Percorrer por autor "Sousa, Alexandra"
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- Effect of a HPP pretreatment on thermal inactivation kinetics of polyphenoloxidase obtained from three apple cultivarsPublication . Machado, Maria F.; Sousa, Alexandra; Castro, Sónia M.; Moreira, Sílvia A.; Saraiva, Jorge A.Enzymatic browning due to the action of polyphenoloxidase (PPO) is highly undesirable and efficient methodologies to avoid/reduce it are of great interest for food industry. The effect of a pressure pretreatment (100 MPa, 15 min, room temperature) on the activity of PPO extracts obtained from three apple cultivars (Bravo de Esmolfe [BE], Reineta [RN], and Golden delicious [GD]), and subsequent thermal inactivation kinetics was evaluated, as a way to more efficiently achieve thermal inactivation of PPO. The effect of pH on PPO activity was also assessed to define the value at which carry out the thermal inactivation of PPO. The enzymatic activity decreased in the order BE, RN, and GD. Two log-linear ranges ([62.5-72.5]degrees C and [72.5-80.0]degrees C) of D-value with temperature were found. The pressure pretreatment caused enhanced stability within the range of 62.5-67.5 degrees C, caused no changes at 70.0-72.5 degrees C, and decreased the stability at 75.0-80.0 degrees C (e.g., at 75 degrees C the D-values for BE, GD, and RN ranged, respectively, from 25.6/27.3, 14.5/18.6, and 8.8/10.4, after/before the pressure pretreatment) and increased thermal sensitivity (decreased the z-value), particularly in the lower temperature range studied (up to 72.5 degrees C). Practical applicationsKnowledge of PPO activity level and its thermal resistance for different cultivars is of interest to develop efficient and optimized enzymatic browning control by thermal treatments. Sequential combination of low intensity pressure treatments followed by thermal treatments can be an interesting approach to enhance enzyme inactivation. In this work was found that after a low intensity pressure pretreatment (100 MPa, 15 min), apple PPO temperature stability could be reduced, since a lower stability (lower D-values) and increased sensitivity toward temperature (lower z-value) was systematically found for PPO thermally inactivated at T>72.5 degrees C. These findings are of interest for a more efficient PPO inactivation for enhanced browning control.
- Nutritional therapy in critically IIIPublication . Alves, Ana; Rabiais, Isabel Cristina Mascarenhas; Madureira, Manuela; Freitas, Carlos; Sousa, AlexandraIntroduction: Nutritional therapy has had a major impact on the evolution of the clinical situation on the critical patient as well as the choice of treatment. The oral/enteral feeding is more physiologic and preferable, therefore, whenever possible, should be used the gastrointestinal tract. When this cannot be used, the parenteral is indicated, either supplement or total. Objective: The aim of this study is to clarify the importance of the nutritional therapy in critically ill patients. Material and Methods: A systematic review of the literature by mobilizing the descriptors “Nutritional Therapy”, “Critical Patients” and “Nursing care”, use the method peak. Were selected ten databases imaginable, between 2012-2016, included for analysis nine articles. Results and Discussion: It was found in most of the studies that malnutrition in hospital environment is highly prevalent and is not always recognized by health professionals. Nutritional support is intended to provide an intake of sufficient energy to feed the patient needs, in order to prevent malnutrition or correct a situation of pre-existing malnutrition. A nutritional approach is, among others, by the institution of enteral nutrition and parenteral nutrition, whose impact on improving the nutritional status of the client is very important in reducing morbidity and mortality. These aspects imply optimizing the balance of protein in reviews of Intensive Care Unit (ICU), as well as an improvement of the energy balance. Conclusion: It can be concluded that the treatment of the patient in a critical situation must include nutritional therapy, with the aim of reducing associated complications. After stratified the risks, its necessary to choose the adequate nutritional therapy. This, in a critical patient, can result in a better evolution of the underlying disease with increased survival, improving the quality of life and reduction the time that a patient stays in the hospital.