Comparison of Compositions of Odor Components of Natto and Cooked Soybeans

Natto, a traditional Japanese food product, was prepared from cooked soybeans by fermentation and its odor concentrate was obtained with a simultaneous distillation and extraction system. It was compared to those obtained from soybeans cooked for 0 ~ 3, 3 ~ 5.5 and 5.5 ~ 8 hr, respectively, by gas chromatography and gas chromatography-mass spectrometry. In the odor concentrates of the cooked soybeans, hexanal, (E)-2-hexenal and hexanol contributing to the green and grassy odor of soybeans disappeared or decreased while the cooking was in progress. 2-Pentylfuran and 1-octen-3-ol contributing to the beany odor remained even if the soybeans were cooked for 8 hr and were fermented into Natto. In the odor concentrate of Natto, pyrazines and sulfur containing compounds were important contributors to the characteristic odor of Natto. As the beany odor was not detected for Natto, it was concluded that the pyrazines and sulfur containing compounds cause the characteristic odor of Natto and mask the beany odor.     

Basic and Neutral Compounds in the Cooked Odor from Antarctic Krill

The cooked odor concentrate from precooked krill was obtained by a simultaneous distillation and extraction system. The resulting odor concentrate was separated into basic, carbonyl and carbonyl-free fractions. Each fraction was analyzed by gas chromatography and gas chromatography-mass spectrometry. Fifty seven compounds, including 3 pyridines, 10 pyrazines, 6 thiazoles, 3 dihydro-4H-1,3,5-dithiazines, 11 aldehydes, 10 ketones, 4 alcohols, 6 hydrocarbons and 4 other compounds were identified. Twenty two of these compounds were newly found as the odor components of krill. The low molecular aldehydes, which are known to be a part of the precursors of the secondary formation of the cooked odor, were also investigated by thin layer chromatography. Ethanal, propanal and butanal were newly detected.     

SENSORY AND INSTRUMENTAL FLAVOR ANALYSES OF CHEESE CURD COCULTURED WITH SELECTED YEAST AND BACTERIA

Relationships between odor properties and volatile chemical composition were explored on 39 cocultures of three different yeasts, three Geotrichum candidum and five bacteria, commonly used in bacteria and mold surface ripened cheese. Sensory profiling was performed by ten trained judges by scoring the intensity of 14 odor attributes. At the same time, the volatile compounds of the cocultures were extracted and analyzed by dynamic headspace gas chromatography and mass spectrometry. Sensory and instrumental data were compared and correlated using correlation analysis and partial least squares regression analysis. The sample plot including the whole set of samples evidenced a clustering of the associations containing the yeast strain Kluyveromyces lactis and any bacteria. They developed strong fruity olfactory notes related to their high content of ethyl esters and various alcohols. The sample plot on a restricted set of samples evidenced the fruity characteristics of Debaryomyces hansenii and bacteria associations and the cheesy odors of Yarrowia lipolytica and Geotrichum candidum cocultures that produced sulfur compounds.     

Fractionation and Identification of Volatile Compounds in Patis,a Philippine Fish Sauce

Commercial Philippine fish sauce (Patis) was steam-distilled and the distillate was fractionated into four fractions, neutral, basic, acidic and phenolic and each fraction was analyzed using gas chromatography and gas chromatography-mass spectrometry.

As a result of this study, a total of 66 compounds were identified in Patis, 14 of which were only a tentative identification. Out of these 66 identified compounds, 40 identified compounds have not been reported in previous studies on fish sauces. These identified compounds include 19 acids, 14 alcohols, 12 nitrogen containing compounds, 5 esters, 3 sulfur containing compounds, 1 phenol, 3 carbonyls, 7 hydrocarbons and 2 others. In the acidic fraction, 5 acids were considered major constituents which accounted for about 98% of the total acids. n-Butanoic acid was found to be the most abundant accounting for about 50% of the total acids.     

Thermochemical transformation of sulfur compounds in Japanese domestic Allium, Allium victorialis L

Sulfur compounds contributed to the health promotion in Allium species are produced via enzymic and thermal reactions. Potent antithrombotic agents which have been identified as allyl trisulfides, dithiins, and ajoene in garlic (A. sativum) and caucas (A. victorialis) are thermochemically transformed from allicin (allyl 2-propenethiosulfinate). The leaves and stems of Japanese domestic Allium plant, A. victorialis L. which is widely distributed in the northern part of Japan, under the name "Gyoja-ninniku" is a nutritious vegetable. The significant flavor compounds of caucas are methyl allyl disulfide (Chinese chive odor), diallyl disulfide (garlic-like odor), and dimethyl disulfide and methyl allyl trisulfide (pickles-like odor) among more than 85 peaks on the gas chromatogram. 2-Vinyl-4H-1,3-dithiin and 3,4-dihydro-3-vinyl-1,2-dithiin as platelet aggregation inhibitors were found eliminated in dichloromethane extract of caucas. The significant health promoting factors, allyl trisulfides and dithiins were relatively increased when caucas was cooked on a frying pan.     

