Peach esters

HCOOCHjCHj. Colourless liquid with the odour of peach-kernels b.p. 54 C, Prepared by boiling ethanol and methanoic acid in the presence of a little sulphuric acid the product is diluted with water and the insoluble ester separated and distilled. Used as a fumigant and larvicide for dried fruits, tobacco and foodstuffs. It is also used in the synthesis of aldehydes. 

Flavanols/Procyanidins Catechin, epicatechin, and their gallic acid esters Apples, grapes, plums, pears, mangoes, okra, peaches, Swiss chard, berry fruits and vegetables in general,... 

Yellow or orange fruits, including pumpkins, oranges, and peaches, which primarily contain xanthophyll esters... 

It has long been recognized that boron is required by higher plants [61, 62], and recent research indicates the involvement of boron in three main aspects of plant physiology cell wall structure, membrane function, and reproduction. In vascular plants, boron in solution moves in the transpiration stream from the roots and accumulates in the stems and leaves. Once in the leaves, the translocation of boron is limited and requires a phloem transport mechanism. The nature of this mechanism was only recently elucidated with the isolation of a number of borate polyol compounds from various plants [63-65]. These include sorbitol-borate ester complexes isolated from the floral nectar of peaches and mannitol-borate ester complexes from the phloem sap of celery. The implication is that the movement of boron in plants depends on borate-polyol ester formation with the particular sugar polyol compounds used as transport molecules in specific plants. 

Peaches and nectarines are members of the same species (Prunus persica). There is controversy over whether nectarine is a separate and distinct fruit or merely a variety of peach [68]. Nectarines lack skin fuzz or pubescence. Approximately 100 volatile compounds have been identified in peaches and nectarines, including alcohols, aldehydes, alkanes, esters, ketones, lactones and terpenes [14, 15, 17, 64, 65, 68-71]. Among them, lactones, particularly y-decalactone and d-decalactone, have been reported as character-impact compounds in peaches and nectarines where they process a strong peach-like aroma [66]. Lactones act in association with Ce aldehydes, aliphatic alcohols and terpenes (Table 7.2,... 

Peach et al. developed a general, racemization free, and high yield procedure for the synthesis of O-desyl peptide esters from the poorly nucleophilic benzoin.1261 Employing the cesium salt of the model dipeptide Z-Gly-Phe-OH in acetone the intramolecular hydantoin formation obtained in polar aprotic solvents, such as DMF and DMSO, can be suppressed and a high yield of Z-Gly-Phe-O-desyl with ee >90% can be generated. 261 ... 

Olefin metathesis can be very useful in the CM mode, as shown in the synthesis of insect phere-mones.46 In the first example for the synthesis of the peach twig borer pheromone 23, an excess of 1-hexene was used to increase the yield of the desired product. However, both of the other products could be recycled (Scheme 28.17). In the second example, CM was used to change the ester groups of meadowfoam oil (24) through cleavage of the alkenes rather than ester bonds. The sequence resulted in the synthesis of the mosquito pheromone (25) (Scheme 28.18). 

Place the test tubes in a warm water bath at 60°C for 15 min. Remove the test tubes from the water bath, cool, and add 2 mL of water to each. Note that there is a layer on top of the water in each test tube. With a Pasteur pipet, take a few drops from this top layer and place on a watch glass. Note the odor. Match the ester from each test tube with one of the following odors banana, peach, raspberry, nail polish remover, wintergreen. 

CIC The typical lactony note is produced by 4-decanolide. The flavour industry since years uses mainly the 4-undecanolide, the so called peach lactone . The lactone has to be balanced with fmity esters like 3-methyl butyl acetate, the floral-fmity note of linalool and some green notes like (E)-2-hexenal. 

These terpene notes are supported by (Z)-3-hexenol, (E)-2-hexenal, (E)-2-hexenol with their fresh, green character. Gamma- and delta-lactones (4-decanolide, 5-decan-olide, 4-dodecanolide, 5-dodecanolide-(Z)-7-decen-5-olide) impart the sweet, creamy, buttery, peach and apricot character. 2,5-Dimethyl-4-hydroxy-furan-3(2H)-one and 2,5-dimethyl-4-methoxy-furan-3(2H)-one are responsible for the sweet creamy fruity body. A bouquet of esters imparts the overall fruity character (mainly esters of ethyl-, (Z)-3-hexenyl and butyl alcohol with acetic-, butanoic-, 2-butenoic, 3-hydroxybutanoic- and hexanoic acid). 

