Impact of experimental thermal processing of artificially contaminated pea products on ochratoxin A and phomopsin A

Birgitta Maria Kunz,Alexander Voß,Julia Dalichow,Stefan Weigel,Sascha Rohn,Ronald Maul

doi:10.1007/s12550-020-00413-9

Abstract

Fungi of Aspergillus and Penicillium genus can infect peas (Pisum sativum), leading to a contamination with the nephrotoxic and carcinogenic ochratoxin A (OTA). Under unfavourable conditions, a fungus primarily found on lupines, Diapothe toxica, may also grow on peas and produce the hepatotoxic phomopsin A (PHOA). To study the effect of processing on OTA and PHOA content, two model products—wheat/rye-mixed bread with pea flour addition and pea pasta—were manufactured at small-business scale from artificially contaminated pea flour. The decrease of OTA and PHOA contents were monitored along the production process as indicators for toxin transformation. Pea bread dough was subjected to proofing for 30–40 min at 32 °C and baked at 250 °C to 230 °C for 40 min. OTA content (LODs < 0.1 μg/kg) showed a reduction in the bread crust (initially 17.0 μg/kg) to 88% and no reduction in the crumb (110%). For PHOA (LODs < 3.6 μg/kg), a decrease to approximately 21% occurred in the bread crust (initially 12.5 μg/kg), whilst for crumb, a less intense decrease to 91% was found. Pea pasta prepared with two toxin levels was extruded at room temperature, dried and cooked for 8 min in boiling water. In pea pasta, OTA was reduced from 29.8 to 13.9 μg/kg by 22% each after cooking, whilst 15% and 10% of the initial toxin amounts were found in the cooking water, respectively. For PHOA, 60% and 78% of initially 14.3 μg/kg and 7.21 μg/kg remained in the cooked pasta. As only the decrease of the initial content was measured and no specific degradation products could be detected, further research is needed to characterise potential transformation products. Heat treatment reduces the initial PHOA content stronger than the OTA content during pasta cooking and bread making. However, significant amounts of both toxins would remain in the final products.

Highlights

The current popularity of plant-based protein sources makes protein-rich grain legumes and products thereof promising food items for the human diet
For phomopsin A (PHOA) analysis, limit of detection (LOD) and limit of quantification (LOQ) were close to the maximum level given by the Australian and New Zealand governments for phomopsins of 5 μg/kg in lupine seeds (ANZFSC 2017)
The recoveries obtained for pea flour, pea pasta, cooked and dried pea pasta and cooking water residue (68.7–80% ochratoxin A (OTA) and 72.6–95.1% PHOA) differ from the recoveries of bread with pea flour addition dough, crust and crumb (99.7–104.8% OTA and 132.7– 140.8% PHOA)

Summary

Introduction

The current popularity of plant-based protein sources makes protein-rich grain legumes and products thereof promising food items for the human diet. Various emerging processed food items are made from legumes, for instance, textured meat substitute burger patties from pea protein or pasta made from pea flour. Legume flour is used as an additive in bread manufacturing, as mentioned in German customary law (DLMBK 1994). US American federal law allows the addition of non-wheat flour (CFR 2020a). Grain legumes have been shown to be occasionally contaminated with mycotoxins. Ochratoxin A (OTA; Fig. 1a) was found in soybeans (Glycine max) and products

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Methods

Conclusion