The composition of volatile components of cepe (<Emphasis Type="Italic">Boletus edulis</Emphasis>) and oyster mushrooms (<Emphasis Type="Italic">Pleurotus ostreatus</Emphasis>)

The composition of aroma compounds in cooked and canned cepe (Boletus edulis) and in cooked oyster mushrooms (Pleurotus ostreatus) is studied using capillary gas chromatography and chromatographymass spectrometry. It is found that unsaturated alcohols and ketones containing eight atoms of carbon determine the aroma of raw mushrooms and take part in the formation of the aroma of cooked mushrooms as well. The content of these compounds was the highest in canned cepes. In oyster mushrooms, the concentration of these alcohols and ketones was lower in comparison with cepes. The content of aliphatic and aromatic aldehydes was much higher in oyster mushrooms. Volatile aliphatic and heterocyclic Maillard reaction products and isomeric octenols and octenones formed the aroma of cooked and canned mushrooms.     

Thermophilic Biodesulfurization of Various Heterocyclic Sulfur Compounds and Crude Straight-Run Light Gas Oil Fraction by a Newly Isolated Strain Mycobacterium phlei WU-0103

Various heterocyclic sulfur compounds such as naphtho[2,1-b]thiophene (NTH) and benzo[b]thiophene (BTH) derivatives can be detected in diesel oil, in addition to dibenzothiophene (DBT) derivatives. Mycobacterium phlei WU-0103 was newly isolated as a bacterial strain capable of growing in a medium with NTH as the sulfur source at 50°C. M. phlei WU-0103 could degrade various heterocyclic sulfur compounds, not only NTH and its derivatives but also DBT, BTH, and their derivatives at 45°C. When M. phlei WU-0103 was cultivated with the heterocyclic sulfur compounds such as NTH, NTH 3,3-dioxide, DBT, BTH, and 4,6-dialkylDBTs as sulfur sources, monohydroxy compounds and sulfone compounds corresponding to starting heterocyclic sulfur compounds were detected by gas chromatography–mass spectrometry analysis, suggesting the sulfur-specific desulfurization pathways for heterocyclic sulfur compounds. Moreover, total sulfur content in 12-fold-diluted crude straight-run light gas oil fraction was reduced from 1000 to 475 ppm S, with 52% reduction, by the biodesulfurization treatment at 45°C with growing cells of M. phlei WU-0103. Gas chromatography analysis with a flame photometric detector revealed that most of the resolvable peaks, such as those corresponding to alkylated derivatives of NTH, DBT, and BTH, disappeared after the biodesulfurization treatment. These results indicated that M. phlei WU-0103 may have a good potential as a biocatalyst for practical biodesulfurization of diesel oil.     

An environmental nuisance: odor concentrated and transported by dust

Intensive swine production generates odorous emissions which flow from the buildings housing the animals. High ventilation rates bring in fresh air, remove heat and moisture and enhance pork productivity. Numerous compounds contribute to the uniquely offensive odors from swine facilities, including fatty acids, amines, aromatics and sulfur compounds. Dust particles, which originate predominantly from feces and feed, can adsorb and concentrate odorants in swine facilities. In addition, organic particles can decay and generate odorous compounds. Odorants can exist in much higher concentrations in the dust particles than in equivalent volumes of air. Thus, inhalation of odorous dust and deposition of the dust particles in the mucus overlying the olfactory mucosa are likely responsible for some odor-related complaints by swine farm neighbors. Accurate prediction of odor transport and dispersion downwind from swine farms may require models of dust dispersion and correlation between dust and odorant levels. Unfortunately, many approaches to estimating odor impact currently incorporate filtering of air to remove particulate matter before sensing by humans or electronic sensors. Accelerated progress in understanding this and other 'real world' odor control problems will require methodological innovations that allow quantification of odor in response to air streams containing vapor and particulate phases.     

