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Extrusion cooking is a green technology to manufacture distiller's grain food. In this study, effects of extrusion on the physicochemical properties and antioxidant potential of Baijiu vinasse protein isolate were investigated. Results showed that extrusion could effectively reduce the particle size (reduced from 275.07 ± 3.60 to 120.30 ± 1.13 nm), zeta potential, and surface hydrophobicity but increase the free sulfhydryl group of Baijiu vinasse protein isolate. Moreover, the unfolding, porous and amorphous structure was observed after extrusion by spectral analysis and X-Ray diffraction, endowing good solubility (increased from 59.26 ± 5.64% to 102.26 ± 3.21% at pH 7), foaming, and emulsifying stability. The in vitro protein digest of Baijiu vinasse protein isolates from extruded samples (200 °C, 150 rpm) exhibited most potent antioxidant activities. This study is the first to exploit extrusion as a feasible technology to produce Baijiu vinasse protein-based food. The results will be of great potential in future industrial application of Baijiu vinasse as a sustainable source of food proteins.

Defensins represent a family of cysteine-rich peptides that have broad-spectrum antimicrobial activities and serve as a typical kind of effector molecule in the immunity. Ruminant species have a large number of β-defensins in the absence of α- and θ-defensins. It is well-known that the genomes of sheep and cattle harbor at least 43 and 57 β-defensin genes, respectively. However, the repertoire of the goat β-defensin gene family has not been fully elucidated. In this study, we identified a total of 50 β-defensins from the goat genome, including 48 functional genes and 2 pseudogenes. Cross-species genomic and evolutionary analyses showed that all of the β-defensins in goat chromosomes 8, 13 and 23 present one-to-one orthologous relationships to their sheep and cattle counterparts, whereas some β-defensin genes in goat chromosome 27 are goat-specific. Moreover, we observed that some duplicated genes in goat chromosome 27 may be derived from gene copy number variation, and the annotation of sheep and cattle β-defensins appears to be incomplete in the genome. Importantly, real-time PCR analysis showed that 17 β-defensins are expressed in the small intestine with abundant cBD1s expression. These findings significant increased our knowledge of ruminant β-defensin and provided useful information for genetic studies, as well as providing a foundation for future research exploring the role of defensins in the immune response.