High pressure induced changes in beef muscle proteome: Correlation with quality parameters

The relationship between pressure induced changes on individual proteins and selected quality parameters in bovine longissimus thoracis et lumborum (LTL) muscle was studied. Pressures ranging from 200 to 600 MPa at 20 °C were used. High pressure processing (HPP) at pressures above 200 MPa induced strong modifications of protein solubility, meat colour and water holding capacity (WHC). The protein profiles of non-treated and pressure treated meat were observed using two dimensional electrophoresis. Proteins showing significant differences in abundance among treatments were identified by mass spectrometry. Pressure levels above 200 MPa strongly modified bovine LTL proteome with main effects being insolubilisation of sarcoplasmic proteins and solubilisation of myofibrillar proteins. Sarcoplasmic proteins were more susceptible to HPP effects than myofibrillar. Individual protein changes were significantly correlated with protein solubility, L*, b* and WHC, providing further insights into the mechanistic processes underlying HPP influence on quality and providing the basis for the future development of protein markers to assess the quality of processed meats.     

The effects of salt concentration on conformational changes in cod (Gadus morhua) proteins during brine salting

The effects of different salt concentrations (6%, 15%, 18% and 24% NaCl (w/w)) on the conformational changes of cod muscle proteins during brine salting were examined in this study. Proteins were extracted from the brine salted samples with solutions of 1 M (5.9%) and 4 M (23.4%) NaCl and the quantity of salt soluble proteins (SSP), disulfide bond (S–S), total sulfhydryl (SH) and available SH content in the soluble fraction were determined. Increased salt concentration in cod muscle promoted protein denaturation and aggregation. The SSP and total SH content decreased, whereas the S–S bond and available SH content increased with increased salt concentration in cod muscle. Disulfide bond formation correlated (r = −0.6) with a decrease in total SH groups. Higher SSP and available SH groups of the samples at lower brine concentrations was explained by smaller concentration gradients and salt diffusion rates, resulting in stronger salting-in at early stages of the brining process. There was a significant difference in conformational changes in proteins extracted with a salt solution of 1 and 4 M, mainly due to a different degree of protein aggregation.     

Effect of ice storage on the functional properties of pink perch and oil sardine meat

Ice storage of dressed pink perch (Nemipterus japonicus) and Indian oil sardine (Sardinella longiceps) for 16 and 20 days, respectively, resulted in a decrease in emulsifying capacity (EC), protein solubility (PS), relative viscosity (RV) of salt‐soluble proteins (SSP) and water‐soluble proteins (WSP), water binding capacity (WBC) in terms of absorbed moisture in water (AM_w), absorbed moisture in brine lpar;AM_b), retained moisture in water (RM_w) and retained moisture in brine (RM_b), WSP and SSP, and increase in cook loss (CL). Decrease in protein solubility influenced the EC, RV, CL and WBC in both the species of fish. Significant (P<0.05) correlations existed among various functional properties analysed, in both the fishes during the ice storage. © 1999 Society of Chemical Industry     

Antioxidant activities of pepsin hydrolysates of water‐ and salt‐soluble protein extracted from pork hams

The objective of this study was to evaluate the antioxidant activities of pepsin‐digested water‐soluble protein (WSP) and salt‐soluble protein (SSP) extracted from pork ham. WSP and SSP were hydrolysed by pepsin for 2–10 h with 2‐h increments. The protein hydrolysates by pepsin were analysed by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis, and reducing power of the hydrolysates was measured. In addition, antioxidant activity of the hydrolysates was determined using linoleic acid emulsion system. Protein bands with molecular weight higher than 7 kDa in WSP and SSP were completely hydrolysed by pepsin after 2 h of digestion time. WSP hydrolysates (WSPH) and SSP hydrolysates (SSPH) had higher ferric reducing power than controls (WSP and SSP without pepsin digestion). Reducing powers of WSPH were higher than those of SSPH, regardless of digestion time. The oxidative activity of linoleic acid was predominantly inhibited by the addition of WSPH and SSPH, especially 0.5% protein hydrolysate. These results indicate that several functional peptides of pork protein digested by pepsin might have antioxidant activity, and thus they may be used as an antioxidant agent in muscle food system.     

