Development and application of nitrite-free and low-nitrite meat-curing systems

grantor: University of TorontoNitrite-free and low-nitrite meat-curing systems were developed to eliminate or reduce nitrite in cured-meat products. These curing systems achieve the cured-meat colour by using the cured-meat pigment, dinitrosyl ferrohemochrome (DNFH). The synthesis of DNFH was scaled up from 125 mg to 4 g final product. The material cost of DNFH synthesis was reduced by 93% at the 4 g-scale. Synthesis performed at elevated pressure (620-690 kPa) did not improve pigment quality. The DNFH formation rate was determined by the periodic measurement of the pigment concentration during the synthesis. The kinetic data were modelled and a pseudo first-order reaction rate constant was calculated ('k ' = 0.021 s-1). It was found that the DNFH synthesis is limited by nitrite concentration in the initial phase (30-60 s) of the nitrosation, and that in the later phase pigment formation was the function of hemin concentration. The molar absorptivity value was determined for DNFH solutions in 80% aqueous acetone at 565 nm ([epsilon]565 = 13.5 cm -1 mM-1). The chemical structure of DNFH was confirmed by the measurement of nitric oxide uptake during the synthesis. It was found that the formation of DNFH gives a 1:2 hemin/NO stoichiometric ratio rather than 1:1. It was also shown that, the DNFH yield of the reaction was 90%. The nitrite-free and low-nitrite meat-curing formulations were tested by pilot-plant scale production runs of cured meats (smoked wiener, sausage, salami, bologna, jagdwurst sausage and ham). These products contained standard curing formulations with or without nitrite in combination with the microencapsulated DNFH, antioxidants and antimicrobial agents. While nitrite-free products had acceptable colour, these were visually distinguishable from the nitrite-cured controls. Low-nitrite products (98 to 99% nitrite reduced) had matched the colour of a product containing 200 mg/kg nitrite. Microbiological tests indicated that while sodium hypophosphite produced acceptable stability, sodium lactate was not effective at the 1.5% level. Low-nitrite products were more stable than the nitrite-free parallels. The microbial stability of the nitrite-cured control products was better than those of the low-nitrite and nitrite-free products. Proximate composition, antioxidant stability and texture profile of nitrite-free and low-nitrite products were matched to the traditionally nitrite-cured products. Nitrite-free and low-nitrite cured meats contained no detectable (