Ronald B. Pegg

Free-radical scavenging capacity and antioxidant activity of selected plant species from the Canadian prairies

Ethanolic extracts from the roots of wild licorice (Glycyrrhiza lepidota), narrow-leaved echinacea (Echinacea angustifolia), senega (Polygala senega), leaves of bearberry (Arctostaphylos uva-ursi) and aerial parts of two varieties of horsetail (Equisetum spp.) were prepared and evaluated for their free-radical scavenging capacity and their antioxidant activity, by a number of chemical assays. Assays employed included a b-carotene-linoleic acid (linoleate) model system, reducing power, scavenging effect on the DPPH � free radical and capacity to scavenge hydroxyl free radicals (HO � ), by use of electron paramagnetic resonance (EPR) spectroscopy. The bearberry-leaf extract consistently exhibited the highest antioxidant activity based on the tests performed, and seems to be a promising source of natural antioxidants. The polyphenolic constituents appear to be responsible, at least in part, for the extract’s radical-scavenging capacity. Research is progressing to characterize the antioxidant compounds in the bearberry-leaf extract and their mode of action in imparting antioxidant activity to various food systems. # 2003 Elsevier Ltd. All rights reserved.

Unraveling the chemical identity of meat pigments

This review examines the chemistry of nitrite curing of meat and meat products as it relates to the development of cured meat color and provides a detailed account of how nitrite-free processed meats could be prepared using the preformed cooked cured-meat pigment (CCMP). Thus, a chemical description of meat color, both raw and cooked, and characterization of nitrosylheme pigments follows. Based on electron paramagnetic resonance (EPR), visible and infrared spectroscopic studies, evidence has been provided to support the hypothesis that the chemical structure of the preformed CCMP is identical to that of the pigment prepared in situ after thermal processing of nitrite-cured meat and is in fact a mononitrosylheme complex. An appendix, which describes the basic principles of EPR spectroscopy used in the context of this review, is attached.

Nitrite-free meat curing systems: Update and review

Abstract Several nitrite-free meat curing systems consisting of the pre-formed cooked cured-meat pigment (CCMP), an antioxidant and/or a sequesterant and possibly an antimicrobial agent, have been formulated. Application of this pigment in different formulations to comminuted and solid cuts of muscle foods has been achieved. Colour, oxidative stability and flavour of the treated samples were similar to those of their nitrite-cured counterparts. Microbial stability of meat systems was assured by the incorporation of a known antimicrobial agent or low-dose, low temperature irradiation.

Chemical composition and nutritional value of processing discards of cod (Gadus morhua)

Cod offal from Atlantic species (Gadus morhua) during the intense summer inshore fisheries, June–August, was analyzed for its chemical composition and energy value. The crude protein content of the samples was 14·3% and this included 2·55% collagen. The total lipid content of the offal was 4·3% and its ash content averaged 3·95%. Thus, the energy value of the offal was calculated as 413 kJ/100 g. The offal had an increased content of glycine, alanine, serine, proline and hydroxyproline as compared to the cod muscle proteins. Based on the content of selected amino acids, the calculated PER value for the offal was 1·88–2·36 as compared to 2·86–3·24 for the cod muscle. The fatty acid composition of the offal was similar to that of the cod-liver oil.

Absence of volatile N-nitrosamines in cooked nitrite-free cured muscle foods

Nitrite-free cured pork systems were prepared using the preformed cooked cured-meat pigment (CCMP) and sodium ascorbate. Absence of volatile N-nitrosamines in cooked nitrite-free systems was confirmed using a gas chromatography-thermal energy analyzer (GC-TEA) methodology. Similar results were obtained when cod, cod surimi or mixtures containing pork with 15 or 50% cod or cod surimi were used. However, counterpart samples cured with sodium nitrite (156 ppm) and sodium ascorbate (550 ppm) produced N-nitrosodimethylamine at 1·0 ppb levels or less. Results demonstrate that nitrite-free curing of meat and meat/fish systems containing the preformed CCMP is successful in yielding products devoid of volatile N-nitrosamines.

Colour characteristics of cooked cured-meat pigment and its application to meat

Abstract The colour characteristics of comminuted pork treated with pre-formed cooked cured-meat pigment and protoporphyrin-IX (PP-IX) were compared to that of nitrite-cured meat. Hunter L, a, b values indicated that pigment-treated meat, at 12 ppm level, upon cooking, closely resembled that of nitrite-cured meat. Addition of sodium tripolyphosphate (STPP) and/or sodium acid pyrophosphate (SAPP) did not have a significant (P

Effect of L-Glucose and D-Tagatose on Bacterial Growth in Media and a Cooked Cured Ham Product

