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  • Author or Editor: William M. Walter Jr. x
  • HortScience x
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The sugar content of the sweetpotato cultivars Centennial, Coroner, Georgia Red, Jewel, and Sweet Red was measured by nign performance liquid chromatography (HPLC) and compared to the sugar content found by measuring the refractive index of cellular sap and converting the refractive index value to sugar concentration. The sugar content and refractive index values were measured for just-harvested, cured and stored roots. Changes in the sugar content as determined by refractive index were found to be linearly related to changes 1n sugar content measured by HPLC, indicating that this method can be used to monitor changes in postharvest sugar content.

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The sugar content of five sweetpotato [Ipomoea batatas (L.) Lam.] cultivars (`Centennial', `Cordner', `Georgia Red', `Jewel', and `Sweet Red') was measured by high-performance liquid chromatography (HPLC) and compared to the sugar content of the cellular sap measured by refractive index (RI). The HPLC and RI sugar contents were measured at harvest, after curing, and during storage. Changes in the sugar content, as determined by the RI, were found to be linearly related to changes in the sugar content of cell sap and tissue, as measured by HPLC, indicating that this method can be used to monitor changes in postharvest total sugar content.

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Abstract

Protein and dry matter contents were determined for 16 cultivars of sweet potatoes (Ipomoea batatas (L.) Lam.) planted May 28 and harvested on 4 different dates. Means of protein contents of cultivars differed significantly and ranged from 4.17% to 6.51%, dry basis. Protein content decreased at the rate of 0.0067% per day and dry matter decreased at the rate of 23% per day.

Open Access

Abstract

A population of 100 sweet potato seedlings from 7 parent clones was grown for one season in order to evaluate root protein quantity and quality. Protein content of the 100 seedlings ranged from 4.38% to 8.98% with a mean of 6.29%; the 7 parents ranged from 4.96% to 6.53% with a mean of 5.72%. The mean of the seedlings was not significantly different from that of the parents. The 10 seedlings with highest protein (7.40% to 8.98%) were selected for further study of protein quality. Levels of nonprotein nitrogen (NPN) in these high protein selections were not significantly different from those of the parents. The correlation between the percentage of protein and the percentage of NPN was low (r = 0.30). The amino acid pattern in the high protein selections differed significantly from the parents with lower levels of valine, cysteine, methionine, tyrosine, and phenylalanine. Trypsin inhibitor activity (TIA) levels in the selected seedlings did not vary significantly from the parents. TIA and the percentage of protein were not significantly correlated (r = 0.15). The results indicate it is possible to obtain high protein cultivars without increasing the percentages of NPN and TIA. With the exception of valine, the aromatic and sulfur-containing amino acids, the overall protein quality was not changed in the seedlings with increased protein content.

Open Access