:  Bioactive peptides are protein fragments which have a positive impact on the functions and conditions of living beings. Peptides have shown several useful properties for human health, including antimicrobial, antifungal, antiviral, and antitumor activities. These compounds are produced by almost all species of life. However, they are produced in limited quantities in nature. As a result, researchers have tried to synthesize bioactive peptides to study their properties and applications in various areas. Among their applications in food preservation, peptides have been incorporated into packaging materials. This review begins with a brief description of the methods used for the synthesis, purification, and characterization of peptides. Also, the main bioproperties and mechanisms of action of peptides are discussed. Finally, some applications of peptides are presented, especially their use in active packaging, their effects on the polymeric matrix, and peptide migration.

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Rot and damage caused by post-harvest phytopathogenic fungi affect fruit quality. Essential oils (EO) are considered as an alternative to fungicides. Postharvest diseases of fruits may also be controlled by the bagging approach and the use of antimicrobial packaging. Based on the beneficial properties of EO and the concepts of bagging and antimicrobial packaging, this study aimed to develop sachets containing EO to be used as part of an antimicrobial packaging system. The activities of oregano, cinnamon and lemon grass EO were evaluated testing the sachets in vitro against the phytopathogenic fungi Alternaria alternata, Fusarium semitectum, Lasiodiplodia theobromae and Rhizopus stolonifer. The effects of the sachets on the microbiological and physicochemical parameters of post-harvest papaya were also evaluated. Both pure and sachet-incorporated EO showed antifungal activity in vitro against all tested fungi. For papaya, sachets containing cinnamon, oregano and lemon grass showed a significant reduction in the growth of mesophilic aerobic bacteria, yeasts and mould, with the cinnamon sachet causing the greatest reduction in microorganisms at the end of the storage time. Physicochemical parameters of papaya, such as weight loss, colour, firmness, total soluble solids/titratable acidity ratio and pH were not significantly altered by the presence of EO sachets, thus not affecting the natural ripening process of the papaya.

We report the synthesis of 10,12-pentacosadyinoic acid (PCDA) and PCDA + cholesterol (CHO) + sphingomyelin (SPH) vesicles dispersed in water and the determination of their colorimetric response induced by small amount of organic solvents. In the absence of solvent, PCDA and PCDA/CHO/SPH vesicles showed an intense blue color. The addition of CHCl(3), CH(2)Cl(2), and CCl(4) caused a colorimetric transition (CT) in both structures with the following efficiency: CHCl(3) > CH(2)Cl(2) ≅ CCl(4). However, CH(3)OH did not cause a blue-to-red transition. By microcalorimetric technique we also determined, for the first time, the enthalpy change associated with the CT process and the energy of interaction between solvent molecules and vesicle self-assembly. We observed that the chloride solvents induced a colorimetric transition, but the thermodynamic mechanism was different for each of them. CT induced by CHCl(3) was enthalpically driven, while that caused by CH(2)Cl(2) or CCl(4) was entropically driven.

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