Peroxidation studies indicated that phospholipids, microsomes and mitochondria from cured pork samples are less susceptible to metmyoglobin/hydrogen peroxide-catalyzed peroxidation than their counterparts from nitrite-free pork samples. The reaction of phospholipids and polyunsaturated fatty acid ethyl esters with dinitrogen trioxide increased their stability to peroxidative changes. Phospholipids from cured pork and those lipids reacted with dinitrogen trioxide were capable of nitrosating a secondary amine. These data, together with infrared analyses, indicate that nitrite or dinitrogen trioxide reacts with unsaturated lipids to form nitro-nitroso derivatives, thus stabilizing the lipids toward peroxidation changes. This mechanism can, in part, explain the antioxidant role of nitrite in cured meats.

Two experiments were carried out to ascertain if supplementation of a semipurified diet to Swiss-ICR mice with either ascorbic acid (AA), vitamin E (Vit E) or a combination of the two would modulate the carcinogenic effects of N-nitrosopyrrolidine (NPyr) and of its probable precursors (nitrite-N02 and pyrrolidine-Pyr) in Experiment I or of NPyr in Experiment II. Results indicated that neither AA nor Vit E modulated the carcinogenic effects of NPyr or of its probable precursors (NO2 and Pyr). Results verified a previous report from our laboratory showing that NPyr increased the number of malignant tumors by some 5–8 fold over controls. There was a lower incidence of tumors in the control group on the semi-purfied diet than in the groups given NO2 and Pyr, although both treatments had a low frequency of malignant tumors (163 versus 572 survivors). Results support our earlier study suggesting that neither NO2 nor Pyr alone or in combination together contribute to cancer—at least in the laboratory mouse.

The Maillard reaction, which involves Amadori rearrangement as a key step, also results in sugar fragmentation and free radical formation. The imidazoquinoline meat mutagens (2-amino-3-methylimidazo[4,5-f]-quinoline, or IQ, and 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, or MeIQ) are formed from a reaction mixture containing alkylpyridine free radicals and creatinine. The imidazoquinoxaline meat mutagens (2-amino-3,4-dimethylimidazo[4,5-f]-quinoxaline, or MeIQx, and 2-amino-3,4,8-trimethylimidazo[4,5-f]-quinoxaline, or 4,8-DiMeIQx0) may be produced by reacting a mixture containing dialkypyrazine free radicals and creatinine. Two different pathways for free radical formation are proposed. One involves bimolecular ring formation from the enaminol form of the glycoaldehyde alkylimine and is followed by oxidative formation of the free radical. The other pathway involves formation of N,N1-diaklylpyrasinium ions from glyoxal monoalkylimine followed by reduction to produce the free radicals. The respective intermediates (glycoaldehyde alkylimine and glyoxal monoalkylamine) are formed by reacting glycoaldehyde and glyoxal with amino compounds. The glycoaldehyde system reacts faster and produces more free radicals than the glyoxal system. The reactions help to explain the formation of imidazoquinoxaline meat mutagens and their predominance in fried fish and why these mutagens are present in larger quantities in fried ground beef than the imidazoquinoline-type meat mutagens. These two pathways may not be the only mechanisms involved in formation of meat mutagens, but other free radical reactions may also contribute to meat mutagenicity and are mentioned briefly. An explanation of how BHT enhances mutagenicity and some of the pathways by which free radical scavenger-type antioxidants (such as BHA, PG, and TBHQ) and sulfiting agents and nitrite inhibit mutagenicity are also proposed.

This study investigated the effects of the phenolic antioxidants (BHA, BHT and PG) on the mutagenicity of IQ, MeIQ and MeIQx by the Ames test. Results demonstrated that MeIQ, IQ and MeIQx were all mutagenic when tested with the Ames test with their potency being in the order listed above. This was true on testing with both TA98 and TA100, both of which required added S-9 for activation. It was clearly demonstrated that BHA and PG significantly inhibited the mutagenicity of IQ, MeIQ and MeIQx. On the other hand, BHT had little effect on the mutagenicity of IQ and MeIQ at low concentrations, but significantly increased their mutagenicity at high concentrations. BHT slightly inhibited the mutagenicity of MeIQx at all concentrations tested.

The chapter describes the formation of meat mutagens during processing and their relationship to the natural precursors that are present in meat. It focuses on methods for measuring mutagens and factors influencing their formation during the cooking of meat. Mutagens can be formed in muscle foods when subjected to various cooking and processing methods. These mutagens are probably produced by creatinine, aldehydes, and/or the Maillard reaction products. The presence of these mutagens in meat is a cause of public health concern about the safety of consumption of cooked meat. However, it should be borne in mind that at the moment the mutagens are formed, some antimutagenic compounds are also generated in the cooked meat. Carcinogens are chemical, physical, or biological agents to which the exposure of animals or humans increases the probability of tumor induction. The carcinogenic process consists of at least two main steps: initiation and promotion.

