The effect of browning intensity on the protein quality of qurshallah

摘要

The effect of browning intensity of qurshallah, a popular bakery product in Jordan leavened by ammonium bicarbonate and baked twice, on the protein quality was investigated. Light, medium and dark toasted qurshallah samples baked at the same temperature but for different times were used. Data on the proximate analysis of the three different levels of toasted qurshallah indicated significant differences (P < 0.05) regarding the moisture content of the three toasting levels, and in the fat content between the light and the dark toasted samples. Net protein utilization (NPU) using Sprague-Dawley rats, was determined for diets containing the toasted qurshallah samples. Food consumption and gain in body weight of rats decreased with increasing toasting level. Dark toasting of qurshallah caused loss in body weight of animals. The values for NPU operative (NPUop), NPU Standardized (NPUst) and net dietary protein as a percentage of total energy (NDpE%) for light, medium and dark toasted qurshallah diets were significantly different (P < 0.05). The highest values obtained were for the light toasted (75.5, 82.0 and 6.6 respectively), and the lowest values for the medium toasted qurshallah (56.4, 56.3 and 3.7 respectively). The results indicate that intense browning of chemically leavened bakery products might be deleterious to health and should be avoided.