PhD defence: Carlotta Pietroni

DNA Metabarcoding to evaluate food authenticity, quality and safety: a case study on highly processed meat products

Join the (online) Zoom PhD defence here.

Associate Professor Anders Johannes Hansen, GeoGenetics , GLOBE institute, University of Copenhagen
Professor Maria D’Amato , University of the Western Cape, South Africa

Associate Professor Tobias Guldberg Frøslev , GeoGenetics, GLOBE institute, University of Copenhagen

Assessment committee:
Associate Professor Antton Alberdi (chair), GLOBE Institute, University of Copenhagen
Professor Maurizio Casiraghi,  University of Milano-Bicocca
Head of Department  Esther J. Kok, Wageningen University

DNA metabarcoding is a new tool that is used to describe the biological composition of foods. The methodology may lend itself to the rapid identification of undeclared ingredients in food. Furthermore, it may be applied to detect contamination by substances that are added to food products unintentionally along the production process.

The thesis presents the optimisation of a cost-effective and time-efficient protocol for an extensive scale screening and high throughput food control surveillance using DNA metabarcoding. The protocol was used in a case study to test the authenticity of ready-to-eat meat products collected in South Africa (2016-2018) and to evaluate the extent of contamination/substitution of these products. The detected rate of accidental contamination or deliberate substitution of animal ingredients was significant (~50%). Of all animal contaminations/substitutions, the ones of major interest were the game (Burchell's zebra, blue wildebeest, gemsbok, hartebeest, red hartebeest and common eland) and kangaroo (eastern grey kangaroo, red kangaroo and wallaby) species. These species are all edible, yet the concern of their presence may arise from a health perspective. The undeclared nature of these ingredients would preclude the existence of a record if the wild meat was processed under appropriate sanitary conditions. On a positive note, no trace of pork was detected in products labelled as “Halaal” or “Kosher”. Besides the animal ingredients, undeclared plant allergens – soya (15%) and wheat (12%) – were also discovered. This project also aims at investigating the quality and safety of food products within the same set of samples examined for authenticity. The presence of spoilage and foodborne microorganisms, as a result of contamination during the production, was investigated by using DNA metabarcoding. Overall, the study substantiates the concern on the ability of the existing laws and enforcement system in place in South Africa to protect consumers from adulterated food. It highlights the importance of implementing food compliance testing by South African regulatory bodies. The implementation of a higher system for food control may provide an incentive for manufacturers to increase internal quality control throughout the production chain. Moreover, it may offer tangible benefits to the protection of the customer, but also food producers.