Release of iron bound to animal and vegetable protein sources was investigated. Ferrous and ferric iron complexes with wheat gluten, soy protein isolate, and casein were prepared under conditions shown to bind large quantities of iron to the insoluble residue. These mixtures were lyopbihzed and ground to a fiie powder. Treatment of the 1yophIlized protein-iron-mixtures with O.lN HCl released 30-68% of the bound iron. Digestion in an HCl-pepsin or an HCl-pepsin-pancreatin system released 64-94% and 85-97% of the bound iron, respectively, indicating that protein-bound iron should be readily freed for absorption within the gastrointestinal tract. Using the hemoglobin repletion technique, protein-bound ferrous iron was statistically as biologically avaiIable as the standard, ferrous sulfate. Estimates of the relative biological values for the protein-ferric mixtures were somewhat lower than reported in the literature for ferric pyrophosphate, the free salt used in binding.

The binding of iron from ferrous sulfate and ferric pyrophosphate by wheat gluten, soy isolate, zein, albumen and casein was determined in aqueous dispersions over the pH range 4-10 and at temperatures and times up to 87°C and 180 min. Under many of the experimental conditions more than 50% of the 20 mg Fe added per gram of protein became bound to the insoluble fraction of the various proteins. Lesser amounts were bound by the soluble fraction. Iron distributions between precipitated protein, soluble protein and ultrafiltrates of soluble protein were influenced by iron source, protein source, pH, temperature and time.

Two strains of I/ parahaemolyticus were studied with respect to salt requirements in Nutrient Broth, effects of freezing and heat stresses on salt requirements, and growth in nonmarine foods. Nutrient Broth containing 0.0235M Na plus K ions was supplemented with NaCl, KCl,' Na,SO, and K,SO, in concentrations from O.Q342M-0.5132M. V. parahaemolyticus did not grow without supplementation. Both strains grew at a mimimum total NaCl concentration of 0.0855M (0.5%) and maintained viability at 0.0513M (0.3%) NaCl. Strain 17802 could utilize KCl, Na, SO, and K, SO, as alternate ion sources and gave essentially the same growth patterns as with equimolar concentrations of cation from NaCl. Strain 27519 required slightly higher concentrations of KC1 and Na, SO, than strain 17802 but did not grow at any level of K,SO, supplementation. NaCl requirements in Nutrient Broth were only very slightly changed by stresses of frozen storage at -18°C up to 30 days and were esentially unchanged by heating at 50°C for 15 min. Both strains grew profusely in beef, turkey, pudding, milk and egg at 37°C and 25"C, reaching levels within 12 hr, in most cases, sufficient to cause food poisoning by pathogenic strains. To a more moderate degree growth also occurred at 9"C, reaching viable counts of lo5 /ml in 12 hr in all of these foods except egg. At 9°C none of the foods exhibited visual or odor changes indicative of spoilage even after 72 hr, while at the higher temperatures such signs of spoilage were absent in several cases where counts exceeded lo'-lo* /ml. Green beans of pH 4.95 did ~ not support growth or maintain viability of either strain. The levels of NaCl in the Nutrient Broth and foods that supported growth of V. parahaemolyticus in these studies were lower than generally reported in the literature.