UV-C and hyperoxia abiotic stresses to improve healthiness of carrots: study of combined effects

Phenolic compounds are phytochemicals with high health-promoting properties. Carrot is a vegetable highly worldwide consumed although its phenolic content is low compared to other plant products. The aim of this work was to evaluate changes in phenolic compounds in carrots caused by abiotic stresses. The phenylalanine ammonia-lyase (PAL) activity, phenolic compounds and total antioxidant capacity (TAC) changes during storage up to 72 h at 15 °C after wounding (shredding), 9 kJ UV-C m−2 pretreatment and hyperoxia (80 kPa) conditions of carrots were studied. Shredding and hyperoxia storage induced the highest phenolic compounds and TAC enhancements. Accumulation of phenolic compounds in shredded carrots could be structured in the following phases: 1st phase (<24 h): unchanged phenolic compounds levels with minimum PAL activity; 2nd phase (24–48 h): moderate phenolic increases (≈600–700 mg CAE kg−1 accumulated in 24 h) concurring with the greatest increase of PAL activity; 3nd phase (48–72 h): high phenolic increases (≈1600–2700 mg CAE kg−1, accumulated in 24 h) while a moderate increment of PAL activity was registered. Although UV-C pretreatment of shreds reduced phenolic accumulation, 600 % increments were still registered in those samples stored under hyperoxia conditions for 72 h. However, the contents of chlorogenic acid at 72 h were 1.4-fold higher in irradiated shreds under hyperoxia compared to the same samples under air conditions.Authors are grateful to the Spanish Ministry Economy and Competitiveness (Project AGL2013-48830-C2-1-R) and FEDER for financial support. We are grateful to V. Díaz-López for his skillful technical assistance

Modeling the Impact of the Type of Cutting and Storage Temperature on the Bioactive Compound Content, Phenylpropanoid Metabolism Enzymes and Quality Attributes of Fresh-Cut Strawberries

The aim of this work was to model the effect of the type of cutting (whole without hull, halved, and quartered), storage temperature (2, 6, and 13 °C) and time on the changes of bioactive compounds, phenylpropanoid metabolism enzyme activities, and quality attributes of fresh-cut strawberries. The effect of increasing the intensity of wounding revealed an activation of the phenylalanine ammonia lyase (PAL) enzyme, with the consequent synthesis of phenolic compounds. Results revealed that quartered strawberries stored at 2 °C for 15 days accumulated up to 22% more phenolics than whole strawberries. The changes on quality parameters (soluble solids, pH, and color), total anthocyanins, and polyphenol oxidase were adequately fitted with zero order kinetic. All rate constants of these attributes, except for anthocyanins, fitted appropriately with Arrhenius equation. Changes on total phenolic contents and on PAL activity were fitted with a consecutive reaction mechanistic kinetic model. The rate constants of phenolics kinetic showed no dependence with temperature. However, rate constants of PAL activity fitted appropriately with Arrhenius equation. This global study offers a better understanding of the effects of processing and storage conditions on general quality, bioactive compounds, and phenylpropanoid metabolism enzymes of fresh-cut strawberries.Fil: Van de Velde, Franco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química; ArgentinaFil: Fenoglio, Cecilia Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química; ArgentinaFil: Piagentini, Andrea. Universidad Nacional del Litoral. Facultad de Ingeniería Química; ArgentinaFil: Pirovani, Maria Elida. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentin