首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Raccach M  Tilley HR 《Meat science》2006,72(4):751-756
The equation, y(t) = y(0)ekt, was fitted (R = 0.9281, 0.9220 and 0.9117, respectively) to thermal inactivation data (55, 60 and 65 °C) of the traditional meat starter culture Pediococcus pentosaceus (107 cfu/ml) in a meat model system. The population reduction constant (‘k’) increased (about 2.5- and 3-fold) with an increase in the treatment temperature (from 55 to 60 °C and from 60 to 65 °C, respectively). The Q10 (55–65 °C) for ‘k’ was 7.63. Thermal treatments of 19.1, 9.0 and 3.1 min (55, 60 and 65 °C, respectively) reduced the population of P. pentosaceus by 2.0 logs. The value of ‘k’ and the duration of the thermal treatment played an important role in the extent of the inactivation of the culture. The “zero inactivation” temperature (T0) for P. pentosaceus was 49.9 °C. About 5 logs of the culture would be destroyed at 63 and 68 °C within about 15.5 and 6.5 min, respectively.  相似文献   

2.
The post mortem changes in water mobility and distribution were followed in porcine muscle (M. longissimus dorsi) samples using continuous low-field NMR relaxation measurements and simultaneous measurement of changes in muscle impedance as an indirect measure of membrane integrity as well as muscle contraction measurements using a rigormeter instrument. Distributed exponential fitting analysis of NMR T2 relaxation data revealed the presence of three distinct water populations (T20, T21, T22) within the muscle during its conversion to meat. Comparison of T2 relaxation patterns and contraction data indicates that rigor development affects the attributes of the T21 water population and thereby contributes to myofibrillar water characteristics post mortem, as the T21 water population is believed to reflect inter/intra-myofibrillar water. The volume of the water population believed to reflect extra-cellular water (T22) in the living muscle. Early post mortem T22 decreased slightly within the first 2–3 h post mortem followed by an increase and a change in its characteristic time constant. This was ascribed to an initial muscle cell swelling followed by water being expelled from the cellular space into the extra-myofibrillar space. Comparison of changes in the T22 water population and impedance characteristics within the muscle during its conversion to meat revealed close relationship between progresses in the two attributes. Obtained data strongly support that the post mortem reorganization of water is closely associated with membrane properties, which moreover was found to affect the final water-holding capacity of the meat. Finally, a model for early post mortem events leading to changes in the distribution of water within muscles is proposed.  相似文献   

3.
The relationships between water distribution, measured with low-field NMR (LF-NMR) transverse (T2) relaxometry and sensory properties in tumbled and non-tumbled cured-smoked loins from 30 female Hampshire crossbred pigs were investigated. Upon distributed analysis of the T2 relaxation, three populations centred at about 2, 40 and 600–800 ms, respectively, were detected. Clear differences in the characteristics of the intermediate population (T21) were observed between loins from carriers and non-carriers of the RN allele, which implies differences in water–protein interactions between the two genotypes. PLS regressions between NMR T2 variables and sensory attributes revealed significant correlations between NMR T2 variables and the sensory attributes juiciness, acidulous taste and meat taste, which mainly could be ascribed to the T21 time constant. In addition, the number of unappealing pores assessed by the sensory panel was highly related to the relative T2 populations, implying that the microstructure is directly reflected in the NMR T2 populations. However, prediction of the processing yield from NMR T2 variables was poor. The correlation improved when RN genotypes and tumbling conditions were included as predictors. Thus, other effects of tumbling treatments and RN genotypes unrelated to NMR T2 relaxation were observed.  相似文献   

4.
Interaction between flaxseed gum and meat protein   总被引:7,自引:0,他引:7  
Thermal properties, dynamic rheological properties, texture and microstructure of salt-soluble meat protein and flaxseed gum (SSMP-FG) mixtures were investigated. Two transitions, 57.0 °C (TSSMP1) and 63.2 °C (TSSMP2), were observed for SSMP without FG with differential scanning calorimetry (DSC). Addition of 2% FG to SSMP increased TSSMP1 and TSSMP2 by 1.9 °C and 5.9 °C, respectively. Two transitions, 53 °C (TSSMP1′) and 75 °C (TSSMP2′), were also observed for SSMP without FG with dynamic rheological measurement. Addition of 2% FG to SSMP increased TSSMP1 and TSSMP2 by 9 °C and 14 °C. These results indicated that addition of FG increased thermal stability of SSMP. Addition of FG also increased the storage modulus G′, gel strength, decreased syneresis, and changed the microstructure of SSMP gels with texture analyser and scanning electron microscope (SEM), respectively, suggesting that an interaction between FG and SSMP may have occurred. The results of addition of destabilizer to SSMP gels indicated that electrostatic forces seemed to be the main force involved in the formation and stability of protein–polysaccharide gel.  相似文献   

