Investigation of plant protein functionality for food applications and health benefits

In recent years, the global food system has faced increasing pressure to transition towards more sustainable and plant-based diets, driven by the need to address climate change and support a growing population. This thesis aims to explore the properties, health benefits, and consumer acceptance of legume-based plant proteins to support their development as sustainable and functional dietary alternatives. Understanding consumer attitudes and barriers towards plant-based products (PBPs) is crucial for facilitating this shift. The first study investigated the relationship between Chinese consumer characteristics and their willingness to adopt PBPs through an online survey (N = 2097). Flexitarians exhibited the highest willingness to change their dietary habits, significantly differing from other dietary groups (omnivores, pescatarians, vegetarians, and vegans), with a medium effect size (Partial η² = 0.089). All participants expressed a strong desire for more information about PBPs, with no significant differences between groups (p > 0.05). Open-ended responses, visualized in a word cloud, revealed a positive attitude towards exploring a wider variety of PBPs, even among omnivores. These findings highlight the significant potential for increasing the consumption of innovative PBPs among Chinese consumers. To further explore the functional properties of plant proteins, the next study examined the structural and emulsifying properties of red lentil protein isolate (RLPI) under different pH and heating conditions. RLPI was treated at pH 2 and 7 at 85 °C for up to 24 hours. Transmission electron microscopy (TEM) and SDS-PAGE analyses indicated that prolonged heating led to the hydrolysis of RLPI into peptides, eventually forming fibrillar and particulate aggregates at pH 2 and 7, respectively. Fourier transform infrared spectroscopy (FTIR) results showed an increase in random coil motifs due to excessive heating. Fibrillar proteins exhibited superior emulsifying capabilities compared to particulate proteins, attributed to their structural properties and surface charge. Notably, fibrillar aggregates formed a gel network structure at pH 2, demonstrating stronger interactions. These findings provide valuable insights for the processing and utilization of plant proteins in beverages and dietary supplements. Building on these results, the effects of NaCl concentration on the physicochemical properties and functionality of lentil protein and fibrillated lentil protein emulsions were investigated. SDS-PAGE analysis revealed that fibrillated proteins primarily exhibited bands below 20 kDa, indicating degradation under low pH and heat. Increasing NaCl concentration led to protein aggregation, as evidenced by fluorescence spectroscopy and FTIR analysis, which showed a red shift in emission spectra and an increase in β-sheet content, respectively. Fibrillated proteins demonstrated higher structural stability and produced more stable emulsions with enhanced rheological properties, maintaining smaller and more uniform droplet sizes compared to native proteins. Emulsion stability tests over 7 days at 4°C confirmed that fibrillated proteins were more resistant to phase separation, even at higher NaCl concentrations. These results suggest that fibrillated lentil proteins are promising materials for food systems requiring stable emulsions. Given the growing interest in the health impacts of plant proteins, a study was undertaken to investigate their effects on gut microbiota modulation through in vitro simulated intestinal fermentation. Four plant proteins (Lentil, Faba bean, Soy, and Pea) were evaluated using pooled faecal samples over 24 hours. Bacterial enumeration and 16s rRNA gene sequencing revealed a significant increase in lactic acid bacteria, Bacteroides, and Bifidobacterium levels during fermentation. Short-chain fatty acid (SCFA) analysis showed a significant increase in acetic acid production, with Soy inducing higher levels of isovalerate compared to other proteins (p < 0.01). Alpha diversity decreased over the fermentation period, and KEGG pathway annotation indicated that bacterial genes were primarily involved in metabolic functions. These findings contribute to understanding how different plant proteins modulate gut microbiota and their potential health benefits. Finally, a human intervention study was undertaken to compare the effects of dietary plant protein (lentil protein isolate) versus animal protein (whey and egg white) on muscle repair, recovery, and performance following intense exercise. A 12-week randomized controlled trial with 24 participants (18-35 years) included resistance training and protein supplementation. Muscle function and recovery were assessed using Biodex isokinetic dynamometry and vertical jump tests, while gut microbiota-derived SCFAs were analyzed via gas chromatography flame ionization detection (GC-FID). Results showed that both plant and animal protein supplementation significantly improved muscle strength and performance, with no significant differences between the two protein sources. SCFA analysis revealed increased acetate production in all groups, suggesting a role of exercise and diet in modulating gut health. These findings demonstrate that lentil protein is as effective as animal protein in promoting muscle recovery and strength, supporting its use as a sustainable alternative for athletes. In conclusion, this research highlights the potential of plant-based proteins in addressing key challenges in food sustainability, consumer acceptance, and health. By exploring the functional properties of plant proteins, their impact on gut microbiota, and their efficacy in muscle recovery, this study provides a comprehensive foundation for the development of innovative plant-based products and their integration into sustainable diets.

Grantor dc:publisher

University College Cork

Year dc:date.issued

2025

Author dc:creator

• Du, Han

Advisors dc:contributor.advisor

• Miao, Song
• Stanton, Catherine
• Ross, R. Paul
• Zannini, Emanuele

• Plant protein
• Gut microbiota
• Emulsion
• Fermentation
• Physicochemical properties
• Functional properties

Statement dc:rights

• © 2025, Han Du.

Licence dc:rights.uri

• https://creativecommons.org/licenses/by-nc-nd/4.0/

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10468/18888

OAI identifier oai:identifier

oai:cora.ucc.ie:10468/18888