Combined Effect of Extraction and Purification Conditions on Yield, Composition and Functional and Structural Properties of Lupin Proteins

Abstract

Lupin meal presents great potential as an alternative plant-based source of proteins for human nutrition. In the present work, different conditions of extraction and purification were evaluated for production of lupin protein isolates. The results showed that the protein extraction yield was comparable at acidic and conventionally used alkaline extraction pH (37% vs. 40–45%, respectively). Proteins extracted were principally composed of globulins. The ionic strength negatively impacted the protein extractability at pH 2, whereas no significant differences were observed between extractions at 20 to 50 °C. The selected extraction conditions (pH 2 and 7) combined with purification by isoelectric precipitation or ultrafiltration process generated the isolate-grade products. Interestingly, further characterization revealed a partial denaturation of proteins extracted at pH 2 resulting in loss of protein solubility at pH 6 and 7 (10–50%), modifications in secondary structure, lower thermal stability, and formation of protein aggregates. However, foaming and emulsifying properties were generally similar for almost all lupin isolates. Further investigation might be of interest with regard to the extraction behaviours and structural and functional properties of specific lupin protein fractions.

Optimization of extraction parameters of protein isolate from milk thistle seed: Physicochemical and functional characteristics

“…The difference in secondary structure may result from the isolation of different types of proteins, depending on the extraction conditions. A study conducted by Albe-Slabi et al (2022) revealed that the secondary structures of lupin proteins isolated using different pHs changed depending on the pH, and the alpha helix structure was better preserved at high pH (Albe-Slabi et al, 2022). The secondary structures of proteins are closely related to their physical properties and biological activities (Liu et al, 2020).…”

Optimization and Characterization of Lupin Protein Isolate Obtained Using Alkaline Solubilization-Isoelectric Precipitation

“…Legumes also present other benefits, since they are adapted to a wide range of climatic conditions and fix atmospheric nitrogen. Among them, lupins have a high proportion of proteins and they have emerged as a cheap functional food [2,3]. In fact, protein contents ranged between 30 and 50%, depending on the lupin specie, with an excellent amino acid profile, particularly rich in lysine in contrast to other plant proteins [3].…”

“…Among them, lupins have a high proportion of proteins and they have emerged as a cheap functional food [2,3]. In fact, protein contents ranged between 30 and 50%, depending on the lupin specie, with an excellent amino acid profile, particularly rich in lysine in contrast to other plant proteins [3]. However, taking into account their potential use in the food industry and in human nutrition, lupins are underused legumes [4].…”

The investigation of the functional properties of single and mixed milk/lupine protein systems

“…Lupine seeds contain 30–42% protein, of which 87% are globulins (Grasberger et al ., 2023). While there is limited research on the emulsifying ability and interfacial properties of lupin proteins, few studies suggest that lupin proteins exhibit good emulsifying properties (Albe‐Slabi et al ., 2022).…”