A greatly improved aseptic processing apparatus and method for pumpable foods is provided which gives accurate, uniform aseptic cooking conditions (e.g, time, temperature and pressure) while at the same time preserving the integrity of particulates in the food product. In preferred forms, the apparatus includes a reciprocating piston food pump which generates a continuous product stream at a substantially constant nominal pressure. This stream is fed to a heat exchanger in order to elevate the temperature of the product, whereupon the stream passes through a holding tube to complete the aseptic cooking process. A metering device such as a rotary pump is located downstream of the holding tube for creating a substantially constant flow rate of product from the apparatus. Use of a downstream metering device in conjunction with an upstream constant pressure pump permits attainment of even, relatively high system pressures which in turn facilitates accurate temperature control and eliminates localized internal steam flashing which can deleteriously affect product quality. By virtue of the present apparatus and method, aseptic processing of low acid heterogeneous food products such as stews and chilies can be safely accomplished on a commercial scale.