Evaluation of the Antioxidant Potential of Hyssop (Hyssopus officinalis L.) and Rosemary (Rosmarinus officinalis L.) Extracts in Cooked Pork Meat

ABSTRACT: The objective of this work was to study the ability of rosemary and hyssop extracts to inhibit lipid oxidation and metmyoglobin formation in pork meat, thereby stabilizing meat color. We also evaluated their effects on iron release from the heme moiety of pork meat. Meat samples were blended with hyssop and rosemary extracts and cooked. The cooked meat was chopped into pieces and stored for 8 d at 4 °C. Heme iron, TBA values, metmyoglobin percentage, and meat color were calculated. Hyssop and rosemary were seen to inhibit lipid oxidation and degradation of heme pigments caused by cooking and storage. Both spices delayed metmyoglobin formation and stabilized the red meat color during storage of the cooked meat.     

无硝干腌肉制品中锌-原卟啉Ⅸ形成的研究进展

对无硝干腌肉制品中锌-原卟啉Ⅸ形成的研究进展进行了较为系统的阐述。锌-原卟啉Ⅸ是无硝干腌肉制品中的主要红色色素,研究结果表明其生成量与工艺条件密切相关,通过优化工艺参数可促进肉制品中锌-原卟啉Ⅸ,但其形成机制还尚待进一步阐明。     

Total Heme and Non-heme Iron in Raw and Cooked Meats

ABSTRACT: This study provides data on the total heme and non-heme iron contents in poultry (chicken, turkey), beef, veal, lamb, horse, ostrich, rabbit, and pork meat cuts. The effect of cooking on heme iron content was also studied. Total iron and heme iron contents markedly differed between muscles in poultry. Heme iron in red meats ranged from 72 to 87%. Heme iron in rabbit and pork was 56 and 62% of total iron. Heating decreased heme iron, the severity of the losses depended on cooking methods: in poultry, losses ranged from 22 to 43%; less severe impact was detected in pan-cooked meat, where the losses ranged from 1 to 24%.     

The effect of phytic acid on oxidative stability of raw and cooked meat

The effects of phytic acid addition (0.1, 1 and 5 mM) to pork and beef homogenates on TBARS and metmyoglobin levels in raw meat, and TBARS and heme iron contents in cooked meat during 3 days of storage at 4 °C were investigated. Also, the role of inositol as a potential synergist of IP₆ (phytic acid) was examined. IP₆ effectively decreased the TBARS accumulation in raw and cooked meat homogenates. The metmyoglobin formation was inhibited in raw beef by phytic acid in a dose-dependent manner. The effect of IP₆ was more pronounced in cooked meat than in raw and in cooked beef homogenates more than pork. Inositol did not enhance antioxidant action of phytic acid in minced meat.     

Available iron and zinc in major lean meat cuts and their contribution to the recommended trace element supply in Switzerland

The objective of the present study was to analyze iron and zinc in major lean meat cuts in order to estimate the contribution of the average lean meat consumption in Switzerland (1995) for these trace elements. Iron, heme iron and zinc contents were analyzed in following muscles: pork (longissimus dorsi muscle and shoulder), beef (longissimus dorsi muscle and shoulder), veal (longissimus dorsi muscle) and chicken (breast and thigh). Beef and pork shoulder were the best sources of iron, heme iron and zinc. Pork and veal longissimus dorsi muscle and chicken were relatively poor in these trace elements. With an average daily lean meat consumption of 105 g, iron and zinc intake were about 1.1 mg/d and 3.8 mg/d, respectively. Recommendations for daily iron intake were met to 11% (men) and 7% (women) and for zinc to 25% (men) and 32% (women). Applying a modified Monsen model, the requirements for absorbed iron were met in the range of 10-30% and 7-20% for men and women, respectively. Taking into account a zinc absorption rate from meat of about 20-36%, the daily requirements for absorbed zinc were covered to 32-56%. In conclusion, the average amount of lean meat as consumed in Switzerland was high enough to be an important source of available iron and zinc, particularly for people with low iron and zinc status.     

