Monitoring the effects of high pressure processing and temperature on selected beef quality attributes

The combined effects of high pressure processing (HPP) and temperature on meat quality attributes were assessed in bovine M. pectoralis profundus, with particular focus on lipid oxidation and fatty acid composition. Beef samples were pressurised at 200, 300 and 400 MPa at two different temperatures 20 °C and 40 °C. Both pressure and temperature regimes had significant effects on colour, cook loss and lipid oxidation. Pressurisation at 200 MPa had a lower impact on colour parameters than higher pressurisation levels. Cook loss also increased when higher levels of pressure were applied. Across all pressure conditions, lower cook loss was observed at 40 °C compared to 20 °C. An increase in TBARS values was observed at the higher pressure levels (300, 400 MPa). While some alterations of individual fatty acids were observed, high pressure had no effect on polyunsaturated/saturated fatty acid (PUFA/SFA) or omega 6/omega 3 (n6/n3) ratio. The temperature at which HPP was applied had a significant effect on the sum of saturated (SFA), monounsaturated (MONO) and polyunsaturated (PUFA) fatty acids. HPP at 40 °C showed higher SFA and PUFA and lower MONO compared to HPP at 20 °C. These results show that high pressure at low or moderate temperatures improves the microbiological quality of the meat with minimal affects on meat quality.     

Application of high pressure processing to reduce verotoxigenic E. coli in two types of dry-fermented sausage

The effect of high pressure processing (HPP) on the survival of verotoxigenic Escherichia coli (VTEC) in two types of Norwegian type dry-fermented sausages was studied. Two different types of recipes for each sausage type were produced. The sausage batter was inoculated with 6.8 log₁₀ CFU/g of VTEC O103:H25. After fermentation, drying and maturation, slices of finished sausages were vacuum packed and subjected to two treatment regimes of HPP. One group was treated at 600 MPa for 10 min and another at three cycles of 600 MPa for 200 s per cycle. A generalized linear model split by recipe type showed that these two HPP treatments on standard recipe sausages reduced E. coli by 2.9 log₁₀ CFU/g and 3.3 log₁₀ CFU/g, respectively. In the recipe with higher levels of dextrose, sodium chloride and sodium nitrite E. coli reduction was 2.7 log₁₀ CFU/g in both treatments. The data show that HPP has a potential to make the sausages safer and also that the effect depends somewhat on recipe.     

High pressure induced changes on sarcoplasmic protein fraction and quality indicators

The combined effect of pressure and mild temperature treatments on bovine sarcoplasmic proteins and quality parameters was assessed. M. longissimus dorsi samples were pressurised in a range of 200–600 MPa and 10–30 °C. High Pressure Processing (HPP) induced a reduction of protein solubility (p < 0.001) compared to non-treated controls (NT), more pronounced above 200 MPa. HPP at pressures higher than 200 MPa induced a strong modification (p < 0.001) of meat colour and a reduction of water holding capacity (WHC). SDS–PAGE analysis demonstrated that HPP significantly modified the composition of the sarcoplasmic protein fraction. The pressurisation temperature mainly affected protein solubility and colour; a smaller effect was observed on protein profiles. Significant correlations (p < 0.001) between sarcoplasmic protein solubility and both expressible moisture (r = −0.78) and colour parameters (r = −0.81 to −0.91) suggest that pressure induced denaturation of sarcoplasmic proteins could influence to some extent WHC and colour modifications of beef. Changes in protein band intensities were also significantly correlated with protein solubility, meat lightness and expressible moisture. These results describe the changes induced by HPP on sarcoplasmic proteins and confirm a relationship between modification of the sarcoplasmic protein fraction and alteration of meat quality characteristics.     

Aroma development in high pressure treated beef and chicken meat compared to raw and heat treated

Chicken breast and beef muscle were treated at 400 and 600 MPa for 15 min at 5 °C and compared to raw meat and a heated sample (100 °C for 15 min). Vacuum-packed beef meat with a smaller fraction of unsaturated fatty acids showed better oxidative stability during 14 days of cold storage, as shown by a low steady-state level of hydroperoxide values, than vacuum-packed chicken meat. Accordingly, the critical pressures of 400 MPa and 600 MPa for chicken breast and beef sirloin, respectively, were established. Volatiles released after opening of the meat bags or during storage of open meat bags, simulating consumer behaviour, were measured under conditions mimicking eating. Quantitative and olfactory analysis of pressurised meat gave a total of 46 flavour volatiles, mainly alcohols (11), aldehydes (15), and ketones (11), but all in low abundance after 14 days of storage. Overall, beef meat contained less volatiles and in lower abundance (factor of 5) compared to chicken meat. The most important odour active volatiles (GC-O) were well below the detection thresholds necessary to impart a perceivable off-flavour. Lipid oxidation was significantly accelerated during 24 h of cold storage in both cooked chicken and beef when exposed to oxygen, while the pressurised and oxygen-exposed chicken and beef meat remained stable. Pressure treatment of beef and chicken did not induce severe changes of their raw aroma profiles.     

