The main purpose of this study is to determine the hygroscopicity of the food supplement products which contain probiotics and yeast. Measurement is performed by using the water activity meter in the laboratory of Metagenics Belgium. The measured data will be used to keep the Aw-value of the powder mixtures lower than 0,2 during the processing and storage.
A humid environment is a breeding ground for all sorts of microscopic organisms and can also cause physical and chemical changes which will harm the product. The lowest water activity value needed for the growth of mold is 0,6, but bacteria need an Aw-value of 0,8 to be able to grow. High humidity can also promote vitamin inactivation, lipid oxidation and enzymatic/non-enzymatic reactions in a product. Each of the named factors has a specific min/max Aw-value and promoting any of them can reduce the shelf life and the quality.
Before measuring the hygroscopicity or sorption behaviour of a product in function of time, the product is dried. The drying method can be chosen depending on the product. The temperature sensitive powder mixtures are dried by reducing the environment humidity using standard salt with 6% Relative Humidity (RH). The non-temperature sensitive powder mixtures were dried in the oven for two hours at 75°C. Thereafter, the powder gets moistened with 58%/75% RH standard salt.
As the moisture moves from the standard salt to dried product, the water activity of the product will rise and the time will be recorded by the computer.
The tested products, Probactiol Junior Chewable, Probactiol Plus and Probactiol DUO-V2, each showed two deflections on the graph, Nutrimonium-3-0 and Probactiol DUO had only one. The time (in minutes) that powders needed to reach the water activity 0,2 was respectively 18 from Aw 0,096, 31 from Aw 0,104, 127 from Aw 0,036, 24 from Aw 0,084 and 81 from Aw-value of 0,068.
Some products showed deflections on the graph after reaching a certain Aw-value. This is a specific characteristic of each product. The hygroscopicity of a powder mixture is dependent on his composition and presence of polar/non-polar substances. Nutrimonium is the most hygroscopic product due to its composition and probactiol DUO is the least hygroscopic product.
By taking into account the time a product needs to reach a certain water activity, the product can be prevented from exceeding 0,2 Aw-value. This can limit the growth of microorganisms and deactivate components in a product.
- Kolom: Primsep 100 5µm 250mmx4,6mm
- Kolomtemperatuur: 35°C
- Debiet mobiele fase: 0,5mL/minuut
- Injectievolume staal: 10µl
- Temperatuur ELSD: 40°C
- Gasflow: 1,5L/minuut
- Gain: 1
- Looptijd: 25 minuten
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