Aroma pineapple

C6Hg03, Mr 128.13, is a constituent of pineapple and strawberry aroma and is also found in other foods. It forms colorless crystals (mp 77-79 °C) with a relatively weak, nonspecific odor. Dilute solutions develop a pineapple, strawberry-like odor. It can be prepared by cyclization of hexane-2,5-diol-3,4-dione in the presence of an acidic catalyst [186]. The dione is the ozonization product of 2,5-hexynediol, which is obtained by ethynylation of acetaldehyde. 

The volatile compounds of juices made from freshly cut pineapple fruits from different cultivars from Costa Rica, Ghana, Honduras, Cote d Ivoire, the Philippines, Reunion, South Africa, and Thailand were studied in comparison to that of commercial water phases/recovery aromas, juice concentrates as well as commercially available juices [12]. The qualitative pineapple fruit flavour profile showed several methyl esters, some characteristic sulfur-containing esters, and various hydroxy esters were responsible for the typical pineapple flavour profile. 

Twenty-nine odour-active compounds were detected by using aroma extract dilution analysis (AEDA) [60]. The results of AEDA together with GC-MS analysis showed ethyl 2-methylbutanoate (described as fruity flavour), followed by methyl 2-methylbutanoate and 3-methylbutanoate (fruity, apple-like), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (sweet, pineapple-like, caramel-like), d-decalactone (sweet, coconut-like), l-( ,Z)-3,5-undecatriene (fresh, pineapple-like), and a unknown compound (fruity, pineapple-like) as the most odour-active compounds. 

The highest OAVs were found for 4-hydroxy-2,5-dimethyl-3(2H)-fura-none, followed by ethyl 2-methylpropanoate, ethyl 2-methylbutanoate, methyl 2-methylbutanoate and ( ,Z)-l,3,5-undecatriene. It is assumed that these odorants contribute strongly to the aroma of pineapples [50]. However, FD factors and OAVs are functions of the odorants concentrations in the extract, and are not psychophysical measures for perceived odour intensity [71,72]. To take this criticism into account, aroma models are prepared on the basis of the results of the quantitative analysis (reviewed in [9]) and in addition omission experiments are performed [9]. 

In the case of pineapples, the 12 odorants listed in Table 16.7 were dissolved in water in concentrations equal to those determined in the fruit [50]. Then the odour profile of this aroma model was evaluated by a sensory panel in comparison to fresh pineapple juice. The result was a high agreement in the two odour profiles. Fresh, fruity and pineapple-like odour notes scored almost the same intensities in the model as in the juice. Only the sweet aroma note was more intense in the model than in the original sample [50]. In further experiments, the contributions of the six odorants showing the highest OAV (Table 16.7) were evaluated by means of omission tests [9]. The results presented in Table 16.8 show that the omission of 4-hydroxy-2,5-dimethyl-3(2H)-furanone, ethyl 2-methylbutanoate or ethyl 2-methylpropanoate changed the odour so clearly that more than half of the assessors were able to perceive an odour difference between the reduced and the complete aroma model. Therefore, it was concluded that these compounds are the character-impact odorants of fresh pineapple juice. 

Herz and Chang (21) examined several furan compounds which had a wide variety of aromas, but none of them were meaty, Furans that do not contain sulfur are usually fruity, nutty, and caramel-like in odor. The furanones described above have burnt pineapple and roasted chicory odors, but these contribute to overall flavor impression of meat and important N and S meat flavor compounds might be formed from them during cooking. 

White ports vary in style, depending on the duration of maturation. When aged in oak barrels for many years, the wine acquires a golden color that resembles a very old tawny wine and picks up a nutty character from the wood (Mayson, 2003). White ports destined to be drunk young are crisp, with an intense bouquet that combines aromas of melons and peach, with hints of citrus fruit, camomile, and lemon balm flowers. In contrast, white ports aged in wood present a complex aroma of tropical fruits, such as pineapple and banana, with a touch of almond and vanilla. 

The aroma of DMHF is pineapple-like, and is not considered too detrimental. However, it can mask the fresh orange-like aroma at levels above 0.05 ppm. Shu et al. (41) noted that DMHF is a precursor of various flavor materials when reacted with amino acids at high temperatures. Many acyclic carbonyl and 3(2H)-furanone derivatives can be formed as primary and secondary degradation products during thermal degradation of DMHF (42). 

