PHYSICOCHEMICAL AND STRUCTURAL CHARACTERIZATION OF POWDERED CURCUMA LONGA L

Turmeric (Curcuma long L.) is an herbaceous plant belonging to the family Zingiberaceae. Its rhizome is rich in curcumin, an orange-yellow bioactive compound that gives turmeric functional properties to which it can be used in the food industry as a natural additive. Thus, the objective of this work was to evaluate the granulometry, physicochemical and structural properties of the rhizome of turmeric powder (TP), seeking to contribute to the incentive of its use in the food industry. Granulometry, proximal composition (moisture, ashes, lipids, proteins, carbohydrates and total dietary fiber), color instrumental parameters, phenolic compounds, DPPH radical scavenging capacity and TP structural characteristics were determined. A percentual of 80.12% of TP was retained in the 0.842 mm sieve and 18.47% in the sieve of 0.25 mm, with a fineness modulus of 4.97. The uniformity index was represented by 80% of regular particles, and 19% of fine particles, and the mean particle diameter was 2.85 mm. These results shows the uniformity of this raw material, being of fundamental importance, since the properties of a food and the techniques used in the processing may depend on the homogeneity of the initial mass. The TP powder presented moisture of 11.77 g 100 g-1 ± 0.009, which ensures its microbiological stability during storage. In addition, it presented a high energy value (368,98 kcal 100 g-1 ± 0.97 w.b.), mainly due to the high carbohydrate content (68,18 g 100 g-1 ± 0.9), and lipids. The ashes content (4.76 g 100 g-1 ± 0.06) is an indicative of mineral content, which were the lowest components, compared to proteins (8.27 g 100 g-1 ± 0.3) and lipids (7.02 g 100 g-1 ± 0.44 ). TP presented high total dietary fiber content (17.84 g 100 g-1 ± 0.39), a food component that plays an important role in the prevention of cardiovascular and gastrointestinal diseases. In addition, TP presented high phenolic compounds (1175.01 mg gallic acid 100 g-1), and moderate DPPH radical scavenging capacity (37.53%). The phenolic compounds responsible for the antioxidant properties of TP are curcuminoids (curcumin, desmethoxycurcumine, and bisdemetoxicurcumine), and the presence of these compounds in a diet is of fundamental importance, since they play a crucial role in aging, protecting the body against atherosclerosis, age immune decline, and some degenerative processes, as well as preventive properties against some types of cancer. Regarding the instrumental parameters of color, TP presented a positive b* coordinate (59.51), approaching the yellow color with a relatively high chroma value (C*) (61.84), and color intensity (Hue angle) tending to yellow-orange (74.19). This tonality tending to yellow-orange in TP is possibly due to the high content of curcuminoid pigments that are present in the rhizome. The infrared spectrum showed the presence of water, fatty acids, sugars and aromatic compounds. Considering these results, it is possible to conclude that TP has a nutritional composition that values it as a promising ingredient to the development of new food products with added nutritional and functional values.