A mixture of 3 mL of 2-pentanol, 3 mL of isovaleric acid and 1 mL of concentrated H2SO4 in a test tube is heated in the flame of the gas burner after a while the obnoxious smell of the starting materials is replaced by a pleasant banana-like smell. The ester which is formed (b.p. 190 C) is present in bananas and is used in artificial pineapple and peach oils. 

Lactones are cyclic compounds with relatively high boiling points and an ester functional group. They have the characteristic ester notes fruity, oily, and sweet. y-Undecalactone, with a peach-hke aroma, has a boiling point of 297°C. 

Ceratocystis sp. Banana, pear, peach, plum Alcohols, esters, monoterpene alcohols, lactones... 

Hydrolysis. Carboxylesterases are frequently one of the major factors in OP resistance. In some insects, for instance the house fly (28), there are highly substrate specific esterases which attack only one or a very few molecules. "Malathionase", the prominent esterase responsible for many cases of malathion resistance, is highly specific for malathion. It cleaves one or both of the ethyl ester groups leaving malathion mono- or diacid (29). This enzyme is a true serine carboxylesterase that is inhibited by malaoxon (28) and does not hydrolyze any of the phosphoester bonds. In Anopheles stephensi from Pakistan, the malathion resistance decreased with adult age, but there was no concommittant decrease in general esterase activity as measured with 1- and 2-naphthylace-tate as model substrates (301. other mosquitoes have a carboxylesterase with broad substrate specificity that is associated with resistance (31-331. As mentioned above, the green peach aphid has a carboxylesterase, E4, with broad substrate specificity that sequesters toxicants (24). 

Spadone et al. (1990) also identified aliphatic unsaturated aldehydes, long-chain 2-alkanones, lactones and esters which are only present in green coffee and would give the beans the characteristic soapy, fatty and fruity (coconut, peach, apricot) notes. They were the first authors to find (3-damascenone (Section 5,D.38) in raw coffee, a compound that resists roasting and contributes highly to the tea-like and fruity flavor of the beverage,... 

This ester has a very diffusive and penetrating, sweet-ethereal, fruity odor. In extreme dilution it is reminiscent of apple peel with a slightly fatty peach-like undertone (Arctander, 1967). It has a fruity, over-ripe, cheesy flavor (Chemisis, 1999). The probable threshold would be 43 ppb in water (confidence limits 15-120 ppb) according to Ahmed et al. (1978) and the probable flavor threshold 59 ppb (confidence limits 23-150). 

Table II. Deterrence of green peach aphid feeding by sucrose esters from type B glandular trichomes of S. berthaultii (PI 473331) applied to diet membranes. Adapted from (24)...

Synonyms Persic oil acid, ethyl ester Definition Ethyl ester of the fatty acids derived from either apricot kernel oil or peach kernel oil Uses Emollient in cosmetics... 

Persian red. See Lead chromate oxide Persic oil. See Apricot (Prunus armeniaca) kernel oil Peach (Prunus persica) kernel oil Persic oil acid, ethyl ester. See Ethyl persate Persoftai ASA Cone., Persoftai BFB. See Polysiloxane... 

PCA glyceryl oleate Peach (Prunus persica) kernel oil Peanut (Arachls hypogaea) oil Peanut oil PEG-6 esters PEG-42 babassu glycerides... 

Myristyl propionate 2-Octyl-1-decanol Octyidodecanol Octyidodecyl myristate Octyidodecyl stearate Octyl pelargonate Oleth-2 Oleth-5 Oleyl erucate Olive (Olea europaea) oil Olive oil PEG-6 esters Orange (Citrus aurantium dulcis) peel wax Palm glyceride Palm glycerides Peach (Prunus persica) kernel oil... 

Many fruits and vegetables (e.g., grape, citrus, olive, black pepper, spices, soya, cereals) and the derived foods and beverages are a good source of phenolic antioxidants and constitute an important part of our daily diet [4,5,25,26,107-109,111-115]. A good correlation between phenolic content and antioxidant activity is often observed, as reported for monomeric and dimeric hydroxycinnamates of rye bran [75] and various caffeoyl quinic esters in peach puree [116],... 

Do et al. [74] investigated flavor development in peaches as influenced by harvest maturity and artificial ripening. Peaches obtain most of their characteristic flavor from lactones, and of course, these lactones increase as stage of maturity advances. Artificial ripening of the peaches does not result in similar levels of lactones in the ripe fruit. Artificially ripened peaches contained only about 20% of the total lactone content of tree ripened peaches. Benzaldehyde and total esters in the artificially ripened peaches reached only 20% and 50% of their respective concentrations found in tree-ripened fruit. 

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