Electrochemical profiling using copper nanoparticle-plated electrode for identification of ostrich meat and evaluation of meat grades

Electrochemical (EC) profiling employing copper nanoparticle-plated screen-printed electrode (Cuⁿ-SPE) exhibited specific selectivity and sensitivity to peptides that could efficiently differentiate ostrich meat from pork, beef and chicken, and to evaluate grades and freshness of ostrich meat. The four meats were differentiated in 5 min by characteristic chromatographic profiles consisting only four major peaks. Peak identification by LC/MS/MS suggested that while lysine and glutamine were shown as common components, anserine were the avian-specific and carnosine was the ostrich-missing peptide in the EC profile. Statistical analysis (ROC curve) demonstrated that peak ratios could be used to evaluate ostrich meat grades with high sensitivity (up to 95%) and specificity (up to 100%). The effects of storage temperature and time were studied for potential use of Cuⁿ-SPE to evaluate meat freshness. This HPLC-EC method appeared to be superior to UV detection in terms of profile simplicity and devoid of derivatisation process or complex sample extraction procedures, rendering it a suitable method for routine rapid differentiation of ostrich meat from common meat species with the ability to simultaneously differentiate ostrich meat grades.     

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.     

Tenderization and fragmentation of myofibrillar proteins in bovine longissimus dorsi muscle using proteolytic extract from Sarcodon aspratus

The objective of this study was to examine the Sarcodon aspratus extract including protease how to affect tenderness of the bovine longissimus dorsi muscle. In addition, we investigated myofibrillar protein fragmentation, particularly in myosin, and its influence on meat tenderness. Beef loin chunks were marinated with 0.5 g/100 g, 1 g/100 g, and 2 g/100 g powdered S. aspratus extract, 0.2 g/100 mL papain, and distilled water (control), respectively. Although tenderness of meat is increased by adding S. aspratus extract, differences in meat quality traits, such as muscle pH and meat color, were small and not considered to have practical importance between the control and enzyme-treated samples. Furthermore, the S. aspratus extract influenced the myofibril fragmentation index (MFI) as well as protein solubility. The changes in MFI and protein solubility were due to the myofibrillar protein degradation. Through Western blotting, we found that the S. aspratus extract, as well as papain, caused fragmentation of the myosin heavy chain, but the mushroom extract induced more fragmentations of myofibrillar proteins, and caused more tender meat.     

Interactions between whey soybean protein (WSP) and beta-conglycinin (7S) during the formation of protein particles at elevated temperatures

In this study, the amount, size, calcium sensibility, and composition of heat-induced protein particles in the mixture of beta-conglycinin (7S) and whey soybean protein (WSP) dispersion are compared with those of 7S and WSP dispersion to investigate the interactions between WSP and 7S during heating. The addition of 7S prevents WSP from forming large protein particles which can be precipitated by centrifugation at 10,000g for 10 min. The protein in the heated mixture of 7S and WSP (7S/WSP = 1/1) coagulates at higher calcium concentrations than that in the mixture of heated 7S and heated WSP at a ratio of 1/1. This result strongly indicates that 7S and WSP interact with each other during heating and form complex protein particles which have special surface properties that are different from individual 7S and WSP protein particles. Particle size distribution analysis has also shown that 7S prevents WSP from forming larger protein particles during heating. SDS-PAGE analysis shows that lipoxygenase (LOX), beta-amylase, and lectin of WSP and the beta subunit of 7S tend to form a particulate fraction, while the KTI, alpha, and alpha′ subunits tend to form a soluble fraction. WSP, 7S, and their mixture have been heated at 60, 65, 70, 75, 80, 85, 90, and 95 °C for 10 min, and ultracentrifugation analysis shows that about 77–85% of the protein particles were formed at 65–75 °C in all three dispersions. SDS-PAGE analysis indicates that LOX and β-amylase have been denatured and that they have participated in the formation of protein particles when heated within 65–75 °C, while lectin has begun to participate in particle formation at above 85 °C. It is concluded that WSP plays an evident role in the formation of protein particles in soymilk during heating.     

