Nutritional quality and the presence of anti-nutritional factors in leaf protein concentrates (LPC)

Abstract

Leaf protein concentrates were prepared from 25 different plant species. The concentrates contained acceptable levels of all essential amino acids; except methionine which was limiting with chemical scores ranging between 13.5-96%. LPCs from sesbania, nebergrass, lufa and sweet pepper were lethal to the rats. PER ranged between 0.28 for safflower LPC up to 1.95 for rape. Positive nitrogen balance was obtained with diets based on LPCs with mean values ranging between 6.4 and 22.42 mg N per day. True nitrogen digestibility fluctuated between 72.4% for sweet potato LPC up to 97.9% for LPC prepared from safflower. BV ranged between 60.5 for sunflower LPC to 97.26 for carrot LPC. NPU values of LPCs were 49.4 for sunflower LPC up to 86.5% for rape LPC. There was a positive correlation coefficient between BV and the respective NPU. Highest utilizable protein was obtained with turnip LPC. Tested LPC's contain 0.6-6.8% tannin. Saponin was absent in 11 LPCs. Lufa LPC showed the highest saponin content followed by nebergrass and sesbania LPCs. Trypsin inhibitory activity was quite low. Prelimenary results show that rats consumed diet based on lufa, nebergrass and sesbania LPCs died within the first few days of the experiment. Low growth rates were obtained for drum-dried samples prepared from carrot, but this was not the case for drum-dried samples prepared from chard. The activity of liver alanine amino transferase was also determined and indicated toxicity of some LPCs to liver.