Optimization of enzymatic digestions on tomato seeds to recover proteins and peptides

Giorgia Benati ¹, Maura Ferri ¹, Annalisa Tassoni ¹

Department of Biological, Geological, and Environmental Sciences, University of Bologna, via Irnerio 42, 40126 Bologna Italy ¹

The present work is part of the AgriLoop EU project, which aims at promoting sustainable agricultural production by valorizing its by-products. Specifically, the goal of this study is to successfully extract proteins and peptides from tomato seeds for potential use in food or other applications based on the biological activities of the extracts. The excessive consumption of animal-based proteins and the use of plant proteins predominantly as animal feed for meat production is proved to be environmentally unsustainable, and this research seeks to offer an eco-friendly alternative. Initially, seven proteases and five cell-wall hydrolytic enzymes were tested at different concentrations on dried and grounded tomato seeds. The resulting digestates were analyzed for protein content, but also for reducing sugars and polyphenols contents. After identifying the best enzymes, a two-step approach was tested, starting with the best cell-wall hydrolytic enzyme followed by one of the best proteases. However, this method did not significantly improve protein yield with respect to the use of proteases alone. SDS-PAGE was performed to gain an overview of the molecular weight distribution of the proteins and peptides extracted. When treated with proteases, tomato seeds exhibit a high proportion of low molecular weight peptides. To further refine the protocol and try to improve the peptide yield and pool, additional trials were conducted. Enzymatic digestions were also applied to: precipitated proteins from tomato seeds, autoclaved and sonicated fresh seeds and defatted ones. An optimization of the extraction conditions was also performed by lowering the incubation temperature and the addition of hydration and sonication steps. Based on the results of protein content the best approach selected was protease treatment with either Papain, Bromelain, Protamex or Trypsin using a lower incubation temperature. The evaluation of antioxidant activity of the extracts using ABTS assay is ongoing. Further steps include peptide sequencing and the assessment of additional biological activities to better characterize the extracts and gain a deeper understanding of the benefits of the extracted peptides. This project has received funding from the European Union’s Horizon Europe research and innovation programme under the grant agreement No. 101081776, the UK Research and Innovation (UKRI) fund under the UK government’s Horizon Europe funding guarantee, the Swiss State Secretariat for Education, Research and Innovation (SERI) and from the National Key Research and Development Program supported by the Ministry of Science and Technology of the People's Republic of China (No. 2023YFE0104900). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of neither of the aforementioned Funding authorities. Neither the European Union, the United Kingdom, the Swiss Confederation or the People’s Republic of China nor the European Commission, UKRI, SERI or NKRDPC can be held responsible for them.

Main author career stage: PhD student

Contribution type: Poster

First choice session: 4. Structure, physiology, and development

Second choice session: 6. Plants, Fungi and Society