Asked by: Ouardia Zini
asked in category: General Last Updated: 2nd April, 2020

How do you calculate relative humidity from water activity?

Water activity is equal to equilibrium relative humidity divided by 100: (a w = ERH/100) where ERH is the equilibrium relative humidity (%). Relative humidity sensors of great variety are available for this purpose, including electric hygrometers, dewpoint cells, psychrometers, and others.

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Also asked, how is water activity related to relative humidity?

When vapor and temperature equilibrium are obtained, the water activity of the sample is equal to the relative humidity of air surrounding the sample in a sealed measurement chamber. Multiplication of water activity by 100 gives the equilibrium relative humidity (ERH) in percent.

Also Know, what water activity is ideal for dried foods? Dried fruits The majority of microorganisms that cause spoilage or foodborne disease grow well in foods with a water activity (Aw) of 0.91 to 0.99.

Herein, how do you measure water activity in food?

Instead, water activity is measured by placing the sample into a closed chamber and equilibrating the liquid-phase water in the sample with the vapor-phase water in the headspace and measuring the relative humidity of the headspace.

What does low water activity mean?

Unbound water will exert vapor pressure which can be used to determine microbial spoilage, chemical, and physical stability. In relation to cupcakes, a water activity measurement of 0.5 or lower would mean the likelihood of microbial growth is very low.

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