
Reference Chemistry Limitations and Challenges with Mineral Additives
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Introduction
The testing of animal feeds has great importance in part due
to the raising of various animals for consumption. In order
to obtain the highest quality meats, the diets of the animals
are strictly controlled to maximize their profitability. Obtaining
accurate and repeatable reference results on these animal
feeds is of paramount importance. In the US, animal feed is
tested under AOAC 920.29, an ether extraction method, while
in Europe, it is tested under ISO 11085, an acid hydrolysis
method. This difference in technique often leads to differences
in fat values. The AOAC extraction method utilizes ether as
the solvent and cannot extract any bound fat. Conversely, the
ISO acid hydrolysis method can potentially extract non-lipid
components, thereby inflating the fat values. In addition to the
risk of inaccurate results from under- or over-extraction, both
methods suffer from poor repeatability, caused by the wide and
often changing variety of grains, protein sources, roughage, and
other added minerals that comprise animal feeds.
Since the ORACLE™ was introduced in 2016, it has proven to be incredibly successful in accurately determining fat values in countless applications, without the need for calibration or method development. In several independent studies, the ORACLE has proven to be just as accurate and more precise than the chemical analysis methods for a broad range of applications. However, animal feed samples showed significantly lower results on the ORACLE, compared to reference chemistry methods. To determine the cause of this discrepancy between the two results, several different animal feed certified reference materials (CRM) were sourced and analyzed with the ORACLE, as well as both extraction methods listed above.
Since the ORACLE™ was introduced in 2016, it has proven to be incredibly successful in accurately determining fat values in countless applications, without the need for calibration or method development. In several independent studies, the ORACLE has proven to be just as accurate and more precise than the chemical analysis methods for a broad range of applications. However, animal feed samples showed significantly lower results on the ORACLE, compared to reference chemistry methods. To determine the cause of this discrepancy between the two results, several different animal feed certified reference materials (CRM) were sourced and analyzed with the ORACLE, as well as both extraction methods listed above.
Current Issue
When analyzing animal feeds on the ORACLE, some samples
had lower than expected fat values. Several hypotheses were
considered, most of which centered on a comparison of the
reference methods and rapid techniques. The initial hypothesis
was that the extraction techniques were over extracting nonlipid
components, similar to what has been observed with Whey
Protein Concentrates (WPC).1 Upon testing the CRM animal
feed samples, it was observed that most of the samples
produced results comparable to the reference method with
excellent precision. Certain samples, however, had low results
that were outside of the acceptable statistical range. Upon
analysis of the NMR data, it was discovered that there was a
rapidly relaxing fat signal that corresponded to the difference
between the ORACLE result and the reference technique.
To understand why this portion of the fat signal behaved
differently, a detailed study of the composition of these feeds
was performed.