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Water Acvity E.R.H % Wall Guide

aW

Why measure water acvity ? • • •

Water ac$vity ( Equilibrium % Rela$ve Humidity ) is the free moisture available. Water ac$vity is scaled 0 -1 aw or 0- 100 % ERH . Water ac$vity can determine the quality of your products or ingredients as a tool for micro – growth poten$al, stability, texture , taste and shelf-life Quality Control measures.

e.r.h %

Taking reliable readings : • • • •

Always let warm or cool samples reach room temperature before opening ! Ensure samples are homogenised (crushed, s$rred or mixed-up evenly). Prepare samples in the plas$c cups provided and fill to approx. 2/3 full. Maybe you could write up a simple test procedure (SOP) ?

• • • •

Calibrate against the re- useable SAL-T salt tablets at least every 2 months. Change the sensor protec$ve filter ( EVC21) every 2 months at least . Keep the sensor chamber clean and free of sample build up. Ensure that rou$ne maintenance and calibra$on is carried out by Novatron .

Calibraon & maintenance :

What readings to expect :

0.6 aW

0.1 aW

0.75 aW

0.8 aW

0.93 aW

0.85 aW

0.98 aW

Microbiological growth potenal ( spoilage ) : WAT E R A C T I V I T Y C H A R T %RH a w Va l u e s

10 .1

20 .2

Growth limits of micro-organisms

30

.3

40 .4

50 .5

60 .6

70 .7

90

80 .8

le le ile hi st hi ph s op st lop eria Mo ngi ro ld fu Xe ou Orm Yea Ha act M B

.9

t os t M eas y

Novatron Scientific Ltd, 46 London Rd, Horsham, West Sussex RH12 1AY . T 01403 754416 F 01403 754480. sales@novatron.co.uk www.novatron.co.uk UKAS laboratory no. 0669 . ISO 9001 : FS540804

100

1.0

t os ia M cter Ba

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