Valorisation of pumpkin leaf by-product proteins through enzymatic modification in a biorefinery concept for meat emulsion application

Zorica Knežević-Jugović; Jelena Mijalković; Maria Skoufi; Sonja Jakovetić Tanasković; Nataša Šekuljica; Hristina Hristova; Zora Dajić Stevanović; Verica Đorđević

doi:10.18485/meattech.2025.66.3.76

Zorica Knežević-Jugović University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia https://orcid.org/0000-0003-3009-1698
Jelena Mijalković University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia https://orcid.org/0000-0002-0343-1872
Maria Skoufi InnoHive, Larisa, Greece https://orcid.org/0009-0001-5334-5964
Sonja Jakovetić Tanasković University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia https://orcid.org/0000-0002-8344-5376
Nataša Šekuljica Innovation Centre of Faculty of Technology and Metallurgy, Belgrade, Serbia https://orcid.org/0000-0001-8260-6556
Hristina Hristova Venus Roses Labsolutions Ltd. – VRLS, Sofia, Bulgaria https://orcid.org/0000-0003-2894-6933
Zora Dajić Stevanović University of Belgrade, Faculty of Agriculture, Belgrade, Serbia https://orcid.org/0000-0001-9275-4499
Verica Đorđević University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia https://orcid.org/0000-0002-2154-7502

DOI: https://doi.org/10.18485/meattech.2025.66.3.76

Keywords: alternative proteins, pumpkin leaves, antioxidant peptides, enzymatic hydrolysis, interfacial functionality, functional meat ingredients

Abstract

The valorisation of agricultural and industrial side-streams within integrated biorefinery concepts is gaining increasing importance in the context of sustainable protein production and the circular bioeconomy. In this context, waste green biomass is emerging as an alternative protein source with potential applications in food formulations. This work investigated the possibility of improving the techno-functional and antioxidant properties of protein isolated from pumpkin leaves by partial enzymatic hydrolysis.

The white protein fraction, mainly composed of RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) was isolated from green juice obtained by pressing pumpkin leaves through thermocoagulation, acid precipitation, subsequent resolubilisation and lyophilisation, and further treated with endopeptidase from Bacillus licheniformis in a stirred batch reactor under the reported optimal conditions (pH 8, 55 °C). Enzymatic treatment at the optimal enzyme-to-substrate ratio (E/S = 6.5 wt.%, 75 min, degree hydrolysis ~ 15%) markedly improved protein solubility, emulsifying capacity, interfacial functionality, and antioxidant activity, supporting the potential application of pumpkin leaf protein as natural emulsifiers and antioxidants in meat products.