Foodborne diseases are one of the most serious problems the food sector has to confront, while questions have been raised concerning the effects of several antimicrobial additives on consumer health. Nisin is a peptide produced primarily by Lactococcus lactis with antimicrobial properties mostly against Gram-positive bacteria. It is generally recognized as safe (GRAS) for use in a wide range of food categories. However, its interaction with components of the food matrix, its susceptibility to proteolytic degradation, or the competitive presence of other components may limit its activity. To enhance its effectiveness against Gram-negative bacteria, its combination with essential oils or other antimicrobial components has been investigated. In addition, its encapsulation in several types of nano-delivery systems has been used to protect nisin from food matrix sequestering while regulating its release. In this review, we present how nisin is utilized, alone or in combination with other antimicrobial agents in a range of emulsion types, as well as the standard techniques for the physicochemical characterization of these systems.

It is shown that the on-channel concentration procedure for the analysis of dilute monodisperse colloidal samples in sedimentation field-flow fractionation, as established in a previous work(1), provides an accurate methodology for the concentraion and particle size analysis of dilute polydisperse colloidal samples. In order to test the methodology experiments are described using polyvinyl chloride (PVC) latex beads in the diameter range 0.173–0.334 μm. A series of fractograms were run in which the amount of the PVC sample was held constant while the volume in which it was contained was varied over a 20,000-fold range. The weight average particle diameters and the particle size distribution curves (histograms or cumulative distribution curves), determined by the on-channel concentration procedure at various experimental conditions, are in excellent agreement with those obtained under normal experimental conditions, in which a small concentrated volume of the same sample is injected directly into the column. Moreover, varying the density of the carrier solution, apart from the weight average particle diameter or the particle size distribution curve, the density of the PVC latex beads was obtained in accordance with that found by a common method.

The technique of Sedimentation/Steric Field Flow Fractionation (Sd/StFFF) is applied to the kinetic study of cells proliferation of Saccharomycescerevisiae strains. The experimental parameter varied is the time from the preparation of the yeast sample dispersion in the culture medium. The determination of the size and mass distributions of the yeast cells is combined with the growth of the yeast cells and their life cycle. The experimental results are compared with those obtained by scanning electron microscopy (SEM) and those found in the literature. Useful conclusions concerning the budding and the fission of these yeast cells were extracted.