Conventional freezing plus high pressure-low temperature treatment: Physical properties, microbial quality and storage stability of beef meat

Meat high-hydrostatic pressure treatment causes severe decolouration, preventing its commercialisation due to consumer rejection. Novel procedures involving product freezing plus low-temperature pressure processing are here investigated. Room temperature (20 °C) pressurisation (650 MPa/10 min) and air blast freezing (−30 °C) are compared to air blast freezing plus high pressure at subzero temperature (−35 °C) in terms of drip loss, expressible moisture, shear force, colour, microbial quality and storage stability of fresh and salt-added beef samples (Longissimus dorsi muscle). The latter treatment induced solid water transitions among ice phases. Fresh beef high pressure treatment (650 MPa/20 °C/10 min) increased significantly expressible moisture while it decreased in pressurised (650 MPa/−35 °C/10 min) frozen beef. Salt addition reduced high pressure-induced water loss. Treatments studied did not change fresh or salt-added samples shear force. Frozen beef pressurised at low temperature showed L, a and b values after thawing close to fresh samples. However, these samples in frozen state, presented chromatic parameters similar to unfrozen beef pressurised at room temperature. Apparently, freezing protects meat against pressure colour deterioration, fresh colour being recovered after thawing. High pressure processing (20 °C or −35 °C) was very effective reducing aerobic total (2-log₁₀ cycles) and lactic acid bacteria counts (2.4-log₁₀ cycles), in fresh and salt-added samples. Frozen + pressurised beef stored at −18 °C during 45 days recovered its original colour after thawing, similarly to just-treated samples while their counts remain below detection limits during storage.     

高压对肉类基本成分的影响

高压处理能够在不破坏肉类风味和营养成分的前提下延长肉类制品的保藏期,同时,肉类经高压处理后其感官性状、组织结构都会发生明显的变化,而这些变化都与肉类的基本组成成分具有密切的关系。综述了压力处理对肉类基本成分的影响。     

Synergistic cooperation of high pressure and carrot dietary fibre on texture and colour of pork sausages

In order to investigate the synergistic cooperation between high pressure treatment (HP) and carrot dietary fibre, two formulations of pork sausages containing different percentage of carrot dietary fibre were pressurized at 500 and 600 MPa, for 1 second, 3, 6, and 9 min at 40, 50, and 60 °C. HP treatments significantly increase Young's Modulus and affect Hencky strain values. We conclude that HP processing and carrot dietary fibre markedly improved emulsion strength resulting in firm sausages. Colour changes were investigated and significant increase in L* value and decrease in a* value were found, indicating that HP, temperature, and dietary fibre can affect physico-chemical properties of the meat matrix altering the intrinsic ability to absorb or reflect light. The sensory evaluation showed that HP treatment synergistically cooperate with carrot dietary fibre improving sensorial attributes like homogeneity, creaminess, fattiness, and firmness as detected by Napping in combination with Ultra-Flash Profile.     

Simultaneous application of transglutaminase and high pressure to improve functional properties of chicken meat gels

Low-fat protein gels obtained by pressure are softer than those processed by conventional heat treatment. In this study, microbial transglutaminase (MTGase) (0.3%) was added to chicken batters in order to investigate the combined effect of pressure and enzyme on the functional properties of gels. Batters of meat with egg proteins were treated at 500 MPa for 30 min at 40 °C and then heated at 75 °C for 5 min to inactivate the enzyme. Treated samples showed, under confocal microscopy, a more compact and homogeneous microstructure and exhibited a notable increase in hardness and chewiness as compared to controls that were pressurized but contained no MTGase. They were also harder, more chewy and springy but had a similar cohesiveness and cutting force to those obtained by heat alone.     