Zinc-protoporphyrin IX promoting activity in pork muscle

Zn-protoporphyrin IX (ZPP) is a major red pigment in dried hams made without nitrates. In this study, an assay procedure was developed for the measurement of ZPP-promoting activity in meat extracts. The method, adapted from assays already in use with other matrices, is based on the incubation of the meat extract with zinc and protoporphyrin IX (the reaction substrates) and recording of the resulting fluorescence at 590 nm, i.e. the emission wavelength of ZPP. When used to test pork samples, the assay procedure, whose relative standard deviation was <6%, revealed an average activity of 1.7 (enzyme activity units/g dried meat) with large inter-sample variation (CV=66%). Several substances, amongst those typically used in the meat industry, were tested for their effects on the assay performance, showing that sodium chloride and, to a lesser extent, sodium ascorbate significantly (P<0.05) enhance ZPP formation, whereas nitrate and glucose have no effect. It is concluded that fresh meat contains a ZPP-promoting activity, likely a zinc-chelatase enzyme, whose behaviour fits the chemical conditions occurring in hams undergoing the dry-curing process.     

Measurement and Content of Nonheme and Total Iron in Muscle

A method for determining the nonheme iron content of meats was evaluated and used to determine the nonheme and heme iron content of selected muscles from beef, pork, and lamb. The method allows a quantitative determination of nonheme iron in meat and is influenced to only a minor degree by the presence of heme iron. Heating meat in a boiling water bath increased the nonheme iron content of the meat. Possibly, heating accelerates oxidative cleavage of the prophyrin ring thereby allowing release of the iron from the heme complex. Total iron content differed between muscles in pork and beef but not in lamb. Heme iron, expressed as percent of the total iron, in raw pork, lamb, and beef average 49, 57, and 62%, respectively.     

Minerals in Pork Meat and Edible Offal

Pork meat contains important minerals, including iron and zinc, all of which are essential for good health throughout life. Edible offal is also a form of meat and in general possesses a higher content of minerals, than muscular tissue. The mineral levels in pork meat, and edible offal are variable. Major sources of variation in animal products are the proportion of lean to fat tissue, and the proportion of edible to inedible materials. The aim of this paper is to provide an overview of the existing scientific literature on the mineral levels in pork meat and edible offal.     

Nitric oxide inhibits the formation of zinc protoporphyrin IX and protoporphyrin IX

The aim of this study was to elucidate the mechanism by which curing agents, especially nitrite, inhibit the formation of zinc protoporphyrin IX (ZPP) in dry-cured hams such as Parma ham. The oxidation–reduction potential of model solutions was increased by the addition of nitrite, but it was not clear whether the formation of ZPP is inhibited by the oxidizing property of nitrite. The effect of nitric oxide (NO) produced from nitrite on the formation of ZPP was examined. The amount of ZPP formed was decreased by the addition of NO donors. The amount of protoporphyrin IX (PPIX), which is the precursor of ZPP, was also decreased by the addition of NO donors. It is concluded that NO produced from nitrite inhibited the formation of PPIX and ZPP was therefore not formed in cured meat products with the addition of nitrite or nitrate.     

