Document Type Master's Dissertation Author Terblanche, Francois Cornelius email@example.com URN etd-09062001-100658 Document Title Die karakterisering, benutting en vervaardiging van produkte herwin vanuit Lippia scaberrima Sond. (Afrikaans) Degree PhD(Ing.Chem) Department Chemical Engineering Supervisor
Advisor Name Title Gerrit Kornelius Keywords
- Lippia scaberrima
- essential oil
- water distillation
- continuous microwave distillation
- physical properties
- herbal tea
- batch microwave distillation
- chemical properties
Date 2001-09-07 Availability unrestricted AbstractThe genus Lippia Houst. (family Verbenaceae Juss.) has been used medicinally for centuries in various cultures. Numerous traditional medicinal applications of the South African Lippias are known, and among these is Lippia scaberrima Sond., the "Beukesbossie". Products recovered from L. scaberrima include essential oils by means of batch microwave distillation and a herbal tea manufactured by various methods.
Microwave heating occurs through direct absorbtion of input energy. The whole sample is heated simultaneously with a heating rate much faster than for water distillation. Microwave distillation times can be expected to be less than corresponding water distillation times.
A large number of parameters influence essential oil composition and yield. Various geographical, climatic, botanical, production and other parameters were identified and listed.
The natural distribution of airdried leaves and flower heads and water as solvent was used in a domestic type microwave oven. Microwave distillation production parameters were studied and optima determined with respect to maximum oil yield. The batch microwave distillation production parameters studied (irradiation time, ratio of water used to plant material used, plant material moisture content, solvent recycling, physical size of plant material, addition of a surface tension modifier, soaking as pretreatment, load size, distillation kinetics and alternative solution medium namely ethanol) lead to a better understanding of microwave essential oil production. It enabled design of prototype continuous microwave distillation apparatus.
Mobile, continuous microwave distillation equipment enables extraction of essential oils in a rural environment. It allows rapid investigation of a large variety of plants, and retrieval of essential oils in an economical and uncomplicated manner.
Water distillation represents a classical technique for essential oil retrieval whereas microwave distillation is probably the most modern method. Physical and chemical properties of microwave and water distilled oils were determined. This enabled comparison of the microwave technique to a standard, industrially accepted production method.
Tea was manufactured from L. scaberrima by means of the green tea, Rooibos tea and black tea methods as a first iteration in the production of a commercial tea. Drying curves was developed as well as appropriate regions of production variables like withering- and fermentation temperatures and times.
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