Effects of Storage Conditions on General Deterioration and Stability of Nutrients in Experimental Diets

摘要

The effects of storage conditions on the shelf life of the AIN-76 semipurified diet and NIH-07 natural ingredient diet were investigated. The diets were stored at -70 degrees C, 4 degrees C, 20 degrees C and 23-30 degrees C under atmospheric air and at 4 degrees C and 20 degrees C under argon. Levels of vitamin A, thiamine, rancidity, bacteria and mold were monitored during 168 days of storage. A 41.3% loss of vitamin A occurred in AIN-76 stored at 23-30 degrees C. Loss of thiamine was significantly greater in AIN-76 stored at 20 degrees C or above, and greater when stored under air than under argon. Rancidity in the AIN-76 reached a level previously shown to be associated with a disagreeable odor and taste (peroxide value > 140) within 30, 50 and 90 days when stored at 23-30 degrees C or 20 degrees C under air and 20 degrees C under argon, respectively. None of the nutritional parameters tested reached unacceptable levels in any of the groups stored at 4 degrees C or colder. No changes in the levels of bacteria or molds were observed. These results indicated that AIN-76 should be stored at 4 degrees C or colder. An argon atmosphere extended the shelf life and was additive with lower temperatures. The NIH-07 appeared to be stable with respect to peroxide, vitamin A, thiamine, bacteria, and mold levels under all storage conditions.