Another group of compounds that have been related to the aroma of heated foods is the furanones. Teranishi (1971) summarized the findings on several of the furanones (see Figure 7-23). The 4-hydroxy-2,5-dimethyl-3-dihydrofuranone (1) has a caramel or burnt pineapple odor. The 4-hydroxy-5-methyl-3-dihydrofuranone (2) has a roasted chicory root odor. Both compounds may contribute to beef broth flavor. The 2,5-dimethyl-3-dihydrofuranone (3) has the odor of freshly baked bread. Isomaltol (4) and maltol (5) are products of the caramelization and pyrolysis of carbohydrates. 

Aroma components of citrus fruit juice128-132 are different from that of essential oils (see Section 4.15.4.5 for composition of the latter).133-135 Other familiar fruits like apples,136 grapes,137 strawberries,129 138 bananas,139 and pineapples140 were analyzed as well. Place of origin (e.g., grapes) and ripeness of the obtained fruit (e.g., pineapples), in many cases, bring substantial difference in its composition and enantiomeric properties (Table 14).141... 

Methods for the capillary gas chromatographic separation of optical isomers of chiral compounds after formation of diastereoisomeric derivatives were developed. Analytical aspects of the GC-separation of diastereoisomeric esters and urethanes derived from chiral secondary alcohols, 2-, 3-, 4- and 5-hydroxy-acid esters, and the corresponding jf- and -lactones were investigated. The methods were used to follow the formation of optically active compounds during microbiological processes, such as reduction of keto-precursors and asymmetric hydrolysis of racemic acetates on a micro-scale. The enantiomeric composition of chiral aroma constituents in tropical fruits, such as passion fruit, mango and pineapple, was determined and possible pathways for their biosynthesis were formulated. 

Tropical fruits, such us passion fruits, mangos or pineapples, contain many chiral aroma constituents. So far, their enantiomeric composition is unknown, because the conventional method, measuring optical rotation, can not be applied to these components, which can be isolated from the fruits only in small amounts. The new techniques of capillary GC analysis of diastereoisomeric derivatives made it possible to characterize the enantiomeric composition of several chiral trace constituents. These results may be used to gain insight into the biogenesis of aroma components or to control natural aroma concentrates. 

As shown in Figure 7 ethyl 3-hydroxyhexanoate, isolated from purple passion fruit possessed the (R)-configuration, comparable to the hydroxyacid ester obtained by the reduction with baker s yeast. In contrary to that methyl 3-hydroxyhexanoate, which was isolated from aroma extracts of pineapple, consisted of the (S)-enantiomer (91 %). ... 

In addition to 3-hydroxy- and 3-acetoxyacid esters, pineapples contain 5-hydroxy- and 5-acetoxyacid esters, y -hexalactone and 6 -octalactone as characteristic chiral aroma constituents (2 ). The capillary GC investigation of R-(+)-PEIC derivatives made it possible, to determine the enantiomeric composition of these components for the first time (Figure 8). 

The aromas contributed by these black grape glycosides are of interest, as the hydrolysates gave aromas which were unlike that produced from hydrolysis of glycosides isolated from white grapes. In white varieties, attributes such as lime, pineapple and toasty were important to the aroma of the hydrolysates. The attributes honey and tobacco (as well as the related tea attribute) are common in each of the studies carried out (7-11). 

Figure 1 shows part of a reconstructed ion chromatogram of a pineapple aroma extract isolated after incubation of pineapple slices with 3-hydroxyhexanoic acid-3-di. GC-MS detection of deuterated compounds showed that the following pathways are active (a) esterification leading to methyl and ethyl esters, (b) dehydration to (E)-2-and (E)-3-hexenoates, and (c) chain elongation to methyl 5-hydroxy octanoate followed by acetylation (methyl 5-acetoxyoctanoate) and cyclization ( 6-octalactone). 

Figure 1. Part of a capillary gas chronatogram (reconstructed ion detection) of an aroma extract of pineapple tissue, isolated after addition of 3-hydroxyhexanoic acid-3-di (CP Wax 52 CB column,...

