OBTENTION, FREEZE-DRYING AND CHARACTERIZATION OF LEMON GRASS (Cymbopogon citratus D.C.) AND HIBISCUS (Hibiscus sabdariffa L.) EXTRACTS
Despite vegetable extracts, like lemongrass and hibiscus, do not present medicinal properties, they are suitable for applications in food due to its features and properties to assign flavors and also improve appearance. An aqueous extract can be converted into powder. This process improves its conservation and commercialization. The aim of this study was to obtain and freeze-dry lemongrass and hibiscus extracts. The following physical-chemical analyses were performed in triplicate: total soluble solids (TSS), total titratable acidity (TTA), pH and color. For the lemon grass, the TSS for the freeze-dried product was 49.10°Brix; pH and TTA analyses for aqueous extract and powder were similar – around 1.5 and 5.55, respectively; b* values of the aqueous extract and freeze-dried samples were significantly different, however both presented yellow color tendency. Hibiscus freeze-dried sample presented a TSS of 43°Brix. ATT of the aqueous extract was 7.53 g of citric acid/100g, which was approximately twice as much when compared to the freeze-dried sample; a* levels increased after the treatment applied. Consequently the L* values decreased, tending towards red color. h(°) values obtained from aqueous extract and freeze-dried samples were 27.00 and 10.67, respectively; which indicates that the smallest angle represents a greater intensity, color range between yellow and blue, representing the purple. Freeze-drying process is indicated to produce a dehydrated product with high soluble solids content and quality in terms of sensory and color aspects.