Determination of Aflatoxins and Ochratoxin A in Traditional Turkish Cereal-Based Fermented Food by Multi-Affinity Column Cleanup and LC Fluorescence Detection: Single-Laboratory Validation

Abstract

Tarhana is a traditional fermented, sun-dried Turkish food containing yogurtand cereals. There are several potential sources of mycotoxins in tarhana, such as contamination of ingredients or formation during preparation, when water activity is suitable for fungal growth and may lead to mycotoxin production during fermentation or subsequent sun-drying. To optimize an immunoaffinity column method and carry out single-laboratory validation for the determination of aflatoxins B, B₂, G, and G₂ together with ochratoxin A (OTA) in tarhana. A homogenized sample was extracted with methanol-acetonitrile-water (25 + 25 + 50) using a high-speed blender. The sample extract was filtered, diluted with phosphate buffered saline (PBS) solution, and applied to a multi-immunoaffinity column (AFLAOCHRA PREP®). Aflatoxins and OTA were removed with neat methanol and then directly analyzed by reverse-phase LC with fluorescence detection using post-column bromination (Kobra Cell). Test portions of blank tarhana were spiked with a mixture of total aflatoxins and OTA to give levels ranging from 2.5 to 10.0 and 1.5 to 6.0 μg/kg, respectively. Recoveries for total aflatoxins and OTA ranged from 82 to 93 and 78 to 94%, respectively, for spiked samples. Based on results for spiked tarhana (30 replicates, each at three levels), the relative standard deviation for repeatability ranged from 1.4 to 7.2 and 3.6 to 7.7% for total aflatoxins and OTA, respectively. The performance characteristics for recovery, repeatability, and sensitivity have demonstrated that the method meets method performance criteria for use for official purposes. The method was demonstrated as being applicable to naturally contaminated samples of tarhana of varied composition obtained from local markets in Turkey. This is the first immunoaffinity column method for simultaneous analysis of aflatoxins and OTA in traditional Turkish food (tarhana). Suitability was demonstrated by single-laboratory validation for official purposes in Turkey. The method was demonstrated as suitable for naturally contaminated samples of tarhana of varied composition.

The Comparison of the Microbiological Characteristics of Wet Dough and Dry Powder Tarhana’s and Evaluation of Possible Health Risks

“…Penicillium species also have conidiophores and conidia similar to those in our study (Visagie et al, 2014). There are also studies that determine aflatoxin, which can be produced by Aspergillus species, and ochratoxin, which can be produced by Penicillium species in various tarhanas (Özçam et al, 2014;Kaymak et al, 2019). It is accepted that food products with high TMAB and TYM counts are not produced and preserved under hygienic conditions.…”

“…Besides that, there are some food products similar to tarhana in other countries, which are called different names such as "tahonyaltakuna" (Hungary), "talkkuna" (Finland), "trahana" (Greece), "atole" (Scotland), "kishk" (Syria, Jordan and Egypt), "kushuk" (Iraq) (Kabak and Dobson 2011;Uçar and Çakiroğlu, 2011;Özçam et al, 2014;Arslan-Tontul et al, 2018). Although various vegetables, herbs and spices are used in different proportions in the production of tarhana, cereal products such as wheat flour and yoghurt are indispensable ingredients (Özçam et al, 2014;Kaymak et al, 2019). It is usually produced at home, but it is also one of the leading commercially produced instant soups.…”

“…The desired ingredients are made into dough, and this dough is fermented for 1-7 days with yeast and lactic acid bacteria (LAB). Then the fermented dough is dried under the sun (domestic production) or with a hot air dryer (industrial production) and pulverized (Kivanc and Funda, 2017;Kaymak et al, 2019). Powdered tarhana can be stored for a long time and consumed as a soup (Ibanoğlu et al, 1999;Arslan-Tontul et al, 2018).…”

“…Powdered tarhana can be stored for a long time and consumed as a soup (Ibanoğlu et al, 1999;Arslan-Tontul et al, 2018). In some regions of Turkey, it can be spread as a thin layer and dried in the form of chips, and it can be consumed as a tortilla (Kaymak et al, 2019), or sometimes it can be consumed wet without drying (Arslan-Tontul et al, 2018).…”

“…Since the ingredients used in its production are uncooked, the most important risk factors that Tarhana may contain are lack of pasteurization, use of contaminated raw materials and poorly controlled fermentation conditions (Daglioglu et al, 2002;Uçar and Çakiroğlu, 2011). In addition, contamination of ingredients is an important source of mycotoxins at every stage of production and up to consumption (Kaymak et al, 2019). Although there are studies examining the effects of different production techniques on tarhana properties, a limited number of studies examining tarhana in terms of microbiology have been carried out (Kivanc and Funda, 2017).…”