ABSTRACT
In order to valorise winemaking grape stalks, subcritical water extraction at 160 and 180 °C has been carried out to obtain phenolic-rich extracts useful for developing active food packaging materials. Red (R) and white (W) varieties (from Requena, Spain) were used, and thus, four kinds of extracts were obtained. These were characterised as to their composition, thermal stability and antioxidant and antibacterial activity. The extracts were incorporated at 6 wt% into polylactic acid (PLA) films and their effect on the optical and barrier properties of the films and their protective effect against sunflower oil oxidation was analysed. Carbohydrates were the major compounds (25-38%) in the extracts that contained 3.5-6.6% of phenolic compounds, the R extracts being the richest, with higher radical scavenging capacity. Every extract exhibited antibacterial effect against Escherichia coli and Listeria innocua, while PLA films with extracts preserved sunflower oil against oxidation.
Subject(s)
Anti-Bacterial Agents , Antioxidants , Escherichia coli , Food Packaging , Listeria , Plant Extracts , Vitis , Food Packaging/instrumentation , Vitis/chemistry , Antioxidants/chemistry , Antioxidants/pharmacology , Plant Extracts/chemistry , Plant Extracts/pharmacology , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/chemistry , Escherichia coli/drug effects , Escherichia coli/growth & development , Listeria/drug effects , Listeria/growth & developmentABSTRACT
BACKGROUND: Physical activity has been shown to have a positive effect on life satisfaction in adolescents. Despite these benefits, physical activity levels constantly drop during adolescence, suggesting potential interfering factors in this link. Since worries about physical appearance are an important issue at this age, this study aims to examine the relationship between physical activity and life satisfaction in adolescents and explores possible moderating effects of social physique anxiety and sex. METHODS: We used data from a longitudinal study with N = 864 vocational students (mean age = 17.87 years, range: 16-25, 43% female) from Switzerland. To test our hypotheses, we used multiple hierarchical regression analyses as well as simple slope analyses. RESULTS: We did not find a significant direct effect of physical activity on life satisfaction. However, we found a significant two-way interaction between physical activity and social physique anxiety. An additional significant three-way interaction occurred, indicating that a positive effect of physical activity on life satisfaction holds only for female adolescents with low social physique anxiety levels. CONCLUSIONS: This study highlights the importance of developing a healthy relationship with one's body to fully benefit from physical activity, especially for female adolescents. Taken together, these results reveal important considerations for physical activity educators.
Subject(s)
Body Image , Exercise , Humans , Female , Adolescent , Male , Longitudinal Studies , Switzerland , Anxiety , Personal SatisfactionABSTRACT
PURPOSE: The present study aimed to examine the link between physical activity (PA) and life satisfaction in a large international study of adolescents. We also aimed to test whether overweight and underweight perceptions act as mediators and whether age and sex acted as moderators. METHODS: For this purpose, we analyzed data from the Health Behavior in School-aged Children study, which comprises 727,865 observations from 44 nations at 4 measurement occasions. RESULTS: Multilevel analyses revealed a positive link between PA and life satisfaction. In addition, underweight and overweight perceptions mediated the effect of PA on life satisfaction. We further found that age and sex acted as moderators. In older adolescents, stronger effects were found in the links between PA and life satisfaction, PA and overweight perception, and both weight perceptions and life satisfaction. In addition, in female adolescents, the link between overweight perception and life satisfaction was stronger. Conversely, the links between PA and both weight perceptions were stronger for boys. CONCLUSION: The results suggest that weight perception explains part of the relationship between PA and life satisfaction in adolescents and that these effects vary as a function of age and sex.