The volatiles of fresh pineapple (Ananas comosus [L] Merr.) crown, pulp and intact fmit were studied by capillary gas chromatography and capillary gas chromatography-mass spectrometry. The fnjit was sampled using dynamic headspace sampling and vacuum steam distillation-extraction. Analyses showed that the crown contains Cg aldehydes and alcohols while the pulp and intact fruit are characterized by a diverse assortment of esters, h rocarbons, alcohols and carbonyl compounds. Odor unit values, calculated from odor threshold and concentration data, indicate that the following compounds are important contributors to fresh pineapple aroma 2,5-dimethyl-4-hydroxy-3(2H)-furanone, methyl 2-methybutanoate, ethyl 2-methylbutanoate, ethyl acetate, ethyl hexanoate, ethyl butanoate, ethyl 2-methylpropanoate, methyl hexanoate and methyl butanoate. 

Esters are responsible for the flavors and aromas of many fruits. Pentyl pentanoate smells like ripe apples. Ethyl butanoate has the aroma of pineapples, and 3-methylbutyl acetate smells like bananas although it imparts a pear flavor to foods. Most natural aromas and flavors are mixtures of esters, aldehydes, and alcohols. 

Re, L., Maurer, B., Ohloff, G. A simple synthesis of 4-hydroxy-2,5-dimethyl-3(2//)-fiiranone (Furaneol), an important aroma compound of pineapple and strawberry. Helv. Chim. Acta 1973, 26, 1882-1894. 

Ripe, fresh pineapple has a sweet, acid, slightly biting taste with a fragrant, sweet, fruity, fresh aroma combined with a fruity caramel like aftertaste. 

Cyclopentenolones with a planar vicinal enol-oxo configuration are known to be powerful aroma active substances with distinct caramel notes. By methylation of the enolic function, this flavour impression is changed drastically to a sweet, mildew, and mouldy odour in the case of 2,5-dimethyl-4-methoxy-3-[2H]-furanone (2). This so-called mesifurane as well as pineapple ketone (1) were stereodifferentiated with modified cyclodextrin [103], Although (1) and (2) can be stereoanalyzed without any racemization, both compounds were detected in strawberries, pineapples, grapes and wines as racemates (Fig. 6.43). 

Diplodascus strains of yeast release an intense fruity aroma reminiscent of apple and pineapple in liquid glucose media(44). The peachy aroma emanating from Sporobolomyces is due to the presence of two lactones, gamma-deca, and gamma-cis-6-dodecene lactone(45, 46). 

Natural fruit aromas are mixtures of certain organic compounds and esters. Synthetic aromas prepared in laboratories are simple mixtures of these same esters and organic compounds. They are used in perfumes, foods and drinks to give taste and pleasant smells. Ethyl acetate, for example, is a colorless liquid with an apple flavour it is known as apple ester and is used in perfumery as a fruit essence. Propyl acetate has the smell of pears, isopentyl acetate that of bananas and ethyl butyrate smells of pineapples. All are colorless liquids. Higher molar mass esters are odorless. 

Esters are mildly polar and have pleasant aromas. Many esters are found in natural foodstuffs banana oil (3-methylbutyl ethanoate common name, isoamyl acetate), pineapples (ethyl butanoate common name, ethyl butyrate), and raspberries (isobutyl methanoate common name, isobutyl formate) are but a few... 

Rodin J.O., Himel C.H., Leeper R.M. and Gortner M.A. (1965) Volatile flavor and aroma components of pineapple. Isolation and identification of 2,5-dimethyl-4-hydroxy-3(2/7)-furanone. J. Food Sci. 30, 280 5. 

The consensus aroma description of the Valencia essence oil was that of a prominent, sweet, pleasant orange aroma. It also possessed warm, spicy, fatty and green undertones. In comparison, the aroma of the Early-Mid essence oil was described as green, fruity and fatty with a weak orange character. Both oils were produced at the same commercial facility, using identical equipment and procedures during the same season. Therefore, any observed differences should be solely due to the composition of the respective cultivars. In Florida, early and mid season oranges are primarily from Hamlin, Pineapple and Parson Brown cultivars. 

Properties Colorless to It. yel. liq., pineapple aroma misc. with alcohol, ether insol. in water m.w. 156.23 dens. 0.887 b.p. 75-76 C flash pt. 151 F ref. index 1.4243 Toxicology LD50 (oral, rat) 218 mg/kg, (skin, rabbit) 300 mg/kg poison by ingestion and skin contact human skin irritant mutation data TSCA listed... 

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