24 25 26 27 28 29 30 31 32 33 34 35 36The effect of repeated tasting may improve the acceptance level and positive emotions associated with an unusual food. Our aim was to analyze this effect on the consumer acceptance, emotional status, purchase intention and optimum level of sensory attributes of a yerba mate (YMI)/black currant (BC) drink with high polyphenol content and low palatability.Beverages formulations (%) were: YMI 50 / BC 30 (S1); YMI 60 / BC 20 (S2); YMI 60 / BC 20/ diet sweetener 0.05% (S3). All samples had 15% maltodextrin, 0.01% aroma and 5.0% sucrose.One hundred participants (70 female, 30 male) aged 25 to 63 years (M = 38.9, SD = 10.9) evaluated the same three samples (S1, S2 and S3) during four sessions to determine the influence of repeated exposure, taking the first session as a control. Acceptance was measured by a 9-point hedonic scale, purchase intent by a 5-point scale and attribute diagnosis (sourness, sweetness, astringency, aroma and body) by a Just About Right scale. Consumers selected at least three terms from a list of 12 words (well-being, displeasure, familiarity, sadness, fear, freshness, anguish, simplicity, relaxation, anger, joy and surprise) to describe their emotional status after tasting the samples. Results showed that the last session displayed the highest values for acceptance demonstrating a repeated exposure effect. The samples with less acceptability in 37 38 39 session 1 (S1 and S2) were those with the greatest increase in session 4. Purchase intention was 40 not affected by product exposure. The oldest consumer group (50-63 years old) exhibited the minimum levels of acceptance and purchase intention. The attribute diagnostic evaluations did not change through the four sessions indicating that the consumer opinion of its optimum point was maintained at the same level as the first impression. The word "familiarity" was selected for 41 42 43 44 all the samples in the fourth and final session and also for sample 3 at session 3, confirming its 45 impact and showing the exposure level necessary to develop it. 46

BACKGROUND: Black currant (BC) and yerba mate (YM) have high contents of polyphenolic antioxidants beneficial for health. Obtaining freeze-dried BC/YM instant drinks can be a means for providing their advantages to consumers. However, their high sugar contents make them very hygroscopic causing undesirable changes in color and bioactives concentration. OBJECTIVE: To solve this problem it is necessary to determine the powder's sorption properties and the temperature/relative humidity's (RH) influence on their color and polyphenol, ascorbic acid and anthocyanins's concentrations. METHODS: We analyzed the sorption isotherms of freeze-dried BC/YM/maltodextrin/sugar powder at 10/20/40 • C and compared them with those from YM/maltodextrin. RESULTS: Of all models tested (Caurie, GAB, Halsey, Oswin) GAB was the best. Monolayer moisture values (Wm) were ≤0.1 kg H 2 O (kg d.m) −1 indicating good stability. Due to its higher sugar content, BC/YM powders were more hygroscopic and with higher exothermic isosteric sorption heat (Q st) than YM powders. Q st and differential entropy decreased exponentially with increasing moisture levels. Within the experimental conditions, isokinetic theory indicated that the whole sorption process was enthalpy controlled. Temperature and RH strongly modified BC/YM's color and ascorbic acid and monomeric anthocyanins concentrations. At all temperatures, optimum levels of these properties required RH ≤33%. To achieve maximum physicochemical quality and stability the powder's moisture content must be ≤Wm, in this case, RH dropped to 9% (10 • C) and 11.3% (20 • C/40 • C).