Ochratoxin A in Cocoa by cvuas


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Residues of Ochratoxin A in Cocoa – Investigations
from 2012

Report from a day in the lab

                                                     In 2012 cocoa samples (powder
                                                     and        paste)         taken         from      the
                                                     administrative districts of Stuttgart
                                                     and Karlsruhe were analyzed at
                                                     CVUA Stuttgart for the presence
                                                     of Ochratoxin A (OTA). A total of
                                                     21       samples            were         analyzed,
                                                     including            3        from           organic

          There are no maximum residue limits (MRL) established for cocoa
          and its products at either the EU or the national level.
          No Ochratoxin A was detected in the three samples from organic
          production. However, because the number of samples analyzed
          was so low, the findings are not representative.
          Only one of the samples from conventional cultivation contained no
          Ochratoxin A. The remaining 17 samples contained an average of
          0.93 µg/kg; the highest amount detected was 1.6 µg/kg.

Since there is no EU- or German established Maximum Residue Limit
(MRL) for cocoa, MRLs for some other foods covered by the EU regulation
1881/2006 can be applied to cocoa as a reference. Roasted coffee, for
example, with an MRL of 5 µg/kg for Ochratoxin A, could be closely com-
pared with cocoa powder. The MRL for cereals and cereal flours is 3
µg/kg and for dried wine grapes, 10 µg/kg.                    These values could be used
as an orientation for, e.g. bitter chocolate, although one must keep in mind
that cereal products are consumed in much greater quantities.

On the basis of our findings, we are therefore pleased to report that the
residue situation with reference to OTA in cocoa is very positive.

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Ochratoxin A is a mycotoxin that is formed from various species of genus
penicillium und aspergillus, which are found throughout the world in na-
ture. When plant-based foods are stored under inadequate conditions, in
contrast to the Aflatoxin species, toxins can develop, even in moderate
climate zones. OTA occurs almost exclusively in plant-based foods such
as cereals, legumes, coffee, beer, wine grapes and their products (e.g.
dried wine grapes, red grape juice, and red wine), cocoa, nuts and spices.
The long half-life of OTA in animal and human organisms is problematic.
After the consumption of contaminated products the process of eliminating
the toxins from the body is very slow. According to present knowledge,
OTA is considered to be especially damaging to the kidneys and is immu-
nosuppressive. Animal studies have shown OTA to have carcinogenic
and teratogenic effects. The International Agency for Research on Cancer
(IARC) has categorized OTA as a probable carcinogen for humans.


  Cocoa Trivia

  Cocoa (also called cacao) comes from the cacao tree in the form of beans, which can also be
  ground into powder. The cacao tree is a long, thin tree with flat, narrow leaves reaching as long
  as 35 cm; it can grow to a height of up to 15 meters. Originally the cacao tree was native to the
  Amazon, but today it is also cultivated in tropical areas as far as 20 degrees further north and
  south. Only in this area is the climate warm and humid enough. In addition to high temperatures
  and precipitation, cocoa also requires wind protection and sufficient shade – it cannot develop
  satisfactorily under direct sunlight. This unique characteristic, stemming from the climactic condi-
  tions in the Amazonian Rainforest, is taken into account on the plantation-like orchards, where a
  mixture of e.g. coco palms, banana-, rubber-, avocado- or mango trees provide the needed
  shade and wind protection. In some cases, local trees are appropriate as intermediary measures.

  Adverse environmental conditions such as too much sun and ground water give additional stress
  to these sensitive trees. They can become susceptible to diseases, in particular fungal diseases
  such as black rot and witches’ broom. Increasingly, however, plant pests are becoming resistant
  to plant protection products, so the employment of pesticides is becoming less and less effective.
  Moreover, in a time when demand for organic products is increasing, application of pesticides is
  not desirable. Alternative remedies should be found for new plant strains. As a rule, the trees are
  cut down to a height of about five meters in order to ease harvesting. The countries with the
  largest production of cocoa include the Ivory Coast (with about 30% of the world’s harvest), Gha-
  na, Indonesia, Nigeria, Cameroon, Brazil, Ecuador, Togo, and Papua New Guinea.

  The blossoms are not pollinated by bees, as with coffee and other crops, but rather by small
  insects. The prevalence and pollinating activities of these insects is, therefore, a crucial limiting
  factor for the cocoa fruit, even more important than the influences of water, nutrients like nitrogen
  and sunlight. Experiments have shown that an increased pollination rate of 10% to 40% doubles
  the cacao crop.
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  In favorable conditions the evergreen cacao tree blooms the whole year, thus bearing fruit year-
  round as well. The first blossoms appear when the tree is five to six years old. The pentamerous
  flowers (having 5 petals) grow directly on the tree trunk; the fruits are yellow, with an outer hard
  shell, are 15–20 cm long und weigh up to 500 g. Up to 50 seeds, commonly called cacao beans,
  are imbedded in a white, sweet, slimy, and flavorful fruit pulp. This pulp can yield a juice with the
  sweet, light, natural taste of cocoa. The raw seeds of the cacao tree, however, do not taste like
  chocolate and contain a high amount of bitter substances. In order to win cocoa from cacao
  beans there are a number of necessary steps:

