An investigation of factors contributing to extended storage life of meat products for the tropics : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Meat Technology at Massey University

Abstract

A combination of factors which could extend the shelf­ life of minced mutton meat during storage under warm conditions (30 °c) while still maintaining a low cost product with acceptable sensory and microbiological properties was investigated. The combination of factors studied involved pH values from 5. 5 to 3. 5 achieved by the addition of acetic acid, water activity ( a w ) values from 0. 9 9 to 0. 91 achieved by the addition of sorbitol and the reduction in moisture contents, heat treatments

from 30 to 50 0 C, and

the use of

different packaging

materials (cellulose, polyethylene and aluminium foil films).

It was expected (from reported work) that stability would

be achieved by reducing aw

to 0. 95 and pH to 5. 2, but

at 30° C the shelf-life was less than one week. Within the limits of the values that were considered, the control of pH was the only significant factor in extending the shelf-life of minced mutton meat stored at 30° C. To achieve a commercial acceptable shelf-life of 8 weeks, a pH of 4. 1 or below was required. Minced mutton with the pH of 4.1 can be organoleptically acceptable with the addition of the right combinations of spices and seasonings suited to specific localities and countries. The practical value of lowering the pH of meat products below 4.1 must be questioned because no additional microbiological protection will be obtained and the increase of the acid level will only decrease the flavour acceptance. Combinat­ions of low acid and spices and seasonings would appear to be a development area of greater promise for tropical countries than intermediate moisture meats