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Augustus 2015
104
RELEVANT
With gratitude to the Maize Trust for financial support of these annual surveys and to the members of Agbiz Grain and
DAFF inspectors for providing the crop and imported maize samples respectively.
The fat content of white maize was slightly lower (0,1%) than the
previous season and 0,2% higher than that of yellow maize. The
protein content of white maize was equal to that of yellow maize
(8,6%). The starch content of both white and yellow maize is higher
than the previous season by 1,5% and 1,2% respectively.
Genetic modification (GM)
The SAGL used the EnviroLogix QuickComb kit for bulk grain to
quantitatively screen 100 of the crop samples for the presence of
the Cry1Ab, Cry2Ab and/or CP4 EPSPS traits. 96% of the samples
tested positive for Cry1Ab, 90% tested positive for the Cry2Ab and
94% for the CP4 EPSPS trait.
Mycotoxins
Mycotoxin levels in grain are governed by two laws in South Africa:
The Foodstuffs, Cosmetics and Disinfectants Act, 1972 (Act No. 54
of 1972) and the Fertilizers , Farm Feeds, Agricultural Remedies and
Stock Remedies Act, 1947 (Act No. 36 of 1947). The first prescribes
maximum levels for only total aflatoxin and aflatoxin B
1
in food for
human consumption. The latter prescribes maximum levels for
aflatoxin B
1
, deoxynivalenol (DON), fumonisin B
1
, ochratoxin A and
zearalenone in farm feeds (12% moisture content) according to the
type and age of animal the feed is intended for.
None of the 350 samples tested positive for aflatoxin, ochratoxin A,
HT-2 or T-2 toxin residues.
The average fumonisin level (sum of B
1
, B
2
and B
3
) on all 350 samples
tested was 186 μg/kg (ppb) and ranged from 0 (not detected [ND])
to 5 357 μg/kg. This average is lower than the previous season’s
257 μg/kg. Of the 350 samples tested, 143 samples (41%) tested
positive for fumonisins and the average of these positive results
was 456 μg/kg.
In the previous season, 45% of the samples tested positive, with
an average of 571 μg/kg. Only one sample’s total fumonisin level
was higher than the lowest maximum level allowed for fumonisin B
1
,
namely 5 000 μg/kg for horses and pets, according to amendments
published in Regulation No. R. 70, dated 12 February 2010 of Act 36
of 1947 Fertilizers, Farm Feeds, Agricultural and Stock Remedies.
All of the fumonisin B1 levels were well below this limit.
The highest deoxynivalenol (DON) level detected was 6 134 μg/kg
compared to the 617 μg/kg of last season. The average level of
all samples tested this season was 289 μg/kg; 21 μg/kg the pre-
vious season.
9% of the samples tested positive for DON last season compared
to 69% this season. The average of the positive results increased
from 225 μg/kg in 2012/2013 to 417 μg/kg in 2013/2014. The maximum
DON levels allowed according to Regulation R. 70, range from
1 000 μg/kg for pigs and pets to 5 000 μg/kg for cattle. Fifteen of
the samples had levels higher than 1 000 μg/kg, of which two was
between 2 000 and 3 000 μg/kg and only one exceeded the maximum
level of 5 000 μg/kg.
17% of the samples tested positive for 15-acetyl-deoxynivalenol
(15-ADON) residues, the average of the positive results was
182 μg/kg. Only one sample tested positive the previous season.
Zearalenone residues were found in 12% of the samples, values
ranged from 0 (ND) to 445 μg/kg. The average of the positive
samples was 78 μg/kg compared to the 31 μg/kg of the previous
season when 2% of the samples tested positive. None of these
values exceeded the lowest maximum content for zearalenone
namely 500 μg/kg for cows and dairy cattle. A sample is seen
as having tested positive when the value exceeds the lowest
concentration level that can be quantified with acceptable precision
and accuracy by the mass spectrometer instrument used by
the SAGL. For the fumonisins and zearalenone, these levels are
20 μg/kg and for DON 100 μg/kg. The 2013/2014 average concen-
tration levels of fumonisin and DON in South African commer-
cial maize are six times lower than the average concentrations
reported in maize in the 2014 Biomin Mycotoxin Survey report
(
www.biomin.net).
Mycotoxin results over seasons
The annual maize crop quality surveys provide an ideal opportunity
to evaluate the occurrence status of mycotoxins throughout all
production regions in South Africa. For the 2010/2011 season, a
total number of 325 samples were analysed for mycotoxin residue
levels. From the 2011/2012 to 2013/2014 seasons, 350 samples
were analysed annually. The samples were selected to represent
all the production regions as well as both white and yellow maize
proportionally.
Locally
Locally, fumonisin and DON were found in samples from all the
maize producing regions. Different patterns of occurrence are
observed in different seasons. Mean concentration levels also differ
over seasons. Fumonisin tends to show higher mean concentra-
tions on yellow maize compared to white maize from the same
region. DON shows higher mean concentrations on white maize
than yellow maize from the same region. Zearalenone mean
concentrations tend to show better correlation between white and
yellow maize from the same region than fumonisins and DON.
Maize imported and exported during the
2013/2014 production season
A total of 79 673 tons of yellow maize was imported from the
Ukraine during the 2013/2014 season (27 April 2013 to 25 April
2014). Five samples of imported maize were received at the SAGL
for quality analysis purposes. One of the samples was graded
YM2 and four of the samples YM3, according to South African
grading regulations. The main grade determining factor was the
percentage of defective kernels below the 6,35 mm sieve.
The percentage of stress cracks observed on the imported maize
is significantly higher than that of local maize. Breakage suscept-
ibility showed the same trend as can be expected. The imported
maize kernels were on average smaller than locally produced maize.
Protein results between imported and local maize compared well.
South African maize of corresponding grades had lower fat and
starch contents on average. The imported maize tested positive for
fumonisin B1, deoxynivalenol and HT-2 toxin. None of these levels
raised any concern.
During the season under review, 925 925 tons of white maize
and 1 129 938 tons of yellow maize were exported to both Africa
and overseas. The Maize Trust investment in the annual crop
quality and imported maize quality surveys has created unique and
extremely useful databases of quality measurements over several
seasons, regions and countries of import.
The detailed results are available on the SAGL website (
www.
sagl.co.za
). The annual crop quality reports in PDF format are also
available to download from the website.
A look at the maize crop quality of the 2013/2014 production season