The Protein Efficiency Ratios of 30:70 Mixtures of Animal:Vegetable Protein Are Similar or Higher than Those of the Animal Foods Alone

Animal foods in general are considered to be foods with high protein qualities, although their qualities are not always similar because of differences in essential amino acids. The purpose of this study was to compare the protein quality of different animal foods and of their mixtures with vegetable foods, mainly cereals, at the 30:70 animal:vegetable protein proportion with experiments performed under the same conditions. The animal foods were eggs, beef, pork, barbecued lamb, chicken, ham, sausage and milk powder. The vegetable foods used in the mixtures were rice, lime-treated corn flour, wheat flour and cooked black beans. The protein concentrations in the raw and cooked materials were analyzed. The protein efficiency ratios (PER) and digestibilities were determined in Fisher 344 weanling rats. Based on the corrected PER, the foods with the best protein quality were egg (3.24), sirloin beef (3.16), lamb (3.11) and chicken breast (3.07), which were significantly different (P < 0.05) from milk powder (2.88) and beef liver and beef round (2.81 and 2.70, respectively). The ham (2.63) and the pork loin (2.57) had a similar protein quality to that of casein (2.50). The lowest protein quality was found in sausages (2.14). In most of the mixtures of animal and vegetable protein (30:70), the PER was similar to or higher than that of the animal food alone. Beans were the vegetable food that showed the lowest response to the addition of animal food. The conclusion of the study is that some 30:70 mixtures of animal:vegetable protein, such as chicken, beef round and pork with cereals could be utilized for regular meals because of their high PER and low cost.