Effect of high pressure treatments on the physicochemical properties of a sulphur dioxide-free red wine

The application of high hydrostatic pressure (HHP) in winemaking for substitution of the use of sulphur dioxide is still at a very early stage of development, since knowledge about the effect on physicochemical and sensorial characteristics of the wine during storage is very scarce. In this work, the evolution of colour, antioxidant activity and total phenolic compounds of SO₂-free red wines treated by HHP and aged in bottles was followed for 12 months. The pressurised wines were compared with wine samples prepared with addition of 40 ppm of SO₂ and without any of these two treatments. After 12 months, the pressurised wines presented higher values of CIELab parameters (a^∗, b^∗, and L^∗) and a lower monomeric anthocyanin content (45–61%) when compared to the unpressurised ones. The pressurised wines showed also a better global sensorial assessment, with the pressure treatments imparting aged-like characteristics to the wines. The wine deposits of pressurised wines had higher total phenolic content, namely proanthocyanidins (3- to 10-fold). The results demonstrate that HHP can influence long term red wine physicochemical and sensorial characteristics, hypothesised to be due to an increase of condensation reactions of phenolic compounds, forming compounds with higher degree of polymerisation that became insoluble in wine along storage.     

Influence of NaCl concentration and high pressure treatment on thermal denaturation of soybean proteins

In the present work the effect of high pressure (HP) treatment in the presence of NaCl on the thermal behavior of soybean proteins was analyzed by differential scanning calorimetry. The thermograms obtained have shown that NaCl addition increased the thermal stability – increase in temperatures of denaturation (Td) – of both glycinin and β-conglycinin. HP treatments increased thermal stability of glycinin, but decreased that of β-conglycinin. High NaCl concentrations decreased (in glycinin) or inverted (in β-conglycinin) the effects of HP on thermal stability. Cooperativity of denaturation of glycinin was enhanced by NaCl and HP. Cooperativity of denaturation of β-conglycinin was enhanced by HP and also by NaCl at 0.2 mol/L but decreased with the combination of treatments. Salt addition increased the enthalpy, ΔH, of denaturation of glycinin and β-conglycinin, being this effect stronger on glycinin. HP treatment provoked the denaturation of both protein fractions. The presence of NaCl protected glycinin against HP-denaturation at any assayed salt concentration and pressure level, while β-conglycinin was only protected at 200 and 400 MPa, but was more denaturated at 600 MPa in the presence of 0.6 mol/L of NaCl.

Industrial relevance

The knowledge provided by this work may be useful in the handling of high pressure-treated food with high NaCl content (e.g. meat emulsions, smallgoods) where soybean proteins are used as additives, in order to choose high pressure values to achieve their denaturation or predict the effects of ulterior thermal treatments. Thus, this knowledge may be useful to increase the use of high pressure in food industry.     

Influence of HPP conditions on selected beef quality attributes and their stability during chilled storage

The aim of this work was to determine the effects of combined pressure and temperature treatments on beef quality attributes after processing and during chilled storage. Beef M. pectoralis profundus samples were pressurised at 400 and 600 MPa at 35, 45 and 55°C and compared with non-treated (NT) and oven cooked samples. High pressure processing (HPP) at higher temperatures (55°C) resulted in lower Warner Bratzler Shear Force (WBSF) and cook loss values than processing at 35°C. Thiobarbituric acid reactive substances (TBARS) values of pressurised samples were lower than cooked samples after processing and throughout refrigerated storage. An increase (p<0.001) in the omega 6/omega 3 (n6/n3) fatty acid ratio was found when pressure-temperature treatments were compared to raw samples, however, oven cooked samples presented the highest n6/n3 ratio among all of the treatments examined. The reported results show that HPP alters meat quality to a lesser extent than conventional cooking, thereby minimising the processing impact.     

Synergistic effect of carbon dioxide atmospheres and high hydrostatic pressure to reduce spoilage bacteria on poultry sausages

Synergistic effect of combining high hydrostatic pressure (HHP) and CO₂ atmospheres has been studied against Leuconostoc carnosum, Brochothrix thermosphacta, Salmonella enteritidis, Campylobacter jejuni and Listeria innocua separately inoculated in poultry sausages. The microbial counts of the HHP treated samples (350 MPa 10 min at room temperature) and CO₂ atmosphere packaged were compared with non pressure treated and air packaged ones, analyzed at 20 h and 7 days after the treatment. The results showed a synergistic effect of the combination of these two preserving technologies against all the microorganisms studied, except in S. enteritidis which showed a greater resistance under CO₂ atmospheres, and C. jejuni, that is especially sensitive at high pressures. It seems that cell damage produced by high pressure facilitates the penetration of carbon dioxide into the microorganisms' cells, affecting their metabolism and consequently their growth. Using CO₂ atmospheres in combination with HHP treatments, pressure could be lowered without compromising the reduction of microbial counts.     

