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Products containing natural additives, including antioxidants, are usually perceived by consumers as safer than those with synthetic ones. Natural antioxidants, besides having a preservative activity, may exert beneficial health effects. Interactions between antioxidants may significantly change their antioxidant activity, thus in designing functional foods or food/cosmetic ingredients knowledge about the type of interactions could be useful. In the present study, the interactions between ascorbic acid (AA; vitamin C) and different black and green tea extracts and the influence on their antioxidant activities were investigated. The antioxidant activities of tea extracts and their mixtures with AA prepared in several different weight ratios were measured using the trolox equivalent antioxidant capacity (TEAC), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and ferric-reducing antioxidant power (FRAP) methods. The type of interaction was determined by interaction indexes and isobolograms. It was found that the weight ratio of extracts to AA significantly influenced the antioxidant activity of a mixture and the type of interaction between these components. The weight ratio of tea extract to AA can cause the change of interaction, e.g. from antagonism to additivism or from additivism to synergism. The observed differences in the type of interactions were probably also a result of different extracts' polyphenol composition and content. The type of interaction may also be affected by the medium in which extracts and AA interact, especially its pH and the solvent used. To obtain the best antioxidant effect, all these factors should be taken into account during the design of a tea extract-AA mixture.

Valence and approach-avoidance motivation are two distinct but closely related components of affect. However, little is known about how these two processes evolve and covary in a dynamic affective context. We formulated several hypotheses based on the Motivational Dimensional Model of Affect. We expected that anger would be a unique approach-related rather than avoidancerelated negative emotion. We also expected that high-approach positive emotions (e.g., desire) would differ from low-approach positive emotions (e.g., amusement) producing a stronger link between valence and approach-avoidance motivation. We also explored other dynamic properties of discrete emotions such as the difference between approach-avoidance motivation and valence as a marker of balance within affective components. We asked 69 participants to provide continuous ratings of valence and approach-avoidance motivation for eight standardized clips representing different discrete emotions. Using multilevel modeling, we established a significant relationship between valence and approach-avoidance motivation with high-approach emotions producing a stronger link between valence and approach-avoidance motivation compared to neutral states and lowapproach emotions. Contrary to expectations, we observed that individuals exhibited an avoidance response during anger elicitation. Finally, we found that awe was a distinct positive emotion where approach motivation dominated over valence. These findings are relevant to the theory and research on diverging processes within the core structure of affect.

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