Determination of water content in tea samples of Cymbopogon citratus S., Matricaria recutita L., Mentha spp. and Pimpinella anisum L. through Gravimetric and Thermogravimetric methods

Abstract

The excess of humidity in materials of plant origin allows the action of enzymes, which can cause degradation of chemical components and enable fungi and bacteria development. The humidity determination is one of the most important and most used measurements in food analysis, as it is tightly related to food quality, stability and composition. Teas are among humanity’s most popular and most broadly diffused drinks, being the most common form of phytoterapeutical products and a natural source of chemical substances with activity against a broad variety of ailments. Humidity determination in teas of Cymbopogon citratus S., Matricaria recutita L., Mentha spp. and Pimpinella anisum L was performed through pharmacopoeia-standards gravimetric analysis, drying by infrared radiation and thermogravimetry, and the results obtained by each method were compared. All humidity indexes obtained were in accordance with the currently available official specifications. Water content values obtained by the pharmacopoeia-standards assay, infrared radiation assay and thermogravimetry presented statistical difference between them, due to the methods’ technical features or the utilized materials’ physical characteristics; still the thermogravimetry and the infrared radiation assay were the methods that presented the least statistical difference between their results. The pharmacopoeia-standards method presented itself as the more adequate method for the determination of water content in materials of plant origin, like teas.