Report No xxxx - Instytut Fizyki JÄ drowej PAN

INVESTIGATION OF PROPERTIES OF FRESH
AND COMMERCIAL ALOE SAP BY NMR SPECTROSCOPY
D. Lewandowska, T. Podoski*, C.J. Lewa
Institute of Experimental Physics, University of Gdańsk, ul. Wita Stwosza 57, 80-952
Gdańsk; * Maritime Academy, ul. Morska 83, 81-225 Gdynia
Abstract
Aloe, as a medicinal plant, is well known to man since time immemorial. Aloe (Liliaceae
Juss) is a perennial evergreen succulent from the lillaceous family with an extraordinarily
rich composition. An aloe vera leaf contains more than 200 biologically active compounds
that have anti-inflammatory, wound healing, analgesic and anti-arthritic activity. The three
main components are glucose and/or mannose (a monomeric sugar constituent), malic acid
(a preliminary stage for sugar in the plant’s organism), and the polysaccharide acemannan,
the core of aloe. After the aloe leaves have been harvested, the lactobacillus causes lactic
acid fermentation to occur. During this process lactic acid – not a natural component of aloe
– is produced. Further substances that are produced by enzymes typical of aloe in the socalled
citric acid cycle are fumaric acid , succinic acid and pyruvate.
The citric acid cycle is interrupted after the harvest takes place but some of enzymes
continue to work on, thus enriching these compounds. Besides the enzymatic decomposition
and fermentation, there is also a chemical decomposition, during which the polysaccharide
releases acetate groups and producing acetic acid. Preservatives should be added to liquid
aloe products to guarantee their stability and avoid chemical and enzymatic degradation.
These additives should be declared in the list of constituents on the product label.
Earlier preliminary investigations of the changes in viscosity and relaxation times of aloe
tissues and juice demonstrated the usefulness of the nuclear resonance method in
observation of time effects and hypothermia.
The present work comprises the results of time and temperature studies of 1H NMR
spectra of fresh and commercial aloe juices . The aim of the studies was to determinate the
effect of selected physical factors on the stability of the fresh and commercial aloe sap.
For fresh aloe saps some distinctions in the NMR spectra have been observed. The results
have shown biological, chemical and enzymatic degradation of the natural aloe juice. In
opposition to fresh sap the spectra of commercial liquids not to be altered during the time
and temperature measurements.
Most of preservatives, sweeteners and fillers added to aloe sap were detectable in NMR
spectra. Spectroscopic data allow the identification of the auxiliary substances added to
commercial products. The method of analysis of 1H NMR spectra seems to be fruitful in
detection of any non-aloe constituents and also in purity and quality control of aloe products.
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