INTRODUCTION
During the IFEAT International Congress on Aromas and Essential Oils on 19-23 October 1997 in Seville (Spain) BACIS presented a lecture entitled "Production, Chemistry and Sensory Properties of Natural Isolates". A summary of this lecture is given below.
SUMMARY
Natural isolates may for instance concern distilled essential oils, cold-pressed oils, extracted oleoresins, concretes and absolutes, plant - or animal exudates, and tinctures. The main aspects of the production of these isolates are the preparation of the plantmaterial, the isolation methods, the yields and economics and the quality control.
The preparation of the plantmaterial may concern e.g.: harvesting, threshing, chipping, drying, grinding, hydrolysis and fermentation. During these preparations various volatile compounds, such as unsaturated aliphatic alcohols and aldehydes, mono- and sesquiterpene oxides, coumarins, polyfunctional benzenoids and irones, can be formed.
Citrus oils can be produced by expression, such as the Italian pellatrice and sfumatrice methods, the American Brown oil extractor, and the FMC apparatus. The biogenesis of limonene in citrus oils will be discussed. Leaf, seed and flower oils are manufactured by steamdistillation, hydrodistillation and hydrodiffusion. The production of mint oil, bitter orange leaf & flower oil and rose oil will be shown. The chemistry of the olfactively character-impact compounds in these oils will be demonstrated. Biogenesis of the following characteristic compounds in Mentha species will be discussed: menthone and menthol in peppermint and cornmint, carvone in spearmint, menthofuran in watermint, pulegone in pennyroyal.
Other natural isolates, such as oakmoss absolute, treemoss absolute and labdanum gum are manufactured by solvent extraction, and for instance rose and bitter orange flower oils can be produced by supercritical fluid carbondioxide extraction. The formation of volatile compounds, such as amberoxide etc., by acidic photochemical oxidation on the labdanum plants will be discussed. Modern continuous distillation and extraction processes are practised today.
Yields and economics of volatile naturals will be commented. Ranges and anomalies in the yields are noticed. Scope and limitations of the economics, such as raw material, capital, energy and labour costs will be discussed.
The physico-chemical standards for many volatile natural isolates oils have been published. The analyses of rose oils and bitter orange flower oils by modern spectroscopic techniques will be treated. The odour intensities of the oils were determined.
Reprinted by Leffingwell & Associates, 2006, with Permission