Arizona Instrument LLC
3375 N. Delaware St. | Chandler, AZ 85225
Tel: (602) 313-0839 | Fax: (602) 281-1745
[email protected]
Maximizing Quality Control in Pet Food
G. Rowe, Lab Manager
Arizona Instrument LLC
Moisture analysis testing is one of the most pervasive test categories across all industries. For pet food manufacturers,
total moisture can be an indication of process quality (dryer efficiency, oven schedule, etc.).
Moisture content can also have a significant impact on the shelf life, nutrition density, and nutrient uptake of a pet food.
Furthermore, moisture content is a major component of the product's mouthfeel and palatability. Even the most nutrient
dense meal means nothing if the pet refuses to eat it.
Total moisture content is not the same as water activity
While the two concepts are usually proportional, they attempt to look at very
different parts of the overall picture. Water activity is concerned with the amount
of water available to sustain bacterial growth. Total moisture content is a
measure of the percentage of the product's total mass is derived from water. As
moisture content increases, water activity normally increases also. Obviously
moisture content can be manipulated by removing water from a system through
drying, or by adding water to a system. Interestingly, the two methods of
manipulation have different effects on the water activity of the material. In
general, at identical moisture levels, a moisture level reached by drying a wet
material will have a lower water activity than a moisture level reached by
humidifying a dry material.
The 3 most common methods to test for moisture are the Oven Test, Karl Fischer Titration and Rapid
Loss on Drying (LOD) Analyzers
So now that the decision has been made to test for moisture, the next question is "What method should I use?" This
question has many potential answers. The three most common methods are: Oven, Karl Fischer titration, and Rapid Loss
on Drying analyzer. Oven loss on drying testing can further be subdivided into loss in weight by heating in a convection
oven, or loss in weight by heating in vacuum oven.
The Oven Test is relatively easy to use but requires long test times
Oven tests are possibly the most ubiquitous tests in the industry. They are
relatively straightforward and easy to conduct. However, oven loss on drying
methods can suffer from low reproducibility if not performed in a completely
consistent manner. In the presence of some preservatives, particularly in the
semi-moist pet food sector, higher temperature LOD analysis is susceptible to
bias due to the evaporation of additional volatile components. Another
downside of oven loss on drying testing is the length of time required for analysis.
Oven tests are typically run for anywhere from 2 to 18 hours. When decisions
about product quality and changes in process need to be made quickly, the time
necessary to conduct these tests is simply unfeasible. In business today time is
money, and this type of cycle time can be expensive.
By Arizona Instrument LLC
Arizona Instrument LLC
3375 N. Delaware St. | Chandler, AZ 85225
Tel: (602) 313-0839 | Fax: (602) 281-1745
[email protected]
Computrac® MAX® 4000XL
Karl Fischer Titration is faster than the oven method, but is complicated to use and requires hazardous
chemical reagents
Karl Fischer titration uses a reaction of iodine with water to
determine moisture content. It typically has better test times than
oven testing, but comes with its own drawbacks. For materials not
directly soluble in the KF analyte solution, the water must be
extracted before testing. Usually this involves methanol extraction
of the sample water. For this type of testing, the producer normally
needs a dedicated lab to perform the analysis. KF titratiors use
fragile glassware and toxic chemicals that are not suitable for a
production floor. Finally, after the analysis consideration must be
given to how to dispose of the spent chemicals.
Rapid Loss on Drying Analyzers are easy to use, fast and do not require chemical reagents or expensive
glassware
Rapid loss-on-drying analyzers come in many shapes and forms. They offers the best of both worlds: fast results with no
toxic chemicals that require disposal. Results are typically obtained in less than 10 minutes and there is no lab requirement
for analysis - meaning that, for most materials, the analysis can be performed right on the production floor. Rapid LOD
instruments do, however, require parameters that are specific to the product being tested.
One academic study that reviewed 20 years of data concluded that for the most commonly used standard oven testing
method in the pet industry, using the same sample, results ranged from 61% to 331% recovery.[1] This wide range of results
underlines the great difficulty in getting these analyses right, even by the experts. What's needed is the simpler method
offered by a rapid loss on drying analyzer. The instrument does most of the heavy lifting, which means more reproducible
results between operators and sites. However, as noted earlier, for accurate results a rapid LOD analyzer requires
parameters that are specific to the material under test. Therefore the ideal solution is an instrument manufacturer who
will partner with the producer to develop optimal parameters for their products. Enter Computrac®, by Arizona Instrument
LLC.
Computrac® offers improved rapid loss on drying technology and
support
The Computrac® MAX® 4000XL moisture and solids analyzer, manufactured by
Arizona Instrument LLC, is a thoroughly modern rapid loss on drying (LOD)
instrument that is sensitive enough to detect moisture loss at parts per million
levels, and rugged enough to move out of the lab and onto the production
floor. It is easy to operate and delivers fast, accurate results. Furthermore,
Arizona Instrument LLC supports its customers with free parameter
development for the lifetime of the instrument. The parameters developed in
the laboratory at AZI correlate to the test results produced by oven or Karl
Fischer titration, but without using harmful chemicals or reagents.
References:
1) Thiex, N and Richardson, C. R. 2003. Challenges in measuring moisture content of feeds. J Anim Sci. 81v12:3255-3266
Maximizing Quality Control in Pet Food
Moisture analysis testing is one of the most pervasive test categories across all industries. For pet food manufacturers, total moisture can be an indication of process quality (dryer efficiency, oven schedule, etc.). Â Download this white paper to learn more.
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