Fractionation and Identification of Volatile Acids and Phenols in the Steam Distillate of Rice Bran

Fractionation of the volatile concentrate obtained from steam-distillate of rice bran and organoleptic tests of each fraction were carried out. The neutral fraction gave a much higher yield than others and was assumed to be indispensable for the reproduction of rice bran odor. The acidic fraction methylated with diazomethane and the phenolic fraction were analyzed by glass capillary gas chromatography to identify 17 carboxylic acids and 7 phenols. 4-Vinylguaiacol and 4-vinylphenol identified in the steam volatile concentrate were considered to be produced from ferulic and p-coumaric acids during steam-distillation. 4-Vinylphenol was the main component in the steam volatile concentrate of rice bran, having a characteristic unpleasant odor.     

Roles of odor, taste, and toxicity in the food preferences of lambs: implications for mimicry in plants

In the traditional sense, food ingestion consists of prehending, masticating, swallowing, and digesting plant matter. It is also possible to ingest plants without eating them. Volatile compounds are inhaled directly into the lungs and transported from the lungs into the bloodstream. Volatiles in high concentrations could presumably produce toxicosis, without an herbivore ever ingesting a plant in the customary sense. Volatile compounds may be aposematic, serving to warn potential predators of toxins in plants. We conducted three experiments to explore the roles of odor, taste, and toxicity in the food preferences of lambs. The first experiment determined if brief exposure to a novel odor followed by lithium chloride (LiCl)‐induced toxicosis caused lambs to avoid a familiar food that contained the odor. Lambs that sniffed coconut‐flavored barley and then received LiCl subsequently ate less coconut‐flavored barley than lambs that did not receive LiCl. The second experiment determined if lambs were deterred from eating a familiar food by the odor of Astragalus bisulcatus. A. bisulcatus is a malodorous (to humans) sulfur‐containing herb considered unpalatable and toxic. Neither odor nor intraruminal infusions of A. bisulcatus deterred lambs from feeding. The third experiment also determined how the degree of familiarity with the odor of A. bisulcatus, along with toxicosis, influenced preference of lambs for food with or without the odor of A. bisulcatus. Lambs with 8 d exposure to the odor but not given LiCl ate similar amounts of food, with and without the odor of A. bisulcatus, whereas lambs given LiCl showed a mild aversion to food with the odor during testing. Lambs with 1 d exposure to the odor but no LiCl ate similar amounts of food, with and without the odor, whereas lambs given LiCl showed a strong but transient aversion to food with the odor. Collectively, these findings show that lambs responded strongly to novel odors, but their response was transient and depended on the postingestive consequences of toxins and nutrients associated with odor inhalation. Thus, we submit that odor alone, in the absence of toxicosis or nociception, is not a deterrent to herbivores that continually sample foods and adjust intake based on the postingestive effects of toxins and nutrients. It also is unlikely that non‐toxic plants can mimic the odors of toxic plants to avoid herbivory (Batesian mimicry), unless the odors are indistinguishable by herbivores, again because herbivores constantly sample foods.     

Alterations in blood pressure due to chronic exposure to natural sour gas leakage containing sulfur compounds

In order to show the alteration of blood pressure in subjects chronically exposed to natural gas containing sulfur compounds, the present study was done. The blood pressure of 94 (43 males, 51 females) of healthy individuals living in the polluted area of Masjid-i-Sulaiman (Khozestan province, southwest of Iran) was measured. The non-parametric Sign test was applied in order to detect differences between the study subjects and the normal mean values according to the sex and age of subjects. Statistical analysis showed that the systolic blood pressure significantly decreased (Z=-2.74; P=0.0031) while the diastolic blood pressure (Z=+2.11; P=0.0174) and heart rate (Z=+3.62; P<0.001) significantly increased in individuals living in the contaminated areas compared with those of normal mean values. The systolic and diastolic blood pressure decreased and increased, respectively, in individuals chronically exposed to natural sour gas containing sulfur compounds.     

Comparison of Volatile Compounds from Chungkuk-Jang and Itohiki-Natto

Volatile compounds from two South-East Asian fermented soybean foods, Chungkuk-jang (CKJ) and Itohiki-natto (natto), were analysed by gas chromatography-mass spectrometry (GC-MS), gas chromatography (GC), and GC-sniffing. A total of 112 compounds were identified. A large amount of ethanol was detected from CKJ, while acetone and methyl isobutyrate were major components of natto. The characteristic odor compounds of CKJ were some ethyl esters of short chain fatty acids, diallyl disulfide, and several natto-like odor compounds were identified as ammonia, 2,5-dimethylpyrazine, and 2-methylbutanoic acid.     

