Oxidation stability of sausages after cold extraction

Importance of the topic

Assessing lipid oxidation in sausages is crucial for determining shelf life, sensory quality and nutritional value. Cold extraction preserves the native state of the fat, preventing artifacts associated with heat-induced oxidation. Accurate measurement of oxidative stability supports quality control, product development and regulatory compliance in meat processing.

Objectives and Study Overview

This application note outlines a protocol for isolating fat from sausage samples at ambient temperature and evaluating its oxidation stability using the 892 Professional Rancimat. Two sausage types (cervelat and bratwurst) are compared to demonstrate method reproducibility and practical relevance for industrial laboratories.

Methodology and Instrumentation

• Sample Preparation
  • Peel off casing and dice the sausage.
  • Combine with three times sample mass of low-boiling petroleum ether (boiling point 30–40 °C).
  • Stir at ambient temperature for ≥ 1 h; optional fine grinding accelerates extraction.
  • Filter the extract and remove solvent under vacuum (15 mbar) at room temperature.
• Oxidation Stability Measurement
  • Weigh extracted fat into the Rancimat reaction vessel.
  • Expose to constant airflow and set temperature (120 °C).
  • Record conductivity increase to determine induction time.
• Instrumentation
  • Low-boiling petroleum ether as solvent.
  • Rotary evaporator for solvent elimination.
  • 892 Professional Rancimat with eight parallel measuring positions.
  • StabNet software for instrument control, data acquisition and evaluation.

Key Results and Discussion

• Cervelat fat showed an average induction time of 5.69 h (SD 0.04 h; 0.6 %).
• Bratwurst fat exhibited an average induction time of 4.31 h (SD 0.02 h; 0.5 %).
• Low relative standard deviations confirm high method reproducibility.
• Variations in induction times reflect differences in fatty acid profiles and antioxidant levels.

Benefits and Practical Applications

• Selective analysis of the lipid fraction without interference from proteins, water or additives.
• Preservation of the original oxidation state ensures reliable shelf life predictions.
• High throughput analysis of up to eight samples simultaneously streamlines QA/QC workflows.

Future Trends and Opportunities

• Application of accelerated oxidation tests to screen novel antioxidant formulations.
• Extension of the protocol to other complex food matrices such as pâtés and emulsified products.
• Coupling with chromatographic or spectrometric techniques for detailed oxidation product profiling.
• Development of miniaturized extraction and micro-Rancimat systems for rapid on-site testing.

Conclusion

The combination of cold extraction and the 892 Professional Rancimat delivers a robust, precise and reproducible approach to evaluate oxidative stability in sausage fats. This method facilitates accurate shelf life assessment, antioxidant efficacy studies and routine quality control in meat processing laboratories.

Reference

Metrohm Application Note AN-R-032: Oxidation stability of sausages after cold extraction.