Protein Extraction from Stinging Nettle Leaves: Comparison of Novel Approaches to Conventional Extraction

Aim: This study aimed to compare the efficiency of protein extraction methods from stinging nettle leaves. Focusing on the application of pulsed electric fields (PEF) combined with proteolytic enzymes, extraction with Fusarium spp. fermentation and conventional extraction. The objective was to evaluate the effectiveness of each method in terms of protein yield and potential applications in the food industry.

Method: Stinging nettle leaves were treated with three different extraction methods: (1) PEF treatment combined with the use of proteolytic enzymes, (2) fermentation with Fusarium spp. to extract proteins and (3) conventional extraction through alkaline solubilization and acid precipitation. The protein extraction processes were optimized, and the extracted proteins were analyzed for their yield, and functional properties.

Result: The PEF and proteolytic enzymes extraction method yielded a higher protein content (75,9% ± 1,5) compared to the extraction through Fusarium spp. Fermentation (54,5% ± 1,4). With the conventional method the proteincontent reached 53,8% ± 0,4 The combination of PEF and proteolytic enzymes efficiently disrupted the plant cells, resulting in enhanced protein release. Additionally, the proteins demonstrated functional properties suitable for various food applications, such as solubility and geling abilitys in a joghurt. In contrast, the proteins obtained from Fusarium spp. fermentation showed a slightly lower protein yield and differed strongly in the sensory profile.

Conclusion: This study highlights the comparison of three protein extraction methods from stinging nettle leaves, specifically comparing PEF and the use of proteolytic enzymes, extracting via fermentation by Fusarium spp. and conventional methods. The PEF and proteolytic enzymes approach demonstrated superior protein extraction efficiency, resulting in higher protein content. The extracted proteins exhibited functional properties suitable for diverse food applications. While the Fusarium spp. fermentation method also yielded proteins, its efficiency and sensory profile were lower than the PEF and proteolytic enzymes method. This study provides valuable insights into the selection of appropriate protein extraction techniques and highlights the potential of PEF and proteolytic enzymes for efficient protein extraction from plant sources. Future research can focus on further optimizing the extraction conditions, the sensory aspects, improve the colour intensity and evaluate the sustainability aspects of these methods.