The antioxidant and antimicrobial effects of pecan shell (PSW), combined with roselle flower (RS) and red pepper (CA) were analyzed in beef patties by several methods during chilled storage for 13 days. Additionally, the antioxidant and antimicrobial activities of PSW, RS and CA extracts were determined. The PSW extract exhibited a higher radical scavenging activity (by the DPPH method) and more total phenolic compounds than RS and CA. RS presented the best antimicrobial capacity. Nine formulations of beef patties were prepared, including a control (CM), a synthetic preservative (CAMPA N.3 (A)) and different combinations of PSW, RS and CA. The bacterial counts of the beef patties with RS (4–5 log colony-forming units (CFU)/g meat) were significantly lower than those of the control sample (CM) (6–7 CFU/g meat) at day 6. The thiobarbituric acid-reactive substance (TBARS) values at day 7 of all treatments were similar to the values of samples containing the synthetic antioxidant and significantly lower than the CM group. The order of stability assessed by the TBARS values were in agreement with the hexanal content. Thus, these results support the hypothesis that the combination of PWS, RS and CA could represent a good natural food preservative.

Two very stable organic radical adducts 1 and 2 formed by an electron donoracceptor system with bipolar charge transport behavior have been investigated. Both present the same electron donor moiety, 3,6-bis(N-carbazolyl)carbazole, and are distinguished by the paramagnetic electron-withdrawing moiety, tris(2,3,5,6-tetrachlorophenyl)methyl radical (DTM) in 1 and tris(2,4,6trichlorophenyl)methyl radical (TTM) in 2. They exhibit low band gaps (difference between HOMO and LUMO orbitals), 1.54 and 1.81 eV for 1 and 2, respectively, absorbing in the visible rang of the electromagnetic spectrum.Both radical adducts present suitable charge transport results with the DTM derivative 1 showing the best performance. Thus, 1 with higher structural congestion displays a well-balanced ambipolar behavior and the highest hole and electron mobility values.