Study of Formulation and Stability of Co-surfactant Free Water-in-Olive Oil Nano- and Submicron Emulsions with Food Grade Non-ionic Surfactants

Nanoemulsions are of great interest in food industry finding various food applications. However, oil-in-water (o/w) nanoemulsions have been intensively investigated, but there are few studies on w/o nanoemulsions. In the present work the preparation of nanoemulsions with olive oil using non-ionic surfactants (Tween 20, 40, 60, 80, Span 20, 80) without the addition of a co-surfactant was studied and their emulsion properties and stability were examined. The stable nanoemulsions were presented in ternary phase diagrams (oil–water-surfactant) for each surfactant and the emulsifying ability of the efficient surfactants was determined. The nanoemulsions properties were evaluated in relationship to compositional components. From the results of this study it can be concluded that stable olive oil nanoemulsions without use of a co-surfactant were obtained and moreover the most efficient type of emulsifier and its ratio of addition in the system were determined.     

High pressure treatment of brine enhanced pork affects endopeptidase activity,protein solubility,and peptide formation

In order to study the effect of high-pressure (HP) treatment and two different methods of brine addition (important for lysosomal membrane destabilisation) on lysosomal enzymes activity and protein degradation, pork semitendinosus muscle was brine enhanced by injection or tumbling, and HP treated at 600 MPa following storage at 2 °C for up to 8 weeks. In this report a novel protocol for SDS gelatin zymography was established, and an increase of cathepsin B and L activity after HP treatment was shown followed by a decrease during storage. No calpain activity was detected following HP treatment. HP treatment was shown to induce a decrease in protein solubility in both myofibrillar and sarcoplasmic fractions. LC–MS analysis of these fractions showed changes in the peptide pattern during storage. Western blot analysis showed that troponin-T was indeed degraded during storage after HP treatment. The results therefore suggest that HP treatment induced an increase in cathepsin activity, which subsequently affected the myofibrillar protein degradation pattern in pork meat.     

Compression of gellan gels. Part II: Effect of sugars

The effect of sucrose, glucose, fructose and their mixtures on the gelation of 0.5 wt% low acyl gellan in the presence of potassium chloride (100 mM) was investigated by large deformation compression experiments. The sugar concentration varied from 0 to 15 wt% whereas all their combinations at a final concentration of 15 wt% were also studied. Stress at failure and strain at failure along with Young's modulus were calculated from each compression curve. Samples prior to compression were refrigerated at 5 °C for 1, 2 and 24 h. Glucose showed no contribution to the gellan network strength but decreased the firmness of the gels. On the other hand, fructose and sucrose enhanced the strength of the network, with sucrose being slightly more effective, but had no effect on firmness. This behaviour depended solely on the presence of each sugar and not in their concentration. The elasticity of the gels was not significantly altered by the addition of sugars or their mixtures. Strength and firmness shared similar profiles when mixtures of sugars were used to promote gelation. Sugars, when in mixtures, showed no synergistic interactions whereas their type seems to affect the properties of the resulting gels.