Volatile compounds in ground beef subjected to high pressure processing: A comparison of dynamic headspace and solid-phase microextraction

The effect on the volatile profile of cooked beef meat, previously subjected to high pressure (400 MPa, 10 min at 12 °C) followed by a 3-d refrigerated storage, was investigated by comparing two extraction techniques i.e. dynamic headspace and solid-phase microextraction. Dynamic headspace was more efficient in extracting 2,3-butanedione and secondary alcohols. Solid-phase microextraction, being more efficient in extracting substances such as 1-alcanols, ethyl esters and acids, permitted to better categorize the effects caused in the volatile fraction by refrigerated storage and high pressure processing.     

Effect of high pressure on binding aroma compounds by maize starches with different amylose content

Hylon VII, waxy maize starch and their mixtures were subjected to high pressure treatment (650 MPa/9 min). To obtain starch-odorants products: (i) the pressurised and native starches were incubated with odorants; and (ii) the native starches mixed with odorants were treated under high pressure (650 MPa/9 min). The sorption capacity of odorants by investigated starches was studied using capillary gas chromatography.The sorption capacity of odorants by native starches was found to stronger depend on hydrophobicity and molecular structure of odorants rather than the starch botanical origin. The highest sorption was observed for polar hydrophobic compounds (hydrocarbons) and for aliphatic esters, whereas the lower one—for guaiacol and methyl anthranilate. The high pressure-treated Hylon VII demonstrated slight changes in melting enthalpy and degree of gelatinisation compared to other starches and it showed the highest sorption capacity of the majority of odorants. The treatment of a starch with odorant under 650 MPa for 9 min resulted in a diminished average sorption of the aroma compounds. However hexanol, guaiacol and methyl antrinilate, that were slightly or not sorbed by native and high pressure-treated starches, demonstrated the highest degree of binding with waxy starch and its mixtures under high pressure conditions.     

Effect of phosvitin on lipid and protein oxidation in ground beef treated with high hydrostatic pressure

In this study, we aimed to examine the effect of phosvitin on lipid and protein oxidation of raw and cooked ground beef treated with high hydrostatic pressure (HHP). Ground beef patty with 0, 500, or 1000 mg phosvitin/kg meat was treated with HHP at 0.1, 300, or 600 MPa. Half of the patties were used in a raw meat analysis, and the other half were used in a cooked meat analysis. Phosvitin and HHP treatment at 300 MPa synergistically reduced microbial growth, and HHP treatment at 600 MPa reduced microbial counts to undetectable levels (< 1 log CFU/g) throughout the length of the study in all samples. Phosvitin delayed lipid and protein oxidation in HHP-treated cooked and raw ground beef, respectively. However, phosvitin had no effect on the color changes of raw ground beef attributable to HHP. The results indicated that phosvitin could enhance the stability of lipids and proteins but not color changes of raw ground beef caused by HHP.     

Effects of high pressure/thermal treatment on lipid oxidation in beef and chicken muscle

Lipid oxidation was studied in beef and chicken muscle after high pressure treatment (0.1–800 MPa) at different temperatures (20–70 °C) for 20 min, prior to storage at 4 °C for 7 days. Pressure treatment of beef samples at room temperature led to increases in TBARS values after 7 days storage at 4 °C; however, the increases were more marked after treatment at pressures ?400 MPa (at least fivefold) than after treatment at lower pressures (less than threefold). Similar results were found in those samples treated at 40 °C, but at 60 °C and 70 °C pressure had little additional effect on the oxidative stability of the muscle. Pressure treatments of 600 MPa and 800 MPa, at all temperatures, induced increased rates of lipid oxidation in chicken muscle, but, in general, chicken muscle was more stable than beef to pressure, and the catalytic effect of pressure was still seen at the higher temperatures of 50 °C, 60 °C and 70 °C. The addition of 1% Na₂EDTA decreased TBARS values of the beef muscle during storage and inhibited the increased rates of lipid oxidation induced by pressure. The inhibition by vitamin E (0.05% w/w) and BHT (0.02% w/w), either alone or in combination, were less marked than seen with Na₂EDTA, suggesting that transition metal ions released from insoluble complexes are of major importance in catalysing lipid oxidation in pressure-treated muscle foods.     