         The fruits growing directly on the tree trunk are chopped down with machetes. Because
         the tropical climate lends itself to plant diseases, the tree bark must not be injured, in order
         to avoid the influx of germs.
       • The harvested fruits are then cut open with machetes and spread out on banana leaves or
         filled in vats. The sugary fruit pulp begins to ferment very quickly, and reaches tempera-
         tures of about 50 °C. The beginning germination of the seeds will be stopped by the alcohol
         in the fermentation and the beans will thereby lose some of their bitterness. Part of the al-
         cohol will be oxidized into acetic acid. The acetic acid degrades the plant material and re-
         leases the aroma. Most of the acetic acid will be removed by the final drying process. The
         cocoa beans develop their characteristic flavors and aromas, as well as their color, during
         this approximately 10 day-long fermentation process.
       • Traditionally, the beans are dried in the sun; however, in some growing regions drying ov-
         ens are used due to climatic problems. Drying the beans in conventional ovens is contro-
         versial, however, because a possible ensuing smoky flavor can make the beans unsuitable
         for chocolate production. This problem can only be solved with a heat-exchange system.
       • After being dried, the beans are reduced to 50% of their original size. They are then packed
         in sacks and shipped to chocolate-producing countries, mainly in Europe and North Ameri-
       • Here the beans will be further processed into a cocoa paste which, among other things, is
         important for the manufacturing of chocolate.

  Cocoa is said to have various positive effects on our health. The European Food Safety Authority
  EFSA has assessed cocoa flavanol as having a positive influence on normal blood flow. Depend-
  ing on the amount of cadmium in the soil where the cacao trees are growing, however, cocoa can
  be contaminated with relatively high amounts of cadmium. Dark chocolates that have a high
  percentage of cocoa, such as the premium quality Criollo, have been found with the highest
  amount of cadmium, for which there is so far no maximum limit established. There are large
  differences in types of cultivation between the different continents. In America cacao is grown on
  large plantations, by which the natural environment is lost and monocultures are established. In
  contrast, Africa predominantly produces cacao on small family farms.

  Increasing demand, reduced production, and price speculation have recently caused a new peak
  in the price of cocoa, within a short period of time. Cocoa cultivation is among the most contro-
  versial activities of global enterprises. It has been reported that the government and rebels in the
  Ivory Coast have financed the civil war with income from the cocoa trade. Existence wages for
  workers on small farms, exploitation, and child labor (including child trafficking and slavery in
  West Africa) are widespread. Due to sustained consumer protests the first large cocoa companies
  decided to sell cocoa under the Fair Trade system. Trans Fair e.V. (fair trade association) hopes
  that other companies will follow suit, so that progress can be made especially against the rural
  flight, monocultures, illegal child labor and slavery in West Africa. The 778,000 kg of fair-trade
  chocolate sold in 2009, however, was still only a small fraction of the cultivated amount of 3 mil-
  lion tons.
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The following table shows the results of the cocoa sample analyses for
Ochratoxin A.

Table 1
Comparison of Ochratoxin A Results in Cocoa Powder from Organic and
Conventional Production
                            No. Samples
  Ochratoxin A              with Content Ochratoxin A No. Samples
                             > Limit of
                                 3                 0       -     -
                                18           17 (94,4%)   0,9   1,6
* Limit of determination for Ochratoxin A: 0.4 µg/kg

The results showed that 94.4% of the conventionally produced cocoa
samples were found to contain Ochratoxin A, with an average of 0.9 µg/kg
per sample. The highest detected quantity was 1.6 µg/kg.

So far there is no European or German-established maximum limit for
cocoa and cocoa products. All in all, however, the situation vis-à-vis
Ochratoxin A residues can be viewed as positive.
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[1]      IARC 1993: International Agency for Research on Cancer, 1993.
         Ochratoxin A (Group 2B). Summaries and Evaluations 56: 489. Lyon,
         France.       http://www.inchem.org/documents/iarc/vol56/13-ochra.html

[2]      Wikipedia Online-Lexicon

[3]      Stuttgarter Nachrichten (newspaper), Nr. 128, from 5 June, 2012, p. 22

[4]      Hans-Heinrich Bass: Structural Problems of West African Cocoa Exports
         and Options for Improvement, in: African Development Perspectives
         Yearbook, Volume 11, 2005/06: Escaping the Primary Commodities Di-
         lemma, Münster: Lit-Verlag 2006, pp. 245-263.

[5]      C. Heiss, P. Kleinbongard, A. Dejam, S. Perré, H. Schroeter, H. Sies, M.
         Kelm: Acute consumption of flavanol-rich cocoa and the reversal of endo-
         thelial dysfunction in smokers. In: Journal of the American College of
         Cardiology, Nr. 46 (7), 4. Oktober 2005, S. 1276-1283.

[6]      Adwoa Pinnamang-Tutu and Stephen E. Armah: An Empirical Investiga-
         tion into the Costs and Benefits from Moving up the Supply Chain: The
         Case of Ghana Cocoa, in: Journal of Marketing and Management, 2 (1),
         May 2011, pp. 27-50

Photo credits:
Eine Kakaofrucht mit Bohnen - getrocknet, Helene Souza, Pixelio.de,
Image-ID= 560956.
Unreife Kakaofrucht, Theodora Kessoglou, Pixelio.de, Image-ID= 445459.

Tamara Hummel, Renate Schnaufer.

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