Jorge Abel Ringuelet

Nutritional and sensory quality during refrigerated storage of fresh-cut mints (Mentha piperita and M. spicata)

The effect of storage time on quality attributes of refrigerated fresh-cut mints (Mentha×piperita and M. spicata) was studied. Atmosphere composition, respiratory activity, weight loss, surface colour, total chlorophyll, carotenoids, browning potential, total phenols, flavonoids, radical-scavenging activity, ascorbic acid and essential oil yield and composition were analysed. Respiratory activity of peppermint and spearmint samples diminished moderately (42% and 28%, respectively) after 21days at 0°C. A slight modification of the internal atmosphere was achieved. Surface colour, chlorophyll, carotenoid and antioxidant compounds remained almost constant. The yield of essential oil did not change or it showed an apparent increase after 21days at 0°C, depending on plant growth stage. The characteristic flavour components of peppermint (menthone and menthol) increased, while the contents of the main constituents of spearmint essential oil showed minor variations after storage. The conditions assayed for packaging and storing fresh-cut mints were adequate to achieve a relatively long shelf life and they retained their antioxidant properties.

In Vitro Fungistatic Effect of Essential Oils Against Ascosphaera apis

Abstract Different essential oils were tested against the fungus Ascosphaera apis, the causal agent of Chalkbrood Disease of honey bees. Essential oils from lavandin (Lavandula x intermedia Emeric ex Loiseleur), coriander (Coriandrum sativum L.), laurel leaf (Laurus nobilis L.), false camphor (Cinnamomum glandulifera Nees), basil (Ocimum basilicum L.), tagetes (Tagetes minuta L.), rosemary (Rosmarinus officinalis L.) and eucalyptus (Eucalyptus globulus Labill.) were assayed to prove their fungistatic activity at different concentrations: 700, 800 and 900 μ.L/L. Strains of Ascosphaera apis were collected from apiaries of different places of Buenos Aires province (Argentina). At all concentrations tested, coriander oil was the most effective fungistatic control while basil and tagetes oils were effective only at 800 μL/L. No differences in effectiveness of oils were observed against the different strains of Ascosphaera apis.

Utilización de Aceite Esencial de Lemongrass (Cymbopogon citratus Stapf) Como Repelente de Diuraphis noxia Kurdj. (Hemiptera: Aphididae) en Trigo

Una herramienta alternativa para el manejo integrado de plagas, es la utilizacion de productos naturales, como aceites esenciales y extractos vegetales. El objetivo del trabajo fue evaluar la actividad repelente del aceite esencial de lemongrass (Cymbopogon citratus Stapf) sobre el pulgon ruso (Diuraphis noxia Kurdj.) en trigo (Triticum aestivum L.). El aceite esencial se formulo en solucion acuosa empleando como emulsionantes propilenglicol al 5% y lecitina de soja al 0,5%. Las concentraciones evaluadas fueron 0,5; 1; 2; 3 y 4% y testigos en blanco, con cinco repeticiones por tratamiento. Se utilizaron dos tecnicas de aplicacion: impregnacion de papeles y pulverizacion directa, cuando las plantas de trigo se encontraban al estado de dos hojas completamente desarrolladas. Luego de la aplicacion, se colocaron 10 pulgones adultos por maceta y se realizo el recuento a las 6 h. Los resultados obtenidos se transformaron en porcentaje de repelencia y se analizaron por ANDEVA y test de Tukey (P = 0,05). Para las tecnicas de aplicacion, se obtuvo un porcentaje de repelencia de 66,07 y 74,33% para pulverizacion e impregnacion de papeles, respectivamente. Al evaluar las formulaciones con los dos emulsionantes, lecitina de soja y propilenglicol, el porcentaje de repelencia fue de 64,78 y 75,63%, respectivamente. Para las concentraciones de lemongrass, el porcentaje de repelencia oscilo entre 65 y 89%. Se concluye que los volatiles de C. citratus demostraron poseer actividad repelente sobre D. noxia.

Propagation Methods and Leaf Yield in Peppermint (Mentha ×piperita L.)

ABSTRACT The effect of two propagation methods (use of stolons in winter and shoots in spring) on the yield of fresh and dried leaves of peppermint (Mentha Xpiperita L.) was studied in a field experiment in the La Plata zone of Argentina. Fresh and dry weights were greater for plants propagated from stolons in winter and harvested in summer (in full bloom and post-bloom) and from shoots planted in spring if plants were harvested post-bloom.