A Novel Functional Wrapping Design by Complexation of ε-Polylysine with Liposomes Entrapping Bioactive Peptides

Physical and Oxidative Water-in-Oil Emulsion Stability by the Addition of Liposomes from Shrimp Waste Oil with Antioxidant and Anti-Inflammatory Properties

Liposomes made of partially purified phospholipids (PL) from Argentine red shrimp waste oil were loaded with two antioxidant lipid co-extracts (hexane-soluble, Hx and acetone-soluble, Ac) to provide a higher content of omega-3 fatty acids. The physical properties of the liposomes were characterized by Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS) and Differential Scanning Calorimetry (DSC). The antioxidant and anti-inflammatory activity of the lipid extracts and liposomal suspensions were evaluated in terms of Superoxide and ABTS radical scavenging capacities and TNF-α inhibition. Uni-lamellar spherical liposomes (z-average ≈ 145 nm) with strong negative ζ potential (≈ -67 mV) were obtained in all cases. The high content of neutral lipids in the Hx extract caused structural changes in the bilayer membrane and decreased entrapment efficiency regarding astaxanthin and EPA + DHA contents. The liposomes loaded with the Hx/Ac extracts showed higher antioxidant and anti-inflammatory activity compared with empty liposomes. The liposomal dispersions improved the physical and oxidative stability of water-in-oil emulsions as compared with the PL extract, inducing pronounced close packing of water droplets. The liposomes decreased hydroperoxide formation in freshly made emulsions and prevented thio-barbituric acid-reactive substances (TBARS) accumulation during chilled storage. Liposomes from shrimp waste could be valuable nanocarriers and stabilizers in functional food emulsions.

Lipid-Encapsuled Grape Tannins Prevent Oxidative-Stress-Induced Neuronal Cell Death, Intracellular ROS Accumulation and Inflammation

The central nervous system (CNS) is particularly vulnerable to oxidative stress and inflammation, which affect neuronal function and survival. Nowadays, there is great interest in the development of antioxidant and anti-inflammatory compounds extracted from natural products, as potential strategies to reduce the oxidative/inflammatory environment within the CNS and then preserve neuronal integrity and brain function. However, an important limitation of natural antioxidant formulations (mainly polyphenols) is their reduced in vivo bioavailability. The biological compatible delivery system containing polyphenols may serve as a novel compound for these antioxidant formulations. Accordingly, in the present study, we used liposomes as carriers for grape tannins, and we tested their ability to prevent neuronal oxidative stress and inflammation. Cultured catecholaminergic neurons (CAD) were used to establish the potential of lipid-encapsulated grape tannins (TLS) to prevent neuronal oxidative stress and inflammation following an oxidative insult. TLS rescued cell survival after H2O2 treatment (59.4 ± 8.8% vs. 90.4 ± 5.6% H2O2 vs. TLS+ H2O2; p < 0.05) and reduced intracellular ROS levels by ~38% (p < 0.05), despite displaying negligible antioxidant activity in solution. Additionally, TLS treatment dramatically reduced proinflammatory cytokines’ mRNA expression after H2O2 treatment (TNF-α: 400.3 ± 1.7 vs. 7.9 ± 1.9-fold; IL-1β: 423.4 ± 1.3 vs. 12.7 ± 2.6-fold; p < 0.05; H2O2 vs. TLS+ H2O2, respectively), without affecting pro/antioxidant biomarker expression, suggesting that liposomes efficiently delivered tannins inside neurons and promoted cell survival. In conclusion, we propose that lipid-encapsulated grape tannins could be an efficient tool to promote antioxidant/inflammatory cell defense.

Protein-based natural antibacterial materials and their applications in food preservation

Plastics materials used for food packaging are recalcitrant, leading to a growing global environmental problem, which arouses the attention of environmental protection departments in many countries. Therefore, to meet the increasing demand for sustainable and environment-friendly consumer products, it is necessary for the food industry to develop natural antibacterial materials for food preservation. This review summarizes the common biodegradable natural antimicrobial agents and their applications in food preservation; as well as an overview of five commonly used biodegradable protein-based polymers, such as zein, soy protein isolate, gelatin and whey protein, with special emphasis on the advantages of protein-based biopolymers and their applications in food packaging industry.

