Improving potato protein I. Evaluation of selection techniques

Abstract

Nitrogen, amino acids and protein analyses were compared for determination of tuber protein. Micro-Kjeldahl nitrogen provided a poor estimate of both protein and amino acids (r = 0.55 and 0.45 respectively). Potato protein contains about 13.5% nitrogen, making 7.5 an appropriate conversion factor. Autoanalyzer determinations of amino acids were correlated with protein analyzed by a modified Potty technique (r = .82). Amounts of six specific protein-bound amino acids were also correlated. with protein. Free amino acids accounted for about 10% of the total and non-essential amino acids constituted over 90% of this free pool. Only 23% of total nitrogen was accounted for in the free pool. Protein content and tuber size were not correlatel. Protein content was similar in the cortical, medullary and pith region. Loss in tuber protein during six months of storage at about 3 C (38-40 F) was 3%.