Influence of nanoliposomes incorporation on properties of film forming dispersions and films based on corn starch and sodium caseinate

The incorporation of potentially antimicrobial volatile compounds (orange essential oil and limonene) into soy and rapeseed nanoliposomes was carried out by encapsulating them trough sonication of their aqueous dispersions. Nanoliposomes were added to starch-sodium caseinate (50:50) film forming dispersions, which were dried to obtain films without losses of the volatile compounds. Structural, mechanical and optical properties of the films were analysed, as well as their antimicrobial activity against Listeria monocytogenes. The addition of liposomes in the polymeric matrix supposed a decrease of the mechanical resistance and extensibility of the films. The natural colour of lecithin conferred a loss of lightness, a chroma gain and a redder hue to the films, which were also less transparent than the control one, regardless the lecithin and volatile considered. The possible antimicrobial activity of the films containing orange essential oil or limonene was not observed, which could be due to their low antilisterial activity or to the inhibition effect of the encapsulation which difficult their release from the matrix.Jiménez Marco, A.; Sánchez González, L.; Desobry, S.; Chiralt Boix, MA.; Arab Tehrany, E. (2014). Influence of nanoliposomes incorporation on properties of film forming dispersions and films based on corn starch and sodium caseinate. Food Hydrocolloids. 35:159-169. doi:10.1016/j.foodhyd.2013.05.006S1591693

Location of PRODAN in lipid layer of HDL particle: a Raman study

FT Raman spectroscopy has been applied to determine the location of PRODAN within HDL and to investigate its influence on the structure of the particle. The complex spectra of HDL and HDL labeled with PRODAN were divided into three regions according to the wave numbers, and adherent spectra were compared separately. Additionally, recorded spectra of protein and lipid fractions of HDL were used as a support for the assignment of particular vibrations in intact particles. In high frequency region, the shift in vibrational frequencies of CH3 groups but almost negligible shift of CH2 groups suggests that PRODAN is situated at the water/lipid interface in the vicinity of the protein. The statement is supported by the observed influence of PRODAN on particular lipid vibrations of phospholipids head-groups. In the fingerprint region, the influence of PRODAN is observed as the slight change in beta-strand secondary structure of apolipoprotein and strongly reduced vibrations of the acyl chain in lipids. That additionally confirms that PRODAN mainly interacts with the lipid domain of the particle. In the low frequency region, the lack of change in Tyr Fermi resonance doublet and only slight differences in the pattern of CS and SS stretching vibrations in labeled HDL confirms that PRODAN has no influence on structure of apolipoprotein embedded in lipid domain. The main conclusions drawn from the vibrational spectra of HDL with and without PRODAN clearly confirm that PRODAN induces negligible changes in HDL structure and hence is reliable fluorescent label for the structural analysis

How Subvisible Particles Become Invisible - Relevance of the Refractive Index for Protein Particle Analysis

The aim of the present study was to quantitatively assess the relevance of transparency and refractive index (RI) on protein particle analysis by the light-based techniques light obscuration (LO) and Micro-Flow Imaging (MFI). A novel method for determining the RI of protein particles was developed and provided an RI of 1.41 for protein particles from two different proteins. An increased RI of the formulation by high protein concentration and/or sugars at pharmaceutically relevant levels was shown to lead to a significant underestimation of the subvisible particle concentration determined by LO and MFI. An RI match even caused particles to become "invisible" for the system, that is, not detectable anymore by LO and MFI. To determine the influence of formulation RI on particle measurements, we suggest the use of polytetrafluoroethylene (PTFE) particles to test a specific formulation for RI effects. In case of RI influences, we recommend also using a light-independent technique such as resonant mass measurement (RMM) (Archimedes) for subvisible particle analysis in protein formulations