Mafalda A. C. Quintas

Nanoemulsions of β-carotene using a high-energy emulsification–evaporation technique

Nanoemulsions of b-carotene were prepared using a high-energy emulsification-evaporation technique based on a 2 3 level factorial design. Results show that it is possible to obtain dispersions at a nanoscale range. Process parameters such as time and shear rate of homogenization affected significantly particle size distribution in terms of volume-weighted mean diameter and surface-weighted mean diameter. The obtained nanoemulsions presented a volume-surface diameter ranging from 9 to 280 nm immedi- ately after the production of particles, displaying in all cases a monomodal size distribution. Those nano- emulsions showed a good physical stability during 21 days storage. The stability was evaluated by the maintenance of size distribution. However, b-carotene retention inside the micelles and color were affected by storage. Processing conditions also influenced storage stability.

Molecular mobility, composition and structure analysis in glycerol plasticised chitosan films

This study was developed with the purpose to investigate the effect of polysaccharide/plasticiser concentration on the microstructure and molecular dynamics of polymeric film systems, using transmission electron microscope imaging (TEM) and nuclear magnetic resonance (NMR) techniques. Experiments were carried out in chitosan/glycerol films prepared with solutions of different composition. The films obtained after drying and equilibration were characterised in terms of composition, thickness and water activity. Results show that glycerol quantities used in film forming solutions were responsible for films composition; while polymer/total plasticiser ratio in the solution determined the thickness (and thus structure) of the films. These results were confirmed by TEM. NMR allowed understanding the films molecular rearrangement. Two different behaviours for the two components analysed, water and glycerol were observed: the first is predominantly moving free in the matrix, while glycerol is mainly bounded to the chitosan chain.

The Effect of Polymer/ Plasticiser Ratio in Film Forming Solutions on the Properties of Chitosan Films

In this work physical-chemical properties of chitosan/ glycerol film forming solutions (FFS) and the resulting films were analysed. Solutions were prepared using different concentrations of plasticising agent (glycerol) and chitosan. Films were produced by solvent casting and equilibrated in a controlled atmosphere. FFS water activity and rheological behaviour were determined. Films water content, solubility, water vapour and oxygen permeabilities, thickness, and mechanical and thermal properties were determined. Fourier transform infrared (FTIR) spectroscopy was also used to study the chitosan/glycerol interactions.Results demonstrate that FFS chitosan concentration influenced solutions consistency coefficient and this was related with differences in films water retention and structure. Plasticiser addition led to an increase in films moisture content, solubility and water vapour permeability, water affinity and structural changes. Films thermo-mechanical properties are significantly affected by both chitosan and glycerol addition. FTIR experiments confirm these results.This work highlights the importance of glycerol and water plasticisation in films properties.

Molecular Dynamics and Structure in Physical Properties and Stability of Food Systems

Physical properties and stability are critical for delivering safe and healthy food to the consumers and thus is a theme that attracts food scientists for a long time. Recently, literature suggests that stability can be fully grasped only if food molecular dynamics and structure are taken into consideration, i.e. an appropriate understanding of the behaviour of food products requires knowledge of its composition, structure and molecular dynamics, through the three-dimensional arrangement of the various structural elements and their interactions. Food systems behaviour is strongly dependent on the water molecular dynamics. Understanding changes in location and mobility of water represents a significant step in food stability knowledge, since water “availability” profoundly influences the chemical, physical and microbiological quality of foods. Nuclear magnetic resonance has been presented as a powerful technique to investigate water dynamics and physical structures of foods through analysis of nuclear magnetisation relaxation times, because it provides information on molecular dynamics of different components in dense complex systems. The application of this technique may be very useful in predicting food systems physicochemical changes, namely texture, viscosity or water migration. This paper aims at reviewing some of the main aspects related to food physical properties and stability, and the role of water in these properties. More specifically, this paper intends to contribute to a deeper understanding of the relationship of molecular constituents–structure–function of food systems, contributing to the development of foods with improved functionality.

Skill development in food professionals : a European study

Abstract The food sector is the largest employer in the European Union, yet it ranks low in innovation and few educated young people pursue food careers. Updating both the skills and the image of food science and technology professionals (FSTs) first requires understanding the current situation. This work compares the view of currently employed FSTs (3,007) with that of food science and technology (FST) employers (602) regarding skills and when and where they should be developed. European FSTs responded to a web-based survey in 2011 and 2012, and FST employers responded to an e-mail-based survey and/or attended brainstorming workshops from 2009 to 2012. Soft skills, especially those related with communication, were the best evaluated by both groups, whereas technical non-food skills were in the lowest positions. FSTs were judged qualified by their employers in some food skills (food safety and quality, product development, production), while others (engineering maintenance, consumer and nutritional sciences, environmental issues) were more poorly evaluated. In general, FSTs believe themselves to be well qualified by higher education programs, and most of them do not continue training once they are working, with the notable exception of those that achieve positions of high responsibility. However, employers appeared to disagree, recommending that education and training in soft, food and technical skills continue throughout working life. Additionally, they recommended more frequent reinforcement of soft than of food or technical skills. A competitive food sector requires FSTs of the highest quality, and understanding the view of FSTs and their employees can contribute to improved training and thus benefit the European food sector.