Evaluation of innovative immersion vacuum cooling with different pressure reduction rates and agitation for cooked sausages stuffed in natural or artificial casing

- Effects of operational parameters on IVC of different sausages were studied.
- Natural casings had a higher successful rate (87.5%) than artificial casings (75%).
- Optimal linear pressure reduction rate for beef collagen casings was 30 mbar/min.
- Cooling time to 4 °C for natural casing was reduced by 40.78% at 60 mbar/min.

Effects of different pressure reduction rates and liquid agitation (523 rpm) on sausage successful rate, cooling time, cooling loss, texture properties, chemical and physical parameters were analysed by ANCOVA. Tested linear pressure drop rate from 320 mbar to 50 mbar was 20 (L 20), 30 (L 30), or 40 (L 40) mbar/min for artificial casing sausages (ACS) and 60 (L 60), 80 (L 80), or 100 (L 100) mbar/min for natural casing sausages (NCS). From 50 mbar until 6.4 mbar, 5 mbar/min was used for both casings. NCS were more suitable than ACS for IVC. The recommended pressure reduction rate was 30 mbar/min for ACS and 60 mbar/min for NCS. ACS under 30 mbar/min with agitation (LA 30) presented significantly higher texture property values than that without agitation (L 30) (P < 0.05). Cooling time (to 4 °C) of NCS under 60 mbar/min and agitation (LA 60) was significantly shorter than that without agitation (L 60) (P < 0.05). This study could assist meat processors or manufactures when choosing a suitable pressure drop rate for different types of sausages.