Improved extruders and methods for the extrusion cooking of comestible products such as human foods or animal feeds are provided wherein the products may be produced with very low specific mechanical energy (SME) inputs as compared with conventional processing. The methods preferably involve introduction of very high levels of steam into the extruder barrel (12) during processing, which concomitantly reduces necessary SME inputs required to achieve desired cook and expansion levels in the products. In accordance with the invention, fully-cooked pet foods can be fabricated with SME inputs of up to about 18 kWhr/T, whereas aquatic feeds can be fabricated with SME inputs of up to about 16 kWhr/T. In preferred forms, the extruder (10) includes specially configured, intermeshed extrusion screws (18, 20) and a plurality of obliquely oriented steam inlets (48, 50), and an upstream, dual-shaft preconditioner (90) is used having individual variable frequency drives (98, 100) which allow infinite variablility in the speed and rotational direction of the preconditioner shafts (94, 96).設有一種用於擠壓烹煮諸如人類食品或動物飼料等可食用產品之改良式擠出機與方法。相較於習知的處理方式，可以利用非常小的特定機械能量(SME)輸入而製造上述產品。此方法較佳地牽涉到在處理期間將非常高程度的蒸氣引進到擠出機筒身(12)內，如此伴隨地可減少為了使產品內達到想要的烹煮與膨脹程度所需之SME輸入。根據本發明，以高達約18kWhr/T的SME輸入可製造出全熟的寵物食品，而以高達約16kWhr/T的SME輸入則可製造出水生物飼料。在較佳形式中，擠出機(10)包括兩個具有特殊結構且相互嚙合的擠壓螺桿(18、20)，且包括多個傾斜定向的蒸氣入口(48、50)。而且，使用一個位於上游處的雙軸式前調節器(90)，其具有個別的可變頻率驅動裝置(98、100)，這些可變頻率驅動裝置能允許在前調節器的軸(94、96)中對於其速度與旋轉方向產生無限變化。
