125 / 166
Statistical analysis
Data analysis was performed by custom macros using
Excel, Microsoft Office 2013. Statistical significance
was calculated at 95% confidence.
Results and discussion
In-market survey of GF oatmeal
The ‘in-market’ assessment of GF labelled oatmeal
was conducted from July through December, 2014.
Nine hundred and sixty-five servings (
~
45
–
50 g per
serving) were acquired from store shelves. These were
from two well-known US producers and spanned
twenty-one different date codes. The number of serv-
ings obtained per date code varied from a low of ten
up to a maximum of 108 servings.
The survey had two parts, divided by time and
laboratory. The first was comprised of 329 servings
acquired in the summer of 2014. All of these sam-
ples were tested at our internal analytical laboratory.
This is referred to as the ‘7/14 Assessment’
(Table 1). The second part was comprised of 636
additional servings acquired late 2014. These samples
were tested at a recognised external laboratory. This
is referred to as the ‘12/14 Assessment’ (Table 1).
The focus of our in-market survey was to examine
whether the tested samples were in compliance with
FDA gluten regulation (
<
20 mg kg
–1
). So, once we
knew the gluten content of a sample was above or
below 20 ppm, we did not do further analysis. That
was the reason that we did not further dilute sample
extracts with
>
80 ppm readings (upper limit of the
quantification curve of R-Biopharm R7001 ELISA
kit) to obtain the exact gluten contents (Fig. 1 and
Table 1).
The 965 total servings were acquired to characterise
the overall state of affairs of GF oatmeal labelling
compliance at the serving size level and to gain insight
into differences/biases that exist between laboratories,
time frames and producers. In this latter regard, statis-
tical comparisons were made via chi-square contin-
gency tests between laboratories/time frames (‘7/14’ vs.
‘12/14’), between producers (‘Producer 1’ vs. ‘Producer
2’), between the two time frames for each producer
(Producer 1 ‘7/14’ vs. Producer 1 ‘12/14’ and Producer
2 ‘7/14’ vs. Producer 2 ‘12/14’) and between date
codes. No ‘statistically significant’ differences in ‘pro-
portion of servings found noncompliant’ were found.
Consequently, based on this data set, no evidence was
found that the noncompliance rate at the serving size
level differed between these two laboratories/time
frames, producers or date codes.
As Table 1 shows, about 95% of the 965 servings
were found to have a gluten content below the limit of
quantification (BLQ) of the gluten testing kit, R-Bio-
pharm 7001 (i.e.
<
5 ppm). It is worth mentioning that
BLQ results do not equate to true zero results (and as
gluten testing methodologies evolve, lower BLQ levels
will no doubt be achieved). Continuing, 3.21% were
found to be gluten positive but compliant, namely hav-
ing a gluten content from 5 to
<
20 ppm, and 1.76%
were found noncompliant, with a gluten content of
≥
20 ppm. Additionally, 0.62% of the 965 were found
>
80 ppm, which is the quantification limit (ALQ) of
the gluten testing kit. This equates to about one in
every fifty-seven servings exceeding the FDA defined
Table 1
Oatmeal survey results
Product
# of
Date
codes
Qty. of
servings
tested
BLQ
(
<
5 ppm)
5
–
20
ppm
20
–
80
ppm
>
80 ppm
Positives
(
>
5 ppm)
Observed
non
conforming
(
≥
20 ppm)
7/14 Assessment
(Internal
Laboratory tested)
Gluten-free oatmeal
from Producer #1
5
228
Count
216
7
4
1
12
5
% of Total
94.74% 3.07% 1.75% 0.44% 5.26%
2.19%
Gluten-free oatmeal
from Producer #2
2
101
Count
95
4
2
0
6
2
% of Total
94.06% 3.96% 1.98% 0.00% 5.94%
1.98%
Gluten-free oatmeal
from both
7
329
Count
311
11
6
1
18
7
% of Total
94.53% 3.34% 1.82% 0.30% 5.47%
2.13%
12/14 Assessment
(indep.
Laboratory tested)
Gluten-free oatmeal
from Producer #1
6
316
Count
302
6
5
3
14
8
% of Total
95.57% 1.90% 1.58% 0.95% 4.43%
2.53%
Gluten-free oatmeal
from Producer #2
8
320
Count
304
14
0
2
16
2
% of Total
95.00% 4.38% 0.00% 0.63% 5.00%
0.63%
Gluten-free oatmeal
from both
14
636
Count
606
20
5
5
30
10
% of Total
95.28% 3.14% 0.79% 0.79% 4.72%
1.57%
Both studies
Internal and external
studies combined
21
965
Count
917
31
11
6
48
17
% of Total
95.03% 3.21% 1.14% 0.62% 4.97%
1.76%
Bold values indicate % servings noncompliant.
©
2016 PepsiCo, Inc. International Journal of Food Science & Technology published
by John Wiley & Sons, Ltd. on behalf of Institute of Food Science and Technology
International Journal of Food Science and Technology 2016
Kernel-based gluten binary-like outcomes
R. D. Fritz and Y. Chen
3