Development of nitrite-free meat curing systems

Pegg, Ronald Bruce (1993) Development of nitrite-free meat curing systems. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

The pigment responsible for the colour of cooked cured-meats has been synthesized from bovine red blood cells directly, or indirectly through a haemin intermediate using sodium nitrite and nitric oxide, respectively. The preformed cooked cured-meat pigment (CCMP) so obtained exhibited absorption characteristics similar to those of pigments extracted from a nitrite-cured sample of ham. Since the CCMP is sensitive to light and oxygen and ultimately decomposes in their presence over a short period of time, the pigment was encapsulated in carbohydrate-based wall materials in an effort to extend its shelf-life and for its easy handling. The resultant powdered cooked cured-meat pigment (PCCMP) remained stable during 18 months of refrigerated storage in some preparations. Application of CCMP or PCCMP to comminuted meat systems produced upon thermal processing the typical pink colour of nitrite-cured products. The colour characteristics of pigment-treated meats depended on both the myoglobin content of muscles from the various species used as well as the level of pigment added. Presence of some myoglobin was deemed necessary in order for the pigment to impart a cured colour to meats. No detrimental effects on the colour or oxidative stability of CCMP-treated pork systems were noted after radiation processing at levels of 5 and 10 kGy. The absence of N-nitrosamines in cooked nitrite-free meat and fish systems containing CCMP was confirmed using a gas chromatography-thermal energy analyzer (GC-TEA) methodology. -- Pilot-scale preparation of CCMP-treated frankfurter and salami products was successful, and the flavour characteristics were indistinguishable from their nitrite-cured counterparts even after 30 days of refrigerated storage. Application of nitrite-free curing pickle containing CCMP to solid cuts of pork conferred the characteristic cured-meat colour throughout the muscles after thermal processing. The concentration of CCMP in pickle had a more pronounced effect on the extent and rate of the pigment's penetration throughout the meat than did the effect of temperature of the pickle. -- The oxidative stability of cured-pork meat and the methodology of the modified 2-thiobarbituric acid (TBA) test were examined. Addition of sulphanilamide played a beneficial role in evaluating the oxidative state of cured meats prepared with the addition of ≥ 100 ppm of sodium nitrite. In the absence of nitrite, sulphanilamide reacted with malonaldehyde forming a 1-amino-3-iminopropene complex. Multiple interactions between malonaldehyde and sulphanilamide, TBA or their combinations were examined. The structures of the above complexes were elucidated using ultraviolet-visible (UV-VIS), infrared (IR), nuclear magnetic resonance (NMR) and mass spectroscopic (MS) techniques. -- Pentanal and hexanal were the dominant volatile aldehydes generated from cooked pork during storage as determined by a rapid headspace-gas chromatographic (HS-GC) methodology. The concentration of hexanal increased faster than any other aldehyde and it has been suggested to serve as an index of meat flavour deterioration (MFD). Hexanal levels of cooked pork increased during the first 6 days of storage and then declined quite markedly. Caution should be exercised when using hexanal as an indicator of lipid oxidation because a given hexanal level may correspond with two points during the storage period of cooked meats. The hexanal and pentanal concentrations of CCMP-treated and nitrite-cured pork systems were depressed even after 4 weeks of refrigerated storage.

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