Given these comparisons of amino acid content among plant
and animal proteins. it is now relevant to ask about their nutri
tional significance in reference to meeting the needs of human
protein nutrition. Hence, we introduce the topic of protein nutri
tional quality. Various approaches have been used to assess the
comparative nutritional value of food proteins (see ref 15 for
review). One example is the rat bioassay procedure termed the
protein efficiency ratio (PER), which has been in widespread and
official use since first proposed in I 9 19 ( 16). However, this pro
cedure does not necessarily predict satisfactorily the nutritional
value of all plant protein foods intended for direct human consumption (1 7, 18). This is particularly so for legume and oil-seed
proteins. Alternative procedures that would be more directly ap
plicable to human protein and amino acid nutrition have been
proposed and developed.
.