Present situation

Mycotoxins are a problem in the Mediterranean basin as a health hazard to the population as well as a trade issue for the export of local produce. The type and level of mycotoxins vary by country and in some cases by geographic location within a country. The results of existing studies are best summarized by product.

Dried figs and other dried fruits

This fruit is a good substrate for fungal invasion and aflatoxin formation. Figs are one of the top Turkish export commodities, so intensive studies have been carried out on the occurrence of aflatoxins in dried figs. Of 284 fig samples from different storage and processing stages, 4% were contaminated with aflatoxins amongst the poorer grade figs (Boyacioglu and Gonul, 1990). In another study, 103 fig samples from various locations and different stages of drying and processing were examined, with 29% containing aflatoxins (maximum 63 ng/g) and 3% containing ochratoxin A (maximum 8.3 ng/g). Aflatoxin formation begins while the fruit is on the tree, as the moisture and aw values of firm, ripened and shriveled figs are suitable for my-cotoxin formation (Ozay and Alperden, 1991). Harvesting the fruit by hand, treating it with different solutions, and using solar drying systems all effectively reduced the contamination level (Ozay et al., 1995). A correlation between BGYF (Bright Greenish Yellow Fluorescence) under UV light and aflatoxin Bj was found for figs (Steiner et al., 1988) and selection of BGYF fruits on the processing line is used widely in Turkey to reduce the aflatoxin level in fig lots (Duzbastilar and Arikan, 1992; Duzbastilar and Arasiler, 1992). In Egypt, among various dried fruits surveyed for mycotoxin contamination, apricots (50-110 ng/g), figs (60-120 ng/g), and plums (210-280 ng/g), all could be found with high levels of aflatoxins while raisins were free of aflatoxins (Zohri and Abdelgawad, 1993). Three of 25 Tunisian date samples were contaminated with aflatoxin at the first stage of maturation, but no aflatoxin was detected at the final, edible mature stage of the fruit (Shenasi et al., 2002).

Grapes

Fungal growth occurs optimally at aw between 0.95 and 0.99 and a temperature of 20-36°C, which corresponds with optimal conditions for ochratoxin production (Belli et al., 2005). In a survey in Italy during 1999-2000, ochratoxin was found in both grapes and wine (Battilani and Pietri, 2002). As a result of a survey (1998-2000) in Greece, dried vine fruits (currants and sultanas) were found contaminated with ochratoxin A. Sultanas were less contaminated (n = 27, median 0.6 ng/g ) than were currants (n = 54, median 1.3 ng/g). Seasonal variation occurred in the contamination levels (Stefanaki et al., 2003). The most comprehensive study of ochratoxin A in grapes and wine has been the subject of the EU project WINEOCHRA-RISK (Battilani, Chapter 21). This project identified the key risk elements for ochratoxin A in grape and wine, and developed preventive and corrective actions for the occurrence of ochratoxin producing molds and ochratoxin formation by using HACCP principles.

Nuts

Another group of mostly susceptible commodities, nuts, have been subjected to many studies. A survey was made of the occurrence of mycotoxins and mycotoxin production poten-

Table 1. Aflatoxin sampling plan designs (CX/FAC 05/37/23, December 2004).

Authority

Sample Product size (kg)_

Maximum aflatox-in level (ng/g)

European Union

30 Raw shelled peanuts destined for further processing 30 Tree nuts destined for further processing 10 Samples of consumer-ready peanuts and tree nuts 20 Raw shelled peanuts 22 Raw shelled peanuts destined for further processing 10 Pistachio nuts

European Union

European Union

Codex Alimentarius U.S. Department of Agriculture

U.S. Pistachio Industry

15 - total tial by molds isolated from nuts (almonds, peanuts, hazelnut and pistachios). Aflatoxin was identified in a sample from almonds (95 ng/g aflatoxin B1 and 15 ng/g aflatoxin B2) and peanuts (< 10 ng/g) in Spain (Jimenez et al., 1991). Similar results were obtained in Tunisia (Boutrif et al., 1977b). Pistachio nuts are the commodity most at risk for aflatoxin formation from the Mediterranean Basin. Twenty-six of 50 pine nut samples were contaminated with up to 2,000 ng/g aflatoxin B1. Traditional pudding made from pine nuts contained 80% of the aflatoxin Bi originally present (Boutrif et al., 1977a). In another study of hazelnuts and walnuts, 90% of the hazelnuts were aflatoxin positive (25-175 ng/g) and 75% of the walnut samples contained aflatoxin in the range of 15-25 ng/g. One sample also was contaminated with zearalenone (Abdelhafez and Saber, 1993).

Turkey is the world's main producer of hazelnuts with a 75% share of the total world production and 70-75% of the total world's export. Sometimes Turkey encounters technical barriers for hazelnut exports due to excessive levels of aflatoxin. A wide scope project on this topic began in 2002 whose main objective was to minimize the risk of aflatoxin formation in hazelnuts during maturation, harvesting, drying and storage. Training hazelnut growers, traders and processors also was included in the project. Field studies were conducted at 72 sites representative of the hazelnut growing region near the Black Sea in Turkey. Alternative drying techniques also were used to shorten the drying period. Toxigenic mold strains were identified and their aflatoxin production ability evaluated.

Since aflatoxin is a serious problem in terms of consumer health and economic losses, both mycotoxin management efforts and studies of analytical methods have continued (Whitaker, 2003). Aflatoxin limits vary in regulations for different countries. In the United States a guidance maximum level for total aflatoxins of 20 ng/g for nuts intended for human consumption was set by the Food and Drug Administration (FDA), whereas the corresponding limit set by the European Commission is 4 ng/g. Sampling and analytical procedures for detecting and quantifying aflatoxin is very important in relation to the acceptance and rejection of shipments. Since high levels of aflatoxin may be present in a very small portion of nuts in a lot, sampling is a critical procedure and sample size usually is the key issue (Table 1). The sampling step is the largest source of error and relatively large samples are required to reduce the error associated with the aflatoxin test procedure (and thus reduce the exporters' and importers' risks) to acceptable levels (Whitaker, 2003).

We conducted a study of the sampling of hazelnuts for aflatoxin analysis to determine the total error associated with testing commercial shelled hazelnuts for aflatoxin; particularly

Table 2. Regulations on mycotoxins in nuts and dried fruits in the Mediterranean countries (after FAO, 2004).

Country

Commodity

Aflatoxins (ng/g)

51 Ways to Reduce Allergies

51 Ways to Reduce Allergies

Do you hate the spring? Do you run at the site of a dog or cat? Do you carry around tissues wherever you go? Youre not alone. 51 Ways to Reduce Allergies can help. Find all these tips and more Start putting those tissues away. Get Your Copy Of 51 Ways to Reduce Allergies Today.

Get My Free Ebook


Post a comment