Browsing by Author "Amaro, Ana Luísa"
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- Fresh-cut melon nutritional and functional quality throughout the production processing line and during storagePublication . Pereira, Maria João; Amaro, Ana Luísa; Carvalho, Susana; Pintado, Maria ManuelaFruits processing conditions can be described through representative flowcharts with the identification of the process variables. However, integrated information about the effect of each processing step on phytochemical properties of the processed fruits is still lacking. This study aims at development of a system to audit postharvest handling systems and processing lines for the preservation of health-promoting phytochemicals and to optimize processing conditions to maintain fruit quality. A nutritional and functional audit of postharvest handling systems and processing lines of a fresh-cut fruits enterprise was performed and the effects of the production process upon the nutritional and phytochemical composition of melon were determined. Three replicated samples were collected at each step of the production flowchart of fresh-cut cantaloupe melon: at fruit reception, after washing and decontamination and after processing. All samples were frozen with liquid nitrogen and stored at -80 °C until analyzed for nutritional characterization. Total antioxidant activity was assessed by the ABTS method, total phenolics by Folin Ciocalteau´s method and phenolic compounds and carotenoids were analyzed by high performance liquid chromatography (HPLC-DAD). Throughout cantaloupe melon processing, a significant decrease in total phenolic compounds and antioxidant capacity was observed, while total carotenoids levels were relatively maintained. Contrarily, as processing advanced, ascorbic acid concentration increased significantly after decontamination step. After the nutritional audit to the process and to evaluate nutritional quality during storage, simulating the company´s commercial conditions and product´s shelflife, fresh-cut cantaloupe samples were placed in polypropylene clamshells (236 mL) or in packages heat sealed with a low oxygen transmission rate film (78 mL) and stored at 5 °C for 6 days. Except for ascorbic acid concentration, which was better maintained in filmed packages, overall nutritional quality of fresh-cut melon is better maintained during storage in clamshell packages.
- Modeling the effect of oxygen availability and storage temperature on fresh-cut strawberry respiration ratePublication . Amaro, Ana Luísa; Pereira, Maria João; Carvalho, Susana; Vasconcelos, Marta; Pintado, M.Fresh-cut commodities shelf-life is limited by minimal processing operations and storage conditions. Wound damage is sensed by sensors/receptors that recognize increased concentrations of endogenous molecules or their fragments, and tissue response involves an increase in respiration rate. Respiration behavior of fresh-cut strawberries is affected by wounding, storage temperature and oxygen availability. Modified atmosphere packaging and refrigerated storage are frequently used to reduce the respiration rate without negatively affecting the physiology of the fruit and to increase shelf life. Mathematical models have been proposed to correlate the respiration rate with different storage parameters such as gas composition and temperature, but the two factors have rarely been considered simultaneously and the systematic approach to modified atmospheres packaging design involves the knowledge of respiration rate kinetics at different temperatures. The objectives of this study were to determine respiration rate of fresh-cut strawberries as a function of oxygen and temperature conditions during storage and to develop and validate mathematical models for predicting respiration rate. Freshly harvested strawberries were processed into wedges and placed in 750 mL glass jars. The glass jars containing fresh-cut strawberries were then flushed with different oxygen concentrations (2.5; 5; 10 and 20% O2) and stored in three different temperatures (0, 5 and 10 °C), for 5 days. The experiments were performed in three replicates. Oxygen and carbon dioxide concentrations inside the glass jars were analyzed throughout refrigerated storage with a gas analyzer, measuring at two hours intervals in the first 48 hours and then in 12 hours intervals until the end of the 5 days. Initial oxygen partial pressure and temperature had significant effects on fresh-cut strawberry respiration rate with significant decreases with lower initial oxygen levels and lower temperature. The models developed are useful for supporting decision on fresh-cut strawberry optimal storage conditions based on physiological response.
- Phenolic compounds content and antioxidant activity of wild strawberries (Fragaria Vesca L.)Publication . Pereira, Maria João; Amaro, Ana Luísa; Carvalho, Ana; Pintado, M. E.Strawberries are usually consumed in high quantities and can thus be a valuable source of phenolic compounds, vitamin C and other antioxidant compounds. The main phenolic compounds in strawberries are anthocyanins, responsible for the red color in strawberry flesh, combined with flavonoids, flavanols, and derivatives of hydroxycinnamic and ellagic acid (Aaby et al, 2007; Pinto et al, 2008). Wild strawberries (Fragaria Vesca L.) are usually claimed as more antioxidant and more rich in specific phenolic compounds. So the aim of this work was to characterize the phenolic compounds profile and evaluate the antioxidant capacity of wild strawberries in order to ascribe the relevant nutritional and functional properties of these strawberries. Total phenolics were assessed by Folin Ciocalteau's method, total anthocyanins by spectrophotometric methods, total antioxidant activity by the ABTS method and the phenolic compounds were analyzed by high performance liquid chromatography (HPLCDAD). The results obtained reveal that wild strawberries are indeed a great source of phenolic compounds (catechin, epigallocatechin gallate, rutin and ellagic acid) and anthocyanins (cyanidin-3-O-galactoside, cyanidin-3-O-glucoside, pelargonidin-3-O-glucoside, pelargonidin-3- O-rutinoside). All of these compounds have importance for the high antioxidant activity demonstrated by these strawberries. Thus, this study highlights the potential of these wild strawberries as a source of bioactive compounds consumed in human diet.
- Physiological and phytochemical quality of ready-to-eat rocket leaves as affected by processing, modified atmosphere and storage temperaturePublication . Amaro, Ana Luísa; Pereira, Maria João; Carvalho, Susana; Vasconcelos, Marta; Pintado, Maria ManuelaRocket leaves are widely consumed as a ready-to-eat (RTE) leafy vegetable, valued by its wide range of health promoting phytonutrients, including vitamin C and phenolic compounds. Processing and storage conditions are known to affect quality of RTE rocket leaves, with package atmosphere and low temperature as key factors in quality maintenance throughout processing to consumption. However, information on rocket leaves nutritional quality as affected by modified atmosphere and storage temperature is scarce. In order to generate recommendations to optimize phytochemical preservation of rocket leaves during processing, a nutritional audit of the processing line of a fresh-cut vegetables enterprise was performed. Samples were collected at each step of the production flowchart of RTE rocket-leaves: at rocket leaves reception, after washing and decontamination, after centrifugation and after packaging. All samples were analyzed for nutritional characterization. Furthermore, the effect of modified atmosphere and temperature conditions during storage on physiological and phytochemical quality of RTE rocket leaves was evaluated and the relative changes determined. To study modified atmosphere effects on quality, freshly harvested rocket leaves were processed, packaged in low oxygen permeability film bags, flushed with different oxygen concentrations (2.5; 5; 10 and 20% O2), thermo sealed with a vacuum packing machine and to analyze the effect of temperature on quality, freshly harvested rocket leaves were processed, packaged and stored at different temperatures (0, 5 and 10 °C) for 14 days. All rocket leaves samples were assessed for respiration rate, chlorophyll content and phytochemical composition during storage. Processing, modified atmosphere and storage temperature significantly affected respiration rate, chlorophyll content and phytochemical composition of RTE rocket leaves. The integration of these results contributes to the understanding of the effects of processing and storage conditions on overall quality of RTE vegetables and provide useful information for developing processes aimed at the modulation of nutritional quality and shelf-life extension.