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<p>Chia seed (<i>Salvia hispanica</i>)
has shown potential as an alternative source of nutrients with a high content
of fiber (36 %), protein (25%), and fat (25%). Unfortunately, the presence of a
viscous biopolymer (mucilage), surrounding the chia seed (CS), limits the
accessibility of the protein and other nutrients. Nevertheless, this
biopolymer’s chemical composition makes it suitable for the development of
biodegradable films. Regarding CS protein, disulfide bonding, and
nonprotein-protein interactions often frequent in plant protein, have limited
its technological application in food matrices. Therefore, scientists have
pointed at processing methods involving enzymatic proteolysis to improve the
functionality of plant protein ingredients. The objective of this study was to
establish processing techniques to exploit the functionality, extraction, and
health benefits of chia seed components. First, ultrasonication followed by
vacuum-filtration was used to separate mucilage from CS prior to fat extraction
by oil press. Mucilage-free and defatted CS were treated using conventional
(enzymatic hydrolysis with alcalase) or sequential (enzymatic hydrolysis with
alcalase+flavourzyme), and under water bath or microwave-assisted hydrolysis.
Chia seed protein hydrolysates (CSPH) derived from the sequential hydrolysis
with microwave treatment showed superior (p<0.05) in vitro antioxidant
activity. The highest (p<0.05) cellular antioxidant activity was achieved by
the sequential (94.76%) and conventional (93.13%) hydrolysis with microwave.
Dipeptidyl peptidase-V inhibition was higher (p<0.05) for sequential
hydrolysis with water bath, while Angiotensin-Converting Enzyme (ACE)
inhibition activity increased (p<0.05) with hydrolysis for all treatments
compared to the control. Regarding functionality, sequential hydrolysis with
microwave showed higher (p<0.05) solubility at lower pH (3 and 5), while
conventional hydrolysis with microwave was better at pH 7 and 9. Emulsification
properties and foaming capacity were also higher in conventional hydrolysis with
microwave, but conventional hydrolysis with water bath was more stable for
foaming properties only. In terms of mucilage applicability, biodegradable
films were developed by casting technique where CS mucilage was plasticized
with different polyol mixtures (sorbitol and glycerol). CS mucilage films with
higher sorbitol content showed superior tensile strength (3.23 N/mm<sup>2</sup>),
and lower water vapor permeability (1.3*109 g/ m*s*Pa) but had poor flexibility
compared to other treatments. Conversely, films with high glycerol content
showed high elongation at break (67.55%) and solubility (22.75%), but reduced
water vapor permeability and tensile strength. The hydrophobicity, measured as
water contact angle, was higher (p<0.05) for mixtures containing equal
amounts of polyols. Lastly, Raman Spectroscopy analysis showed shifts from 854
to 872 cm<sup>-1</sup> and 1061 to 1076 cm<sup>-1</sup>, which corresponded to
β(CCO) modes. These shifts represent an increase in hydrogen bonding,
responsible for the high tensile strength and decreased water vapor
permeability. This study demonstrated that ultrasonication followed by vacuum
filtration can successfully separate mucilage from chia seeds;
microwave-assisted and enzymatic hydrolysis generated protein hydrolysates with
improved bioactivity and functionality. Finally, chia seed mucilage was able to
form films with potential to be used in drug delivery and edible food coating
applications.</p>
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| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/10713065 |
| Date | 14 January 2021 |
| Creators | Uriel C Urbizo Reyes (7909295) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/IMPROVEMENT_OF_FUNCTIONAL_AND_BIOACTIVE_PROPERTIES_OF_CHIA_SEED_SALVIA_HISPANICA_PROTEIN_HYDROLYSATES_AND_DEVELOPMENT_OF_BIODEGRADABLE_FILMS_USING_CHIA_SEED_MUCILAGE/10713065 |
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