Effects of different cooling methods on shelf-life of cooked jumbo plain sausages

Three different cooling methods: commercial cooling and immersion vacuum cooling (IVC) with two different initial water temperatures (20 degrees C and 80 degrees C) were applied to cooked sausages. Linear pressure drop rate of 60 mbar/min with agitation was employed in the current experimental trials. Chemical (moisture and pH) and quality (colour and microbial analysis) parameters after cooling were monitored during 29 days of cold room storage (4 degrees C) and the shelf-lives of the sausages were determined. Results showed that IVC with cold water (IVCC) could achieve not only rapid cooling time to 4 degrees C (31 min), compared to IVC with hot water (IVCH) (41 min) and commercial cooling (251 min), but also a longer shelf-life. pH of IVCC samples was more stable during cold room storage than the other cooling methods. Core colour of IVCH sausage turned to be darker with time; all the samples became slightly redder after 15 days of storage. It was concluded that IVC could surpass commercial cooling method in terms of cooling time and shelf-life of the sausages. Additionally, IVCC (if the tap water used was hygienic enough) did not introduce external detrimental bacteria and possessed a higher cooling rate than IVCH without compromising the quality properties. (C) 2013 Elsevier Ltd. All rights reserved.