Studies on toxicity and processing of guar meal

Abstract

Guar meal has been shown to contain a toxic factor which decreases the growth rate of chicks and egg production and egg size of the laying hens. Such activity can be destroyed by heating the guar meal for a period of one hour at a temperature of 110°C with the introduction of superheated steam in the cooker for a period of fifteen minutes when the cooker attains a temperature of 110°C. The presence of trypsin inhibitor in guar meal extract has been demonstrated by enzymatic studies, and the presence of trypsin inhibitor has been correlated with the growth inhibiting properties of the meal observed in studies with chicks and laying hens. When the guar meal extract was heated for a period of 10 minutes, 50 per cent of the trypsin inhibitor activity was destroyed; heating for 60 minutes destroyed 60 percent of the inhibiting activity; and heating for 80 minutes destroyed almost all the trypsin inhibitor activity. Dialyzing guar meal extract against phosphate buffer pH 7.6, for various time periods demonstrated that guar meal trypsin inhibitor is a macromolecule. These studies suggested that the guar meal trypsin inhibitor may be a protein. Trypsin inhibitor in guar meal extract has been expressed in units. The addition of guar gum to the chick diets at levels of 1.8 and 2.7 percent depressed chick growth. The gum is apparently not digested by the chick. The level of processed guar meal which can be added to chick diets may possible be limited by the level of the gum residue of the meal. Experiments carried out to study the effect of the enzyme pectinase demonstrated that pectinase added to the chick diets containing processed guar meal increased the weight gain, possibly by hydrolyzing the polysaccharide. Hypocholestrolemic activity of guar gum in chicks has been demonstrated. The addition of guar gum to the diets has been shown to reduce the cholesterol level in blood produced by exogenous cholesterol. Histopathological studies demonstrated no adverse effect produced by guar meal trypsin inhibitor on heart, liver, or kidney, but there was a definite increase in the size of the pancreas. Amino acid analyses of the blood from hens fed processed guar meal and from hens fed raw guar meal were conducted. A higher serum content of sulfur-containing amino acids was in the blood of hens fed processed guar meal as compared to the hen fed raw guar meal.