Controlled release of antifungal volatiles of thyme essential oil from ?-cyclodextrin capsules

Thyme essential oil (TO) is a good antimicrobial agent, however, its high volatility and reactivity limits its application as food preservative. ?-cyclodextrin (?-CD) is able to encapsulate organic molecules, forming host-guest complexes with hydrophobic and volatile molecules such as TO constituents, controlling volatility and reactivity. In addition, controlled released of the ?-CD trapped compounds could be possible by exposing the capsules to high relative humidity (RH). With this in mind, the controlled release of antifungal volatiles throughout exposure of TO:?-CD capsules to high relative humidity was studied. Thymol (TOL) was the major constituent of TO, detected by gas chromatography before and after encapsulation. Capsules of the 8:92 ratio (TO:?-CD) showed the highest TOL content. Hydrogen bonds and hydrophobic interactions were detected between the oil constituent and ?-CD by IR and 1H NMR spectroscopy. During moisture sorption, the TO capsules showed a lower water uptake compared with free ?-CD. Similar behavior was observed during water desorption. In all cases, a hysteresis process was observed when comparing sorption and desorption isotherms. At high RH, TOL is displaced and almost 76% is released to the headspace. The growth of Alternaria alternata was inhibited significantly by the addition and exposure to TO:?-CD as measured by both the agar dilution and the headspace method, respectively. Therefore, the encapsulation of antifungal volatile compounds as TO in ?-CD, could be an alternative to control the release of natural antimicrobials that can be of interest to the agricultural area. � Springer Science+Business Media B.V. 2010

Effect of ripening on physico-chemical properties and bioactive compounds in papaya pulp, skin and seeds

47-59Byproducts generated by the food industry represent an alternative to obtain functional ingredients. Byproducts of tropical fruits, such as papaya skin and seeds, represent a source of bioactive compounds (BC), which could change during fruit ripening. Effect of ripening stage (RS) on BC content and antioxidant properties of edible pulp, skin and seeds of papaya cv. Maradol was determined. Papaya skin showed significantly higher ascorbic acid (~250 mg AAE/100 g) content than seeds (~20 mg/100 g), while pulp had the highest values (~600 mg/100 g). However, papaya skin presented higher total phenolic content (~560 mg GAE/100 g) and flavonoids (~1000 mg QE/100 g) than pulp and seeds. Also, papaya skin showed the highest values followed by pulp and seeds with TEAC, FRAP and DPPH. Papaya skin had higher carotenoids and α-tocopherol (~1500 µg/100 g and ~4000 µg/100 g, respectively) content than pulp and seeds. BC content in each byproduct varied in all RS. Therefore, among the papaya byproducts, skin represents a good source of BC with good antioxidant properties, which may be used to extract them for its incorporation in functional foods depending on RS