Method of microwave sterilizing canned food

A method of sterilizing and canning food products within a non-metallic jar, comprising the steps of

• placing the food products into said jar with a small quantity of liquid sufficient to cover the bottom of the interior of said jar;
• placing a non-metallic lid having means capable of air-tight sealing over the mouth of said jar;
• enclosing said jar and lid within an enveloping air-tight non-metallic enclosure having a one-way check valve for permitting expulsion of air and steam from the enclosure interior, and having means resiliently urging said lid against the mouth of said jar said means resiliently urging said lid against the mouth of said jar being forceable by the lid away from the jar at a predetermined pressure;
• applying sufficient microwave energy to said enclosure, jar and food products to convert at least a substantial portion of said liquid into steam to sterilize said food products and fill said jar with steam;
• continuing to apply said microwave energy to expand said steam and to expel said steam from said jar between the jar and lid as the steam forces the lid against said resilient urging means and expanding into the interior of said enclosure at said predetermined pressure for a predetermined period of time;
• venting some of said steam from said enclosure through said valve;
• and then discontinuing said application of microwave energy;
• thereafter applying a cooling fluid to at least the lower portions of the exterior of said enclosure while preventing entry of fluids into said enclosure interior to cool said enclosure and its interior faster than said jar and lid, such that any steam surrounding the jar inside the enclosure will condense;
• thereby reducing the pressure around the jar in relationship to the pressure in the jar causing said lid to raise against said resilient means thus
• drawing steam out of the lidded jar until the pressure differential between the interior and exterior of the jar is reduced to a level such that said urging means will permit no further flow of said steam;
• condensing said steam and cooling the food products within the jar while the lid remains resiliently urged against the jar mouth with the pressure within the enclosure and jar being substantially less than the ambient pressure exterior to the enclosure, and
• venting said enclosure interior to ambient pressure, whereby the greater pressure outside the jar and reduced pressure inside the jar serves to urge the lid into an air-tight seal with the jar mouth.