Mycotoxin contamination in meat and meat products

Microbial growth factors in meat and meat products

The factors that determine what type of microorganism proliferates in meat and meat products are determined by the physico-chemical characteristics of food, such as:

• pH Water activity (aw)
• NaCl concentration
• Storage temperature
• Presence or absence of oxygen

Bacteria are predominant in foods with elevated aw (>0.90)

Molds and yeasts constitute the major population in foods with lower aw values. such as cured-matured meat derivatives.

Although mold development does not always imply mycotoxin production, as such conditions tend to be more demanding (Table 1).

How can mycotoxins reach meat?

Mycotoxins can reach meat and its by-products in two ways:

• Through the consumption of meat and meat products derived from animals that have consumed feed that is contaminated with mycotoxins.

• Due to the development of toxigenic molds on the surface of cured-matured meat derivatives. [register]

Mycotoxin contamination from animal feed

In the case of mycotoxin contamination from animal feed, molds can produce toxins during the storage of cereals, food or silage due to storage conditions with low aw and good nutrient availability. as a result, it is within this environment where molds develop with greater ease.

Mycotoxin effects on animals can be very varied. Ranging from: causing mortality due to acute poisoning, or the onset of subclinical mycotoxicosis derived from long term consumption of mycotoxins at low doses.

In addition to this, mycotoxins ingested by animals can accumulate in different organs and tissues. This in turn poses a great danger for consumers, as mycotoxins are not destroyed with regular cooking treatments.

Regulation 574/2011 (European Commission, 2011) sets the maximum level of Aflatoxin B1 and ergot, producer of ergotamine (European Commission, 2011)

Recommendation 2006/576 (European Commission, 2006b) establishes the maximum indicative values that should not exceed the mycotoxins Ochratoxin A, Deoxynivalenol, Zearalenone, and Fumonisins B1 and B2 in foods with a moisture content of 12% (Table 2).

Table 2. Guideline values in mg/kg (ppm) for food with a moisture content of 12% (Recommendation 2006/576/EC and Regulation 574/2011/EC)

Due to the ubiquity of molds, effective controls to lower the risks of mycotoxins contamination in food and silage must be established for storage. Setting environmental conditions that prevent the development of molds and their subsequent mycotoxin production.

Development of molds on the surface of cured-matured meat derivatives

Molds that develop in cured-matured meat derivatives during maturation can have both positive and negative effects in relation to the quality and safety of the final product.

Benefits

They contribute to the proteolytic and lipolytic changes that occur during maturation.

• As a consequence of this activity, there is an increase in the concentration of amino acids and free fatty acids, precursors of desirable volatile compounds in cured-matured meat derivatives

They constitute an antioxidant barrier due to their production of enzymes such as catalase.

• Altogether, molds are related to a decrease in rancidity, which positively influences the sensory level.

Disadvantages

Problems associated with mold growth on the ham surface have been described.

• They can affect sensory perception or cause alterations.

• They can produce mycotoxins, which is highly more worrying from a food security standpoint (Núñez et al. 2007;  Rodriguez et al. 2012)

In recent years there has been a gradual increase in the legal regulations of the European Union setting the maximum content of these contaminants in food. Limits have been set for:

• Aflatoxins (Ministry of Health and Consumer Affairs 2001; European Commission 2010a)
• Ochratoxin A (OTA) (Ministry of Health and Consumer Affairs 2003; European Commission 2010b)(*)
• Patulina (Ministry of Health and Consumer Affairs 2004; European Commission 2006)
• Fusarium toxins (European Commission 2005; European Commission 2007)

(*) In addition, in some countries such as Italy, the maximum permitted level of Ochratoxin A for pork and pork products has been set at 1 ppm (Ministerio della Sanità 1999)

Most of the molds isolated from sausages and cured ham belong to the genera Penicillium and Aspergillus, and are potentially toxigenic (Núñez et al. 1996). In addition, several toxigenic species belonging to these two genera produce mycotoxins when they develop on the surface of cured ham (Núñez et al. 2007; Rodríguez et al. 2012).

Mold control methods in cured-matured meat derivatives

Due to the risks posed by mycotoxins, it is necessary to establish viable strategies to avoid their synthesis during the processing of cured-matured meat derivatives.

There are different procedures to control such danger, such as:

• Physical methods (heat treatments, ionizing radiation or high pressures)

• Chemical methods (controlled atmospheres, organic acids, essential oils or hydrogen peroxide)

Given the not total efficacy and due to the growing demand for additive-free foods, it is necessary to use other alternatives to control the development of toxigenic molds during the maturation of food that avoids the use of these chemical preservatives.

Variations in the ripening conditions of these products could prevent the development of the fungal population, but may impair the sensory quality of the final product.

The industry has to look for alternative strategies to control this threat

One of the possibilities with the best prospects is based on the use of cultures of non-toxigenic strains that contribute to the maturation of the product where they are inoculated.

The ability of these microorganisms to implant and exert their effect will be better if they are strains isolated from cured-matured products, given their suitability to those particular ecological conditions.

The use of these microorganisms as protective cultures does not imply a break with the usual microbiota in these products.

Among the microorganisms present in this type of products that can slow down the development of toxigenic molds or the formation of mycotoxins, lactic acid bacteria, yeasts and molds that produce antifungal proteins stand out.

This work has been funded by the Ministry of Economy and Competitiveness, Junta de Extremadura and FEDER (AGL2013-45729-P, GR15108).

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