Grassy Odor Research Articles

Extraction and identification of chemicals causing grassy odors in flavor profile analysis (FPA) reference standards

The extraction and identification of natural fresh grass odor standard was studied. Fresh grass was allowed to sit in water until it released its grassy components to the water. The resulting grassy samples were analyzed and the chemicals responsible for the characteristic odors identified by Flavor Profile Analysis and sensory GC analysis. Closed-Loop Stripping Analysis was used for the isolation of volatile non-polar compounds and Simultaneous Distillation Extraction was used for the isolation of more polar chemicals of moderate volatility. A primary grassy odor standard (cis-3-hexenyl acetate) and a secondary grassy odor standard (cis-3-hexen-1-ol) were identified by Mass Spectroscopy and Sensory GC. Dose-Response curves were plotted and corresponding odor threshold concentrations (OTC) were determined for the cis-3-hexen-1-ol the cis-3-hexenyl acetate. It was found that cis-3-hexenyl acetate was approximately 50 times more odorous than the cis-3-hexen-1-ol. The OTC of cis-3-hexenyl acetate was found to be between 1 and 2 μg/l.

Evaluation of odour removal by pilot-scale biological treatment process trains during spring runoff in an ice-covered river

Biological water treatment has been shown to effectively remove biodegradable organic matter, chlorinated by-products and ozonation by-products from drinking water during a large pilot-scale study for the American Water Works Association Research Foundation using the North Saskatchewan River, at Edmonton. In addition to studying total organic carbon, assimilable organic carbon, chlorine demand, haloacetic acid formation potential, trihalomethane formation potential, adsorbable organic halide formation potential, chloral hydrate and aldehydes, this study used a flavour profile panel to follow the removal of odour through different process trains involving biological treatment during the annual spring runoff which has historically caused odour incidents in the water supply. Over the 5-week period of the study, the raw water was found to develop from a very mild grassy odour to a strong odour, variously characterized as septic, manure, musty, earthy and hay-like. The odour persisted and changed character to varying degrees through the various process trains under study. The results verified the futility of relying on a strictly oxidative treatment like ozone for odour removal as well as showing that biological treatment using granular activated carbon could produce an essentially odour-free effluent during a transient raw-water odour event.

The use of reference materials in sensory analysis

In descriptive sensory techniques, reference materials are used to establish a common vocabulary for various aromas and flavors. A reference standard can be any chemical or natural material that adequately represents the particular characteristic described. This paper evaluates the utility of various reference materials that have been proposed as odor standards. The odor reference library used included odors commonly attributable to microbiological and industrial sources. The results of utilizing reference standards demonstrated that some materials were very good; that is, they yielded a distinctive odor that transcended cultural and language differences, as well as different levels of experience. Other aromas required several standards to distinguish among subtle but important differences, e.g., geosmin and 2-methylisoborneol to differentiate earthy/musty odors. These standards also included natural materials prepared in various states to reference different types of common odors in water - for example, grass clippings (in water) that had been freshly cut to represent a grassy odor, or had been held for a week to represent a septic odor, as well as dried grass for a hay odor. Other reference materials yielded bimodal distributions in which, primarily, two groups centered around different descriptors; these kinds of materials would not make good reference standards.

Extraction and identification of chemicals causing grassy odors in Flavor Profile Analysis (FPA) reference standards

The extraction and identification of natural fresh grass odor standard was studied. Fresh grass was allowed to sit in water until it released its grassy components to the water. The resulting grassy samples were analyzed and the chemicals responsible for the characteristic odors identified by Flavor Profile Analysis and sensory GC analysis. Closed-Loop Stripping Analysis was used for the isolation of volatile non-polar compounds and Simultaneous Distillation Extraction was used for the isolation of more polar chemicals of moderate volatility. A primary grassy odor standard (cis-3-hexenyl acetate) and a secondary grassy odor standard (cis-3-hexen-l-ol) were identified by Mass Spectroscopy and Sensory GC. Dose-Response curves were plotted and corresponding odor threshold concentrations (OTC) were determined for the cis-3-hexen-lol the cis-3-hexenyl acetate. It was found that cis-3-hexenyl acetate was approximately 50 times more odorous than the cis-3-hexen-l-ol. The OTC of cis-3-bexenyl acetate was found to be between 1 and 2 µg/l.