Films from poly-γ-glutamic acid and poly-ε-lysine as the potential wound dressings – formulation, preparation and evaluation

Film wound dressings represent one of the options in wound therapy. Various polymers can be used for their production. Currently, research focuses on materials of natural origin, more friendly to the human body, which are in many cases able to participate actively in the wound healing process. These include polyamino acids of bacterial origin, substances that are biodegradable, non-toxic, and have a great potential for an application not only in the medical field. From the point of view of film wound dressing formulation, poly-γ-glutamic acid (PGA), as a film-forming agent, and poly-ε-lysine (PL), characterized by antimicrobial activity, are of interest from this group. Therefore, the aim of our experiment was to prepare films consisting of PGA or a combination of PGA and PL with the addition of different plasticizers. The films were prepared by solvent evaporation method and then evaluated for their organoleptic (appearance, colour, transparency, ease of handling), physicochemical (thickness, density, opacity, surface pH), and mechanical properties (tensile strength and tear resistance). As a result, films showing mutual compatibility between the two polymers were obtained, with satisfactory properties for wound application.

Multifunctional betanin nanoliposomes-incorporated gelatin/chitosan nanofiber/ZnO nanoparticles nanocomposite film for fresh beef preservation

The objective of this study was to fabricate betanin nanoliposomes incorporated gelatin/chitosan nanofiber/ZnO nanoparticles bionanocomposite film (G/CH NF/ZnO NPs/B NLPs) and investigate its effects on the preservation of fresh beef. The scanning electron microscopy image of nanocomposite film displayed a good inter-connective porous morphology. Fourier transform infrared and X-ray diffraction analysis confirmed the formation of new hydrogen bonds and enhanced crystallinity through the addition of CH NF, ZnO NPs, and B NLPs. The G/CH NF/ZnO NPs/B NLPs film exhibited satisfactory mechanical properties and high surface hydrophobicity (water contact angle = 92.49 ± 3.71°). The incorporation of ZnO NPs and B NLPs in the nanocomposite film provided high antibacterial activity and DPPH inhibition activity (53.02 ± 3.26%). The growth of inoculated bacteria, lipid oxidation, and the changes in the pH and color quality of the beef samples were controlled by packaging with the fabricated film. In conclusion, the G/CH NF/ZnO NPs/B NLPs nanocomposite has a high potential for meat preservation.

Antimicrobial, microscopic and spectroscopic properties of cellulose paper coated with chitosan sol-gel solution formulated by epsilon-poly-l-lysine and its application in active food packaging

Cellulose paper-chitosan (CC) double-layer films containing epsilon-poly-l-lysine (ε-PL) (0.5 and 1% w/v) were developed. FTIR analysis showed a strong association between the ε-PL and CC film. Antimicrobial activity against Listeria monocytogenes was investigated both in vitro and in the chicken breast meat. The CC films without ε-PL showed no antimicrobial activity, while the addition of ε-PL induced significant (p < 0.05) effects. During the 28 days of storage at 4 ^°C, no significant difference was found on the anti-listeria activity of films. When storage temperature was raised from 4 to 22 ^°C, the antimicrobial activity was reduced. Films containing 1% ε-PL exhibited 1.5 log₁₀ CFU/g reduction in L. monocytogenes population during 12 days storage of meat at 4 ^°C, while no significant reduction was found in CC films with 0.5% ε-PL (p > 0.05). This study revealed an antimicrobial activity for CC films impregnated with ε-PL, to control foodborne pathogens in meat.

