Atriplex hortensis L., also known as orach, is a leafy vegetable from the Amaranthaceae family, which has historically been consumed as a potherb, like spinach. The brightly colored leaves are a source of high quality protein, but may also be of interest as a potential source of natural food pigments. An aqueous extraction was obtained from the freshly harvested leaves of the'Triple Purple' variety of A. hortensis. The extract was spray-dried into a powder, and individual pigments were analyzed using HPLC and LC-MS. The powder was also included as a color additive in a typical stabilizer/sweetener preparation and mixed into plain yogurt. Two batches of colored yogurt were held under light and dark conditions and tested for pH and color (L*a*b*) every 15 days. A visual sensory panel was performed on days 0, 45, and 90 to evaluate the color acceptance.A total of three types of betacyanins and six types of anthocyanins were tentatively identified by HPLC and/or LC-MS. Orach pigments in yogurt were not stable under full light exposure. The color of samples exposed to light degraded within days. There were statistically significant differences found in L*a*b* scores in the dark treatment, beyond 30 days; but these modest changes in dark-stored samples were not found to be statistically significant in the consumer sensory panel. The tentative identification of both anthocyanins and betacyanins in orach is a novel finding in botanical research, as the literature indicates that these two pigment classes are mutually exclusive. The application of heat during pigment extraction, spray drying, and yogurt color additive preparation, did not appear to appreciably affect stability of orach pigments, indicating that orach extract could be used as a color in different process applications, if protected from light.

Parmi les stimuli environnementaux, la couleur est une expérience perceptuelle omniprésente. Elle est capable d’infléchir la motivation d’approche et d’évitement des individus sans qu’ils en aient conscience. Elliot et ses collaborateurs (2007) ont en en effet montré qu’en contexte d’accomplissement, le rouge agissait subtilement sur les processus cognitifs et moteurs en évoquant une menace. L’objectif de cette thèse a été d’enrichir ce paradigme des couleurs à l’aide de variables et de tâches non testées. Notre travail a tout d’abord montré l’effet délétère du rouge sur la variabilité de la fréquence cardiaque et la mémoire de travail lors d’un test cognitif. Cet effet négatif a ensuite été mis en évidence sur l’efficience motrice lors d’une tâche de force maximale. Sur la base d’une validation partielle en langue française du questionnaire de mesure des tempéraments (Elliot & Thrash, 2010), il a ensuite été suggéré que l’effet débilitant du rouge sur la mémoire pouvait être modulé par le tempérament d’évitement. Enfin, nous avons étudié de façon exploratoire la modulation de l’effet menaçant du rouge par l’origine culturelle. Les différentes significations accordées au rouge par des étudiants chinois et français pourraient être à l’origine d’une modulation de l’effet de cette couleur sur l’efficience motrice. / Among the environmental stimuli, the color is a ubiquitous perceptual experience. It is able to influence the approach and avoidance motivation outside of consciousness. Elliot and colleagues (2007) have indeed shown that in an achievement context, red acts as a subtle threat-cue on cognitive and motor processes. The aim of this thesis was to extend this empirical and theoretical work, using novel variables and tasks. Our results have first shown the deleterious effect of red on the heart rate variability and the working memory in a cognitive test, and then on the motor efficiency during a maximum voluntary contraction task. Based on a partial French validation of the approach-avoidance temperament questionnaire (Elliot & Thrash, 2010), it was then proposed that the negative effect of red on the memory could be modulated by the avoidance temperament. Finally, we have studied in an exploratory fashion the modulation of the threatening red effect by the cultural origin. Our results have suggested that differences in meanings given to red between Chinese and French students could have different consequences on motor efficiency.