Use of high pressure treatment to attenuate starter bacteria for use as adjuncts for Cheddar cheese manufacture

Attenuated starter bacteria cannot produce acid during cheese manufacture, but contain enzymes that contribute to cheese ripening. The aim of this study was to investigate attenuation of starter bacteria using high pressure treatment, for use in combination with a primary starter for Cheddar cheese manufacture, and to determine the effect of such adjunct cultures on secondary proteolysis during ripening. Lactococcus lactis ssp. cremoris HP and L. lactis ssp. cremoris 303 were attenuated by pressure treatment at 200 MPa for 20 min at 20 °C. Cheddar cheese was manufactured using untreated cultures of both these starter strains, either alone or in combination with their high pressure-treated equivalents. High pressure-treated starters did not produce acid during cheese manufacture and starter counts in cheeses manufactured using high pressure-treated starter did not differ from those of the controls. Higher levels of cell lysis were apparent in cheese manufactured using high pressure-treated strains than in the controls after 26 d of ripening. Small differences were observed in the peptide profiles of cheeses, analysed by reversed-phase HPLC; cheeses manufactured using high pressure-treated starters also had slightly higher levels of amino acids than the relevant controls. Overall, addition of high pressure-treated starter bacteria as a secondary starter culture accelerated secondary proteolysis in Cheddar cheese.

Industrial relevance

Attenuated starters provide extra pool of enzymes, which can influence cheese ripening, without affecting the cheese making schedule. This paper presents an alternative method for attenuation of starter bacteria using high pressure treatment and their subsequent use to accelerate secondary proteolysis in Cheddar cheese during ripening.     

Combination effects of ultra-high pressure and temperature on the physical and thermal properties of ostrich meat sausage (yor)

Ostrich meat sausages (yor) were subjected to ultra-high pressures of 300, 500 and 700 MPa for 40 and 60 min at 40 and 60 °C. Subsequently the physical properties of the products, colour, released and expressible water, gel strength and stress relaxation as well as their thermal characteristics (by differential scanning calorimeter, DSC) were determined. The effects of pressure, temperature and holding time significantly influenced the L^∗, a^∗ and b^∗ values. The amount of released plus expressible water significantly decreased with increasing pressure, temperature and holding time. The gel strength and equilibrium stress increased with increasing severity of treatment. DSC thermograms indicated that pressures of 700 MPa yielded gel networks involving completely denatured protein with the ability to retain water.     

Application of organic acid salts and high-pressure treatments to improve the preservation of blood sausage

Blood sausages are traditional products in many parts of the world. In most cases, a very short shelf-life limits their consumption to the areas in which they are produced. In this work, different mild preservation methods were applied to Morcilla de Burgos, a Spanish blood sausage, consisting of a range of organic acid salts (OAS) and high-pressure processing (HPP), with the aim of increasing its shelf-life. In the first experiment, three batches of morcillas were produced using three different commercial OAS-PL (3% potassium lactate), PL+SL (3% potassium and sodium lactate) and PL+SD (2.5% potassium lactate and sodium diacetate)-together with a control batch and were stored under chill conditions (4 degrees C) for 35 days. In a further experiment, vacuum-packaged morcillas were treated at three different pressure levels-300, 500 and 600MPa-for 10min, and stored under chill conditions for 28 days. In both batches, a sensory difference test was performed on day 1 after treatment and the morcilla samples were subjected to microbiological and sensory analysis after each week in storage. The results suggest that, in both cases, an addition of PL+SL and the application of 600MPa for 10min increases the shelf-life of the morcillas by 15 days. Once again, it is evident that the initial opportunities for contamination play a very important role in improving the shelf-life of food products.     

Contribution of lean,fat, muscle color and degree of doneness to pork and beef species flavor

Flavor is an important contributor to consumer acceptability of meat, our objective was to characterize the impact of species-specific fat/lean sources, fat level, degree of doneness and muscle color are on pork and beef flavor. Three separate experiments were conducted. Patties were formulated differently for each experiment in order to evaluate the desired variables. Experiment. 1: Flavor from combination patties (same species lean/fat or combination of species lean/fat) was not impacted by degree of doneness (66 °C vs. 71 °C). Beef flavor was highest in samples made with beef lean, regardless of species fat type. Pork flavor was highest in samples made with pork lean and had higher flavor intensity scores. Experiment. 2: Beef flavor was not increased in all-beef patties formulated with higher fat levels. Pork patties formulated with higher fat content increased pork flavor. Experiment. 3: All-beef and all-pork patties formulated with light or dark lean did not impact flavor in either species.