Natural occurrence of fumonisins and ochratoxin A in some herbs and spices commercialized in Poland analyzed by UPLC–MS/MS method

Highlights

• Above the acceptable level was 22.3% of samples with OA.

• Only 5 samples of cayenne pepper contained high levels of FBs above 50 ng g⁻¹.

• ERG content was positive correlated with mycotoxins.

• The highest correlation coefficient was obtained between ERG and OA.

Abstract

Unsanitary conditions during harvesting, drying, packing and storage stages in production and processing of spices and herbs could introduce mycotoxin contamination. The occurrence of ochratoxin A and fumonisins in popular spices and herbs was studied, using liquid chromatography-electrospray-mass spectrometry. Apart from mycotoxins, ergosterol as a factor indicating fungal development was also analysed. A total of 79 different samples commercialized in Poland were randomly purchased from popular markets were tested for mycotoxins. The frequency of samples with fumonisins was lower (31%) than ochratoxin A (49%). Free from mycotoxins were samples of bay leaf and white mustard. ERG content – in spice samples with high concentration level of mycotoxins – was also significantly higher than in samples with little to no mycotoxins.

Introduction

The mycological quality of some commercially available spices, especially black, red and white pepper, is relatively poor, as they carry many genera and species of fungi. Most fungi present on pepper are of the post-harvest and storage type, which develop after harvest if relative humidity is not controlled during storage (Freire et al., 2000, Salari et al., 2012).

The most frequent fungal contaminants of spices and herbs are species from the genera Aspergillus and Penicillium and less often Fusarium (Koci-Tanackov et al., 2007; Hashem and Alamri, 2010). Some of these species can biosynthesize toxic metabolites such as mycotoxins. Several factors affect mycotoxin occurrence, the most important being plant genotype, fungus strain and environmental conditions (Stępień et al., 2011a, Stępień et al., 2011b, Waskiewicz et al., 2008, Waskiewicz et al., 2010). In planta mycotoxin contents are influenced by numerous factors, especially oxidative stress components, i.e. drought, water, temperature, light, free radicals and heavy metals (Czaban et al., 2006, Esteban et al., 2004; Mitchell et al., 2004).

The first studies concerning the detection of mycotoxin presence in spices and medicinal plants applied the TLC technique (Aziz et al., 1998, El-Kady et al., 1995, Freire et al., 2000, Halt, 1998). Analyses determined mainly the presence of aflatoxins, ochratoxin A, zearalenone, and less frequently T-2 toxin, penicillic acid, citrinin and sterigmatocystin (Almela et al., 2007, Valle-Algarra et al., 2011). Mycotoxins were found both in herbs (chamomile, peppermint, lime tree, fennel, lemon balm) and spices (black, red and white pepper, ginger, cinnamon, turmeric, marjoram, rosemary, thyme, safflower, black cumin, coriander). Intensive development of chromatographic techniques made it possible to apply more precise detection methods for fungal metabolites in various plant matrices, such as e.g. ELISA, HPLC–FLD/PDA or LC–MS/MS (Colak et al., 2006, Monbaliu et al., 2010, Trucksess et al., 2006, Yang et al., 2010). Apart from the above mentioned plants, later studies analysed also red paprika, chili (Santos et al., 2010, Zinedine et al., 2006), cardamom, cloves (Elshafie et al., 2002), cinnamon (Al-Jurafani, 2011), nutmeg, bay leaf (Mandeel, 2005), curry (Cho et al., 2008), licorice, green anise, rosemary (Santos et al., 2009) and traditional Chinese medicinal plants (Yang et al., 2010) in terms of the presence of mycotoxins, primarily ochratoxin A and aflatoxins. To date few reports have been published on other mycotoxins, including fumonisins (Martins et al., 2001, Omurtag and Yazicioglu, 2004, Santos et al., 2009).

Fumonisins (FBs) are the most important group of mycotoxins formed by Fusarium verticillioides, Fusarium proliferatum or Aspergillus niger (Covarelli et al., 2012, Jurado et al., 2010, Palumbo et al., 2011, Stępień et al., 2011b, Waskiewicz et al., 2010, Waskiewicz et al., 2012a; Waśkiewicz and Stępień, 2012). They are a family of polyketide derivatives, structurally related to sphinganine, compounds disrupting sphingolipid metabolism, causing different toxicological effects in humans, animals as well as plants (Desjardins, 2006). The most abundant fumonisin produced in nature is fumonisin B₁ (FB₁), a suspected risk factor for esophageal (Marasas, 2001) and liver (Ueno et al., 1997) cancers, neural tube defects (Missmer et al., 2006), and cardiovascular problems (Fincham et al., 1992). Taking into consideration available toxicological evidence, the International Agency for Research on Cancer classified FB₁ as probably carcinogenic to humans (class 2B carcinogen) (IARC, 2002).

Among ochratoxins, ochratoxin A (OA) is the most abundant and the most toxic compound and it is produced by secondary metabolism of many filamentous species belonging to the genera Aspergillus and Penicillium (Almela et al., 2007, Khoury and Atoui, 2010). There is general agreement that Aspergillus species are important in OA biosynthesis in warmer regions (Varga et al., 1996), while in colder areas, especially in temperate climate (Schmidt-Heydt et al., 2010), only the activity of Penicillium verrucosum is significant (Arroyo et al., 2005, Park et al., 2005). Studies show that this molecule can have several toxicological effects, e.g. nephrotoxic, hepatotoxic, neurotoxic, teratogenic and immunotoxic (Lund and Frisvad, 2003). The International Agency for Research in Cancer classified ochratoxin A as possibly carcinogenic to humans (group 2B) (IARC, 1993). To date the European Commission has established limits for OA in cereals, dried fruits, wine, coffee, spices and infant foods (European Commission, 2005, European Commission, 2012).

Apart from mycotoxins, fungal biomass is also an important parameter and ergosterol (ERG) was suggested as a factor indicating fungal development (Abramson et al., 1998). ERG is a specific component of the fungal cell membrane, and it is either absent or a negligible constituent of higher plants and insects (Parsi and Gorecki, 2006). A good positive correlation has been established between ergosterol content and fungal growth (Bankole et al., 2010, Janardhana et al., 1999, Waskiewicz et al., 2010, Waskiewicz et al., 2012).

Despite numerous studies on the mycoflora and mycotoxins in agricultural products, only a few are concerned with spices and herbal medicines that are used more and more commonly and play an important role in our daily diet. Fungi and their secondary metabolites reduce the quality of these commodities. Although spices are not major sources of food-borne diseases, they are nevertheless a potential health hazard, particularly if spices are added at the end of cooking or to meals prepared without thermal treatment. The aim of this study was to assess the contamination levels of fumonisins and ochratoxin A in commonly used herbs and spices, and to control fungal biomass by measurement of ergosterol content using modern chromatographic techniques.