Shotgun proteomics profiling of chia seeds (Salvia hispanica L.) reveals genotypic differential responses to viability loss.

Introduction: Exposure to elevated temperatures and relative humidity expedites the seed aging process, finally leading to seed viability loss. In this context, certain proteins play a pivotal role in safeguarding the longevity of seeds. However, the seedproteomic response to loss viability in Salvia hispanica L., commonly known as chia, remains incompletely understood. Methods: This work explores the application of proteomics as a potent tool for uncovering molecular responses to viability loss caused by artificial aging in two chia genotypes, WN and MN. Results: By using a quantitative label-free proteomics analysis (LC-MS/MS), 1787 proteins wereidentified in chia seeds at a 95% confidence level, including storage proteins, heat shock proteins (HSPs), late embryogenesis abundant proteins (LEA),oleosins, reactive oxygen species (ROS)-related enzymes, and ribosomal proteins. A relatively low percentage of exclusive proteins were identified in viable and non-viable seeds. However, proteins exhibiting differential abundancebetween samples indicated variations in the genotype and physiological status. Specifically, the WN genotype showed 130 proteins with differential abundancecomparing viable and non-viable seeds, while MN displayed changes in the abundance of 174 proteins. While both showed a significant decrease in keyproteins responsible for maintaining seed functionality, longevity, and vigor withhigh-temperature and humidity conditions, such as LEA proteins or HSPs, ROS, and oleosins, distinct responses between genotypes were noted, particularly in ribosomal proteins that were accumulated in MN and diminished in WN seeds. Discussion: Overall, the results emphasize the importance of evaluating changes in proteins of viable and non-viable seeds as they offer valuable insights into the underlying biological mechanisms responsible for the maintenance of chia seed integrity throughout high-temperature and humidity exposure.

Extraction method impact on the physicochemical characteristics of lipids from chia nutlets applicable to long-term storage studies.

Lipids are relevant during the seed aging process, for which it is pertinent to choose an extraction method that does not alter their nature. Thus, three methods were applied to extract lipids from chia seeds: one used as reference (Soxhlet) and two at room temperature using hexane/ethanol (COBio) and hexane/isopropanol (COHar). The fatty acid composition and the tocopherol content of the oils were analyzed. Also, their oxidative status through the peroxide index, conjugated dienes and trienes, and malondialdehyde were determined. Besides, biophysical techniques, such as DSC and FT-IR, were applied. The extraction yield was not affected by the extraction method, while the fatty acid composition presented slight differences. Despite the high content of PUFAs, the oxidation level was low in all cases, especially in COBio, associated with the high content of α-tocopherol. DSC and FT-IR outcomes coincided with those obtained by conventional studies, resulting in efficient and fast characterization tools.

Release of yerba mate antioxidants from corn starch-alginate capsules as affected by structure.

Encapsulation of yerba mate (Ilex paraguariensis) extract in a proper matrix enhances the possible applications of this natural antioxidant in food systems. To start, calcium alginate capsules were used as carriers of yerba mate extract and a filler material (corn starch at 2%) was added to the alginate matrix to improve the structural properties and to modulate the release of the active compounds. Next, kinetics and swelling mechanisms involved in the release of yerba mate polyphenols in simulated digestive fluids were analyzed. A lower rate of release was obtained with calcium alginate-starch capsules as compared to control ones, which was attributed to the lower porosity of filled capsules. The release profiles of both systems were satisfactorily fitted with semi-empirical models, which indicated that a combined mechanism of polymer-chain relaxation and diffusion was taking place.

Effect of starch filler on calcium-alginate hydrogels loaded with yerba mate antioxidants.

A liquid extract of yerba mate (Ilex paraguariensis), with antioxidant properties was encapsulated in calcium-alginate hydrogels containing corn starch as filler at different concentrations. Hydrogel beads were characterized for morphological and size aspects, encapsulation efficiency, Fourier Transform Infrared Spectrometry (FT-IR) and thermal behavior. Addition of starch improved the encapsulation efficiency from 55 to 65%. In vitro release of polyphenols was analyzed in model gastric and intestinal media. The recovery of encapsulated polyphenols occurred mainly in the simulated gastric fluid (85%). Kinetics and release mechanism were satisfactorily fitted to semi-empirical models. The incorporation of starch filler (2 g/100 mL) in calcium alginate hydrogels modified the release profile of polyphenols in acidic medium. In calcium alginate beads, a release mechanism combining erosion and diffusion was observed. Whereas, for polyphenols release of starch loaded beads, only diffusion was relevant.