5.
The effect of grape seed extract (GSE) and bearberry (BB), on lipid oxidation (TBARS, mg malondialdehyde (MDA)/kg muscle), colour (CIE ‘a’ redness value), pH, microbial status (log10CFU colony forming units/g pork) and sensorial properties of cooked pork patties was investigated. GSE (0–1000 μg/g muscle) and BB (0–1000 μg/g muscle) were added to raw pork (M. longissimus dorsi) patties which were stored in modified atmosphere packs (MAP) (75% O2:25% CO2) for up to 12 days at 4 °C. Cooked pork patties were stored in MAP (70% N2:30% CO2) for up to 4 days at 4 °C. Mesophilic plate counts and pork pH were unaffected by GSE and BB. GSE and BB addition decreased (P < 0.05) lipid oxidation (TBARS) in raw pork patties on days 9 and 12 of storage, relative to controls. Antioxidant activity of GSE and BB was observed in cooked pork patties demonstrating the thermal stability of GSE and BB. The ‘a’ redness values of raw and cooked pork patties marginally increased with increasing GSE concentration. The sensory properties of cooked pork patties were unaffected by GSE and BB addition. Results obtained demonstrate the potential for using health promoting nutraceuticals in meat and meat products.  相似文献   

6.
The influence of sorbitol (0–40 wt.%) on the thermal denaturation and gelation of bovine serum albumin (BSA, pH 7.0) in aqueous solution has been studied. The effect of sorbitol on heat denaturation of 0.5 wt.% BSA solutions was measured using ultrasensitive differential scanning calorimetry. The unfolding process was irreversible and was characterized by the thermal denaturation temperature (Tm). As the sorbitol concentration increased from 0 to 40 wt.%, Tm increased from 73.0 to 80.9 °C. The rise in Tm was attributed to the increased thermal stability of the globular state of BSA relative to its native state. The dynamic shear rheology of 4 wt.% BSA solutions containing 200 mM NaCl was monitored as they were heated from 30 to 90 °C at 1.5 °C min−1, held at 90 °C for 120 min, and then cooled back to 30 °C at −1.5 °C min−1. Sorbitol increased the protein gelation temperature (ΔTgel +10 °C for 40 wt.% sorbitol), decreased the isothermal gelation rate at 90 °C, but increased the final shear modulus of the gels cooled to 30 °C. The impact of sorbitol on gel characteristics was attributed to its ability to increase protein thermal stability, increase the attractive force between proteins and decrease the protein–protein collision frequency.  相似文献   

7.
In today's market, fresh red meat is cut and packaged at both the wholesale and retail level. Greater economies could result if the wholesaler prepared all consumer cuts centrally, but the short storage life of meat limits distribution. Use of CO2-controlled atmosphere, master packaging, and strict temperature control (−1.5±0.5°C) can enhance storage life and, therefore, distribution ease. An insulated shipping and storage container was designed and tested for its suitability to distribute master-packaged meat. Shelves in the container supported 36 master trays (508 × 381 × 60 mm), with the source of refrigeration being injected liquid nitrogen (N2). Electric fans dispersed the N2 gas throughout the container. To reduce costs, 36 saline water bags (10% w/v NaCl) were used to thermally simulate the meat. Temperatures of 20 bags were recorded during storage experiments. The container was tested at outside temperatures of 15, 0 and −15°C with 4 internal fans and at 30°C with 2, 4 and 6 fans. In all instances, bags cooled from 10°C to an equilibrium temperature of −1.5°C within 5.5 h. Minimum equilibrium temperatures during any 8 h trial were −2.6, −2.0 and −2.0°C for 2, 4 and 6 fans, respectively. Correspondingly, maximum temperatures were −0.2, −0.7 and −0.3°C. Initial chilling of the product required, on average, 19 kg of N2, while equilibrium was maintained at a N2 consumption rate of 5.5, 4.0, 2.6 and 0.93 kg/h at outside temperatures of 30, 15 0 and −15°C, respectively, with 4 fans. The N2 use for 2 and 6 fans was 5 and 6.3 kg/h, respectively, at an outside temperature of 30°C. During simulated power failure or when the N2-tank ‘ran dry', temperatures in the container rose 0.9 and 2.0°C/h, respectively. When the door to the container was opened long enough to remove three trays, temperature was restored within 5 min. Convective heat transfer coefficients between saline water bags and circulating N2 were in the range of 80–100, 115–135, and 140–155 W/(m2·K) for 2, 4 and 6 fans, respectively. Heat transfer to meat will be limited by conduction in master packaged meat if similar convection coefficients prevail.  相似文献   