Parallel enzymatic and non-enzymatic formation of zinc protoporphyrin IX in pork

Zinc protoporphyrin is formed in pork homogenates in both enzymatic and non-enzymatic reactions. Ferrochelatase is active in formation of the highly fluorescent pigment known from Parma ham as demonstrated by inhibition with N-methylmesoporphyrin and by thermal inactivation. A non-enzymatic transmetallisation reaction, exchange of iron in myoglobin by zinc(II), is demonstrated by Pb(II) inhibition of zinc protoporphyrin formation at low Pb(II) concentrations, but promoted at higher Pb(II) concentrations. The non-enzymatic reaction is characterised as a slow bimolecular reaction between protoporphyrin IX and zinc(II) with a second-order rate constant of 0.63 l mol⁻¹ s⁻¹ at 35 °C and a high energy of activation of 98 kJ mol⁻¹ for acetone:water (3:1, v/v) as solvent. Zinc protoporphyrin formation is concluded to be thermodynamically controlled with a formation constant of 4 × 10⁵ M (35 °C, acetone:water (3:1)). An efficient inhibition of formation of zinc protoporphyrin by nitrite is related to myoglobin as substrate and involves both enzymatic and non-enzymatic reactions.     

Fluorimetric detection of protoporphyrins as an indicator for quality monitoring of fresh intact pork meat

In fresh meat production fast and non-destructive quality monitoring along the distribution chain is a key aspect to guaranteeing high quality and safe products for consumption. The applicability of fluorescence spectroscopy using protoporphyrins as indicators for meat ageing was investigated. Porcine musculus longissimus dorsi (MLD) was stored in slices over 20 days at 5 and 12 °C and measured every day with an excitation of 420 nm and an emission range of 550–750 nm. Additionally, pH, drip loss and colour were examined to assess possible correlations.The obtained spectra of the MLD showed an increase in three peaks at 592, 638 and 705 nm which could be reconstructed using the spectra of standard solutions of protoporphyrin IX (PP) and zinc protoporphyrin IX (ZnPP) or magnesium protoporphyrin (MgPP), respectively.Using principal component analysis (PCA) on the fluorescence spectral data, the meat slices stored at 5 °C showed differences in the fluorescence signal after the 10th day and 5th day when stored at 12 °C. An interrelationship between the additional analyses and the fluorescence intensities on these relevant days could not be established.In conclusion, the increase of ZnPP fluorescence due to temperature related changes of physiological meat properties is capable of serving as a quality indicator with regards to inadequate conditioning (e.g. during transportation and/or storage) of pork meat.     

Nondestructive Hygiene Monitoring on Pork Meat Surface Using Excitation–Emission Matrices with Two-Dimensional Savitzky–Golay Second-Order Differentiation

To develop a rapid and nondestructive hygiene-monitoring system in meat-processing plants, plate count and ATP content on pork meat surfaces were quantitatively determined with particular attention to NAD(P)H fluorescence produced by microorganisms. An excitation (Ex)–emission (Em) matrix (EEM) was obtained, and the five fluorescence peaks of tryptophan, NAD(P)H, zinc protoporphyrin IX, protoporphyrin IX, and riboflavin were observed. Plate count and ATP content were predicted with good accuracy [r _p?=?0.90–0.94 and root mean square error of prediction (RMSEP)?=?log₁₀ (0.68–0.79 CFU cm^?2) for plate count and r _p?=?0.84–0.89 and RMSEP?=?log₁₀ (0.61–0.71, mol cm^?2) for ATP content]. Two-dimensional Savitzky–Golay second-order differentiation was found to be a powerful preprocessing tool of EEMs to improve prediction accuracy. Better prediction accuracy was obtained when the sensitivity of the fluorescence spectrophotometer was set to focus on fluorescence from NAD(P)H than that from both tryptophan and NAD(P)H. However, little linear relationship was observed between plate count and fluorescence intensity from NAD(P)H (R ²?=?0.31). The absolute value of regression coefficient (RC) of partial least-squares regression (PLSR) at the wavelength assigned to NAD(P)H, zinc protoporphyrin IX, protoporphyrin IX, and riboflavin was high. It can be concluded that a good prediction model was developed in which four fluorescence compounds of NAD(P)H, zinc protoporphyrin IX, protoporphyrin IX, and riboflavin contribute to the prediction model, and these compounds are probably produced by microorganisms.     

