Effect of milling procedures on mycotoxin distribution in wheat fractions: A review

https://doi.org/10.1016/j.lwt.2013.05.040Get rights and content

Highlights

  • Overview of the fate of mycotoxins during the milling process of wheat.

  • Data on worldwide mycotoxin contamination in wheat are given.

  • Estimates of economic losses associated with mycotoxins are provided.

  • Milling reduces mycotoxin concentration in fractions used for food products.

  • Milling concentrates mycotoxins into wheat fractions mainly used as animal feeds.

Abstract

Cereals and cereal by-products constitute a major part of human and animal diet. It has been estimated that up to 25% of the world's crops may be contaminated with mycotoxins. The relevance of mycotoxins on human/animal health prompted the European Community to introduce maximum permissible limits in foods and feeds. Considering the levels indicated by the European legislation, results from literature indicate that sometimes the limits proposed for cereal-derived products may be not warranted by the limit for unprocessed cereals. Therefore, the understanding of how mycotoxin distribution and concentration change during the milling process is a worldwide topic of interest due to the high economic and health impact.

This paper reviews the most recent findings on the effects of wheat milling process on mycotoxin distribution in products and by-products. Published data confirm that milling can minimize mycotoxin concentration in fraction used for human consumption, but concentrate mycotoxins into fractions commonly used as animal feed. The concentration of mycotoxins in wheat by-products may be up to eight-fold compared to original grain. Other physical processes carried out before milling, such as sorting, cleaning, and debranning, may be very efficient to reduce the grain mycotoxin content before milling. Published data show a high variability in mycotoxin repartitioning and sometimes appear conflicting, but this may be mainly due to the type of mycotoxins, the level and extent of fungal contamination, and a failure to understand the complexity of the milling technology. A precise knowledge of such data is vital and may provide a sound technical basis to mill managers to conform to legislation requirements, support risk management and regulatory bodies in order to reduce human and animal exposure to mycotoxins, reduce the risk of severe adverse market and trade repercussions, and revise legislative limits.

Introduction

Cereals and cereal by-products constitute a major part of the daily diet of the human and animal populations. The end products of wheat processing are, other than semolina or flour, several by-products coming from the surface layers, characterised by higher micronutrient and bran contents, and mainly used as animal feeds. However, they may represent a source of compounds with unique physico-chemical, nutritional, and functional properties which may have a high value for human nutrition, too (Hemery, Rouau, Lullien-Pellerin, Barron, & Abecassis, 2007).

Among the most important risks associated to wheat product consumption are mycotoxins. Mycotoxins are fungal secondary metabolites that have a great impact on human and animal health (Hussein & Brasel, 2001). This prompted the European Community to establish appropriate maximum levels in foodstuffs and feedstuffs (Commission Directive 2003/100/EC, Commission Recommendation 2006/576/EC, Commission Regulation and EC, 2006, Commission Regulation EC, 2007). Considering the levels indicated by the European legislation, results from literature indicate that sometimes the limits proposed for cereal-derived products may be not warranted by the limit for unprocessed cereals. Therefore, based on occurrence data, the European limits for mycotoxin in cereals could impact the availability of high fibre cereal products. The fate of mycotoxins during cereal processing, such as sorting, cleaning, milling and thermal processes, was studied by several Authors (Brera et al., 2006, Bullerman and Bianchini, 2007, Hazel and Patel, 2004, Kabak, 2009, Kushiro, 2008, Scudamore, 2008, Scudamore and Patel, 2008, Visconti and Pascale, 2010).

This paper reviews the most recent findings on the effects of the milling process on mycotoxin distribution in wheat milling fractions. A precise knowledge of such data is vital as they may provide a sound technical basis to mill manager and support risk management and regulatory bodies in order to reduce human and animal exposure to dangerous amounts of mycotoxins, and revise legislative limits.

Section snippets

Occurrence of mycotoxins in wheat: a safety, economic, and technological topic

FAO's latest estimates for world cereal production in the period 2011–2012 are approximately 2313 million tons (FAO, 2011). For the feed sector, cereals represent the main components of industrial feeds, which estimated production, worldwide, is more than 717 million tons (Best, 2011). It has been estimated that up to 25% of the world's crops grown for foods and feeds may be contaminated with mycotoxins (Hussein & Brasel, 2001). This means that, if the estimated world cereal production is about

Sorting and cleaning

Physical and mechanical processes, such as sorting and cleaning prior to milling, may reduce mycotoxin contamination in wheat, by removing kernels with extensive mould growth, broken kernels, fine materials, and dust (Bullerman and Bianchini, 2007, Hazel and Patel, 2004, Kushiro, 2008). This is the materials (screenings) in which most of the toxins accumulate (Pascale et al., 2011, Visconti et al., 2004). The most recent findings regarding the effect of sorting and cleaning of wheat on

Conclusions and future perspective/trends/needs

Industrial milling technology is a very complex process and presents several key processing steps that differently influence mycotoxin repartitioning in wheat milling fractions. Published data confirm that milling reduces mycotoxin concentration in fractions used for human consumption, but concentrates mycotoxins into fractions commonly used as animal feed. However, these fractions may represent promising novel food ingredients with a high value for human nutrition, too. Physical processes

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