Flexo-Ionic Effect of Ionic Liquid Crystal Elastomers

The first study of the flexo-ionic effect, i.e., mechanical deformation-induced electric signal, of the recently discovered ionic liquid crystal elastomers (iLCEs) is reported. The measured flexo-ionic coefficients were found to strongly depend on the director alignment of the iLCE films and can be over 200 µC/m. This value is orders of magnitude higher than the flexo-electric coefficient found in insulating liquid crystals and is comparable to the well-developed ionic polymers (iEAPs). The shortest response times, i.e., the largest bandwidth of the flexo-ionic responses, is achieved in planar alignment, when the director is uniformly parallel to the substrates. These results render high potential for iLCE-based devices for applications in sensors and wearable micropower generators.     

Development and Characterization of Functional Starch-Based Films Incorporating Free or Microencapsulated Spent Black Tea Extract

Antioxidant polyphenols in black tea residue are an underused source of bioactive compounds. Microencapsulation can turn them into a valuable functional ingredient for different food applications. This study investigated the potential of using spent black tea extract (SBT) as an active ingredient in food packaging. Free or microencapsulated forms of SBT, using a pectin–sodium caseinate mixture as a wall material, were incorporated in a cassava starch matrix and films developed by casting. The effect of incorporating SBT at different polyphenol contents (0.17% and 0.34%) on the structural, physical, and antioxidant properties of the films, the migration of active compounds into different food simulants and their performance at preventing lipid oxidation were evaluated. The results showed that adding free SBT modified the film structure by forming hydrogen bonds with starch, creating a less elastic film with antioxidant activity (173 and 587 µg(GAE)/g film). Incorporating microencapsulated SBT improved the mechanical properties of active films and preserved their antioxidant activity (276 and 627 µg(GAE)/g film). Encapsulates significantly enhanced the release of antioxidant polyphenols into both aqueous and fatty food simulants. Both types of active film exhibited better barrier properties against UV light and water vapour than the control starch film and delayed lipid oxidation up to 35 d. This study revealed that starch film incorporating microencapsulated SBT can be used as a functional food packaging to protect fatty foods from oxidation.     

XRF to support food traceability studies: Classification of Sri Lankan tea based on their region of origin

Food fraud is a concern for the producers of high‐quality food products as it causes brand damage and loss of profit. Tea (Camellia sinensis L.) is one of the major agricultural products of Sri Lanka and accounts for more than 300 million of kilograms per year, roughly 2% of the national GDP. Trace metals and stable isotope ratios in tea samples originating from various regions in Sri Lanka were determined by using X‐ray fluorescence analysis and isotope‐ratio mass spectrometry to explore the possibility of classifying the tea according to its origin. In total, 13 elements (Mg, P, S, Cl, K, Ca, Mn, Fe, Cu, Zn, Br, Rb and Sr) were determined in 58 tea samples originating from four production districts in Sri Lanka (Hantana, Thalawakelle, Passara and Ratnapura). Two multivariate analysis techniques, namely principal component analysis and canonical discriminant analysis, were applied to explore the differences in elemental contents among the tea produced in these regions and to find a method for compositional classification. This study, although limited by the number of samples available, clearly shows that the differentiation and classification of tea samples according to the four regions of origin is possible by using the elemental contents and applying canonical discriminant analysis. Copyright © 2017 John Wiley & Sons, Ltd.