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Soy and Chickpea Protein Hydrolysates: Investigation of Functional and Sensory Attributes for Development of Novel Functional Ingredients Using Hydrolysate Fractionation
- Publication Year :
- 2023
-
Abstract
- Consumer demands for ethically sourced and environmentally friendly food products have led to development efforts to replace animal-based proteins with plant-based alternatives. However, plant-based protein ingredients can be limited by their functional and sensory properties, and thus processing techniques to improve these properties must be explored. Enzymatic hydrolysis has been suggested to improve key functional properties, such as solubility, but the research methodology in this area is questionable and hydrolysis does not fully address sensory deficits in plant-protein ingredients, notably bitterness. In this dissertation, commercial extruded snack products containing soy protein hydrolysates were used as a model to quantify bitterness and test the viability of reformulation with flavor maskers or alternatively processed proteins to improve off-flavor. This study revealed that commercial flavor maskers are not effective at reducing bitterness in products containing soy hydrolysate, but soy protein hydrolysates made by different manufacturers with different processing methods proved a viable replacement with improved off-flavor. In search for conclusive evidence that enzymatic hydrolysis results in improved functionality, a review of literature was conducted. This review concluded that enzymatic hydrolysis process may result in the formation of insoluble aggregates, which in most studies are removed by centrifugation or filtration during processing, thus artificially increasing the reported solubility values for plant-protein hydrolysates. The phenomenon of hydrolysis induced aggregation was confirmed for protein isolates from soy and as well as a pulse protein alternative to soy, chickpea, which were hydrolyzed by Flavourzyme and Alcalase. Analysis of physical and structural properties of the hydrolyzed proteins revealed that hydrolysis led to protein destabilization, causing hydrogen-bond mediated aggregation during thermal enzyme inactivation. The knowledge of formation of insoluble material during hydrolysis led to consideration of whether those large aggregates had desirable functional properties, and if the functional properties of the hydrolysates differed by the size of the protein fragments formed. Additionally, the evidence of molecular weight dependence on peptide bitterness also suggested that separations of hydrolysates by size may help sequester bitter compounds, thus increasing consumer acceptability. Alcalase hydrolysates of chickpea protein separated by centrifugation and ultrafiltration into insoluble, >10 kDa, 5-10 kDa, and 10 k Da and 5-10 kDa fractions had improved solubility, oil binding, foaming, and emulsifying properties compared to the unhydrolyzed protein and unfractionated hydrolysate, while the insoluble fraction had universally low functionality. Sensory analysis of hydrolysate fractions concluded that the most highly functional fractions, >10 kDa, and the unfractionated hydrolysate had the highest bitterness levels, while the unhydrolyzed protein, insoluble fraction, and 10 kDa peptide fractions. While their formation is contradictory to previously reported results, hydrolysis induced aggregates may be useful as texturized plant-based proteins for meat and dairy alternatives which do not require high solubility. The use of hydrolysate fractionation highlights the dependence of hydrolysate functionality and sensory characteristics on the ingredient processing and demonstrates the potential of creating multiple novel value-added ingredients from a single source. Overall, enzymatic hydrolysis of soy and chickpea proteins show promise as a means to create functional alternatives to animal-based proteins for a variety of applications, while more work is required to address the bitterness associated with highly functional fractions.
Details
- Language :
- English
- Database :
- OpenDissertations
- Publication Type :
- Dissertation/ Thesis
- Accession number :
- ddu.oai.etd.ohiolink.edu.osu1689198499542789