Post-mortem changes of muscle from fresh water prawn (Macrobrachium rosenbergii) as influenced by spawning stages

Post-mortem changes of the muscle from pre- and post-spawned fresh water prawn (Macrobrachium rosenbergii) were comparatively monitored during 7 days of iced storage. During the storage, the muscle of pre-spawned prawn had a greater value of trichloroacetic acid (TCA) soluble peptide, heat soluble collagen and pepsin-soluble collagen (PSC) contents than did post-spawned counterpart. Those components in the muscle of both prawns increased markedly after 3 days of storage (p < 0.05). Conversely, insoluble collagen (ISC) content, shear force value and texture liking of both prawns decreased (p < 0.05), indicating the softening of muscle. No changes in protein patterns were observed, except the decreased band intensity of 66 kDa protein in water soluble fraction of both prawns was found after 3 days of storage. T_max and enthalpy of PSC from both prawns decreased during the first 4 days of storage (p < 0.05), suggesting the degradation or denaturation of collagen in the muscle. Light microscopic study showed the lowering of intercellular connection of raw meat and higher gaping in cooked meat when the samples were stored for a longer time. Therefore, post-mortem characteristics of prawn muscle was affected by storage time and spawning stages.     

Mathematical modeling of the heat transfer process and protein denaturation during the thermal treatment of Patagonian marine crabs

Southern Ocean swimming crab Ovalipes trimaculatus and the Patagonian stone crab Platyxanthus patagonicus are fishing resources with commercial value. Thermal treatment of crabs is necessary to denature muscle proteins, facilitating meat detachment from the crab shell (picking procedure). The proximal composition, protein patterns of crab muscle, thermophysical properties and heat transfer coefficients were determined. Heat transfer during thermal processing of body (i.e., cephalothorax) and claws of both crab species was simulated using a finite element computational code; the simulations were experimentally validated. Color changes in crab muscle during the heating process were measured. Thermal denaturation kinetics of myofibrillar proteins was determined using Differential Scanning Calorimetry (DSC) in small samples previously heated in water under controlled conditions. DSC thermograms of raw crab muscle showed two peaks at 49.0 ± 0.4 and 77.5 ± 0.6 °C corresponding to myosin and actin respectively. Activation energies for the denaturation of myosin (145.70 kJ/mol) and actin (156.42 kJ/mol) were calculated from Arrhenius equation. The degree of denaturation achieved by the myofibrillar proteins at the coldest point of the muscle in body and claws during the heating process was established by considering the protein denaturation kinetics determined by DSC, the activation energies and the heat penetration curves. Adequate conditions for the detachment of meat from the crab exoskeleton were established. The obtained results may help in determining the optimal heating times during the industrialization of these crustaceans.     

Characterization of the pectic polysaccharides from pumpkin peel

The alcohol insoluble polysaccharide (AIP) was extracted from pumpkin (Cucurbita moschata Duch) peels, and they were fractionated subsequently into water soluble pectic substance (WSP), EDTA soluble pectic substance (ESP) and alkali soluble pectic substance (ASP) fractions. ASP fraction (24.78 and 46.07 g/100 g) contained the highest total sugar and uronic acid contents compared with WSP (17.78 and 4.89 g/100 g) and ESP (18.43 and 23.99 g/100 g) fractions. WSP fraction had 2 peaks with a small one close to 205 kDa and a major one close to 13 kDa, while ESP and ASP fractions had 3 peaks with higher molecular weight distributions than WSP. The sugar peaks in the ion exchange chromatography were detected in a low concentration of ammonium acetate buffer, but uronic acid peaks were detected in a high concentration of ammonium acetate buffer and 0.2 mol/l NaOH. ESP had higher glucose retardation effect than that of WSP and ASP, while WSP and ASP had higher bile acid retardation effects than that of ESP. AIP fractions activated growth in Lactobacillus brevis, Bifidobacterium bifidum and Bifidobacterium longum, whereas they inhibited growth in Escherichia coli and Clostridium perfringens in RCM medium.     