Fluorimetric detection of protoporphyrins as an indicator for quality monitoring of fresh intact pork meat

In fresh meat production fast and non-destructive quality monitoring along the distribution chain is a key aspect to guaranteeing high quality and safe products for consumption. The applicability of fluorescence spectroscopy using protoporphyrins as indicators for meat ageing was investigated. Porcine musculus longissimus dorsi (MLD) was stored in slices over 20 days at 5 and 12 °C and measured every day with an excitation of 420 nm and an emission range of 550–750 nm. Additionally, pH, drip loss and colour were examined to assess possible correlations.The obtained spectra of the MLD showed an increase in three peaks at 592, 638 and 705 nm which could be reconstructed using the spectra of standard solutions of protoporphyrin IX (PP) and zinc protoporphyrin IX (ZnPP) or magnesium protoporphyrin (MgPP), respectively.Using principal component analysis (PCA) on the fluorescence spectral data, the meat slices stored at 5 °C showed differences in the fluorescence signal after the 10th day and 5th day when stored at 12 °C. An interrelationship between the additional analyses and the fluorescence intensities on these relevant days could not be established.In conclusion, the increase of ZnPP fluorescence due to temperature related changes of physiological meat properties is capable of serving as a quality indicator with regards to inadequate conditioning (e.g. during transportation and/or storage) of pork meat.     

Metmyoglobin Reducing Capacity of Fresh Normal, PSE, and DFD Pork During Retail Display

Fresh pale, soft, exudative (PSE), dark, firm, dry (DFD), and normal pork were stored under light or dark conditions at 4°C for 7 days. Sample pH, metmyoglobin reductase activity, oxygen consumption rate, and relative surface metmyoglobin and oxymyoglobin contents were determined. DFD pork had the highest metmyoglobin reductase activity and oxygen consumption rate. Enzyme activity of PSE was lower than that of normal pork, but no difference existed in oxygen consumption rate between PSE and normal samples. Metmyoglobin reductase activity dropped slowly during meat storage; oxygen consumption rate sharply decreased during the first day of storage. Both metmyoglobin reductase activity and oxygen consumption rate declined more rapidly in the light. Results can help develop guidelines for display and packaging of pork.     

Effects of different storage conditions on quality related porphyrin fluorescence signatures of pork slices

This study evaluated the potential of fluorescence as an indicator of pork quality by determining the effects of various conditions on fluorescence signatures (excitation at 420 nm, emission at 550-750 nm).Storage of porcine musculus longissimus dorsi in PE bags led to a clear increase in porphyrin fluorescence intensity after approx. 10 d post mortem. Modified gas atmosphere (70% O₂, 30% CO₂) inhibited the fluorescence emission of zinc protoporphyrin and protoporphyrin IX due to quenching by oxygen. Bleaching processes caused similar effects by halogen light exposure during meat storage. However, already formed signals could not be manipulated by oxygen or halogen light. Storage under vacuum reduced the quenching effects and resulted in increased fluorescence intensities. Freezing and thawing of meat samples delayed and reduced the increase in fluorescence intensity. Only minor effects could be detected at long-term frozen storage for two months.Consequently porphyrin fluorescence analysis is a potential means to indicate changes of pork quality and remaining shelf life.     

Oxidative stability of gelatin coated pork at refrigerated storage

As consumers are chiefly concerned with odor and appearance, refrigerated meats have a greater possibility of rejection due to their perishability. A treatment was designed to preserve the quality parameters such as color and oxidation rate. The treatment encompassed coating pork loin samples with aqueous porcine gelatin solutions (175 bloom) at three concentrations (0%, 10% and 20%) and studying its effect on lipid oxidation, protein oxidation, oxidation pre-cursors, color and purge of meat. Vacuum packed Longissimus dorsi muscle was cut into 10 × 5 × 1 cm samples and randomly dipped in one of three solutions. Samples were stored at 4 °C and analyzed for thio-barbituric acid reactive substances, metmyoglobin content, protein carbonyls, heme iron content and color change. There was a significant difference (p < 0.05) for TBARS values, protein carbonyls, heme iron content, total color change, metmyoglobin content with treatments maintaining values more similar to a fresher product when compared to control on days 3, 5 and 7. There was no significant difference (p > 0.05) between 10% and 20% gelatin coating on any of the parameters between storage days.     