The effect of salt and pH on the colour stability (oxymyoglobin) in the sarcoplasmic extract (SPE) prepared from pre- and post-rigor beef muscle was studied in the presence or absence of mitochondria and microsomes during 96 h at 4°C. The sarcoplasmic extract from the post-rigor meat (pH 5·4) or from the pre-rigor meat adjusted to pH 5·4 contained more oxymyoglobin (MbO(2)) than the pre- or post-rigor SPE maintained at pH 7·4. The presence or absence of mitochondria and microsomes in the SPE at pH 5·4 had little effect on the percentage of MbO(2). At pH 7·4, however, the percentage of MbO(2) decreased in the SPE in the presence of mitochondria, whereas the percentage of MetMb was lower in the presence of microsomes. The relative proportion of MbO(2) decreased and that of metmyoglobin (MetMb) increased with increasing salt concentration at low pH (more so in the absence of subcellular organelles) and with storage period in the SPE from both pre- and post-rigor meat. However, at pH 7·4, high levels of salt (2-4%) helped to maintain a high percentage of MbO(2) in SPE in the absence of subcellular organelles, especially the mitochondria. The first-order interactions of pH value × subcellular organelles (P < 0·01) and pH value × salt concentration (P < 0·01) accounted for about 55% of the total variation in the percentage of MbO(2) in the SPE. It is suggested that depressing microbial growth may be the operative mechanism by which added salt stabilizes the colour in pre-rigor minced meat rather than by enzymic effects of subcellular organelles.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMonoclonal antibody-based enzyme-linked immunosorbent assay for C19-.DELTA.16-steroids in sera of boar pigsMohamed M. Abouzied, Ali Asghar, Albert M. Pearson, J. Ian Gray, Elwyn R. Miller, and James J. PestkaCite this: J. Agric. Food Chem. 1990, 38, 1, 331–335Publication Date (Print):January 1, 1990Publication History Published online1 May 2002Published inissue 1 January 1990https://pubs.acs.org/doi/10.1021/jf00091a073https://doi.org/10.1021/jf00091a073research-articleACS PublicationsRequest reuse permissionsArticle Views75Altmetric-Citations8LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTESR spin-trapping studies of free radicals generated by hydrogen peroxide activation of metmyoglobinYuan Xu, Ali Asghar, J. Ian Gray, Albert M. Pearson, Alfred Haug, and Eric A. GrulkeCite this: J. Agric. Food Chem. 1990, 38, 7, 1494–1497Publication Date (Print):July 1, 1990Publication History Published online1 May 2002Published inissue 1 July 1990https://pubs.acs.org/doi/10.1021/jf00097a014https://doi.org/10.1021/jf00097a014research-articleACS PublicationsRequest reuse permissionsArticle Views213Altmetric-Citations18LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Odor thresholds for each of the five C(19)-Δ(16)-steroids believed to contribute to boar odor in pork were determined using duo-trio test methodology. Threshold values for 5,16-androstadien-3β-ol (I) and 4,16-androstadien-3-one (II) were approximately 10 μg/g, whereas those for 5α-androst-16-en-3-one (III), 5α-androst-16-en-3α-ol (IV) and 5α-androst-16-en-3β-ol (V) were about 1 μg/g. Statistical comparisons of the mean threshold values for each of these compounds showed no difference (P < 0·05) among the mean thresholds of III, IV and V or between compounds I and II. The mean thresholds of compounds I and II were different (P < 0·05) from those of compounds III, IV and V. Triangle test methodology was employed to measure the ability of trained panelists to differentiate the odors of each of these five compounds either singly or in all combinations. Results showed that panelists were able to differentiate (P < 0·05) between the odors of the C(19)-Δ(16)-steroids possessing ketone groups (II and III) and those containing alcohol groups (I, IV and V). Panelists were not able, however, to differentiate (P < 0·05) between the odors of the three alcoholic steroids (I, IV and V), nor were they able to differentiate between the odors of the two ketonic steroids (II and III).

Charqui, a popular salted and dried beef product consumed in Brazil, was produced using 20% salt (w/w) with the following salt preparations: (1) refined salt, (2) rock salt, (3) refined salt plus BHA/BHT, (4) refined salt plus α-tocopherol, and (5) refined salt plus nitrate. Samples of charqui were analyzed after 0, 15, 30 and 60 days' storage at room temperature. Lipid oxidation was monitored by the TBA test, hexanal development and quantitation of cholesterol oxidation products. Charqui prepared using rock salt had the highest initial TBA numbers, apparently due to contamination by Fe and Cu ions. The antioxidants were generally effective in delaying oxidation for up to 15–30 days, but were ineffective on longer storage. Losses of the unsaturated fatty acids occurred in both the triglyceride and phospholipid fractions, even in samples containing antioxidants. Although the hexanal content and cholesterol oxides increased in all treatments during storage, they tended to be lower in the antioxidant-containing salt treatment. Results indicate that the use of refined salt containing antioxidants retarded lipid oxidation during storage of charqui.

ABSTRACTThe effects of dietary tocopherol and oxidized oil on the oxidative stability of membranal lipids in pig muscles and on the oxidative stability of pork products during refrigerated and frozen storage were evaluated. Membrane‐bound α‐tocopherol stabilized the membranal lipids and reduced the extent of lipid oxidation occurring in pork patties and pork chops during storage. Oxidized dietary oil had an adverse effect on the stability of both the membranal lipids and pork products. The addition of salt to the pork patties accelerated the oxidative process when the patties were stored under fluorescent light and in the dark.

Pre- and post-rigor beef was ground and salt was added to give 0·0, 0·5, 2·0 and 4·0% NaCl (w/w). Samples were removed after 0, 24, 48, 72 and 96 h at 4°C and analyzed for pH, TBA numbers and percentages of reduced myoglobin (Mb), metmyoglobin (MMb) and oxymyoglobin (MbO(2)). After holding for 96 h the samples were cooked in a boiling water bath to an internal temperature of 80°C and held at 4°C for 48 h before TBA analysis. Pre-rigor grinding and salting reduced the post-mortem pH decline and the extent of meat discoloration as shown by the differences in the amount of MMb. The extent of lipid oxidation as measured by TBA numbers was not significantly different for the pre- and post-rigor ground salted meat samples, although salt accelerated oxidation during storage. Results demonstrated that pre-rigor grinding and salting of beef produces a more stable bright red color, which appears to be associated with a lower percentage of MMb and a higher ultimate pH in the pre-rigor salted meat.