Nutritional and bioactive composition of different carrot pomace varieties

Abstract

Introduction. Carrot pomace is a by-product with functional value that is usually discarded. This work aimed to evaluate the properties of carrot pomace from four varieties: Baltimore, Belgrado, Niagara and Sirkana. Materials and methods. The proximate composition was determined according to international standards; fiber was determined by acid and alkaline digestion; total polyphenols, β-carotene and antioxidant activity were measured spectrophotometrically; color was analyzed by reflectance and molecular properties were evaluated by FT-IR spectrometry. Results and discussion. Carrot pomace nutritional value differed significantly (p < 0.05) in function of variety. The highest protein, lipids, ash and fiber content and the lowest carbohydrates amount was observed in Sirkana carrot pomace. Sirkana variety also presented the greatest total polyphenols and β-carotene content, while the highest antioxidant activity was observed for Baltimore carrot pomace. Sikrana pomace was also distinguished by its highest hue angle and yellow index, while Baltimore exhibited the greatest white index. FT-IR spectra confirmed the presence of polyphenols, fibers and β-carotene as main bioactive compounds. The lowest transmittance for almost all the main peaks identified were for Niagara, followed by Sirkana, Baltimore and Belgrado. Niagara carrot pomace powder presented different vibrations at 2929, 2853 and 2375 cm-1 compared to the other samples. The relationships between variables indicated that Baltimore carrot pomace can be differentiated from the other varieties by its dry matter content, white index, carbohydrates content and antioxidant activity, while Sirkana can be distinguished through its total polyphenols, ash and fiber content. Strong positive correlations (p < 0.05, r > 0.95) were observed among some of the chemical components (proteins and fibers, ash and β-carotene) and between lipids content and color parameters (yellow index and hue angle). Conclusion. These results suggest that carrot pomace characteristics depend on variety. This by-product can be successfully used as a functional ingredient to enhance staple food nutritional value.