The relative organoleptic stability of the British fresh pork sausage among meat products has been shown in this study to be due more to a biochemical effect of SO2 than to its antimicrobial activity (except for an inhibition of coliforms). Sulphiting doubled the storage life of film-wrapped sausages to four days at 20-22°C, prevented the formation of a strong cheese-like aroma, reduced the degree of colour change observed, prevented the accumulation of valeric acid, reduced the amounts of lactic acid, and a second unidentified acid, formed by ca. 50%, caused the accumulation, by preventing the metabolism, of C12-C20 free fatty acids (but did not prevent the hydrolysis of glycerides), and limited the concomitant change in pH to 0.5 units. The microbial association which developed under these conditions did not differ significantly in composition or size from that detected in unsulphited sausages, a finding which agreed with the results of Abbiss (1978) and Brown (1977). Organoleptic change in the sulphited product, from acceptable to unacceptable, occurred when the microbial association at its surface exceeded 108 c.f.u./g. The climax at ca. 108.5 c.f.u./g. quickly followed, and the subsequent wave of post climax cell lysis was thought to contribute significantly to the quality changes perceived. It was found that both the growth of the flora, and the pH change, were affected by glucose when SO2 was present. A supply of glucose was envisaged as necessary to sustain the flora and maintain organoleptic stability, but a limitation to its availability was necessary to prevent too rapid microbial growth, an earlier climax, and, as a result, a shorter shelf-life. Of the sources of glucose studied, sausage rusk was found best to satisfy these requirements cheaply. In addition it contributed a "baked cereal" component to the aroma of the sausage, and this was regarded as a characteristic and desirable feature.
|Date of Award||1979|