The use of reference materials in sensory analysis

In descriptive sensory techniques, reference materials are used to establish a common vocabulary for various aromas and flavors. A reference standard can be any chemical or natural material that adequately represents the particular characteristic described. This paper evaluates the utility of various reference materials that have been proposed as odor standards. The odor reference library used included odors commonly attributable to microbiological and industrial sources. The results of utilizing reference standards demonstrated that some materials were very good; that is, they yielded a distinctive odor that transcended cultural and language differences, as well as different levels of experience. Other aromas required several standards to distinguish among subtle but important differences, e.g., geosmin and 2-methylisoborneol to differentiate earthy/musty odors. These standards also included natural materials prepared in various states to reference different types of common odors in water - for example, grass clippings (in water) that had been freshly cut to represent a grassy odor, or had been held for a week to represent a septic odor, as well as dried grass for a bay odor. Other reference materials yielded btmodal distributions in which, primarily, two groups centered around different descriptors; these kinds of materials would not make good reference standards.

Evaluation of odour removal by pilot-scale biological treatment process trains during spring runoff in an ice-covered river

Biological water treatment has been shown to effectively remove biodegradable organic matter, chlorinated by-products and ozonation by-products from drinking water during a large pilot-scale study for the American Water Works Association Research Foundation using the North Saskatchewan River, at Edmonton. In addition to studying total organic carbon, assimilable organic carbon, chlorine demand, haloacetic acid formation potential, trthalomethane formation potential, adsorbable organic halide formation potential, chloral hydrate and aldehydes, this study used a flavour profile panel to follow the removal of odour through different process trains involving biological treatment during the annual spring runoff which has historically caused odour incidents in the water supply. Over the 5-week period of the study, the raw water was found to develop from a very mild grassy odour to a strong odour, variously characterized as septic, manure, musty, earthy and hay-like. The odour persisted and changed character to varying degrees through the various process trains under study. The results verified the futility of relying on a strictly oxidative treatment like ozone for odour removal as well as showing that biological treatment using granular activated carbon could produce an essentially odour-free effluent during a transient raw-water odour event.

Flavour Deterioration of Soya‐bean Oil: Identification of Intense Odour Compounds Formed during Flavour Reversion

AbstractAroma dilution analysis of a volatile concentrate isolated from reverted soya‐bean oil resulted in 11 odour compounds having high aroma values. Nine of these compounds were identified as: 3(Z)‐hexenal, octanal, 1‐octen‐3‐one, 1,5(Z)‐octadien‐3‐one, nonanal, 2(E)‐nonenal, 2(Z)‐nonenal, 3(Z)‐nonenal and 2(E),6(Z)‐nonadienal. 3(Z)‐Hexenal, the C9‐aldehydes and the two vinyl ketones contribute with high aroma values to the beany, grassy odour note of the reversion flavour.

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.

Isolation and Identification of Objectionable Volatile Flavor Compounds in Defatted Soybean Flour

ABSTRACTThe volatile flavor constituents of defatted soy flour were isolated by a specially designed apparatus. The isolated volatiles were fractionated by gas chromatography. The fractions with characteristic beany, grassy, and green odors were identified by infrared and mass spectrometry. A total of 25 compounds was identified, including nine alcohols, six aldehydes, nine ketones, and 2‐pentyl furan. Among the identified compounds, 2‐pentyl furan and ethyl vinyl ketone are probably the key compounds for the beany and grassy odors of the soy flour. All the compounds identified in this study can be postulated as autoxidative decomposition products of soy lipids. Therefore, the presence of these compounds in soy flour might be due to the incomplete removal of lipids in soy flour.

