Aqueous essences

There are two methods available for aroma recovery. In one method, a portion of the water is stripped from the juice prior to concentration and fractionally distilled to recover a concentrated aqueous essence solution. Apple juice requires 10% water removal, peach 40%, and Concord grape 25—30% to remove volatile flavor as an essence. Fractional distillation affords an aqueous essence flavor solution of 100—200-fold strength, which means the essence is 100 to 200 times more concentrated in flavor than the starting juice. A second method of essence recovery is to condensate the volatiles from the last effect of the evaporator they are enriched in volatile flavor components (18). 

Essence oil and aqueous essence (sometimes called aqueous aroma) are both formed from the condensate from steam distillation/evaporation of citrus juices. These products consist of volatile juice compounds and do not contain non-volatile pigments. 

Later, the chemical characterisation of the volatiles from yellow passion fruit essence and from the juice of the fruit was done by GC-MS and GC-olfactom-etry (GC-O) [27]. Esters were the components found in the largest concentrations in passion fruit juice and essence extracted with methylene chloride. Analysis by GC-O yielded a total of 66 components which appeared to contribute to the aroma of passion fruit juice and its aqueous essence. Forty-eight compounds were identified in the pulp of Brazilian yellow passion fruits (Passiflora edulis f. flavicarpa) [48]. The predominant volatile compounds belonged to the classes of esters (59%), aldehydes (15%), ketones (11%), and alcohols (6%). 

Citrus essences are distilled aqueous solutions of the more volatile components from the corresponding citms juices, as defined by Shaw (10). Commercially, they are added to concentrated citms juices to impart fresh fmit flavor that may be lost during the concentration process. Essence may be collected from fresh juice either by partial distillation prior to juice evaporation or by condensation of volatiles from the early stages of evaporation (11). Two phases, namely, aqueous essence and essence oil, are obtained during recovery. 

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 sulfide, 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 the combined peel oil and aqueous essence (10). However, essence oil usually contains a larger amount of... 

The production and concentration of juice lead to downstream products such as peel oil, essence oil and aqueous essence (see 3.2.2.1). All three products constitute important raw materials for the flavour industry. The relationship between the three products - depicted in Fig. 3.13 for the example of orange - shows that peel oil constitutes the major product. It is commercially available as cold pressed oil , as it is the result of a cold pressing process which is applied during juice production. The cold pressed peel oil corresponds to the oil content of the oil glands in the citms fmit s peel (see Fig. 3.14). This type of oil is available for all citms varieties. 

Apart from the taste oils, the aqueous essences synonymously called aroma, water-phase, waterphase aroma or essence waterphase are also retained as part of the aroma recovery during juice concentration. Their flavouring potential is mainly used in reconstituted fmit juices. On the one hand, the watery environment exerts a negative... 

The most simple sample preparation technique is direct gas chromatographic injection of an aqueous essence on a bonded fused silica column. This technique may be employed when aqueous distillates are available. For example, Moshonas and Shaw ( 31) described a method for the analysis of aroma constituents of natural fruit essences. The essences were collected from the first stage of an evaporator and the essence injected directly into a capillary gas chromatograph. 

Yet another valuable flavor product of citrus fruits is the essence oil. The favored method for the transport of citrus juice is in the form of a frozen juice concentrate. The fruit juice is partly dehydrated by distilling off under vacuum the greater part of the water and frozen. Distilling off the water results in significant losses of the desirable volatiles responsible for the aroma of the fruit. These volatiles are captured in several cold traps and constitute the aqueous essence or essence oil that has the typical fruity and fresh fragrance, but slightly less aldehydic than that of the oil. This oil is used to enhance the flavor of the reconstituted juice obtained by thawing and dilution with water of the frozen concentrate. 

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