Citms essences

This method allows the fractionation of citms oils based on the different polarity of terpene and aroma fraction ]20, 21]. Their different adsorption characteristics on stationary phases can be employed for the selective separation of these complex mixtures of natural substances. The method originates from analytical laboratory techniques and its application on various stationary phases is realised industrially today ]22, 23]. Adsorption on stationary phases and their subsequent desorption with various solvents is possible for different adsorption materials. Also partition chromatographic methods play an important role in citms flavour concentration processes, especially for aqueous citms essences. 

Essences generally are stored separately from the bulk concentrates for stabiHty, and their addition prior to retail packaging is essential to restoring much of the natural fresh flavor of the starting juice otherwise lost during processing. Unlike citms, which affords both an aqueous and an oil-phase essence, only an aqueous-phase essence is obtained for deciduous fmit. Virtually no essential oil is present in the peel or juice in the latter. 

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. 

There is considerable interest in the chemical composition and properties of citrus oils and essences as well as the role they play in food and nonfood industries. Citrus peel oils and essences possess a pleasant aroma, with oxygenated compounds being the major constituents that account for their characteristic odor. Terpenes, the most abundant components in cold-pressed citms peel oil, are removed in concentrated oil production, usually by use of adsorbant and supercritical carbon dioxide, to increase the concentration of oxygenated compounds and to enhance the qualification of the oil. Meanwhile, citms seed oils are composed largely of triacylglycerols and are rich in oleic and linoleic acids. 

Citms oils and essences are unstable to heat, light, oxygen, and metals. Thus, they should be stored under appropriate conditions in order to avoid compositional changes that lead to their quality deterioration. Citms oils and essences are widely used in food and nonfood industries. Applications in the health-related areas are forthcoming. 

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. 

---