Citrus essences

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. 

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. 

They stressed that the availability of fused silica capillary columns coated with cross-linked non-polar liquid phases permitted development of this technique. Such columns resist the deterioration which was previously encountered with aqueous samples. These authors applied this technique to several citrus essences as well as to fruit essences such as grape, apple and strawberry. 

Belletti, N., M. Ndagijimana, C. Sisto et al., 2004. Evaluation of the antimicrobial activity of citrus essences on Saccharomyces cerevisiae. J. Agric. Food Chem., 52 6932-6938. 

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). 

Essential oil, also defined as essence, volatile oil, etheric oil or aetheroleum, is a complex mixture of volatile constituents biosynthesised by living organisms. Essential oils can be liberated from their matrix by water, steam and dry distillation, or expression in the case of citrus fruits [1-5]. Their occurrence and function in nature is still a question and the subject of ongoing research. However, there is evidence that organisms produce essential oils for defence, signalling or as part of their secondary metabolism. As a consequence essential oils comprise an important bio resource for renewable natural products [1-25]. 

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. 

Limonene is a monoterpene that occurs in citrus fruits. Two enantiomers of limonene produce two distinct flavours (—)-limonene is responsible for the flavour of lemons and (+)-limonene for orange. Similarly, one enantiomeric form of carvone is the cause of caraway flavour, while the other enantiomer has the essence of spearmint. 

The use of terpenoids, usually as mixtures prepared from plants, dates from antiquity. The several essential oils produced by distillation of plant parts contained the plant essences. These oils have been employed in die preparation of perfumes, flavorings, and medidnals. Examples are oils of clove (local anesthetic in toothache), lemon (flavoring), lavender (perfume), and juniper (diuretic). Usually essential oil production depends on a simple technology which often involves steam distillation of plant material The perfume industry of Soudiem France uses somewhat more sophisticated procedures in the isolation of natural flower oils since these oils are heat sensitive. The separation of oils from citrus fruit residues m California and Florida is done by machine. 

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. 

A flavouring essence is a traditional flavouring product prepared by washing a selected oil blend (predominately citrus oils) with an aqueous alcoholic solvent mixture (e.g. 60% ethanol/40% water). It is an extraction process in which the aqueous extract phase becomes the flavouring. The process is earned out under cool temperatures, for example, 5-10°C, either batch-wise or by counter-current extraction. The soluble oxygenated flavouring constituents present in the essential oil blend (e.g. citral in lemon oil) are effectively partitioned between the two phases of the mixture. The low temperatures employed ensure that the transfer of any oil into the hydro-alcoholic phase is minimised as a poorly processed essence will tend to cloud when used in the drink formulation. 

Juice Cloud. Mechanical extraction of citrus fruits yields a turbid suspension of wall fragments and cellular organelles in a serum composed primarily of cell vacuolar fluids. In most citrus juice products, such a suspension of fragments and organelles is a desirable component, since it provides most of the characteristic color and flavor (28). Essence and peel oils suspended in juice contribute desirable citrus notes to flavor, and these oils are rapidly adsorbed by juice particulate material shortly after extraction (29). 

The alert panel supervisor will also come to know about each regular panelist s ability to detect the many off-flavors that could possibly occur in citrus products. Of primary concern, other than the common sweet and sour flavor attributes, are the panelists abilities to specifically identify (a) bitterness (naringin and/or limonin induced), (b) heated, processed or pumpout off-flavor, (c) excess peel oily, (d) excess and/or poor essency flavor, and (e) the following off-flavors cardboard, tallowy, castor oil, diacetyl or buttermilk, green or immature, overmature or stale fruit, and spoiled fruit. 

The major problem in sensory evaluation of citrus products containing essence appears to lie mainly in individual preferences as regards essence-add products and individual thresholds for the essence fraction in these products. A significant number of regular, trained panelists at AREC, for example, upon detection of certain essences in citrus products might grade the pro-... 

Serving temperature has not been shown to affect flavor in essence-bearing citrus products. However, if temperature was found to be or suspected of being a significant factor, serving temperature of samples destined for preference-type sensory evaluation should be made at temperatures at which the product would normally be consumed (presumably about 7-13°C). 

There are many applications where the organic compounds are extracted from natural materials. Extraction is used for preparation of pure flavor essences from expressed oils of various citrus fruit. Pyrethrum is recovered from pyrethrum flowers by solvent extraction. A continuous saponification, glycol extraction, and splitting process for converting fat into finished soap base has been used in soap production. 

Fereidoon Shahidi Memorial University of Newfoundland, St. John s, Newfoundland, Canada, Antioxidants Regulatory Status, Antioxidants Science, Technology, and Applications, Citrus Oils and Essences, Dietary Fat Substitutes, ... 

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