生物、杂环类、萜类、烃类、缩醛类和内酯类等11类化合物177种,其中缩醛类和内酯类化合物在栽培苹果品种中没有检测到,90种成分为新疆野苹果特有成分,1-丁醇及大马酮等7种成分为香气值大于1的特征香气成分。因此,新疆野苹果作为栽培苹果遗传改良的珍贵资源,进行“利用保存”的潜力很大。     

Studies on Flavor Components of Foodstuffs

Distribution of tetramethylpyrazine (T.M.P.) in Japanese fermented foodstuffs was investigated by more accurate analytical method.

Namely, the method was successful when trapping T.M.P. with picric acid after flash evaporation of the foodstuffs, followed by analysis with gas chromatography.

T.M.P. was detected in many Japanese fermented foodstuffs, especially in Miso, Soy sause and Natto, which suggests that alkylpyrazines may play an important role as flavor of those foodstuffs.     

Volatile Components of Roasted Chufa-tubers

The desmutagenic activities of some vegetable and fruit juices to the mutagenicity of 2-tert-butyl-p-quinone (t-BQ) were assayed by the Ames test using Salmonella typhimurium TA 100. t-BQ is a strong mutagen and is produced from butylated hydroxyanisole when treated with nitrite under acidic conditions. The juices of sweet pepper, lemon, tomato, orange, strawberry, melon, and kiwi fruit reduced the mutagenicity of t-BQ, the desmutagenic activities being proportionally related to the content of the sulfhydryl group contained in these juices. The authentic sulfhydryl compounds, glutathione, pantetheine and dithiothreitol, were then tested for their desmutagenicity against t-BQ by the induced-mutation frequency method, and they were proved responsible for the desmutagenicity. Glutathione reduced half of the t-BQ to 2-tert-butyl-hydroquinone during the desmutagenic reaction, the other half being suggested to have been a conjugated compound between glutathione and t-BQ.     

Volatile Components of Roasted Shrimp

The components of the strong and favorable aroma obtained from roasted shrimp were investigated. The aroma concentrate of roasted shrimp was isolated by combining the dichloromethane extract and carbon dioxide distillation methods. The concentrate was fractionated into acidic, basic and neutral fractions. Each fraction was analyzed by combined gas chromatography-mass spectrometry. Seventy-seven compounds were identified, among which isovaleric acid, alkyl pyrazines, isovaleramide, ketones and some sulfur-containing compounds were the main and characteristic constituents of the roasted shrimp aroma.

These constituents were compared with those of the volatiles of boiled shrimp, which was prepared by using simultaneous distillation and extraction methods in a modified Likens and Nickerson’s apparatus.     

Studies on Flavor Components in Soybean

Volatile neutral fraction of flavor components in raw soybean was investigated. Ground raw soybean was packed in a glass column, warmed at about 50°C by a water-jacket column, and swept with nitrogen gas. Volatile materials swept out were trapped in bottles dipped in ice-water, solid carbon dioxide-acetone and liquid nitrogen in this order, and were submitted to gas chromatography. The peaks corresponding to basic and carbonyl compounds were eliminated by treating the original volatile materials with 2, 4-dinitro-phenylhydrazine in phosphoric acid, and the residual peaks were compared with authentic alcohols and esters.

Methanol, ethanol, 2-pentanol, isopentanol, n-pentanol, n-hexanol and n-heptanol were found as alcohols, and n-pentanol acetate was found as an ester. Other methods of identification of alcohols were carried out by introducing these into 3, 5-dinitrobenzoate derivatives, which were investigated by thin-layer and paper chromatographies.

Isopentanol, n-hexanol and n-heptanol were considered to be important factors among the volatile neutral components, which gave green bean-like odor to soybean.     

Studies on Flavor Components in Soybean

Ethanol (1:1) extract of defatted soybean flour was fractionated systematically and the resulting phonolic acid fraction was investigated. This fraction had strong phenol-like flavor and contained at least seven phenolic acids including syringic, vanillic, ferulic, gentisic, salicylic, p-coumaric, and p-hydroxybenzoic acids. The main component among these was syringic acid, which was isolated as 3,5-dinitrobenzoate.

In addition, two isomers of chlorogenic acids, presumably isochlorogenic and chlorogenic acids approximately in a ratio of 1 : 10, were found in this extract. These substances have sour, bitter and astringent flavors.     

Studies on Flavor Components in Soybean

Aliphatic carbonyl compounds in soybean were studied. Volatile carbonyl compounds in defatted soybean flour were identified as methanal, ethanal, n-hexanal, 2-propanone, 2- pentanone, 2-heptanone, 2-heptenal, and 2,4-decadienal, while those in raw soybean as ethanal, n-hexanal, and 2-propanone. Four kinds of non-volatile carbonyl compounds were found in defatted soybean, two of which seemed to be carbonyl ester and carbonylic acid. It is probable that the compounds in defatted soybean are mostly the secondary products derived from autoxidation of the residual fatty acids and esters in the defatting process and/or during the storage thereafter. n-Hexanal in raw soybean amounts to approximately 10 p.p.m., which is, owing to its extremely low flavoring threshold, likely to be one of the main components of the green bean flavor.