RESUMO
Renealmia alpinia (Rottb.) Maas pulp was processed by spray drying using Maltodextrin (MDX), and Gum Arabic (GA), and the mixture of both encapsulating agents (MDX-GA). Yield, moisture, water activity (a w ), apparent and bulk densities, size and morphology of capsules, color, and antioxidant potential (antioxidant activity, total carotenoids, and phenolic compounds) were analyzed. The encapsulates were incorporated as pigments in yogurt and the stability of antioxidant compounds (1, 7, 14, 21, and 28 days of storage) and the sensory properties were evaluated. The yields of all formulations (MDX, GA, MDX-GA) were around 17.86% with low moisture and a w range values (2.62-3.29% and 0.276-0.309, respectively). The microcapsules presented multiples particle sizes (0.67-27.13 µm) with irregular and smooth surfaces. Furthermore, these capsulates preserved yellow color and the retention of carotenoids was significantly higher with MDX (34.12 mg/100 g of powder), while the phenolic compounds and antioxidant activity increased with GA (474.17 mg GAE/100 g and 552.63 mg TE/100 g of powder, respectively). The main compounds ß-carotene and gallic acid were identified and quantified in positive and negative mode respectively using LC-MS/MS. Finally, the addition of the encapsulated pigments to yogurt allowed to obtain a yellow coloration and the yogurt added with MDX-GA presented the best formulation with not significant changes in antioxidant activity and acceptable sensory attributes up 28 days of storage.
RESUMO
UNLABELLED: Calyxes from the Roselle plant (Hibiscus sabdariffa L.) were used to prepare cold (22 °C for 4 h) and hot (98 °C for 16 min) infusions/teas from both fresh and dried forms. Aroma volatiles were extracted using static headspace SPME and analyzed using GC-MS and GC-O with 2 different columns (DB-5 and DB-Wax). Totals of 28, 25, 17, and 16 volatiles were identified using GC-MS in the dried hot extract (DHE), dried cold extract (DCE), fresh hot extract (FHE), and fresh cold extract (FCE) samples, respectively. In terms of total GC-MS peak areas DHE â« DCE > FHE â« FCE. Nonanal, decanal, octanal, and 1-octen-3-ol were among the major volatiles in all 4 beverage types. Thirteen volatiles were common to all 4 teas. Furfural and 5-methyl furfural were detected only in dried hibiscus beverages whereas linalool and 2-ethyl-1-hexanol were detected only in beverages from fresh hibiscus. In terms of aroma active volatiles, 17, 16, 13, and 10 aroma active volatiles were detected for DHE, DCE, FHE, and FCE samples, respectively. The most intense aroma volatiles were 1-octen-3-one and nonanal with a group of 4 aldehydes and 3 ketones common to all samples. Dried samples contained dramatically higher levels of lipid oxidation products such as hexanal, nonanal, and decanal. In fresh hibiscus extracts, linalool (floral, citrus) and octanal (lemon, citrus) were among the highest intensity aroma compounds but linalool was not detected in any of the dried hibiscus extracts. PRACTICAL APPLICATION: Hibiscus teas/infusions are one of the highest volume specialty botanical products in international commerce. The beverage is consumed for both sensory pleasure and health attributes and is prepared a number of ways throughout the world. Although color and taste attributes have been examined, little information is known about its aroma volatiles and no other study has compared extractions from both fresh and dried as well as extraction temperature differences. This is also, apparently, the first study to identify the aroma active volatiles in hibiscus beverages using GC-olfactometry. Manufacturers and consumers will now have a better understanding of why hibiscus teas prepared in different ways from either fresh or dried forms have a different flavor quality and intensity.