8.
Enthalpy-Entropy compensation in food vapor adsorption   总被引:1,自引:0,他引:1  
Enthalpy-entropy compensation was analysed for sorption isotherms of potatoes, macadamia nuts, apricots, figs, currants, prunes and raisins. Plots of (ΔHdif)T vs (ΔSdif)T for potatoes and macadamia nuts presented two isokinetic temperatures: TB1 = 272.0 ± 57.7 K (− 1 °C) for potatoes, TB1 = 265.0 ± 18.8 K (− 8 °C) for macadamia nuts and TB2 = 382.5 ± 7.3 K (109.5 °C) for both products. The first isokinetic temperature (TB1) appeared only at the upper portion of the temperature range tested (50, 60 and 70 °C for potatoes and 50 and 60 °C for macadamia nuts). The two isokinetic temperatures observed for potatoes and macadamia nuts suggested that during the initial stages at low aw TB1 is controlled by changes in the entropy of water, whereas the second isokinetic temperature (TB2) is considered to be enthalpy-controlled. Dried fruits presented only one isokinetic curve TB = 315.7 ± 3.5 K (42.7 °C), for raisins, currants and figs (75.2–82.3% d.b. sugars) and TB = 317.7 ± 4.6 K (44.7 °C) for prunes and apricots (51.5–54.5% d.b. sugars), indicating an enthalpy-controlled adsorption process for the whole range of moisture contents covered.  相似文献   

9.
Comaposada J  Arnau J  Gou P 《Meat science》2007,77(4):643-648
The effect of KCl on sorption isotherms was determined on salted minced meat (with 0%, 30% and 100% molar substitution of NaCl by KCl) at 5 °C and 25 °C and meat from a 3 mm thick slice from the surface of dry-cured hams (with 0% and 35% molar substitution of NaCl by KCl) held at 70–75%, 75–80% and 80–85% air relative humidity during the resting period.

The sorption isotherms were determined gravimetrically by exposing the meat samples to several atmospheres of known relative humidity controlled by different saturated salts according to the COST90 method. The sorption equipment consisted of a chamber containing 11 containers, covering the water activity (aw) range from 0.112 to 0.946 at 25 °C. The hermetically closed sorption containers filled with KCl and minced meat samples were irradiated at 3 kGrey (gamma irradiation 60Co). The water content at equilibrium was higher in minced meat with NaCl than in minced meat with KCl (100% molar substitution of NaCl by KCl) at 5 °C within the range of 0.4313 and 0.7565 aw. However, when substitution was 30% in minced meat and 35% in hams the isotherms were similar to isotherm without substitution.  相似文献   


10.
The gelation characteristics of myofibrillar proteins are indicative of meat product texture. Defining the performance of myofibrillar proteins during gelation is beneficial in maintaining quality and developing processed meat products and processes. This study investigates the impact of pH on viscoelastic properties of porcine myofibrillar proteins prepared from different muscles (semimembranosus (SM), longissimus dorsi (LD) and psoas major (PM)) during heat-induced gelation. Dynamic rheological properties were measured while heating at 1 °C/min from 20 to 85 °C, followed by a holding phase at 85 °C for 3 min and a cooling phase from 85 to 5 °C at a rate of 5 °C/min. Storage modulus (G′, the elastic response of the gelling material) increased as gel formation occurred, but decreased after reaching the temperature of myosin denaturation (52 °C) until approximately 60 °C when the gel strength increased again. This resulted in a peak and depression in the thermogram. Following 60 °C, the treatments maintained observed trends in gel strength, showing SM myofibrils produced the strongest gels. Myofibrillar protein from SM and PM formed stronger gels at pH 6.0 than at pH 6.5. Differences may be attributed to subtle variations in their protein profile related to muscle type or postmortem metabolism. Significant correlations were determined between G′ at 57, 72, 85 and 5 °C, indicating that changes affecting gel strength took effect prior to 57 °C. Muscle type was found to influence water-holding capacity to a greater degree than pH.  相似文献   