Coal for water purification

In descriptive sensory techniques, reference materials are used to establish a common vocabulary for various aromas and flavors. A reference standard can be any chemical or natural material that adequately represents the particular characteristic described. This paper evaluates the utility of various reference materials that have been proposed as odor standards. The odor reference library used included odors commonly attributable to microbiological and industrial sources. The results of utilizing reference standards demonstrated that some materials were very good; that is, they yielded a distinctive odor that transcended cultural and language differences, as well as different levels of experience. Other aromas required several standards to distinguish among subtle but important differences, e.g., geosmin and 2-methylisoborneol to differentiate earthy/musty odors. These standards also included natural materials prepared in various states to reference different types of common odors in water - for example, grass clippings (in water) that had been freshly cut to represent a grassy odor, or had been held for a week to represent a septic odor, as well as dried grass for a bay odor. Other reference materials yielded btmodal distributions in which, primarily, two groups centered around different descriptors; these kinds of materials would not make good reference standards.

Chlamydomonas in Storage Reservoirs

During the summer of 1932 the storage reservoirs of the Lehigh Water Company, which supplies Easton, Pennsylvania, were continuously troubled with growths of Chlamydomonas. Although of no sanitary significance, the growths were, at times, so heavy that the water became decidedly objectionable to users. Numerous complaints were received from consumers, beginning about the first week in April and continuing off and on until the early part of November. Many of these complaints were due to an unpleasant taste and odor present in the raw water. This everpresent taste and odor, which we have called with no originality the Delaware River taste, will be discussed elsewhere. However, complaints regarding a green color and turbidity of the tap water, a green ring or sediment in a glass of water which had, for example, stood overnight by a bedside, a greenish scum on boiled water used in cooking, a sediment in pots and pans, and occasionally of a grassy odor were definitely traceable to the reservoirs. One of the most embarrassing complaints came from a beauty parlor where a ring of green scum was formed in white enamel bowls used for heating water. The Lehigh Water Company supplies the city with unaltered1 Delaware River water, purified by chloramine treatment. The pumping station is off the Pennsylvania bank on the northern outskirts of the city, approximately a mile above the junction of the Lehigh River with the Delaware River. The distribution system centers in four reservoirs. The water is lifted from the river into two reservoirs situated about a mile northeast of the river on the side of Paxinosa Mountain. These main reservoirs are in tandem, with a combined capacity of 13

Taste and Odor in the New York City's Supplies

In New York City's supplies, despite the diversity of its sources, the only organisms which have given offense from taste or odors have been Asterionella, Tabellaria, Anabaena, Aphanizomenon (with admixtures of Coelosphaerium, Microcystis and Clathrocystis), Uroglena, Synura, Dinobryon and Peridinium. Asterionella produces a slightly aromatic odor when present in 500 to 1000 standard units per cubic centimeter. At 1000 units, and rarely less, the odor is distinctly similar to that of the geranium. The intensity of odor increases with increasing numbers until a fishy odor is produced by several thousand. The fishy odor may also be produced when smaller quantities die or are destroyed. Tabellaria, and similarly Asterionella, may produce an earthy odor when present in very small amounts (produced also by large amounts of Synedra). The odor passes through the aromatic, geranium and fishy stages with about the same relative quantities of organisms as Asterionella. At times the odor of Tabellaria has suggested illuminating gas, no other organism being present. Anabaena and Aphanizomenon, when present in 500 to 1000 units, produce a faintly grassy odor, like freshly-cut grass. With larger numbers the odor increases until it becomes pungent like nasturtium, or even onions. Upon decay the odor is of vile, pig-pen character. Uroglena produces an oily fishy taste and odor, first noticeable in probably 500 to 1000 units. In larger quantities it is very disagreeable, the flavor being that of cod-liver oil. Synura may cause trouble apparently in any amount judging from our recent experience, at least as little as 50 units. This organism is by far the most persistent and disagreeable of them all. The taste is variously described as cucumber, muskmellon, fishy, etc. It leaves a bitter after-taste when the undestroyed organisms are in the