Inhibitory activity of phosphates on molds isolated from foods and food processing plants.

Six commercial phosphates were evaluated for inhibition of the growth of 17 molds isolated from food sources. The assays were performed at neutral and natural (without pH adjustment) pH values, and the molds were streaked on plate count agar with added phosphates. Phosphate concentrations of 0.1, 0.3, 0.5, 1.0, and 1.5% (wt/vol) were used, and the MIC was determined. The resistance of molds to phosphates depended on the species. At a neutral pH, Aspergillus ochraceus and Fusarium proliferatum were resistant to all phosphates at all concentrations assayed, and Byssochlamys nivea, Aureobasidium pullulans, and Penicillium glabrum were most sensitive. The most inhibitory phosphates were those with chain lengths greater than 15 phosphate units and the highest sequestering power. At natural pH values (resulting from dissolving the phosphate in the medium), inhibitory activity changed dramatically for phosphates that produced alkaline or acidic pH in the medium. Phosphates with alkaline pH values (sodium tripolyphosphate of high solubility, sodium tripolyphosphate, and sodium neutral pyrophosphate) were much more inhibitory than phosphates at a neutral pH, but sodium acid pyrophosphate (acidic pH) had decreased inhibitory activity. The results indicate that some phosphates could be used in the food industry to inhibit molds linked to food spoilage.

Glucagon action upon plasma post-heparin lipolytic and monoglyceride hydrolase activities. Studies involving administration of exogenous hormone during suppression of endogenous hormone secretion with somatostatin.

It has been previously demonstrated that glucagon increased plasma post-heparin lipolytic activity (PHLA) in normal rats, but this was not the case in alloxan diabetic rats. The present work was designed to determine if the administration of exogenous glucagon (0.2 mg i.v.) during suppression of endogenous hormone secretion with somatostatin modifies the plasma post-heparin lipolytic activity in normal rats and the action of such hormone upon monoglyceride hydrolase (MGH) activity. It was found that exogenous glucagon significatively increased PHLA and MGH activity in normal rats after 18-24 hours of starvation. However, both enzymatic activities were not influenced by exogenous glucagon when they were measured during somatostatin administration. Therefore it is believed that the enhancement of these activities observed when somatostatin was not simultaneously given was due to the insulin secretion that follows the glucagon injection.