Effect of lyophilization on the physicochemical and rheological properties of food grade liposomes that encapsulate rutin

The potential use of liposomes as carriers for food active ingredients can be limited by their physical and chemical instabilities in aqueous dispersions, especially for long-term storage. Lyophilization, a process commonly used in the food industry, can also be applied to stabilize and preserve liposomes and to extend their shelf-life. In this work, liposomes with potential use for designing functional foods were prepared with soy phospholipids and rutin. Homogenization and ultrasound were used for particle size reduction. Liposomal stability was evaluated by Dynamic Light Scattering, microscopy and rheological properties. Spherical and unilamellar liposomes were obtained in this work. Zeta potential (ξ = values were around -40 mV), which indicates a great suspension stability even for more than 30 days of storage. Rutin exerted a protective effect by both preventing damage to the liposome bilayer and maintaining the spherical structure after 56 days of storage. Lyophilization caused an increase in the size of the vesicles, reaching sizes around 419 nm and aggregation of vesicles with probably structural damage after 21 storage days. However, it helped to keep the rutin encapsulated (81.9%) for longer time, when compared to refrigerated liposomes. Rheological measurements showed, in general, that the power law model fitted most of the experimental results and dynamic rheological tests showed a sol-gel phase transition between 35 and 45 °C. Lyophilization caused a significant change in all evaluated rheological parameters. For the in vitro release tests, the liposomal bilayer acted as a barrier for the rutin release to the food simulating medium; therefore, the release rate of the antioxidant from the rutin encapsulated liposome was slow compared to the free rutin release rate.

Humectability and physical properties of hydroxypropyl methylcellulose coatings with liposome-cellulose nanofibers: Food application

The objective of this study was to investigate the physical, rheological and humectability properties of edible coating forming suspensions (ECS) based on hydroxypropyl methylcellulose (HPMC) containing: liposomes that encapsulate rutin, glycerol and cellulose nanofibers on sliced surfaces of almonds and chocolate. On average, liposomes measured between 110.6 ± 10.0 nm and were characterized as stable and homogeneous suspensions. Adding these liposomes to the edible coatings produced significant changes (p< 0.05) in the density and surface tension, which favor the final appearance of the coating. The presence of liposomes increased the apparent viscosity of the ECS, showing a purely viscous and fluid behavior with a good fit (R² = 0.9996) with the Power Law model. The presence of liposomes and cellulose nanofibers decreased the value of the cohesive energy of the ECS. The studied ECS partially hydrate the surfaces of almond and chocolate as they showed contact angles under 90°.

Effect of chemical composition and sonication procedure on properties of food-grade soy lecithin liposomes with added glycerol

The effect of two-step and five-step acetone washing of soybean lecithin (SL) on compositional properties of partially purified phosphatidylcholines (PW2 and PW5) was studied. Trace amounts of protein were detected in SL, PW2 and PW5, with a predominance of glutamic acid and aspartic acid. Increasing the number of acetone washing steps significantly reduced the total content of γ-, δ- and α-tocopherol. Similar reductions (≈90%) of neutral lipids were found in both PW2 and PW5, but the removal of free fatty acids was higher in PW5 than in PW2 (78% vs. 71%). Linoleic acid was the main constituent in both the neutral lipids and the phospholipid fractions of SL, PW2 and PW5, accounting for around 53-59% of total fatty acids; however, a considerable amount of it was removed by increasing the number of washing steps. All phospholipid classes were mostly concentrated in the first two-step washing of lecithin. Further washing increased the concentration of phosphatidylcholine (PC) in PW5, as compared to PW2. Glycerol-containing liposomes from PW2 and PW5 were produced using two different-intensity sonication procedures (method A: 120W, 5min; method B: 30W, 2min) using a probe-type sonicator (100mL volume suspension). Liposomes of soy lecithin and liposomes of PW5 without glycerol were also obtained by using strong sonication (method A). The liposomal dispersion with the highest purification and the stronger sonication was clearly distinguished from the others, both in particle size and in zeta potential. DSC results showed noticeable interference of glycerol in the membrane structure, but minimal changes in particle size and surface charge.