11.
Confocal laser scanning microscopy (CLSM) and low-field nuclear magnetic resonance (LF-NMR) relaxometry were combined to characterize microstructural changes and water distribution in fresh and cooked pork during an aging period of 14 days. At day 1 (24 h postmortem) a few muscle fibres, which appear swollen, were observed in both fresh and cooked meat. An identical microstructure was still apparent after 14 days, however, the number of muscle fibres showing distinguished characteristics was found to increase throughout the aging period. Hence, it was apparent that during aging the individual fibres swell and disintegrate at different rates. Development in water-holding capacity (WHC) was followed during the aging period using gravimetric methods, and an increase in the WHC in the fresh meat was observed, which resembled the amount of extramyofibrillar water measured by NMR relaxometry (T22 population). This was consistent with the CLSM images, as a substantial increase in the number of myofibrils that appeared swollen, capable of holding more water, was observed during aging. In the cooked meat the width of the T21c population, reflecting the myofibrillar water in the cooked meat, was seen to decrease during the entire storage period, which corresponds to the development of a more homogeneous structure. In the CLSM data a continuous degradation during the storage period was observed, which could resemble a shift to a more homogeneous structure. Comparison of CLSM of transverse sections of fresh and cooked pork revealed a pronounced shrinkage of muscle fibres upon cooking. This resulted in large gaps between the cooked muscle fibres, which also was visible as shrinkage at the level of the individual myofibrils. This pattern was also reflected in the NMR relaxation data. The cooking-induced shrinkage of the myofibrils occurred concomitantly with a decrease in the amount of intermyofibrillar water within the individual fibre and an increase in the larger extramyofibrillar spaces between fibres, i.e. water is expelled from the myofibrillar matrix upon cooking. Accordingly, the present study demonstrated that the use of CLSM together with NMR relaxometry can provide further information on the relationship between structural characteristics of meat and resultant water distribution.  相似文献   

12.
The post mortem changes in the chemical/physical state distribution of water were followed in pig muscle (M. longissimus dorsi) from heterozygote (n=12) and non-carriers (n=12) of the halothane gene exposed to two different cooling profiles using continuous low-field NMR relaxation measurements. T2 relaxation data were analyzed using distributed exponential fitting analysis. Independent of genotype post mortem changes were observed in the two water populations characterizing water within the myofibrillar space (T21) and the extra-myofibrillar space (T22), respectively, as a function of chilling regime. The effect was most pronounced in samples from heterozygote carriers of the halothane gene. The obtained results strongly suggest that improved water-holding capacity of muscles upon fast chilling can be ascribed to a reduced accumulation of extra-myofibrillar water in the meat post mortem, and it is hypothesized that differences in the accumulation of extra-myofibrillar water post mortem can be ascribed largely to the time at which disruption of cell membrane integrity takes place.  相似文献   

13.
The relationship between water–protein interactions and heat-induced protein denaturation in low temperature long time (LTLT) treated pork Longissimus dorsi was investigated by combining low-field NMR T2 relaxometry with DSC measurements and measures of shrinkage of porcine Longissimus dorsi heated to 53 °C, 55 °C, 57 °C and 59 °C for either 3 or 20 h. Water within the myofibrils, measured by NMR T21 relaxation times, was affected by both temperature and holding time during LTLT treatment between 53 °C and 59 °C. The changes in NMR T21 relaxation times were associated with decreased fiber diameter and increased cooking loss, revealing a relationship between transverse shrinkage, water–protein interactions and cooking loss. DSC measurements revealed a concomitant decrease in ΔH68 °C, which suggests impact of collagen denaturation on the retention of water within the meat during LTLT treatment. Furthermore, a decrease in ΔH75 °C suggested that prolonged cooking (20 h) resulted in actin denaturation leading to decreased T21 relaxation times and higher cooking loss.  相似文献   

14.
Kim YS  Yoon SK  Song YH  Lee SK 《Meat science》2003,63(4):509-513
A total of 1278 head of Hanwoo (Korean native cattle) slaughtered over four seasons were used to evaluate the effect of season on color characteristics of beef longissimus dorsi (LD) muscle. CIE L*, a*, b*, C* values and hue angle were significantly lower (P<0.05) in cattle slaughtered in the winter season. Meat color was darker in the winter than in the spring and autumn seasons. The L* values among three average daily temperature (Ta) categories were different (P<0.05) in order of: [5 °CTa<25 °C] > [Ta25 °C] > [Ta<5 °C], indicating that the meat color of cattle slaughtered at Ta<5 °C was darker. The a*, b*, C* values and hue angle were significantly lower (P<0.05) in cattle slaughtered at Ta<5 °C. Season at slaughter is of great importance for meat color. Namely, meat color of Hanwoo beef was influenced by environmental temperature. Overall, cattle slaughtered in the winter season of Ta<5 °C produced beef with more undesirable meat color properties.  相似文献   

