Isolation and Gelling Properties of Duckweed Protein Concentrate

Abstract

An isolation procedure for proteins from duckweed was optimized based on a previously developed method for protein isolation from sugar beet leaves. Optimization included the protocol for disrupting cells and protein recovery. With the optimized protocol, protein was isolated (protein yield 14.2%, RuBisCO yield 27%). The concentrate was off-white and contained 67.2% protein. The isolation procedure resulted in a large enrichment in RuBisCO (from 48% to 92%). Denaturation of duckweed protein concentrate was observed at 62 °C at pH 7, while heating at pH 4 did not show denaturation peaks. Solubility was good far from the iso-electric point and showed a minimum around pH 5. Gelling was better at pH 7 than at pH 4. At pH 7, duckweed gels were much stronger than soy and only slightly weaker compared to egg white protein, while at pH 4 duckweed gel strength was similar to soy and lower than egg white.

Antimicrobial and Functional Properties of Duckweed (Wolffia globosa) Protein and Peptide Extracts Prepared by Ultrasound-Assisted Extraction

“…Moreover, Nasir et al [ 35 ] found a low Mw of shortfin scad muscle protein hydrolysate (SSMPH), with high potential bioactivity and functional properties particular to SSMPH peptides (<3 kDa) that exhibited the highest ACE inhibitory activity and DPPH scavenging activity. In addition, Nieuwland et al [ 36 ] reported that high concentrations of glutamic acid, arginine and glycine are conditionally essential amino acids in the human diet. Therefore, consumption of the PE and PCH could assist people who suffer from limited synthesis of these amino acids due to pathophysiological conditions.…”

Biorefinery of Green Biomass─How to Extract and Evaluate High Quality Leaf Protein for Food?

“…Similarly, RuBisCo from duckweed have gelation properties comparable with egg white protein and better than soy protein. 15 With regard to the microstructure observed with confocal laser scanning microscopy, RuBisCo gel density is correlated to the protein concentration. Furthermore, an increase in gel network coarseness is observed upon NaCl addition to the gel system at 5% protein concentration resulting in lower gel strength.…”

“…The minimum solubility is observed at pH 3.5–5 (∼10% soluble), which correlates to RuBisCo having a isoelectric point around pH 4.5 . The solubility is slightly higher at pH 2 and increases from pH 5 to a maximum of ∼80% at pH 10. ,,,, Using a pH-shift method where the protein concentrate is solubilized at pH 11 or 12 prior to readjustment to pH 7 increases the protein solubility at pH 7, but the alkaline pH also induce formation of protein cross-linking products, lanthionine, and lysinoalanine, which lowers the content of the essential amino acids, cysteine, and lysine and lowers the protein digestibility and may as well change other functional properties. Similarly, the solubility of leaf protein from perennial ryegrass was improved by solubilizing at alkaline pH before readjusting to neutral pH …”

“…Furthermore, the spinach protein gel has higher storage modulus ( G ′) and gel strength in texture analysis at comparable protein concentrations. Similarly, RuBisCo from duckweed have gelation properties comparable with egg white protein and better than soy protein …”

“…have also recently received interest because of their relatively high protein content and high biomass yield . Other leafy biomass that can be used as protein sources include sugar beet leaves, a byproduct of sugar production − as well as aquatic plants such as duckweed ( Lemna gibba ) . The main protein in the leaves is the enzyme ribulose-1,5-biphosphate carboxylase/oxygenase (RuBisCo), which is involved in the photosynthesis and likely the most abundant protein in the world. , The current approach to leaf protein extraction is mainly linked to green biorefinery where different products such as protein, lysine, lactate, acetic acid, biogas, and biomaterials (e.g., insolation or fiber-PET composites) are produced from green biomass .…”