This vacuum differential pressure puffing system operates based on the DIC (Instant Controlled Pressure Drop) thermomechanical transformation mechanism, integrating variable-temperature gradient regulation, isobaric heat and mass transfer, and instantaneous pressure gradient flash evaporation technology to achieve low-temperature physical puffing and dehydration of agro-food materials.
The entire processing procedure is a continuous thermophysical modification process without chemical additives, which precisely regulates the coupled change of thermal field and pressure field to reconstruct the internal microscopic pore structure of materials.
Firstly, pre-conditioned raw materials with controlled initial moisture content are loaded into the sealed high-pressure puffing chamber. The system implements segmented variable-temperature heating and constant-pressure thermal insulation to form a stable internal and external temperature equilibrium field of the materials. During this stage, interstitial moisture inside the tissue cells undergoes sensible heat absorption and phase change pre-transition, with internal vapor pressure accumulating steadily under isobaric conditions to reach a saturated thermodynamic equilibrium state.
Subsequently, the equipment performs ultra-fast differential pressure relief through a vacuum buffer tank with a multi-fold volume expansion ratio. The instantaneous formation of a high-intensity negative pressure gradient breaks the original thermodynamic equilibrium instantly. The saturated high-pressure moisture inside the material tissue undergoes flash vaporization and adiabatic expansion in a microsecond-level pressure drop process.
The rapid volume expansion of water vapor generates uniform internal tensile stress, which drives the directional expansion and pore opening of the material’s cellular tissue, forming a three-dimensional interconnected microporous network structure. In the subsequent high-vacuum low-temperature holding stage, the system continuously removes residual free water and bound water via vacuum dehydration, realizing low-temperature drying and tissue shaping of the puffed materials.
This physical puffing mechanism effectively avoids high-temperature thermal degradation and oil oxidation damage caused by traditional frying and high-temperature extrusion processes. It achieves high-efficiency puffing molding while maximally retaining the intrinsic bioactive components, dietary fiber, and natural pigment of raw materials, endowing finished products with homogeneous porosity, low water activity, and stable crispy texture.