This study aims to characterize the pectic oligosaccharides (POSs) generated from enzymatically hydrolyzed citrus peel pectin using a selected enzyme. Pectinex Ultra AFP was used to depolymerize citrus peel pectin into POSs. The POSs were analyzed using high-performance liquid chromatography (HPLC) and liquid chromatography coupled with a mass spectrometer (LC/MS) methodology to determine the composition of monosaccharides and the average molar mass distribution based on the retention time. The identified fractions were predominantly neutral sugars (rhamnose, glucose, and galactose) and acidic sugars (galacturonic acid), with corresponding mole percentages of 8.67%, 10.28%, 74.33%, and 6.72%, respectively. The degree of polymerization (DP) was in the range of DP3–DP8, containing three (trimers) to eight (octamers) monomeric units. The low DP indicates an advanced degree of enzymatic hydrolysis of pectin up to the level of pectic POSs.

The objective of this study was to investigate the effects of enzymatic hydrolysis using α-amylase from Bacillus amyloliquefaciens on the mechanical properties of starch-based films. The process parameters of enzymatic hydrolysis and the degree of hydrolysis (DH) were optimized using a Box–Behnken design (BBD) and response surface methodology (RSM). The mechanical properties of the resulting hydrolyzed corn starch films (tensile strain at break, tensile stress at break, and Young’s modulus) were evaluated. The results showed that the optimum DH for hydrolyzed corn starch films to achieve improved mechanical properties of the film-forming solutions was achieved at a corn starch to water ratio of 1:2.8, an enzyme to substrate ratio of 357 U/g, and an incubation temperature of 48 °C. Under the optimized conditions, the hydrolyzed corn starch film had a higher water absorption index of 2.32 ± 0.112% compared to the native corn starch film (control) of 0.81 ± 0.352%. The hydrolyzed corn starch films were more transparent than the control sample, with a light transmission of 78.5 ± 0.121% per mm. Fourier-transformed infrared spectroscopy (FTIR) analysis showed that the enzymatically hydrolyzed corn starch films had a more compact and solid structure in terms of molecular bonds, and the contact angle was also higher, at 79.21 ± 0.171° for this sample. The control sample had a higher melting point than the hydrolyzed corn starch film, as indicated by the significant difference in the temperature of the first endothermic event between the two films. The atomic force microscopy (AFM) characterization of the hydrolyzed corn starch film showed intermediate surface roughness. A comparison of the data from the two samples showed that the hydrolyzed corn starch film had better mechanical properties than the control sample, with a greater change in the storage modulus over a wider temperature range and higher values for the loss modulus and tan delta, indicating that the hydrolyzed corn starch film had better energy dissipation properties, as shown by thermal analysis. The improved mechanical properties of the resulting film of hydrolyzed corn starch were attributed to the enzymatic hydrolysis process, which breaks the starch molecules into smaller units, resulting in increased chain flexibility, improved film-forming ability, and stronger intermolecular bonds.

Nonbiodegradable food packaging films are made from plastics such as polyethylene and polypropylene, which can take hundreds of years to decompose and create environmental hazards. On the other hand, biodegradable food packaging films are made from renewable materials such as corn starch or cellulose, that degrade within a few weeks or months and prove to be more sustainable and environmentally friendly. In this work, we used corn starch hydrolyzed (CSH) with α-amylase to prepare a film with biodegradable properties. The film was tested for 60 days at different accelerated temperatures and relative humidity (RH), 13 ± 2 °C and 65 ± 5% RH, 23 ± 2 °C and 45 ± 5% RH, and 33 ± 2 °C and 30 ± 5% RH, to test its durability and stability. Soil biodegradation of the CSH film was evaluated by visual appearance, microscopic observation, weight loss, scanning electron microscopy (SEM), and Fourier-transformed infrared spectroscopy (FTIR) every 6 days. The film was found to have strong hygroscopic properties and was able to last up to 10 months if it is maintained at 20 ± 5 °C and 45 ± 5% RH. After the biodegradability test for at least 30 days, the film showed a significantly higher weight loss rate and microbial activity on the surface of the film, which indicates that the film is biodegradable. The present work recommends biodegradable CSH films as an excellent environmentally friendly choice for dried foods packaging, due to their good shelf life at room temperature, which is beneficial when shipping and storing products, but these films are not suitable for foods with high moisture content.