Cultured C2C12 cell lines as a model for assessment of bacterial attachment to bovine primary muscle cells

The mechanisms of bacterial attachment to meat tissues need to be understood to enhance meat safety interventions. However, little is known about attachment of foodborne pathogens to meat muscle cells. In this study, attachment of six Escherichia coli and two Salmonella strains to primary bovine muscle cells and a cultured muscle cell line, C₂C₁₂, was measured, including the effect of temperature. At 37 °C, all but one strain (EC623) attached to C₂C₁₂ cells, whereas only five of eight strains (M23Sr, H10407, EC473, Sal1729a and Sal691) attached to primary cells. At 10 °C, two strains (H10407 and EC473) attached to C₂C₁₂ cells, compared to four strains (M23Sr, EC614, H10407 and Sal1729a) of primary cells. Comparing all strains at both temperatures, EC614 displayed the highest CFU per C₂C₁₂ cell (4.60 ± 2.02 CFU/muscle cell at 37 °C), whereas greater numbers of M23Sr attached per primary cell (51.88 ± 39.43 CFU/muscle cell at 37 °C). This study indicates that primary bovine muscle cells may provide a more relevant model system to study bacterial attachment to beef carcasses compared to cell lines such as C₂C₁₂.     

Kinetics of protein physicochemical changes induced by heating in meat using mimetic models: (2) Effects of fibre type,peroxides and antioxidants

Heating-induced changes in meat proteins were investigated using models made of aqueous suspensions of myofibrils according to muscle fibre types and cellular compounds (oxidants and antioxidants). These changes were evaluated by measurements of carbonyl groups and protein surface hydrophobicity. Model results were compared to trial results obtained on pork meat (M. Longissimus dorsi) heated under the same conditions (45 and 75 °C, from 5 to 120 min). Myofibrillar proteins from α-white fibres were more sensitive to oxidation and thermal denaturation than those from β-red fibres. At 45 °C, there were negligible differences due to peroxide or antioxidant types. At 75 °C, organic peroxides (ROOH) were less oxidative than hydrogen peroxide (H₂O₂), and antioxidant enzymes were less efficient than vitamin E and carnosine at protecting proteins against oxidation. Protein oxidation observed in meat is lower than in the mimetic models and the increase in hydrophobicity remained limited in meat.     

Chemical compositions and characteristics of farm raised giant catfish (Pangasianodon gigas) muscle

Proximate composition, chemical and physical properties of dorsal, ventral and lateral line cuts of farm raised giant catfish were determined. Protein, fat and ash content of the different cuts averaged 16.88, 4.45 and 1.24 g/100 g, respectively. Dorsal contains higher protein concentrations (19 g/100 g) than other two parts (p < 0.05). Ventral showed the highest hydroxyproline content (0.83 mg/g). Differences in lipid composition and fatty acid profiles were found among different cuts with highest phospholipids in the dorsal and highest triglyceride in both ventral and lateral line (p < 0.05). All the meat cuts contained high saturated fatty acid, followed by mono- and polyunsaturated fatty acid. High muscle hardness and toughness was found in the dorsal than that in the ventral (p > 0.05). The highest content of myoglobin and total pigment in lateral line resulted in the highest redness index (a*/b*) of this part. Three major nitrogenous compositions classified based on solubility in giant catfish muscle were myofibrillar, sarcoplasmic and alkaline soluble proteins.     

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.     

