Compositional Equivalency of Conventional and Organically-grown Sweetpotatoes

Sweetpotato root composition was determined in eight commercially important sweetpotato cultivars grown in California under conventional and organic production methods. Analyses of root tissues were made after 6 months of storage at 14° C. Large differences in % dry matter existed between cultivars, ranging from 33.4% in the roots of ‘Stokes Purple’ to 18.1% in ‘Bellevue’. No significant difference in dry matter content existed between conventional and organically-grown sweetpotatoes. The principal sugars in the raw roots of all cultivars included the main disaccharide sucrose, followed by the secondary monosaccharides glucose and fructose. Raw roots of ‘Burgundy’ contained the highest amount of sucrose (6.77%), while ‘O’Henry’ contained the lowest amount (2.50%). ‘Diane’ and ‘Bellevue’ contained the highest amount of glucose (2.62%), while ‘Kotobuki’ contained the lowest amount (0.57%). ‘Bellevue’ contained the highest amount of fructose (1.90%), while ‘Kotobuki’ contained the lowest amount (0.52%). ‘Diane’ contained the highest amount of total sugar (9.94%), while ‘O’Henry’ contained the lowest amount (4.57%). No overall difference in any of the individual sugars or total sugar content existed between conventional and organically-grown sweetpotatoes. Crude protein content ranged from 2.71 g/100g fresh weight in ‘Stokes Purple’ to 1.53 g/100g in ‘Bellevue’. No overall difference in crude protein content existed between conventional and organically-grown sweetpotatoes. Potassium (K) was the principal macronutrient element in all cultivars and ranged from 384 mg/100g in ‘Bonita’ to 253 mg/100g in ‘Bellevue’. Phosphorus (P) was the second highest macronutrient and ranged from 78 mg/100g in ‘Stokes Purple’ to 35 mg/100g in ‘Bellevue’. The remaining macronutrients were present in lesser amounts, with generally similar levels found in calcium, magnesium, and sulfur. Iron (Fe) was the principal micronutrient found in all sweetpotato cultivars and the content ranged from 0.72 mg/100 g in ‘Kotobuki’ to 0.34 mg/100 g in ‘Bellevue’. Zinc (Zn) and manganese (Mn) were the secondary micronutrients in all cultivars and found in similar concentrations. Boron and copper were the least abundant micronutrients and also present in similar concentrations. ‘Stokes Purple’ was the cultivar that contained the highest amounts of macronutrients and micronutrients, while ‘Bellevue’ was the cultivar that generally contained the lowest amounts. Although substantial differences in nutrient element composition existed between cultivars, there was no overall difference between conventional and organically-grown roots in most macronutrient and micronutrient concentrations. However, P, Mn, and Zn contents were higher in conventionally-grown roots.