What do you use to check fryer oil quality in the fry vats?

To check fryer oil quality in the fry vats, a test tube is the most appropriate tool. The test tube allows for sampling the oil in a controlled manner, where you can observe the oil's clarity, color, and consistency. This method is effective for assessing the level of contaminants and the breakdown of the oil, which are critical factors in maintaining fry quality, food safety, and taste.

While other tools, such as a dipstick, thermometer, or oil gauge, may serve specific purposes in managing fryers, they do not effectively provide the comprehensive assessment of oil quality that a test tube does. For example, a dipstick might measure oil levels rather than quality, a thermometer measures temperature without assessing degradation, and an oil gauge primarily indicates oil levels, not its condition. Therefore, using a test tube is essential for a thorough evaluation of fryer oil quality.