High-acid vegetables such as tomatoes and pickles are good choices for canning with the water bath method. Vegetables that are low in acidity such as green beans, carrots and corn are normally processed using the pressure canning method.
The water bath canning method creates a high enough temperature to kill bacteria in high-acid fruits and vegetables. High acid means a pH value of 4.6 or lower. Low-acid vegetables need a higher temperature to kill microorganisms that lead to food poisoning. The water bath canning method heats food up to 212 degrees Fahrenheit, while the pressure canning method heats food up to 240 degrees Fahrenheit.