Spices are generally derived from the non-leafy parts of the source plants including the seeds, bark, root, flowers, or fruits (Viuda-Martos et al. 2010). They are widely used to enhance aroma, taste, color, smell, and flavor in daily food preparations (Kabak and Dobson 2017). Due to their preservative characteristics, spices have potential applications in food industry. On the other hand, these products are among the most efficient plant species for medical purposes because of their treatment effects on acute and chronic diseases. In this context, spices are rich sources of various phytochemicals (Srinivasan 2014). Phytochemicals are a large group of bioactive compounds found in plants that have potential protective effects on the health of human (Shan et al. 2005; Srinivasan 2014). These natural compounds are consists of flavonoids and other phenolic chemicals, thus provide protection against oxidation by reacting with free radicals or form complexes with metal ions. For example, several antioxidants from spices, such as gingerol (ginger), eugenol (red pepper), and curcumin (turmeric), coumarin (cumin), were experimentally evidenced to control cellular oxidative stress due to render antioxidant activity and their ability to scavenge free radicals (Embuscado 2015). Besides, antimicrobial, antidiabetic, and immunomodulatory effects of some spices have been confirmed, such as cinnamon. In addition, curcumin as a spice compound is able to act like an anti-inflammatory agent by interacting with various inflammatory processes (Nilius and Appendino 2013). Spices can contribute to the prevention and treatment of some cancers due to their anti-oxidative characteristics (Zheng et al. 2016). In terms of trade value, red chilli, black pepper, paprika, turmeric, cumin, coriander, cumin, nutmeg and ginger are the most important spices used all over the world. spice crops are cultivated worldwide, but most of them originated in India (74%), Bangladesh (6%), Turkey (5%) and China (5%). In recent years, there have been increasing concerns over the food safety of consumers. Several factors including poor harvesting practices, improper storage, processing, packaging, drying method and distribution influence fungal growth responsible for spoilage and mycotoxin production (Thanushree et al. 2019). All the steps during production and storage have critical effects on spice quality. Fungal contamination of spices is one of the main issues may occur at all the steps during production and storage and is very important from human health perspectives. Fungal contamination of spices leads to serious consequences for animal and human health by production of mycotoxins (Richard 2007). Mycotoxins are a limited group of toxic secondary metabolites, mainly synthesized by some fungal species belong to the genera Aspergillus, Penicillium and Fusarium (Almela et al. 2007). To date, over 400 mycotoxins have been identified among these metabolites, ochratoxin A (OTA) is one of them and can contaminate a wide range of agricultural commodities including cereal, coffee, cocoa, nuts, and spices under certain environmental conditions (Trucksess and Diaz-Amigo 2011). OTA is the most studied mycotoxin in spices that its prevalence depends on many specific factors which among them, temperature, storage conditions and processing are the most described factors. Humans are exposed to this metabolite through consumption of contaminated food products (Jalili 2016). Exposure to this mycotoxin is a life threatening problem and can have many toxicological effects on consumers. OTA intake through the consumption of contaminated crops can cause some adverse effects such as kidney and liver diseases, as well can target the nervous system, and immune system in test animals (da Rocha et al. 2014; Ringot et al. 2006). In addition, this molecule has been classified as a possible human carcinogen (group 2B) by the International Agency for Research on Cancer (IARC). To avoid such outcomes, processing protocols and storing conditions must be controlled to obtain a good quality product. However, given the health risks of exposure to OTA, regulatory agencies or commissions, have imposed national standards on its contamination in agricultural products, which may vary in different countries. For instance, the European Commission has established levels up to 15 ng/g for OTA in the spices. Meta-analysis refers to the statistical analysis of collected data from multiple independent studies in order to investigate the integration of results.
To the best of our knowledge, no systematic reviews have been conducted to assess the prevalence and concentration of ochratoxin A in spices; however, some assessments were carried out to measure the mycotoxin levels in different food commodities. Therefore, for the first time, the current investigation aimed to estimate the prevalence and concentration of ochratoxin A in various spices (pepper, paprika, chili, cinnamon, turmeric, nutmeg, ginger, cayenne and curry) via a systematic review and meta-analysis approach.