Essence oils

Essential oils are to be distinguished from the so-called distillates which are ethanol-containing products that are obtained from plant materials by distillation with ethanol or with ethanol-water mixtures. Essence oils are defined as essential oils that separate from the aqueous phase in the distillation receiver during the distillative concentration of fruit juices (usually citrus juices). 

Qtrus oils comprise both essential oils obtained from the peels of citrus fruits and essence oils obtained by concentrating citrus juice (see Section 3.2.1). 

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. 

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. 

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

Lime juice like lemon juice is of less economic value that its peel and essence oils. There are two major cultivars which are responsible for the bulk of lime oil, namely Persian limes and Mexican or Key limes. Mexican or Key lime oils are further separated into two separate classes, type A and type B, depending on how they are prepared. The method of preparation makes a profound difference in their composition. Type A is produced by pricking the peel surface on a needled surface and washing off the oil with water. The water and oil are separated as discussed in Sect. 6.3.1. Type B oil is produced from the distillation of the crushed fruit. Because the oil has come in contact with the hot, acidic juice, acid hydrolysis takes place [48] and this oil contains much higher levels of alcohols than type A juice. 

Isopropanol has been detected in trace quantities in some samples of drinking-water in the United States and as a constitutent of tar-water resulting from the distillation of shale tar. It has also been detected in the volatile fractions of grapefruit essence oil, roasted filbert nuts, lime essence. Reunion geranium oil, Finns densiflora logs and milk products (lARC, 1977). 

ERH. see Equilibrium relative humidity ESI. see Electrospray ionization Essence oils, see specific listings Esterases, comparison to lipases, 371 Esters... 

The following protocols are primarily conducted to ensure the quality of citrus oils during various phases of citrus processing. Citrus processors must account for quality and quantity of citrus oils sold to flavor houses. This not only includes monitoring recovered oils (i.e., cold-pressed oil, essence oil, and J-limonene) but also the total available oil. 

The desired orange flavor is the result of volatile compounds in specific proportions (Shaw, 1991). There are six major contributors to orange flavor acetaldehyde, citral, ethyl bu-tanoate, d-limonene, nonanal, octanal, and a-pinene with two major types of essence oils, early-mid and Valencia (Shaw, 1991). Early-mid oranges include Hamlin and Pineapple. 

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... 

These compositional changes usually negatively influence the odor and flavor of citrus peel oils by generating off-flavor products. It has been shown that nonvolatile residues of citrus peel oil contain some compounds that exhibit antioxidative activities, among which permethoxylated flavones, dehydroabietic acid (46), coumarins, and psoralens have been identified (33). In this respect, cold-pressed citrus peel oil is more stable than distilled oil and essence oil, in which most of the natural antioxidants present are left behind when the oil is distilled (1). 

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. 

The juice oils that are collected during the concentration of fmit juice have generated increasing interest as a valuable source of raw material. These essence oils, also called recovery oil, oil phase or taste oil, correspond mainly to the oil content of the juice vesicles and, depending on the extractive equipment employed, to the varying amount of peel oil which is present in the juice (see 3.2.2.1). 

Also in the essence oil, the characteristic lemon odour is closely associated with citral, an isomeric mixture of neral and geranial. Moreover, the essence oil also features a juicy, earthy, aqueous, refreshing note. 

In contrast to Valencia essence oils, the reduced presence of volatile flavour constituents is significant. 

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

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

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