Orange essence oil

Production of Citrus Essence Oils. Distillative concentration of citrus juices yields essence oils, which separate from the aqueous phase in the receiver when the distillate condenses. The composition of essence oils is similar to that of peel oils, but the essence oils usually contain larger quantities of aliphatic ethyl esters (e.g., ethyl butyrate in orange essence oil). Thus, their aroma resembles that of a particular juice more than that of peel oils. 

Compositional analysis of orange essence oil from Florida was reported by Moshonas and Shaw [23] and more recently by Hognadottir and Rouself [24]. 

Table 3.23 Main components (%) of orange essence oils...

Orange Essence Oils JSA [98] Brazil [48] Blood Orange Essence Oil Italy [48]... 

GC-O and GC-FID Comparison between Early-Mid Season and Valencia Orange Essence Oil... 

Three sensory judges with over 45 years combined citrus experience described the aroma characteristics of the two types of orange essence oil. The undiluted oil was presented on perfumers wands and free choice descriptors were allowed. 

Figure 1. Comparison ofgas chromatograms (polar separation) of commercial Valencia orange essence oil (lower solid line) and that of Early-Mid orange essence oil (upper dashed line). The Early-Mid essence oil is offset and shifted...

Figure 2. Comparison of the major aroma intensity differences between Valencia and Early-Mid season orange essence oils. Peak identification numbers from Table I.

Some of the data is difficult to explain. For example, m-cresol (peak 26) has a pronounced negative aroma character and was found only in the Valencia oil. Despite these difficulties, much of the observed quality differences between Valencia and Early-Mid season orange essence oils can be explained from the lack of positive aroma components in the Early-Mid season oil and the presence in Early-Mid of aroma components which are not particularly positive. 

Distillation of citrus juices yields two volatile fractions, namely, aqueous essences and essence oils that are separated from each other by condensation of the distillate (7). Aqueous essence, the bottom layer of the condensate is comprised of organic acids, alcohols, aldehydes, esters, hydrocarbons, ketones, hydrogen suthde, and oxides (10). Considering many components found in both cold-pressed peel oil and aqueous essence, essence oil has a flavor similar to that of flie combined peel oil and aqueous essence (10). However, essence oil usually contains a larger amount of aUphatic ethyl esters (e.g., ethyl butyrate in orange essence oil) compared with the peel oil (41). Thus, its aroma resembles that of the corresponding juice more than that of the peel oil (7). In general, citrus flavor results from a complex mixture of components in the appropriate proportions (42). 

Because of its excellent flavor properties orange essence oil is a valuable raw material for the creation of flavors and perfumes. Numerous studies on orange essence oil have already been performed to determine the composition of the volatile fraction [1,2]. These studies indicated hydrocarbons, especially limonene, as the most abundant compounds, accounting for more than 97% of the volatile fraction. The other 3% are aldehydes, esters, ketones, and some other oxygenated compounds (Table 1). However, none of these studies tried to evaluate the flavor impact of single-flavor compounds identified in the orange essence oil. 

This study describes the evaluation of the most potent flavor compounds of orange essence oil by AEDA and the enrichment, purification, and identification of new flavor compounds that have not been described for orange flavor. 

Different orange essence oils originating from Florida and Brazil were sensorially evaluated. The oil with the highest quality in freshness, sweet fruitiness, and juiciness originating from Brazil was selected for the investigation. For analysis the essence oil was diluted with diethylether by a ratio of 1 25. 

For the enrichment and purification of unknown compound II, the hydrocarbons of about 20 kg of orange essence oil were removed by column chromatography on silica gel. Subsequently the compound occurring in fraction II was further purified by two-dimensional preparative capillary gas chromatography. Interpretation of the resulting mass spectra finally led to the identification of 8-tetradecenal. The mass spectrum is shown in Fig. 2. 

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