Effect of lysine and milk protein supplements on the protein efficiency ratio of wheat macaroni.

The milling of wheat into flour and semolina is known to diminish the quality of the
protein. For example, Hove, Carpenter & Harrel (1945) found that the protein
efficiency ratio (PER) of wheat, about 1.4, was decreased to 0.84 for patent flour at
dietary levels of protein of 10.2 and 9.8 respectively. Others reported a PER of 0.25
for 70% extraction flour determined at an 8% level of protein in the diet (Harris &
Burress, I9j9) and of 1-68 for whole wheat (Morgan, 1931). Increased consumption
of such milled products in processed forms such as bread and macaroni in countries
where people consume largely vegetarian diets would necessitate fortification of such
products to improve both quality and quantity of protein. The main limiting essential
amino acid of cereals and their milled products is lysine (Osborne & Mendel, 1914,
1919;M itchell &Smuts, 1932;B lock & Mitchell, 1946-7). The possibility of improving
the quality of bread proteins has been studied by several workers, including Carlson,
Hafner & Hayward (1946), Kosenberg & Rohdenburg (1951, 1952), Rosenberg,
Rohdenburg & Baldini (1954), Hutchinson, Moran & Pace (1956a, b), Jahnke &
Schuck (1957), Sabiston & Kennedy (1957), Howard, Monson, Bauer & Block (1958),
Brown, Flodin, Gray & P a p e r (1959), McLaughlan & Morrison (1960) and Morrison
& Campbell (1960), but macaroni products have not received similar attention. Our
investigation was therefore undertaken with a view to improving the protein content
and the nutritive value of macaroni protein by supplements such as lysine and milk
protein, as determined by measurement of PER and of liver composition with weanling
rats.