Using salted egg white in steamed bread: Impact on functional and structural characteristics

Steamed bread has long been an important part of Chinese cuisine. This study investigated the effects of salted egg white (SEW) (5, 10, 15, and 20% w/w) on the quality of steamed breads. Findings revealed that SEW notably enhanced the bread's volume and texture, with a 20% inclusion significantly boosting water retention and rheological properties, albeit reducing bread's lightness. In addition, the H-bond absorption band intensity in the Fourier transform infrared spectroscopy (FTIR) analysis showed increased peak intensities with higher SEW levels, indicative of protein structure alterations. X-ray diffraction confirmed the presence of an amylose-lipid complex. Scanning electron microscope (SEM) and Confocal laser scanning microscope (CLSM) imaging depicted a smooth, consistent protein network with SEW addition. Consumer sensory evaluation responded favourably to the SEW15 steamed bread, suggesting its potential for food industry application. Overall, the study considers SEW an effective ingredient for improving steamed bread quality.

Co-encapsulation of probiotic Lactobacillus acidophilus and Reishi medicinal mushroom (Ganoderma lingzhi) extract in moist calcium alginate beads

Probiotic L. acidophilus La-14 cells were co-encapsulated with Ganoderma lingzhi extract to prolong the viability of the cells under simulated gastrointestinal (SGI) condition and to protect the active ingredients of Reishi mushroom during the storage period. Combinations of distinctive reagents (sodium alginate, chitosan, maltose, Hydroxyethyl-cellulose (HEC), hydroxypropyl methylcellulose (HPMC), and calcium lactate) were tested. Optimal double layer Ca-alginate hydrogel beads were fabricated with significantly improved characteristics. The incorporation of maltose significantly decreases the release rate of mushrooms' phenolics, antioxidants, and β-glucan during the storage time. Significant improvement in probiotic cells viability under SGI condition has been found and confirmed by confocal laser microscopy in maltose containing double layer coated calcium alginate beads variants. The encapsulation of newly formulated prebiotic Reishi extract and probiotic L. acidophilus is creating a new potential food application for such medicinal mushrooms and natural products with unpleasant taste upon oral consumption.

Interfaces with Structure Dynamics of the Workhorses from Cells Revealed through Cross-Linking Mass Spectrometry (CLMS)

The fundamentals of how protein-protein/RNA/DNA interactions influence the structures and functions of the workhorses from the cells have been well documented in the 20th century. A diverse set of methods exist to determine such interactions between different components, particularly, the mass spectrometry (MS) methods, with its advanced instrumentation, has become a significant approach to analyze a diverse range of biomolecules, as well as bring insights to their biomolecular processes. This review highlights the principal role of chemistry in MS-based structural proteomics approaches, with a particular focus on the chemical cross-linking of protein-protein/DNA/RNA complexes. In addition, we discuss different methods to prepare the cross-linked samples for MS analysis and tools to identify cross-linked peptides. Cross-linking mass spectrometry (CLMS) holds promise to identify interaction sites in larger and more complex biological systems. The typical CLMS workflow allows for the measurement of the proximity in three-dimensional space of amino acids, identifying proteins in direct contact with DNA or RNA, and it provides information on the folds of proteins as well as their topology in the complexes. Principal CLMS applications, its notable successes, as well as common pipelines that bridge proteomics, molecular biology, structural systems biology, and interactomics are outlined.

Structural Studies of the Cutin from Two Apple Varieties: Golden Delicious and Red Delicious (Malus domestica)

The cuticle, a protective cuticular barrier present in almost all primary aerial plant organs, has a composition that varies between plant species. As a part of the apple peel, cuticle and epicuticular waxes have an important role in the skin appearance and quality characteristic in fresh fruits destined for human consumption. The specific composition and structural characteristics of cutin from two apple varieties, “golden delicious” and “red delicious”, were obtained by enzymatic protocols and studied by means of cross polarization magic angle spinning nuclear magnetic resonance (CP-MAS ¹³C NMR), attenuated total reflection infrared spectroscopy (ATR-FTIR), and mass spectrometry, and were morphologically characterized by specialized microscopy techniques (atomic force microscopy (AFM), confocal laser scanning microscopy (CLMS), and scanning electron microscopy (SEM)). According to CP-MAS ¹³C NMR and ATR-FTIR analysis, cutins from both varieties are mainly composed of aliphatics and a small difference is shown between them. This was corroborated from the hydrolyzed cutins analysis by mass spectrometry, where 9,10,18-trihydroxy-octadecanoic acid; 10,20-Dihydroxy-icosanoic acid; 10,16-dihydroxy hexadecenoic acid (10,16-DHPA); 9,10-epoxy-12-octadecenoic acid; and 9,10-epoxy-18-hydroxy-12-octadecenoic acid were the main monomers isolated. The low presence of polysaccharides and phenolics in the cutins obtained could be related to the low elastic behavior of this biocomposite and the presence of cracks in the apple cutin’s surface. These cracks have an average depth of 1.57 µm ± 0.57 in the golden apple, and 1.77 µm ± 0.64 in those found in the red apple. The results obtained in this work may facilitate a better understanding that mechanical properties of the apple fruit skin are mainly related to the specific aliphatic composition of cutin and help to much better investigate the formation of microcracks, an important symptom of russet formation.

Microtubule Nucleation Properties of Single Human γTuRCs Explained by Their Cryo-EM Structure

The γ-tubulin ring complex (γTuRC) is the major microtubule nucleator in cells. The mechanism of its regulation is not understood. We purified human γTuRC and measured its nucleation properties in a total internal reflection fluorescence (TIRF) microscopy-based real-time nucleation assay. We find that γTuRC stably caps the minus ends of microtubules that it nucleates stochastically. Nucleation is inefficient compared with microtubule elongation. The 4 Å resolution cryoelectron microscopy (cryo-EM) structure of γTuRC, combined with crosslinking mass spectrometry analysis, reveals an asymmetric conformation with only part of the complex in a "closed" conformation matching the microtubule geometry. Actin in the core of the complex, and MZT2 at the outer perimeter of the closed part of γTuRC appear to stabilize the closed conformation. The opposite side of γTuRC is in an "open," nucleation-incompetent conformation, leading to a structural asymmetry explaining the low nucleation efficiency of purified human γTuRC. Our data suggest possible regulatory mechanisms for microtubule nucleation by γTuRC closure.