Effect of Drying Techniques on Phytochemical and Vitamin Compositions of Three Species of Amaranth

Abstract

Amaranth species are highly valued for their rich phytochemical and vitamin content, making them important for both nutrition and health. However, preserving these nutrients during post-harvest processing, particularly drying, is critical to maintaining their benefits. This study investigates the impact of different drying techniques on the phytochemical and vitamin compositions of three Amaranth species: Amaranthus tricolor, Amaranthus hybridus, and Amaranthus cruentus. The experimental design involved subjecting fresh samples of each species to three different drying treatments: shade drying, oven drying at 40°C, and oven drying at 60°C. Standard analytical procedures were followed to quantify phytochemicals (flavonoids, tannins, saponins, alkaloids, phenols, and phytates) and vitamins (A and C). Data were statistically analyzed using the Statistical Product and Service Solutions (SPSS), with two-way analysis of variance (ANOVA) employed to compare the means across the different drying methods. The results revealed significant variations in the phytochemical compositions across the drying treatments. For Amaranthus tricolor, the phytochemical contents ranged from 13.81 to 15.92 mgCE/g for flavonoids, 1.65 to 2.84 mgTAE/g for tannins, 1.23% to 1.63% for saponins, 2.04% to 4.93% for alkaloids, 5.54 to 10.12 mgGAE/g for phenols, and 0.1% to 0.19% for phytates. Similarly, Amaranthus hybridus showed ranges of 12.01 to 12.71 mgCE/g for flavonoids, 1.01 to 3.65 mgTAE/g for tannins, 1.37% to 1.52% for saponins, 2.95% to 6.76% for alkaloids, 3.62 to 7.83 mgGAE/g for phenols, and 0.16% to 0.91% for phytates. Amaranthus cruentus demonstrated phytochemical ranges of 15.76 to 18.83 mgCE/g for flavonoids, 0.53 to 2.90 mgTAE/g for tannins, 1.75% to 1.87% for saponins, 1.98% to 4.0% for alkaloids, 5.54 to 8.35 mgGAE/g for phenols, and 0.12% to 0.18% for phytates. Vitamin A content ranged from 7.0 to 10.52 mg/100g in Amaranthus tricolor, 8.67 to 10.61 mg/100g in Amaranthus hybridus, and 9.09 to 10.73 mg/100g in Amaranthus cruentus. Vitamin C content ranged from 41.60 to 45.15 mg/100g in Amaranthus tricolor, 33.80 to 37.85 mg/100g in Amaranthus hybridus, and 44.08 to 50.61 mg/100g in Amaranthus cruentus. The findings emphasize that all drying techniques employed—shade drying, oven drying at 40°C, and oven drying at 60°C—are effective in retaining high levels of vitamins and phytochemicals in the three Amaranth species. However, the choice of drying method may be tailored depending on specific nutrient retention goals. This study provides valuable insights for optimizing drying processes to preserve the nutritional quality of Amaranth species.