Aroma vegetal

Furfural was first isolated in the eady nineteenth century. Dobereiner is credited with the discovery. He obtained a small amount of a yellow "oil" (too Htde to characterize) as a by-product in the preparation of formic acid (8). Other chemists found that the same "oil" having a charactedstic aroma could be obtained by boiling finely divided vegetable materials such as oats, com, sawdust, bran, etc, with aqueous sulfuric acid or other acids (9,10). The oil was present in the Hquid resulting from condensation of the vapors produced during heating. The empirical formula was determined by Stenhouse... 

Rectified oils have been redistilled to improve a particular property or characteristic, such as flavor or aroma. Eor example, natural oil of peppermint is frequently rectified to remove dimethyl sulfide, which has a powerful and objectionable cooked vegetable note deleterious to the use of the oil in cmme de menthe Hqueurs. Distillation is also used to remove psoralens, which are harmful photosensitizing agents present in natural bergamot oil. Color may be removed, eg, from cassia oil, by vacuum steam distillation. A desirable component, such as 1,8-cineole (eucalyptol) 85% in eucalyptus oil, may be... 

Sucrose helps minimize earthy tastes of vegetables, while enhancing inherent flavors and aromas, and preserving color and texture (37). Addition of sucrose inhibits enzymatic browning of canned and frozen fmits, and prevents loss of color, flavor, and aroma from fmit during processing (38). 

However, ozone may have some undesirable effects. There have been a few reports of changes in aroma and surface colour of some fruits and vegetables (Kim etal., 1999 Perez etal., 1999). Ozone can also be hazardous to humans. A concentration above 0.1 ppm in air has a strong odour that causes irritation of the nose, throat and skin (Sharma, 2005). In addition, long-term exposure to the gas may lead to mutagenic effects and even death. 

Consumer acceptance of fresh and processed fruits and vegetables is influenced by product appearance, flavor, aroma, and textural properties. Color is a key component that influences a consumer s initial perception of fruit and vegetable quality. Lycopene is the principal carotene in tomato fruit that imparts color. Analytical and sensory... 

Microbial spoilage appears to be one of the major causes of quality loss of fresh fruits and vegetables by formation of off-flavors, fermented aromas, and tissue decay. The shelf-life of many food products may be accurately predicted by quantifying the population of microbes present on the food product (Zhuang and others 2003). The... 

Flavor is one of the major characteristics that restricts the use of legume flours and proteins in foods. Processing of soybeans, peas and other legumes often results in a wide variety of volatile compounds that contribute flavor notes, such as grassy, beany and rancid flavors. Many of the objectionable flavors come from oxidative deterioration of the unsaturated lipids. The lipoxygenase-catalyzed conversion of unsaturated fatty acids to hydroperoxides, followed by their degradation to volatile and non-volatile compounds, has been identified as one of the important sources of flavor and aroma components of fruits and vegetables. An enzyme-active system, such as raw pea flour, may have most of the necessary enzymes to produce short chain carbonyl compounds. 

Ecovio FS Paper is also a compound of Ecoflex FS and PLA with a very high content of renewable resources. This grade was optimized for extrusion coating of paperboard. It can be processed on standard PE equipment and shows an excellent adhesion to card board and paper. The Ecovio coating forms a barrier for fat vegetable and mineral oil, liquid and aroma. Applications of choice are compostable paper cups for hot and cold drinks, freezer boxes or paper wraps for snacks. 

Editor You discussed the camouflage patterns of leaked explosives in soil and vegetation. How long after the puddles dry are MDDs able to find the scent It would seem that, since animals must be trained with particular suites of molecules, or aromas, that these should match the expected field aromas. Do decomposition products become more important and change over time ... 

Many factors affect the volatile composition of fruit and vegetables, e.g. genetics, maturity, growing conditions and postharvest handling. Furthermore, preparation of the fruits and vegetables for consumption and the method for isolation of volatile compounds may change the volatile profile and key aroma compounds compared to non-processed fruits and vegetables. 

Scheme 7.1 Enzymatic degradation of fatty acids by the j -oxidation cycle and formation of various types of aroma compounds in fruits and vegetables...

Scheme 7.2 Pathway for the enzymatic degradation of linoleic acid and linolenic acid via the lipoxygenase (LOX) pathway to Ce key aroma compounds in fruits and vegetables responsible for green notes. HPL hydroperoxide lyase, ADH alcohol dehydrogenase...

A large number of volatile phenols and related compounds occur in vegetables and fruits, and some of them are potent aroma compounds. The majority of volatile phenols and related compounds in plants are formed mainly through the shikimic acid pathway, and are present in intact plant tissue either as free... 

