Elaboração e aplicação de pré-mix de framboesa (Rubus idaeus L.) estabilizado por xantana e ácido tartárico.

Abstract

The objective was to develop pre-mix of raspberry (Rubus idaeus L.) with the conservation of original phytochemicals during storage under freezing, by combined use of tartaric acid and xanthan, with technological characteristics and sensory suitable for use in food products such as non alcoholic drinks. It was varied the concentration of xanthan and tartaric acid as experimental design (full factorial 22) totaling 12 treatments. Total anthocyanins, total phenolics, antioxidant activity, pH, total acidity and colorimetric parameters were evaluated during storage (1, 30, 60 and 90 days). We evaluated the physical stability of pre-mixes diluted in distilled water [70% (w/v)] at 90 days, to select treatments for further elaboration of nectar. The total acidity was positively influenced by the acid, with reduction to 90 days. The pre-mixes remained with microbiologically appropriate pH (2.90 to 3.20). The xanthan influenced by reducing of the anthocyanins and it was verified an compared to baseline (from 37.01 to 41.46mg CYN-3-GLY.100g-1). It was verifies total phenols between 2211.43 and 2446.12mg GAE.100g-1, with high conservation at 90 days. The antioxidant activity ranged from 2.41 to 2.46mM Trolox.g-1, with high percentages of preservation at 90 days. There was a predominance of red color, which was accentuated the end of storage (a*= 15.21 - 18.12 and b*= 4.29 - 5.68), and increased the lightness (L* = 51.98-55, 67).The greater physical stability was obtained with 0.5% xanthan gum and 0.25% tartaric acid, concomitantly influenced by variables, however, it was selected the pre-mixes treatments added 0.07% of xanthan gum and 0.43% of tartaric acid; 0.43% of xanthan gum and 0.43% of tartaric acid, and 0% of xanthan gum and 0.25% tartaric acid, with intermediate stabilities and concentrations that allow to analyze the combined weight of xanthan gum and acid. Three nectars formulations were produced, 1, 2 and 3, using pre-mixes were previously selected, diluted in mineral water 60% (w/v), approximately, and added 13% (w/v) of sugar. It was determined pH, total acidity, soluble solids, instrumental color, anthocyanins and total phenols and antioxidant activity, and we evaluated sensory by the attributes of color, flavor, aroma, texture and overall impression by acceptance test using hedonic scale of 9 points, and test of intent to purchase, through structured scale of five points, applied to 81 tasters untrained, aged between 18 and 59 years. The nectars differed significantly (p ≤ 0.05) with respect to pH, the lower value for the formulation 2 (0.43% xanthan and 0.43% acid). Acidity and soluble solids were not significantly different (p> 0.05). The nectar tended to lighter colors (L*= 34.56 to 34.97). The coordinates a* and b* and H° showed predominantly red color, especially for formulation 2 (a* = 7.87, b* = 1.76 and H° = 12.60). The nectar did not differ in their content of anthocyanins (13.92 and 14.28mg CYN-3-GLY.100g-1). The nectars differed as to the phenol content (between 785.19 and 831.55mg GAE.100g-1). The antioxidant activity was between 1.71 (a formulation with 0.07% xanthan and 0.43% tartaric acid) and 1.22mM Trolox.g-1 for the formulation 3 (0.25% tartaric acid) which differed significantly (p ≤ 0.05). Formulations 2 and 3 were more accepted and did not differ significantly between them, averaging more than 7 ("liked regularly"). Nectar obtained by formulation 3 had higher purchase intent ("probably buy"), the formulation 1 and 2 ranged from "I doubt if you purchase" and "probably buy". The percentage of acid and xanthan used resulted in technologically appropriate characteristics to the product and the conservation of phytochemicals, stability was the distinguishing factor between the pre-mixes. Nectar obtained with pre-mix added 0.43% xanthan and 0.43% tartaric acid showed a better set of attributes and acceptance technological equivalent of nectar with higher intention to purchase.