The rate of metmyoglobin formation in beef, pork, and turkey meat as influenced by pH, sodium chloride, and sodium tripolyphosphate

This study investigated the effects of pH (5·5 to 7·0), sodium chloride concentration (0·0-3·0%), and sodium tripolyphosphate concentration (0·0 and 0·5%) on the rate of metmyoglobin formation in ground beef, pork and turkey meat during refrigerated storage. Increasing the sodium chloride concentration produced a progressive increase in the rate of metmyoglobin formation in ground beef. Increasing the pH between pH 5·5 and 6·5 had no effect on the rate of metmyoglobin formation with ground beef and turkey meat, but produced a marked decrease between pH 6·5 and 7·0. In contrast pH had no consistent effect on the rate of metmyoglobin formation of ground pork and the rate of formation remained low at all pH levels. When ground beef contained 0·5% sodium tripolyphosphate, the effect of pH was reversed and the rate of metmyoglobin formation was lowest at pH 5·5, increased as the pH increased to 6·5 and then plateaued.     

The effect of processing temperature and addition of mono- and di-valent salts on the heme- nonheme-iron ratio in meat

Heme iron from meat has a superior bioavailability compared to non-heme iron and, from a nutritional point of view, processing of meat should be optimised to maintain high levels of heme iron. The effects of heat treatment and addition of NaCl and other ionic species, on the heme-iron/nonheme-iron ratio (H/NH) in meat, have been studied by measuring heme and non-heme iron in minced, vacuum-packed pork. Heating temperature has a gross effect on H/NH with a decrease in heme iron content of 62% after heating at 80°C for 2 h. The correlation (r²) between heme and non-heme iron determinations was −0.92. NaCl increases H/NH in cooked meat by preventing the heme molecule from liberating iron, probably by an increase in the ionic strength of the meat. Calcium ions have a gross negative effect on H/NH during cooking of meat. These effects of sodium and calcium on H/NH in heat treated meat have not been previously reported.     

Comparison of Essential Metals in Different Pork Meat Cuts from the Serbian Market

Pork consumption in Serbia accounts for a large share of total meat consumption. Pork is valuable sources of nutrients. We analyzed metal content in three different cuts of pork collected from the Serbian market during 2014. Analyses of the following isotopes: zinc (⁶⁶Zn), copper (⁶³Cu) and iron (⁵⁷Fe) were performed by ICP-MS. Our data show that Zn, Cu and Fe were present in significantly different levels in hind leg, loin and shoulder, and that shoulder meat was richest in the analyzed metals. The differing mineral status of different pork cuts implies differences in their nutritional benefits for the human diet.     

A comparison of carnosine and ascorbic acid on color and lipid stability in a ground beef pattie model system

Ascorbic acid (0.1%) significantly inhibited metmyoglobin formation on the surface of ground beef but not in the bulk of the product where oxygen tension was lower. Carnosine (1.0%), however, significantly inhibited metmyoglobin formation and brown color development throughout the product. The combinations of carnosine and ascorbic acid were also very effective on inhibition of metmyoglobin formation and brown color development. Carnosine increased meat pH, cook yield and salt-soluble protein, but ascorbic acid had no effect on cook yield, and decreased meat pH and salt-soluble protein. Carnosine was more effective on inhibition of lipid peroxidation than ascorbic acid. Carnosine inhibited copper(II)-catalyzed ascorbate oxidation in a dose-dependent manner in model systems. Carnosine in conjunction with ascorbic acid may be useful as a meat additive for increasing shelf-life as well as stabilizing color of meat products.