The roundish flower head, the curd, of the cauliflower plant (Brasska oleracea var. botrytis) is the edible portion of this vegetable. It can be eaten raw in salads or as a pickled condiment in vinegar. More often it is boiled and eaten with the main meal or is converted into sauces and soups. Over 80 volatile compounds have been identified in raw and cooked cauliflower. Among the compounds potentially active in cooked cauliflower, certain sulfides such as methanethiol, dimethyl sulfide and dimethyl trisulflde have often been incriminated in objectionable sulfurous aromas and overcooked off-flavours [169, 177, 178, 181-183]. Additional aldehydes have been found to be the most abundant cauliflower volatiles, with nonanal as a major component [175,177]. A recent study showed that volatiles such as 2-propenyl isothiocyanate, dimethyl trisulflde, di-... 

The flavour of fruits and vegetables is a very important aspect of quality. This review has focused on the most important aroma compounds in fruits and vegetables of moderate climate and demonstrated that a wide variety of volatile compounds are formed naturally in the products or after processing that influence the aroma and flavour of fresh and processed fruits and vegetables. 

Methionine Methional, methane-thiol, 2-propenal Vegetable-hke aromas... 

Oxazoles have been found in relatively few cooked foods, although over 30 have been reported in coffee and cocoa, and 9 in cooked meat. Oxazolines have been found in cooked meat and roast peanuts, but not to any extent in other foods. 2,4,5-Trimethyl-3-oxazoline has been regularly detected in cooked meat [26], and when it was first identified in boiled beef [27] it was thought that the compound possessed the characteristic meat aroma however, on synthesis it was shown to have a woody, musty, green flavour with a threshold value of 1 mg/kg [28]. Other 3-oxazolines have nutty, sweet or vegetable-like aromas and the oxazoles also appear to be green and vegetable-like [28]. The contribution of these compounds to the overall aroma of heated foods is probably not as important as the closely related thiazoles and thiazolines. 

As for S-containing heterocycles, many N-containing heterocycles are also found in heat-treated foods as secondary flavours as a result of Maillard-type reactions between reducing sugars and amino acids. Pyrazines are N-heterocycles important contributors to the taste and aroma of roasted and toasted foods as well as vegetables and fermented foodstuffs. In cultures of Pseudomonas perolens ATCC 10757, amino acids such as valine, glycine and methionine were shown to... 

The market for flavours and aromas is large and was worth 16 billion in 2003 [7,8]. There are about 6,500 flavours known but of these only 300 are commonly used. At present 50-100 are produced by microbial fermentation, and many of the rest are chemically synthesised. In many cases, flavours and aromas are very complex mixtures extracted from pulp, bark, peel, leaf, bud, berry and flowers of fruit, vegetables, spices and other plants. The particular flavour or aroma will depend on the balance of these compounds, although a number are due to a single compound. 

Study 2 Pvridvl ketones. A narrower range of compounds, a group of pyridyl ketones, was examined by Southwick and Schiffman (. Two-dimensional cross-sections through the three-dimensional space achieved by the MDS are shown in Figures 3a and 3b. The first dimension separates the three 2-pyridyl ketones that have popcorn-nutty aromas from the six other compounds that are green-vegetable in character. 

Considerable effort has been made to examine the volatiles and trace components that contribute to food flavors. Sone early techniques for measuring the volatile components in food products by gas chromatography consisted of analyzing headspace vapors to detect vegetable and fruit aromas (5) and volatiles associated with other food materials ( ). AlTo, sample enrichment has been used in the analysis of Tome food products. However, these techniques require steam distillation or extraction and concentration, or both, before the volatile mixture can be introduced into a gas chromatograph (, 9, 10). Besides being... 

Musty or potato-like flavor and aroma have been observed as a defect in milk (Hammer and Babel 1957) and Gruyere de Comte cheese (Dumont et al. 1975). This off-flavor results from the production of nitrogenous cyclic compounds by Pseudomonas taetrolens and P. perolens (Morgan 1976). Musty-flavored compounds produced by these organisms include 2,5-dimethylpyrazine and 2-methoxy-3-isopropyl-pyrazine. The Gruyere de Comte with potato off-flavor contained 3-methoxy-2-propyl pyridine, as well as alkyl pyrazine compounds (Dumont et al. 1975). Murray and Whitfield (1975) postulated that alkyl pyrazines are formed in vegetables by condensation of amino acids such as valine, isoleucine, and leucine with a 2-carbon compound. Details of the synthetic mechanism in pseudomonads are unknown. 

---