Abstract
Phomopsins are mycotoxins mainly infesting lupines, with phomopsin A (PHOA) being the main mycotoxin. PHOA is produced by Diaporthe toxica, formerly assigned as toxigenic Phomopsis leptostromiformis, causing infections in lupine plants and harvested seeds. However, Diaporthe species may also grow on other grain legumes, similar to Aspergillus westerdijkiae as an especially potent ochratoxin A (OTA) producer. Formation of PHOA and OTA was investigated on whole field peas as model system to assess fungal growth and toxin production at adverse storage conditions. Field pea samples were inoculated with the two fungal strains at two water activity (aw) values of 0.94 and 0.98 and three different levels of 30, 50, and 80% relative air humidity.After 14 days at an aw value of 0.98, the fungi produced 4.49 to 34.3 mg/kg PHOA and 1.44 to 3.35 g/kg OTA, respectively. Strains of D. toxica also tested showed higher PHOA concentrations of 28.3 to 32.4 mg/kg.D. toxica strains did not grow or produce PHOA at an aw values of 0.94, while A. westerdijkiae still showed growth and OTA production.Elevated water activity has a major impact both on OTA and, even more pronouncedly, on PHOA formation and thus, proper drying and storage of lupins as well as other grain legumes is crucial for product safety.
Highlights
Grain legumes, including lupine seeds are globally used for animal feed and human nutrition
Iso‐ topically labeled (d5-)Ochratoxin A (OTA) was purchased from LGC Stand‐ ards GmbH (Wesel, Germany). 15N6-phomopsin A (PHOA) was isolated as a crude extract by preparative LC from liquid cultures of P. leptostromiformis that only received isotopically labeled nitrogen sources during growth according to Schloß et al (2015a)
First incubation experiments without prior autoclavation of the whole peas Prior to the incubation experiments on autoclaved peas under controlled microbial conditions, it was tested if Phomopsis leptostromiformis DSM 1894 and Aspergillus westerdijkiae MUCL 39539 would grow on pea material without prior
Summary
Grain legumes, including lupine seeds are globally used for animal feed and human nutrition. They can be assigned to the emerging mycotoxins, a group of mycotoxins that might potentially be a risk to consumers, but that is still lacking comprehensive data for conducting a risk assessment. In 2010, the European Food Safety Authority (EFSA) conducted a call for data on phomopsin occurrence (EFSA 2010) and a subsequent risk assessment in 2012 where EFSA called for validated analyti‐ cal methods (EFSA 2012). Another call for data collection of phomopsins in food and feed was published in the year 2021 (EFSA 2021). In vitro inoculation experiments under unfavourable conditions have led to high PHOA concentrations in further grain legumes, including peas (Schloß et al 2015b)
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