Solubilization of myofibrillar proteins in water or low ionic strength media: Classical techniques,basic principles,and novel functionalities

The qualitative characteristics of meat products are closely related to the functionality of muscle proteins. Myofibrillar proteins (MPs), comprising approximately 50% of total muscle proteins, are generally considered to be insoluble in solutions of low ionic strength (< 0.2 M), requiring high concentrations of salt (> 0.3 M) for solubilization. These soluble proteins are the ones which determine many functional properties of meat products, including emulsification and thermal gelation. In order to increase the utilization of meat and meat products, many studies have investigated the solubilization of MPs in water or low ionic strength media and determining their functionality. However, there still remains a lack of systematic information on the functional properties of MPs solubilized in this manner. Hence, this review will explore some typical techniques that have been used. The main procedures used for their solubilization, the fundamental principles and their functionalities in water (low ionic strength medium) are comprehensively discussed. In addition, advantages and disadvantages of each technique are summarized. Finally, future considerations are presented to facilitate progress in this new area and to enable water soluble muscle MPs to be utilized as novel meat ingredients in the food industry.     

Colour and sarcoplasmic protein evaluation of pork following water bath and ohmic cooking

The objective of this study was to investigate the effects of ohmic (OH) and waterbath (WB) cooking on colour attributes and sarcoplasmic changes of porcine longissimus dorsi muscle at the same endpoint temperatures (EPTs; range 10 °C–80 °C). The OH treatment was carried out at 10 V cm^− 1, and the WB temperature at 85 °C. The colour parameters, deoxymyoglobin% (DeoMb) and metmyoglobin% (MetMb) of the OH-cooked meat were significantly lower (P < 0.05) than those obtained by WB-cooking at the same EPTs (range 60 °C–80 °C). SDS-PAGE analysis showed that the meat treated with WB-cooking had a lower sarcoplasmic protein solubility (5.97 mg/g vs.14.89 mg/g, P < 0.05) and fainter protein bands than that of OH-cooking thus, indicating paler colour, and lower water-holding capacity especially in WB-cooked meat at EPTs above 40 °C. Strong correlations among lightness, browness, metmyoglobin% and soluble proteins were observed in meat following OH-cooking.     

Physical, Chemical, and Sensory Properties of Bologna Sausage Made with Ostrich Meat

Three formulations of bologna were prepared, differing only by the lean meat used: (1) ostrich meat from Iliofibularis muscle (fan thigh), (2) ostrich meat from Femorotibialis medius muscle (tip thigh), and (3) beef meat from Subscapularis muscle (shoulder). Physical, chemical, and sensory analyses were made. The final products formulated with ostrich meat, although having a dark appearance, were acceptable in chemical composition and other sensory characteristics. The low fat and high protein content for ostrich bolognas will help to ensure that, if marketed in sufficient quantities, ostrich meat can successfully compete with other healthy meat products. The ostrich meat (Iliofibularis muscle) formula reached the highest general quality scores in the sensory evaluation.     

Characteristics of meat batters with added native and preheated defatted walnut

Effects of incorporation of native and preheated defatted walnut on the physicochemical, emulsifying and rheological properties of meat batters, as affected by final heating temperature were investigated. Replacing meat protein with native defatted walnut in meat product formulations reduced (P < 0.05) gel strength and emulsifying properties and hence the firmness and stability of meat batters but enhanced water- and fat-binding properties and hence the yield of a processed meat product. However, incorporation of preheated defatted walnut, in addition to improving (P < 0.05) water- and fat-binding properties during thermal treatment, improved the gelling ability of myofibrillar proteins, probably because the preheating of the defatted walnut promoted interactions between walnut proteins and muscle proteins.     

Ostrich meat: Physico-chemical characteristics and comparison with turkey and bovine meat

In several European countries ostrich breeding has now become quite common. In Italy this has also given rise to the need for regulations for the slaughtering of Ratites. The present work studies and compares the physico-chemical characteristics of the meat from the thigh of the ostrich with the same anatomical cuts of turkey and bovine. The ostrich meat muscle of the thigh was imported vacuum packed from Israel and France, the muscles considered were m. flexor cruris and m. iliofibularis. The turkey thighs were from the domestic market (supermarket) and the bovine muscle m. pectineus was from spent milking animals from an EEC slaughterhouse. Needless to say that the breeding, the feeding and the system of slaughtering could influence some parameters of the different kinds of meat; however these factors could not be assessed. Due to its tenderness, low fat content and cholesterol levels ostrich meat is, in accordance with modern-day nutritional principles, a valid alternative to other kinds of meat.