Cured meats such as ham can undergo premature spoilage on account of the proliferation of lactic acid bacteria. This spoilage is generally evident from a milkiness in the purge of vacuum-packaged sliced ham. Although cured, most hams are at more risk of spoilage than other types of processed meat products because they contain considerably higher concentrations of carbohydrates, approximately 2 to 7%, usually in the form of dextrose and corn syrup solids. Unfortunately, the meat industry is restricted with respect to the choice of preservatives and bactericidal agents. An alternative approach from these chemical compounds would be to use novel carbohydrate sources that are unrecognizable to spoilage bacteria. L-Glucose and D-tagatose are two such potential sugars, and in a series of tests in vitro, the ability of bacteria to utilize each as an energy source was compared to that of D-glucose. Results showed that both L-glucose and D-tagatose are not easily catabolized by a variety of lactic bacteria and not at all by pathogenic bacteria such as Escherichia coli O157:H7, Salmonella Typhimurium, Staphylococcus aureus, Bacillus cereus, and Yersinia enterocolitica. In a separate study, D-glucose, L-glucose, and D-tagatose were added to a chopped and formed ham formulation and the rate of bacterial growth was monitored. Analysis of data by a general linear model revealed that the growth rates of total aerobic and lactic acid bacteria were significantly (P < 0.05) slower for the formulation containing D-tagatose than those containing L- or D-glucose. Levels of Enterobacteriaceae were initially low and these bacteria did not significantly (P < 0.20) change in the presence of any of the sugars used in the meat formulations. Compared to the control sample containing D-glucose, the shelf life of the chopped and formed ham containing D-tagatose at 10 degrees C was extended by 7 to 10 days. These results indicate that D-tagatose could deter the growth of microorganisms and inhibit the rate of spoilage in a meat product containing carbohydrates.

Enhancement of nisin antibacterial activity by a bearberry (Arctostaphylos uva-ursi) leaf extract

Abstract Plant extracts intended for use as antioxidants in foods may also have biological effects on bacteria. The antimicrobial activity of an antioxidant ethanolic extract of bearberry (Arctostaphylos uva-ursi) leaves, alone and in combination with nisin, was determined against 25 food-related bacteria by the spot-on-lawn and the micro-dilution methods. The growth kinetics of four bacteria selected from the 25 were determined in the presence of nisin and bearberry extract by monitoring absorbance at 550 nm , while the degree of sub-lethal injury of these bacteria was determined with bearberry extract alone by plating on agar with and without 4% NaCl. The bearberry extract alone displayed no antimicrobial activity of its own but enhanced the activity of nisin, as determined by minimum inhibitory concentration, against many of the Gram-positive, but none of the Gram-negative, bacteria. The combination of nisin and the bearberry extract slowed the growth of some bacteria, most notably Brochothrix thermosphacta, as compared to nisin alone. Sub-lethal injury was induced in two (Bacillus cereus and Broch. thermosphacta) of the four selected bacteria by the bearberry extract. The extract may have potential as an agent to enhance the antibacterial activity of nisin, but further work is required.

A novel titration methodology for elucidation of the structure of preformed cooked cured-meat pigment by visible spectroscopy

Abstract The chemical structure of preformed cooked cured-meat pigment (CCMP), which is believed to be the pigment of thermally-processed nitrite-cured meat, was investigated by a novel titration methodology. Electronic spectra of reduced haemin and its nitrosyl derivative were recorded in the visible region in an aqueousor a dimethyl sulphoxide-medium. Changes in the electronic spectrum of reduced haemin upon gradual addition of aliquots of a saturated solution of nitric oxide (NO) revealed that only one molecule of NO ligates itself to the iron of the porphyrin molecule. A similar conclusion was reached from the infrared studies of CCMP, which revealed the presence of only one NO stretching band. Thus, preformed CCMP is irrefutably a mononitrosyl, not a dinitrosyl, derivative of reduced haemin. This conclusion is further supported by an independent electron paramagnetic resonance study of CCMP, which showed that the pigment was a pentacoordinated paramagnetic complex.

Nitrite alternatives for processed meats

Abstract Nitrite is an essential ingredient used in the curing of meat products. It is responsible for the characteristic color, flavor and extended shelf-life and microbial stability of cured products. However, it is also responsible for the production of carcinogenic N -nitrosamines in certain cured products under some processing conditions. Nitrite-free meat products such as wieners and salami have been prepared using curing systems consisting of the preformed cooked cured-meat pigment, CCMP, an antioxidant, a sequestrant and an antimicrobial agent. The color, oxidative stability, and flavor of the cooked treated products, as determined by Hunter L, a, b values, 2-thiobarbituric acid (TBA) test, and sensory means, respectively, were similar to those of their nitrite-cured counterparts. Absence of N -nitrosamines in the nitrite-free cooked products was confirmed using a gas chromatography-thermal energy analyzer (GC-TEA) methodology. Similar results were obtained when the above nitrite-free curing mixtures were used in fish-based products, where nitrite curing produced substantial amounts of N -nitrosodimethylamine. Furthermore, rates of color fading of samples treated with either CCMP or nitrite were similar, thus suggesting that presence of residual nitrite in processed meats may not be necessary for color stability of such products.