The increasing popularity of alternative proteins has raised concerns about allergenic potential, especially for plant-, insect-, fungal-, and algae-based proteins. Allergies arise when the immune system misidentifies proteins as harmful, triggering IgE-mediated reactions that range from mild to severe. Main factors influencing allergenicity include protein structure, cross-reactivity, processing methods, and gut microbiota. Disruptions in gut health or microbiota balance heighten risks. Common allergens in legumes, cereals, nuts, oilseeds, single-cell proteins, and insect-based proteins are particularly challenging, as they often remain stable and resistant to heat and digestion despite various processing techniques. Processing methods, such as roasting, enzymatic hydrolysis, and fermentation, show promise in reducing allergenicity by altering protein structures and breaking down epitopes that trigger immune responses. Future research should focus on optimizing these methods to ensure that they effectively reduce allergenic risks while maintaining the nutritional quality and safety of alternative protein products.

The aim of this study was to investigate binding interactions between β-lactoglobulin (BLG) and two different mucins, bovine submaxillary mucins (BSM) and porcine gastric mucin (PGM), using intrinsic and extrinsic fluorescence spectroscopies. Intrinsic fluorescence spectra showed an enhanced decrease of fluorescence intensity of BLG at all pH conditions when BLG was mixed with PGM rather than with BSM. We propose that, unlike BSM, the tertiary structure of PGM changes and the hydrophobic regions are exposed at pH 3 due to protonation of negatively charged residues. Results suggest that PGM also facilitated the structural unfolding of BLG and its binding with PGM by a hydrophobic interaction, especially at acidic pH, which was further supported by extrinsic fluorescence spectroscopy. Hydrophobic interaction is suggested as the dominant interaction mechanism between BLG and PGM at pH 3, whereas electrostatic interaction is the dominant one between BLG and BSM.

In this study, we investigated the formation of protein–phenolic complexes from dephenolized hazelnut meal protein isolates (dHPI) and hazelnut skin phenolic extracts (HSE) and their effects on the bioaccessibility of both hazelnut proteins and phenolics. The dHPI–HSE complexes were of considerable size and were dependent on HSE concentration due to aggregation. Although catechin was the main component of HSE, it did not cause aggregation, except for a slight rise in particle size. According to fluorescence quenching, the hazelnut protein–phenolic extract complex had a linear Stern–Volmer plot expressing static quenching between 0–0.5 mM concentration; the interaction was mainly dependent on hydrogen bonding and van der Waals forces (ΔH < 0 and ΔS < 0), and the reaction was spontaneous (ΔG < 0). According to Fourier transform infrared (FTIR) spectroscopy results, higher phenolic extract concentration caused an increase in irregular structures in hazelnut protein, while the lowest catechin and phenolic concentration altered the regular structure. Skin extracts did not alter the digestibility of dephenolized proteins, but dephenolization reduced the degree of hydrolysis by pancreatin. The formation of the protein–phenolic complex had a beneficial effect on the bioaccessibility of hazelnut skin phenols, predominantly those on the galloylated form of the catechins, such as gallocatechin gallate and epigallocatechin gallate. Thus, the bioaccessibility and antioxidant activity analysis results showed that protein–phenolic complexes obtained from hazelnut meal and skin may promote the transition of phenolic compounds from the gastrointestinal tract without degradation.

Although there is a well-known awareness of the nutritional potential of plant proteins, their utilization within food formulations is currently limited due to insufficient investigation of the functional properties or processing conditions. In this study, the protein contents of the remaining pulps of laurel (bay) (LL) and olive leaves (OL) after alcoholic washing (representing phenolic compound extraction), heat treatment (representing the usage of the leaves for tea brewing or as cooking aid), and deoiling process (representing oil extraction) were investigated. Bicinchoninic acid assay (BCA) indicated that the best protein yield was achieved with a direct isolation process after hexane oil removal. Both LL and OL isolates contained around 80% protein, but high temperature and alcohol content broke down the protein structure as well as decreased the final protein content (similar to 40%). Alcohol treatment appears to remove protein-bound phenols and increase fluorescence intensity in OL protein isolates while potentially causing structural alterations in LL proteins. In addition to a dramatic decrease in fluorescence intensity, the absolute zeta potentials of protein extracts of boiling OL and LL increased by 53 and 24%, respectively. The increased zeta potentials along with the decreased fluorescence intensity indicate the changes in the protein conformation and enhanced hydrophilicity of the protein structure, which can influence the functional properties of proteins. Protein extracts of deoiled LL had the highest Delta H value (180 mJ/mg), which is higher than other laurel and all olive protein samples. Laurel protein isolates became more thermally stable after hexane treatment. Moreover, the protein extracts after hexane treatment showed better emulsion capacity from both laurel (71.57%) and olive (61.87%). Water-binding capacity and thermal stability of the protein extracts from deoiled samples were higher than those of the other pretreatments, but the boiled samples showed higher oil-binding capacity due to protein denaturation. These findings indicate the importance of processing conditions in modulating protein properties for various applications.