Reversible stress softening of collagen based networks from the jumbo squid mantle (Dosidicus gigas)

Effects of Heating Treatment on the Physicochemical and Volatile Flavor Properties of Argentinian Shortfin Squid (Illex argentinus)

In this study, the effect of different heating temperatures (80, 90, 100, and 121 °C) on the physicochemical and volatile flavor properties of fried mantles (Argentinian shortfin) was investigated. The squid mantles were soaked in a maltose syrup solution (20% w/v) for 10 s and fried in soybean oil for 10 s (160 °C), vacuum-packed, and processed at different temperatures for 10 min. Then, the squid mantles were subjected to colorimetric analysis, sensory evaluation, free amino acid analysis, and texture profile analysis. In addition, the volatile organic compounds (VOCs) in the squid mantles were analyzed. The results revealed that lower treating temperatures (80 and 90 °C) improved the chromatic and textural properties, along with organoleptic perception. Additionally, the content of amino acid in the squid mantles treated at 121 °C was significantly lower than that of the samples treated at other temperatures (p < 0.05). Headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) was used to detect 41 VOCs, including their monomers and dimers. Among these detected VOCs, the contents of alcohols, ketones, and pyrazines were positively correlated with temperature. However, the content of aldehydes in the squid mantles gradually decreased as the heating temperature increased (p < 0.05). The combined HS-GC-IMS and E-nose results revealed that the lower temperatures (80 and 90 °C) were more suitable for flavor development and practical processing. This study provides valuable information for properly controlling the heating process of squid products, as well as flavor and practical applications for the aquatic industry.

The differences of muscle proteins between neon flying squid (Ommastrephes bartramii) and jumbo squid (Dosidicus gigas) mantles via physicochemical and proteomic analyses

Neon flying squid (OB) and jumbo squid (DG) mantles were evaluated to reveal the similarities and differences in their physicochemical features and protein abundances. Microstructural results indicated that the OB mantle exhibited numerous myofibril fragments and disordered microstructures after frozen storage compared with DG tissues. Chemical analysis suggested that freezing resulted in a rapid decrease in myofibrillar protein (MP) content, Ca²⁺-ATPase activity, and total sulfhydryl content, and promoted the increase in carbonyl content of MPs in both OB and DG. While, DG presented better MP stability than OB muscle after 120 days of frozen storage. Label-free proteomic analysis detected 24 down- and 33 up-regulated differentially abundant proteins (DAPs) in OB and DG mantles. Identified DAPs including isocitrate dehydrogenase and malic enzyme initiated a rapid decrease in the MP properties in OB samples. Moreover, DAPs were related to cytoskeleton function, including paramyosin, tropomyosin, and troponin C, which improved the stability of DG in response to freezing-induced changes.

Failure of flight feathers under uniaxial compression

Flight feathers are light weight engineering structures. They have a central shaft divided in two parts: the calamus and the rachis. The rachis is a thinly walled conical shell filled with foam, while the calamus is a hollow tube-like structure. Due to the fact that bending loads are produced during birds' flight, the resistance to bending of feathers has been reported in different studies. However, the analysis of bent feathers has shown that compression could induce failure by buckling. Here, we have studied the compression of feathers in order to assess the failure mechanisms involved. Axial compression tests were carried out on the rachis and the calamus of dove and pelican feathers. The failure mechanisms and folding structures that resulted from the compression tests were observed from images obtained by scanning electron microscopy (SEM). The rachis and calamus fail due to structural instability. In the case of the calamus, this instability leads to a progressive folding process. In contrast, the rachis undergoes a typical Euler column-type buckling failure. The study of failed specimens showed that delamination buckling, cell collapse and cell densification are the primary failure mechanisms of the rachis structure. The role of the foam is also discussed with regard to the mechanical response of the samples and the energy dissipated during the compression tests. Critical stress values were calculated using delamination buckling models and were found to be in very good agreement with the experimental values measured. Failure analysis and mechanical testing have confirmed that flight feathers are complex thin walled structures with mechanical adaptations that allow them to fulfil their functions.

Thermal and Rheological Properties of the Mucilage from the Fruit of Cordia lutea

In recent years, natural gums and mucilages have been shown to be useful in the food and pharmacological industries. In this study, the mucilage of the fruit of Cordia lueta has been extracted and characterised in order to explore its potential applications. Thermogravimetric tests were used to measure the water content of this natural mucilage. Differential scanning calorimetry allowed assessing thermal transitions and thermal degradation of the samples. Steady flow rheometry was used to measure the viscosity of the samples as a function of the shear rate. Dynamic oscillatory rheometry was used to study the variation of the storage and loss modulus of the mucilage as function of the oscillatory frequency and stress. The results showed that this mucilage is a polysaccharide network that behaves as a pseudoplastic fluid. Its storage modulus is not completely independent from the oscillation frequency. In addition, the stress sweeps showed that C. lutea mucilage has a reversible stress softening behaviour. The findings reported in the present work suggest that this mucilage can be used as a rheology modifier for commercial foods and biomedical materials.

Failure retardation in body armor

The protective structures that occur in biological systems are complex composite materials that display impressive mechanical properties, considering the weak properties of the individual constituents from which they are assembled. Body armors are hard materials designed to protect an animal from the fangs and claws of their predator. The usual engineering approach to biological materials has focused on treating them like synthetic composite materials designed to achieve higher strength and stiffness. Here, the authors propose that the basic evolutionary design of body armors and biological materials is related to the retardation of catastrophic failure through a variety of mechanisms, most of which directly relate to the absorption of energy during deformation. The authors subsequently reviewed and classified in a systemic way failure retardation mechanisms related to various types of body armor, including fish scales, fish dermal plates, osteoderms, mollusk shells and porcupine quills. These materials are compared with soft materials such as bacterial cellulose, jumbo squid mantles and actin microtubules that exhibit similar failure retardation characteristics. Through comparison of these failure analysis studies, the authors aim to develop a more nuanced understanding of the evolutionary design of the hierarchical structures observed in a variety of biological systems.