Potato tubers had 1.67% N/dry matter. Nitrogen was distributed in all anatomical regions of the tuber. Of the total N content, 43% was dialyzable‐N and 32.9% true protein‐N. The protein, by solubility fractionation, provided 67% albumin, 23% globulin, 1.4% prolamin and 9% glutelins. As revealed by sodium dodecyl sulfate electrophoresis (SDS‐PAGE), the albumin had two major protein species, one of 45 × 103, the second of 12–25 × 103 daltons. Prolamin and glutelins contained protein bands coinciding in molecular weight with those of albumin and globulin. Protein hydrolysis with 4 N methanesulfonic acid was superior to that of 6 N HCL. Amino acid composition of proteins was determined by ion‐exchange column chromatography. Some minor losses in protein composition of potatoes occurred during processing.

No abstract

Total amino acids and composition of raw and cooked tubers were determined by gas-liquid and ion-exchange column chromatography. Peeled raw potato, after reaching the end product state, lost 40% of its free amino acid pool. Processing into dehydrated granules by the freeze-thaw process caused only small losses in total amino acids and little change in their composition. There was only a 4.5% destruction of essential amino acids and a total loss of 2.1% of non-essential amino acids, excluding aspartic and glutamic acids which comprised 48% of peeled and sliced potatoes.