Effect of Pressure Regulating Mechanism on Screw Pressing Efficiency and Production Capacity in Sea Buckthorn (Hippophae rhamnoides) Juice Extraction

This study addresses the optimization of juice extraction from sea buckthorn (Hippophae rhamnoides) to meet the growing demand for healthy, natural food products. An upgraded screw press with a self-regulating pressure adjustment mechanism was developed and evaluated. Four spring types (wire diameters, 1–6 mm; maximum forces, 47.5–800 N) and screw rotation speeds ranging from 140 to 200 rpm were investigated for their effects on juice yield, compression density, internal pressure, and power consumption using sea buckthorn fruits. The results indicated that springs with higher maximum forces yielded greater juice outputs. The highest juice yield of 47% was achieved using a spring with a 3 mm wire diameter and 630 N maximum force (Spring 4) at 185 rpm. This configuration also demonstrated an optimal balance between compression density (948 kg/m3) and internal pressure (320 Pa) while maintaining the lowest power consumption (142 W). The internal pressure within the pressing chamber increased with both spring force and rotation speed. While Spring 2 generated the highest internal pressures (up to 570 Pa at 200 rpm), Spring 4 achieved moderate internal pressures, suggesting an effective pressure transmission. Spring 4 exhibited the lowest power consumption despite the high juice yields and compression densities. The study concludes that utilizing Spring 4 at 185 rpm optimizes the juice extraction efficiency while minimizing energy use. Equipment designs allowing the fine-tuning of pressure and rotation speed can significantly enhance the production efficiency in sea buckthorn juice extraction and potentially in other fruit-juice-processing applications.