Natural occurrence of aflatoxins and ochratoxin A in meju and soybean paste produced in South Korea

Abstract

In this study, we investigated the occurrence of aflatoxins (AFs) and ochratoxin A (OTA) in meju and soybean paste produced in South Korea. Samples were collected from three regions divided on the basis of climate in South Korea. A total of 100 meju samples were analyzed over 3 years (2012-2015), and 45 soybean paste samples were analyzed in 2016. Mycotoxins were extracted with an immunoaffinity column method and quantified by high-performance liquid chromatography. AFs were detected in 10 of meju (10%) and 11 of soybean paste samples (24.4%) with concentrations of 0.2-48.3 μg/kg and 0.88-16.17 μg/kg, respectively. OTA was detected in 50 of meju (50%) and 22 of soybean paste samples (48.9%) with concentrations of 0.1-193.2 μg/kg and 0.88-26.29 μg/kg, respectively. Mycotoxin contamination in meju was more common in the central region than in the southern areas. Thus, more mycotoxins were produced in the central region owing to less fungal competition in meju during fermentation inside households. We also found that about 91% of AFs and 73% of OTA in meju were degraded after the production of soybean paste and soy sauce. Even after degradation of AFs and OTA, the levels of AFB 1 and OTA were 0.5 µg/kg and 7.5 µg/kg in soy sauce and 11.9 µg/kg and 190.4 µg/kg in soybean paste, respectively. Thus, our results suggest the need for constant monitoring of meju and soybean paste for AFs and OTA.

Effects of oilseed substrates (ground nyjer and flax seeds) on the growth and Ochratoxin A production by Aspergillus carbonarius

“…The excitation and emission wavelength for fluorescence detection used were 330 nm and 460 nm, respectively. OTA samples were analyzed using a reverse phase column C‐18 with 4.6 mm internal diameter, 250 mm column length, 3.5 μm particle size and isocratic mobile phase (acetonitrile, 57%; water, 41%, and acetic acid 2%) at a flow rate of 1 ml/min (Bauer & Gareis, 1987; Jeong et al, 2019). Calibration curve was constructed based on eight concentrations of standard OTA from Petromyces albertensis (Sigma‐Aldrich, Milwaukee, WI).…”

“…The slight fungal growth variations among the triplicate plates were considered by taking 1 ml of composite sample containing equal proportions of extracts from the triplicate plates for extraction of OTA. In order to purify the extracted OTA from the fungal cultures, samples were run through OTA immunoaffinity columns (VICAM, MA) (Jeong, Chung, & Hong, 2019). The procedures for purifying through immunoaffinity columns include briefly the addition of 1.5 ml of sample and 4 ml of phosphate buffered saline (PBS) solution into the column followed by a wash of the column with 5 ml of PBS at a flow rate of 1 ml/min.…”

The importance and mitigation of mycotoxins and plant toxins in Southeast Asian fermented foods

“…Most of the AF contaminations were recorded in RYR from Malaysia ( n = 46/50) 33 , 34 and Deonjang ( n = 45/118) 35 – 38 . Zearalenone mostly occurred in Deonjang samples ( n = 32/60) 35 ; ochratoxin A mainly in Meju ( n = 50/100) 37 , RYR from Malaysia ( n = 50/100) 33 and Deonjang (49/109) 33 – 35 ; deoxynivalenol in Soy sauce ( n = 38/40) 35 and Deonjang ( n = 12/60) 35 . RYR were the most vulnerable to citrinin contamination as the number of samples from Malaysia and China positive to citrinin were n = 50/50 and n = 43/114, respectively 33 , 34 , 39 .…”

Aflatoxin Reduction and Retardation of Aflatoxin Production by Microorganisms in Doenjang during a One-Year Fermentation

“…Fermented foods such as doenjang are vulnerable to mycotoxin contamination because of the long duration of fermentation in the natural environment [15]. Mycotoxins, such as aflatoxins, are the most serious toxicants in fermented foods because of their potential toxicity to humans and animals [9,16,17]. Several studies have reported the presence of aflatoxins in different doenjang samples [15,18].…”

“…Occasionally, meju can be contaminated with aflatoxin-producing fungi such as Aspergillus flavus and Aspergillus parasiticus, leading to the contamination of doenjang with aflatoxins [7]. Aspergillus flavus produces aflatoxins B1 and B2, whereas A. parasiticus produces aflatoxins G1 and G2 [8,9]. Aflatoxin contamination poses a serious challenge to food safety, as it is associated with several health hazards.…”