The corrosion behavior of the TiTaNbZrAg alloys with different amounts of tantalum (0%, 10% and 20%) and with distinct surface topography (smooth and rough) was investigated in phosphate buffer solution (PBS) for long-time immersion (1000 h). By this approach, we expect to bring about new insights into the influence of both the amount of Ta in the alloy composition and the surface topography on the corrosion behavior of the Ti-based alloys. The corrosion resistance was studied by Open Circuit Potential (OCP), Potentiodynamic Polarization (PP), and Electrochemical Impedance Spectroscopy (EIS). From the potentiodynamic investigations, it was observed that all types of samples showed good corrosion resistance (i.e., R_corr < 10 µm y⁻¹) and may be used successfully for medical applications. However, the samples with smooth surfaces and with a certain amount of Ta (10% and 20%) exhibit the best corrosion performance (R_corr < 1 µm y⁻¹). As regards the samples with rough surfaces, the results evidenced that they showed lower corrosion resistance (1 < R_corr < 3 µm y⁻¹), suggesting that the Ta presence does not necessarily hinder the corrosion processes. Actually, the synergetic effect of both the presence of Ta and surface roughness plays an important role in corrosion resistance.

The corrosion behavior of Inconel 718 alloy, developed through two different methods—forging (S1) and additive manufacturing (S2)—was evaluated in a seawater environment, and the results were compared with those of Inconel 825 alloy (S3). The corrosion performance of the alloys was examined according to ISO 8044/2024, using open circuit potential (OCP), potentiodynamic polarization (PP), and electrochemical impedance spectroscopy (EIS), in natural seawater at 25 °C over an extended immersion period. After 5000 h of immersion, the corrosion rate (R_corr) estimated from anodic polarization tests was found to be lower for the wrought Inconel 718 alloy (1.21 µm y⁻¹) compared to the wrought 825 alloy (4.1 µm y⁻¹) and to the SLM Inconel 718 alloy (35.1 µm y⁻¹), indicating high corrosion resistance for wrought Inconel 718. A morphological analysis of the alloy’s surface conducted using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) revealed a continuous, compact film with localized salt deposits on wrought Inconel 718 and Incoloy 825. In contrast, SLM Inconel 718 exhibited a porous, inhomogeneous film, leading to reduced protective capabilities and lower corrosion resistance. The results demonstrate that wrought Inconel 718 exhibits excellent corrosion resistance in seawater, making it a promising alloy for marine applications.

This study presents the influence of different contents of tantalum alloying elements on the mechanical and electrochemical properties of TixTa9Nb8Zr2Ag alloys and their corrosion resistance in a 3% NaCl solution. These alloys exhibit a structure with more than 80% of the beta phase, a Young’s modulus between 82 and 55 GPa close to human bone, and good corrosion resistance, with a corrosion rate between 5 and 47 μm y⁻¹. Furthermore, the excellent corrosion behavior of the TixTa9Nb8Zr2Ag alloy with 10 and 15% tantalum content is highlighted, revealed by a nobler corrosion potential, low corrosion rate, and a high passivation tendency in a 3% NaCl solution. The results reported in this work allow us to consider that titanium alloys TixTa9Nb8Zr2Ag with 10–20% Ta could be a valid alternative for use in orthopedic surgery, and the level of tantalum can be customized depending on the nature of the treated bone and the complexity and difficulty of the implant machining, i.e., of the required optimum hardness.