Effects of enzymatic extraction on the simultaneous extraction of oil and protein from full-fat almond flour, insoluble microstructure, emulsion stability and functionality

Effects of hydrolysis degree on the functional properties of hydrolysates from sour cherry kernel protein concentrate

During the processing of sour cherries into different foodstuffs, a large amount of kernels is produced as waste material, which creates a significant disposal problem for the food industry. Sour cherry kernels containing 25.3–35.5% of protein can be used as a functional protein source in food production. Therefore, we aimed to study the effects of hydrolysis degree on the sour cherry kernel protein hydrolysates. Proteins were extracted from the defatted flour by isoelectric precipitation. The resulting protein concentrate was hydrolyzed (5, 10, and 15% hydrolysis) using Alcalase to yield hydrolysates. We determined their oil and water holding, emulsifying, gelation, and foaming properties, as well as apparent molecular weight distribution and proximate compositions. No protein fractions greater than an apparent molecular weight of about 22 kDa were present in the hydrolysates. The hydrolysis of the protein concentrate mostly led to an increase in protein solubility. As the degree of hydrolysis increased from 5 to 15%, the water holding capacity of the hydrolysates decreased from 2.50 ± 0.03 to 2.03 ± 0.02 g water/g, indicating its deterioration. The hydrolysates obtained at different degrees of hydrolysis had a better solubility than the intact protein concentrate. The oil holding capacity, the foaming stability, and the least gelation concentration of the protein concentrate could not be considerably improved by hydrolysis. In contrast, its emulsifying activity index and foaming capacity could be increased with a limited degree of hydrolysis (up to 10%).

Effects of protease-assisted aqueous extraction on almond protein profile, digestibility, and antigenicity

Almonds (Prunus dulcis) are one of the most consumed tree nuts worldwide and have been recognized as a healthy and nutritious food. Nevertheless, almonds are also a source of allergenic proteins that can trigger several mild to life-threatening allergic reactions. The effects of selected extraction conditions (aqueous vs. protease-assisted aqueous extraction) on the protein profile determined by proteomics analysis of excised SDS-PAGE gel bands, in vitro protein digestibility, and immunoreactivity of almond protein extracts, were evaluated. Proteolysis altered almond protein sequential and conformational characteristics thus affecting digestibility and antigenicity. Proteomics analysis revealed that enzymatic extraction resulted in the reduction of allergen proteins and epitopes. While complete hydrolysis of Prunin 1 and 2 α-chain was observed, Prunin 1 and 2 β-chains were more resistant to hydrolysis. Protein in vitro digestibility increased from 79.1 to 88.5% after proteolysis, as determined by a static digestion model. The degree of hydrolysis (DH) and peptide content of enzymatically extracted proteins during gastric and duodenal digestion were significantly higher than the ones from unhydrolyzed proteins. Proteolysis resulted in a 75% reduction in almond protein immunoreactivity as determined by a sandwich enzyme-linked immunosorbent assay and a reduction in IgE and IgG reactivities using human sera. The present study shows that moderated hydrolysis (7% DH) using protease can be used as a strategy to improve almond protein digestibility and reduce antigenicity. This study's findings could further enhance the potential use of almond protein hydrolysates in the formulation of hypoallergenic food products with improved nutritional quality and safety.

From a Single-Stage to a Two-Stage Countercurrent Extraction of Lipids and Proteins from Full-Fat Chickpea Flour: Maximizing Process Extractability and Economic Feasibility

The mainstream adoption of chickpea proteins and lipids requires a thorough understanding of the impact of critical extraction parameters (enzyme use, reaction time, and solids-to-liquid ratio—SLR) and modes of extraction (single-stage extraction—SSE and countercurrent extraction—CCE) on the simultaneous extraction of lipids and proteins from full-fat chickpea flour and economic process feasibility. A kinetics study revealed that 68.5% oil and 87% protein extraction yields can be achieved using 0.5% protease at pH 9.0, 50 °C, 60 min, and 1:10 SLR, highlighting the role of proteolysis and an adequate incubation time on overall extractability. An increased gradient concentration between the matrix and aqueous media solutes at a lower SLR (1:15), and reduced slurry viscosity increased oil and protein extractability to 80 and 91%, respectively. The high-water usage in the SSE was addressed by the development of a two-stage CCE that reduced water usage by 47% while increasing oil and protein extractability to ~96%. Higher extractability and reduced water usage in the two-stage CCE resulted in a higher net gross profit, thus outweighing its higher operating costs. The results presented herein further widen the scope of bioprocessing standards for full-fat chickpea flour and add to the elucidation of the impact of key processing conditions on the extractability and economic feasibility of the production of chickpea ingredients for subsequent food/nutraceutical applications.