成熟度对印度块菌香气成分的影响

研究成熟度对印度块菌Tuber indicum香气成分的影响,并测定成熟印度块菌的关键香气成分。将3种不同成熟度的印度块菌,以固相微萃取(SPME)技术为香气富集方法,利用气相色谱-质谱联用(GC-MS)分析其香气成分。结果表明未成熟印度块菌中仅检测出4种香气成分,中度成熟阶段检测出8种,成熟阶段检测出13种,而且成熟阶段检测出的香气成分大多都是前人报道过对块菌香气有贡献的成分;通过计算成熟块菌各香气组分的香气活度值(OAV),可知二甲基硫醚、2,3-丁二酮、3-甲基正丁醛、2-甲基正丁醛、己醛、1-辛烯-3-醇这6种物质是印度块菌的关键香气成分(OAV>1)。     

口臭微生态治疗技术研究进展

口臭是指呼吸时排出挥发性硫化物等臭味气体,主要由口腔微生态失调引起,具体为生理性菌群数目减少,产臭类菌群种类和数目增加。口臭是局部口腔或全身系统不良代谢状况的一种表现,临床可根据口腔异味来诊断疾病,并通过口腔微生态的调整来治疗口臭。本研究从口臭与微生态的关系、口臭主要相关微生物等方面进行分析,综述机械、化学和中医药等方法调整口腔微生态来治疗口臭的进展。     

Gas Chromatographic and Mass Spectral Analyses of Heated Flavor Compounds of Beef Fats

The volatile compounds from beef fats heated under the cooking condition-145°C, l0 min-were isolated, and nonacidic compounds separated from them were further fractionated into five fractions by silicic acid column chromatography. The odor of nonacidic compounds significantly resembled the heated flavor of beef fats. Several carbonyl compounds, hydrocarbons, alcohols, lactones and pyrazine compounds in the fractionated compounds were identified with the techniques of gas chromatography and gas chromatography-mass spectrometry. Their possible contribution to the heated beef fat flavor was discussed. The typical heated flavor could probably be ascribed to a proper combination of aldehydes, ketones, esters and sulfur-containing compounds.     

Studies on Cereals

Five carbonyl compounds were found in the vapour of cooked rice, of which acetaldehyde, and n-caproaldehyde were identified from their retention times in gas chromatography and by their infrared spectra. Propionaldehyde or acetone, methylethylketone, and n-valeraldehyde were tentatively identified. The mechanisms of the formation of these carbonyl compounds were discussed from the view-point of Strecker degradation and lipid oxidation.

When stored rice (40°C, two months) was cooked, the stale flavor (komai-shu) was clearly detected by sensory test. Direct gas chromatographic analysis of head space vapors over cooked rice showed three main peaks which corresponded to propionaldehyde or acetone, n-valeraldehyde and n-caproaldehyde. On the other hand, the content of linoleic and linolenic acids of the rice decreased during storage at 40°C. This means that the unsaturated fatty acids autoxidized during storage and gave rise to carbonyl compounds responsible for the stale flavor of cooked rice.     

Evolution of Volatile Sulfur Compounds during Laboratory-Scale Incubations and Indoor Preparation of Compost Used as a Substrate in Mushroom Cultivation

Volatile sulfur compounds are known to be produced during the preparation of compost used as a substrate in mushroom cultivation. Because they cause odor problems, attempts have been made to reduce the production of these compounds. The influences of temperature and various additions on the production of volatile sulfur compounds from composting material were tested on laboratory-scale preparations. The production of H₂S, COS, CH₃SH, and (CH₃)₂S was proven to be a biological process with an optimal temperature that coincides with the optimal temperature for biological activity. The formation of CS₂ and (CH₃)₂S₂ was shown to be a nonbiological process. The emission of volatile sulfur compounds during the indoor preparation of mushroom compost appeared to be remarkably reduced (about 90%) as compared with the emission during the conventional outdoor process. Introduction of this indoor composting process would result in a significant reduction in environmental pollution.     

Biotreatment of waste gas containing pyridine in a biofilter

Industrial waste gas emissions containing pyridine are generated from pyridine manufacturing industries, and in industrial operations where pyridine is used as a solvent, as an intermediate for synthesis and as a catalyst for a variety of applications. Pyridine has unpleasant fishy odor with an odor index of 2390 and waste gaseous emissions containing pyridine require proper treatment prior to discharge. A biofilter, packed with compost and wood chips and inoculated with Pseudomonas pseudoalcaligenes-KPN for enrichment of pyridine-degrading microorganisms, was operated on a continuous feed basis for a period of more than 2 years. The results indicate that the biofilter medium with optimal moisture content of 68% and an effective bed retention time (EBRT) of 28.50s could degrade pyridine effectively (>99%) at a loading of 434 g pyridine m(-3)h(-1). The treated waste gas was also found to be free from pyridine odor.