Physicochemical and Functional Properties of 2S, 7S, and 11S Enriched Hemp Seed Protein Fractions

Abstract

The hemp seed contains protein fractions that could serve as useful ingredients for food product development. However, utilization of hemp seed protein fractions in the food industry can only be successful if there is sufficient information on their levels and functional properties. Therefore, this work provides a comparative evaluation of the structural and functional properties of hemp seed protein isolate (HPI) and fractions that contain 2S, 7S, or 11S proteins. HPI and protein fractions were isolated at pH values of least solubility. Results showed that the dominant protein was 11S, with a yield of 72.70 ± 2.30%, while 7S and 2S had values of 1.29 ± 0.11% and 3.92 ± 0.15%, respectively. The 2S contained significantly (p < 0.05) higher contents of sulfhydryl groups at 3.69 µmol/g when compared to 7S (1.51 µmol/g), 11S (1.55 µmol/g), and HPI (1.97 µmol/g). The in vitro protein digestibility of the 2S (72.54 ± 0.52%) was significantly (p < 0.05) lower than those of the other isolated proteins. The intrinsic fluorescence showed that the 11S had a more rigid structure at pH 3.0, which was lost at higher pH values. We conclude that the 2S fraction has superior solubility, foaming capacity, and emulsifying activity when compared to the 7S, 11S, and HPI.

Nutritional Quality, Chemical, and Functional Characteristics of Hemp (Cannabis sativa ssp. sativa) Protein Isolate

“…This finding was in contrast with previous work that reported that the high EAI of the HPI was noted at a neutral pH value (pH 7.0) [ 39 ]. On the other hand, the findings of the current work agreed with [ 38 ], which reported the lowest emulsion ability index of the HPI at pH 7. Obviously, the HPI showed a good emulsion capacity and stability, which emphasizes its potential application in food processing.…”

“…The findings of the current investigation are in line with Britten and Lavoie [ 37 ], who stated that the foaming capacity of protein was increased with increasing the protein concentration up to 2%. The minimum foaming capacity of the HPI was noted at pH 5.0, which is close to the isoelectric point of proteins (pH 4.5–5.0) [ 38 ]. The same trend was noted with the foaming stability, where the foaming stability was increased with increasing the pH values and reached the maximum stability at pH 11, where there was the maximum solubility of the protein isolate.…”

Physicochemical Characterization of Interactions between Blueberry Polyphenols and Food Proteins from Dairy and Plant Sources

“…Protein solubility is typically at a minimum when the pH of its surrounding environment reaches the isoelectric point of that protein or the pH at which the net charge of the protein is zero. Isoelectric points are unique to specific, isolated proteins, and it is critical to note that the protein isolates from this study comprise more than one protein ( Figure 1 B), but present literature estimates isoelectric points of 4.5–4.8 for pea proteins, 5.5–6.4 for hemp proteins and 4.5–5.2 for whey protein [ 46 , 51 , 52 , 53 ]. Based on these values, the increases in turbidity observed for pea and hemp proteins in the absence of polyphenol-containing blueberry powder can be attributed to pH-induced changes in solubility.…”

“…α-Lactoglobulin, which comprises 20% of whey proteins, features 27.6% α-helices, 23.8% β-sheets, 12.6% β-turns and 36.07% random coil, while β-lactoglobulin, which comprises 60% of whey proteins, features 27% α-helices, 29.7% β-sheets, 18.8% β-turns and 24.67% random coil [ 67 ]. By contrast, hemp protein isolate has been estimated to comprise 17.4% α-helix, 26% β-sheet, 10% β-turns and 36% random coil [ 51 ], while pea protein comprises 8% α-helix, 32% β-sheet, 15% β-turn and 45% random coil [ 68 ]. Proteins with compact globular structures typically demonstrate decreased affinity for polyphenols in comparison to loosely structured proteins due to the relative inaccessibility of the peptide backbone [ 69 ].…”

Comparison on Protein Bioaccessibility of Soymilk Gels Induced by Glucono-δ-Lactone and Lactic Acid Bacteria

“…The in vitro protein digestibility of the soymilk gels was calculated based on measuring the pH drop after 10 min of digestion [ 41 ]. The equation was as follows: Y = 210.46 − 18.10X.…”