Protein quality of homemade weaning food mixtures: 1. Biological evaluation and quality

In order to evaluate the actual protein value of some recommended weaning food mixtures, a series of biological determinations of protein quality were completed on fourteen different homemade weaning mixtures. The individual foods were cooked, dried and then mixed in recommended proportions resembling the original meals. Pasta, rice, bulgur and millet were used as the major components of food mixtures; egg, fish, mutton, skim milk powder, chick‐peas and mung beans were used as supplementary foods. Rats of the Sprague‐Dawley strain were used for the bioassays. Protein Efficiency Ration (PER), Net Protein Ratio (NPR), Net Protein Utilization (NPU), Relative Protein Value (RPV) and Nitrogen Growth Index (NGI) were calculated for all fourteen food mixtures. Good agreement was obtained between the slope‐ratio techniques and the classical bioassay procedures. Since the digestibility of the protein is an important component of protein quality, this was also performed on all fourteen food mixtures by in vivo and in vitro methods, and similar values were obtained by the two procedures. Finally, all mixtures, when evaluated by biological procedures, met the goals for protein quality recommended in the formulations.

Key words:

• protein quality
• homemade weaning food mixtures
• bioassays
• slope‐ratio techniques
• digestibility