Fresh, unpasteurized ginger juice lasts only 24 to 48 hours when stored in an airtight container in the refrigerator, due in part to its 5.9 pH; alkaline foods have short shelf lives. Pasteurized ginger juice keeps for two to three months but gradually loses its potency once opened. You can preserve homemade ginger juice by freezing or canning it.
Foods that have a pH above 4.6 require pressure canning for long-term preservation. Pressure canners cook food at up to 250 degrees Fahrenheit for as long as needed to sterilize them; the canning time depends on the food's pH. To preserve ginger juice, pressure-can it at 10 to 15 psi for 1 hour and 25 minutes.
Foe easy preservation, pour the ginger juice in freezer-safe container or an ice-cube tray and pack it in a freezer bag. Ginger juice keeps indefinitely in the freezer.
A.J. Andrews' work has appeared in Food and Wine, Fricote and "BBC Good Food." He lives in Europe where he bakes with wild yeast, milks goats for cheese and prepares for the Court of Master Sommeliers level II exam. Andrews received formal training at Le Cordon Bleu.