At pan-European level there is a need for traceability systems giving information on origin, processing, retailing and final destination of foodstuffs. Such systems shall enhance consumer confidence ...in food; enable the regulatory authorities to identify and to withdraw health hazardous and non-consumable foodstuffs from the market. Animal feeds are an element in this “food-to-farm” approach to public health. Such feedstuffs are preliminary elements of some foods for human consumption, and hence are an inherent element of the food chain.
A harmonised pan-European food traceability protocol would greatly assist authorities in detecting fraud as well as dangerous substances. The food chain comprises a range of sequential and parallel stages bridging the full spectrum from agricultural production to the consumable foodstuffs by consumers. EU legislation on traceability and the technologies needed to implement this system for meat and meat products are the focus of this paper.
Chemical safety of meat and meat products Andrée, Sabine; Jira, W.; Schwind, K.-H. ...
Meat science,
09/2010, Volume:
86, Issue:
1
Journal Article, Conference Proceeding
Peer reviewed
Since the Second World War the consumer behaviour in developed countries changed drastically. Primarily there existed the demand for sufficient food after a period of starvation, afterwards the ...desire for higher quality was arising, whereas today most people ask for safe and healthy food with high quality. Therefore a united approach comprising consistent standards, sound science and robust controls is required to ensure consumers' health and to maintain consumers' confidence and satisfaction. Chemical analysis along the whole food chain downstream (tracking) from primary production to the consumer and upstream (tracing) from the consumer to primary production is an important prerequisite to ensure food safety and quality. In this frame the focus of the following paper is the “chemical safety of meat and meat products” taking into account inorganic as well as organic residues and contaminants, the use of nitrite in meat products, the incidence of veterinary drugs, as well as a Failure Mode and Effect Analysis (FMEA) system assessing (prioritizing) vulnerable food chain steps to decrease or eliminate vulnerability.
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 420nm, emission at ...550–750nm).
Storage of porcine musculus longissimus dorsi in PE bags led to a clear increase in porphyrin fluorescence intensity after approx. 10d 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.
► Potential of porphyrin fluorescence as indicator for storage-related changes of pork. ► Storage at 5°C, modified atmosphere, vacuum, halogen light or after freezing. ► Fluorescence excitation at 420nm with emission range of 550 to 750nm. ► Fluorescence arises at different times post mortem with maxima at 592, 638 and 705nm. ► Contamination with porphyrin-forming microorganisms can be detected non-invasively.
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.
Recently, some nondestructive methods for the assessment of albumen freshness were developed. Among others, visible near-infrared transmission spectroscopy and low-resolution proton nuclear magnetic ...resonance (LR 1H NMR) measurements were proposed. This study was performed to evaluate the potential of the combined measurement of visible near-infrared transmission spectroscopy and LR 1H NMR measurements for the assessment of albumen freshness. Our results show that solely based on the transmission measurements, a good estimation of albumen freshness can be achieved. Based on LR 1H NMR measurements, an estimation of albumen freshness can be achieved if larger egg collectives are used. However, when individual eggs are considered, only a moderate estimation is feasible. Finally, it was observed that combining both spectroscopic techniques did not improve the assessment of albumen freshness when compared solely to transmission measurements.
Meat protein can be substituted by plant protein in meat products, and cereals are particularly well-suited for this purpose as they are high in protein content and have good bioavailability. The aim ...of the present work was to develop real-time PCR assays for the detection and quantification of the six most commonly used cereals barley, oat, rye, maize, rice, and wheat in processed meat products. Emulsified sausages were produced with cereal flours (0.0005–0.1%). Additionally, the effect of different post-processing methods (grilling or storage), packaging materials (cans and artificial sausage casings), and cooking temperatures (75 °C, 117 °C, and 121 °C) were investigated. A negative influence on the detectability of DNA was observed with increasing cooking temperature. All other production parameters showed no significant effect. The limit of quantification was as low as 5 ppm of plant protein for all production conditions, which corresponded to 36–58 mg flour per kg of sausage. The validation of the production of reference material was more accurate for the sausages produced at low than at medium temperatures.
Overall, the two triplex real-time PCR systems can be applied for specific, sensitive, and simultaneous detection of these six cereal species in meat products. However, the reference material for quantification has to be carefully chosen due to the negative influence of heat treatment on the detectability of DNA.
•PCR-based method for the detection of cereal proteins in processed meat products.•Influence of production processes on detectability of cereal species.•Validation of reference material for quantification of cereals in meat products.
A fast breakdown of glycogen is observed in muscles of stress-susceptible pigs leading to pale, soft and exudative (PSE) meat. We report a comparative study of pyruvate kinase from muscles of normal ...and PSE-prone pigs. Compared with enzyme from normal muscle, pyruvate kinase isolated from PSE-muscle shows a five times lower
K
m
for phosphoenol pyruvate and a more than ten times higher
k
cat
K
m
value. The pH-dependency of the enzymatic activity is shifted to more acidic values for pyruvate kinase from PSE muscles. According to isoelectric focusing, pyruvate kinase from PSE muscle consists of three isoforms, while only two isoforms are detectable in pyruvate kinase preparations from normal pigs. The various isoforms were isolated by preparative isoelectric focusing and their steady-state properties were compared. Isoform 3, which is found only in PSE muscle, shows a 10-fold higher specific activity, a 30-fold lower
K
m
value and a 100-fold increased
k
cat
K
m
value for phosphoenol pyruvate compared to isoform 1. The presence of isoform 3 in PSE-muscle appears to be responsible for the high activity of this enzyme under the more acidic conditions prevailing in PSE-muscle.
In vitro phosphorylation and dephosphorylation experiments using total enzyme and purified isoenzyme 1 suggest that isoforms 2 and 3 arise from isoform 1 by phosphorylation. Thus protein phosphorylation seems to be responsible for the shift in activity of pyruvate kinase, a key enzyme of glycolysis, under the acidic conditions of PSE-muscles.
In order to investigate the cell biological causes for the fast breakdown of glycogen which is observed during the development of the PSE (pale, soft, exudative) syndrome in muscles of ...stress-susceptible pigs, muscle glycogen phosphorylase (GP) as a key enzyme in two isoforms, a and b, of the energy turnover was isolated from
M. longissimus dorsi of normal and PSE-prone pigs of the German Landrace. GP b as well as GP a from normal and PSE-muscles exist in a dimeric form with a molecular weight of 97 000 D per subunit. The tendency for tetramerization of GP b increases in the presence of ATP, whereas the enzyme activity is simultaneously inhibited. The catalytic activities of GP a and GP b from both groups of animals show an optimum at pH 7.0. GP b can be activated to GP a by phosphorylation with the result of a 25% higher optimum specific activity in the case of normal and PSE-muscles. In interaction with glycogen and glucose-1-phosphate GP b follows the characteristics of a Michaelis-Menten kinetic, whereas the binding of AMP and phosphate proves to be allosteric. In comparison of the structural and kinetic characteristics of GP from normal as well as PSE-muscles no significant differences could be determined, indicating that GP does not belong to those factors which are triggering an accelerated energy turnover of ATP in muscles of stress-susceptible pigs.
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