Heats of adsorption, free energy of adsorption, and entropy of adsorption for the reversible adsorption of off-flavor compounds onto soy protein isolate were measured by using gas chromatography. Homologous series of alcohols, aldehydes, ketones, hydrocarbons, and methyl esters were used to ascertain the effect of functional group and chain length on adsorption. Triplicate samples were run at 80, 90, and 100 °C, and the resulting data \£ere analyzed by statistical linear analysis. The heats of adsorption

A model system consisting of a uniformly distributed sample of ground pork in conjunction with a nitrite containing curing solution was utilized to evaluate the formation of N-nitrosamines. Utilizing this system a wide variety of compounds were discovered to dramatically reduce the level of N-nitrosopyrrolidine (NPyr) formed during frying. Carbohydrates including the reducing sugars dextrose, ribose, lactose, and maltose, as well as liquid smoke preparations, were found to reduce NPyr levels by as much as 60%. In addition, when low levels of combinations of inhibitors glucose, liquid smoke, and a-tocopherol were incorporated, reductions in nitrosamine levels as great as 80% were observed in model systems as well as in pilot plant manufactured bacon.

Solutes commonly employed in curing solutions were evaluated for their effect on nitrosamine formation utilizing a ground pork model system. Sodium erythorbate and sodium ascorbate were found to be equally effective in reducing nitrosopyrrolidine levels. The incorporation of sodium tripolyphosphate or sucrose had no detectable effect on nitrosamine formation. However, sodium chloride, the solute present at the highest concentration in bacon curing solutions, exhibited a concentration dependent inhibition of nitrosopyrrolidine formation. Nitrosopyrrolidine levels in samples containing no added sodium chloride were found to be 50% higher than samples processed with 1.5% added salt.

A model bacon system has been developed which enables a more reproducible determination of N-nitrosamines when compared to conventional methods of bacon production. Utilizing this system, the effect of slice thickness and frying time on nitrosopyrrolidine (NPyr) formation has been demonstrated. Short frying periods (3 min/side) result in higher NPyr levels for thinrier sliced samples and longer frying periods (5 min/side) result in higher NPyr levels for thicker sliced samples. The level of N-nitrosamine formed is integrally related to slice thickness and frying time and may be explained when two factors are considered, the rate of N-nitrosamine formation and the rate of its volatilization.

Seven laboratories participated In a collaborative study of a method for determination of phosphorus in meat and meat products. Samples are digested In sulfuric acid and hydrogen peroxide; digestion Is complete In approximately 10 mln. Phosphorus Is determined by colorimetric analysis of a dilute aliquot of the sample digest. The collaborators analyzed 3 sets of blind duplicate samples from each of 6 classes of meat (U.S. Department of Agriculture classifications): smoked ham, water-added ham, canned ham, pork sausage, cooked sausage, and hamburger. The calibration curve was linear over the range of standard solutions prepared (phosphorus levels from 0.05 to 1.00%); levels in the collaborative study samples ranged from 0.10 to 0.30%. Standard deviations for repeatability (sr) and reproducibility (sR) ranged from 0.004 to 0.012 and 0.007 to 0.014, respectively. Corresponding relative standard deviations (RSDr and RSDR, respectively) ranged from 1.70 to 7.28% and 3.50 to 9.87%. Six laboratories analyzed samples by both the proposed method and AOAC method 24.016 (14th Ed.). One laboratory reported results by the proposed method only. Statistical evaluations Indicated no significant difference between the 2 methods. The method has been adopted official first action by AOAC.