15.
Aktaş N  Kaya M 《Meat science》2001,58(4):279-419
Intramuscular connective tissue obtained from Longissimus dorsi muscle of a 4-year-old beef carcass was treated with NaCl solutions of 2, 4, and 6% (w/v), and CaCl2 solutions of 50, 100, and 150 mM, and citric and lactic acid solutions of 0.5, 1.0, and 1.5% for three different marinating periods (24, 46, and 72 h). Changes in denaturation characteristics were investigated using differential scanning calorimetry and it was found that the denaturation onset temperature (To) and the denaturation peak temperature (Tp) increased as the NaCl concentration increased but decreased as the CaCl2 concentration increased, irrespective of marinating time. Lactic and citric acid decreased To to about 39°C, from over 60°C breaking the structure of fibrils.  相似文献   

16.
Differential scanning calorimetry (DSC) was used to investigate the protein denaturation characteristics of pork muscles from four quality groups namely RFN (red, firm, and non-exudative), RSE (red, soft, and exudative), PFN (pale, firm, and non-exudative), and PSE (pale, soft, and exudative). The thermograms indicated three endothermic peaks between 45°C to 90°C, corresponding to denaturation of myosin (peak I), sarcoplasmic proteins (peak II), and actin (peak III). The myosin peak was much reduced in PSE samples, while the actin peak remained almost identical in all groups. RFN and RSE samples were found to have very similar protein denaturation characteristics and were not significantly different in their thermodynamic protein denaturation parameters. PFN samples showed similar myofibrilar protein denaturation but significantly different sarcoplasmic protein denaturation characteristics compared to normal (RFN) samples according to their DSC thermograms. Based on these findings, it was suggested that the pale color in PFN pork is linked to sarcoplasmic protein denaturation.  相似文献   

17.
The muscles semitendinosus (ST) and psoas major (PM) were removed from chilled young bull carcasses 24 h after slaughter and stored at 4 °C. At the 1st, 6th and 12th day of post-mortem ageing the chemical composition (moisture, fat, protein, collagen) and contents of free, immobilized and unfreezable water in the muscles were estimated. The muscle steaks were boiled at 100 °C, roasted at 170 °C or fried at 160 °C to an internal temperature of 75 °C, and the amounts of total, free, immobilized, and unfreezable water in heated muscles were evaluated. The unfreezable water was estimated by DSC. In the raw muscles immobilized water constituted 74–75%, free water 16.6–17.6% and unfreezable water 7–8% of the total water. Independent of time of ageing, PM muscle contained significantly more free water than ST muscle. During post-mortem ageing, changes in free, immobilized and unfreezable water in muscles were not significant. The level of free water was highest in boiled and least in fried meat, however the amount of immobilized water was highest in fried and lowest in boiled meat. The amount of unfreezable water in muscles heated after 12 days of post-mortem ageing decreased.  相似文献   

18.
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.  相似文献   

19.
Vada M 《Meat science》1977,1(4):245-252
Rapid chilling was applied to porcine longissimus dorsi muscles at 1 h post mortem in order to observe its effect on the quality of canned products prepared from those of different pH1 values.

The muscle from one side of each animal was removed from the carcase 50 minutes post mortem and divided into two longitudinal strips. One was chilled immediately to 13–15°C (1 h post mortem): the other after a further hour (2 h post mortem) acted as control. After the centre temperature had reached 10°C the muscles were stored in a refrigerator at 3–5°C.

Compared with the control samples (chilled at 2 h p.m.), rapid chilling from 1 h p.m. caused an improvement in the water-holding capacity and the texture of pork meat, which had higher pH1 values and was processed at 2, 4 and 48 h p.m. There was minimum brine retention and texture score if samples—both rapidly chilled and control—were processed at 24 h p.m.

Although brine retention of PSE pork meat could not be increased even by rapid chilling, the texture of heat treated PSE pork showed an improvement during storage, which was more pronounced after ageing for 48 h, if PSE samples were chilled at 1 h p.m.  相似文献   


20.
Water status of cooked white salted noodles evaluated by MRI   总被引:5,自引:0,他引:5  
Transverse relaxation time (T2)-weighted images and T2 maps of white salted noodles (WSN) were investigated by magnetic resonance imaging technique. T2-weighted images and T2 maps clearly showed the differences in water status between noodles. The migration of moisture from surface regions to central regions of boiled WSN at different migration rates were investigated during storage. The distribution of T2 values changed differently depending on the cooking and storage times. The small differences in T2 values between surface region and central region of noodles cooked for 5 and 15 min were attributed to the limited water absorption during short cooking time, which resulted in high firmness. The changes in starch granules morphology observed under scanning electron microscope and the increase of noodle firmness measured by texture analyzer were significantly affected by the water status in noodles. The water status can be controlled by the cooking time.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号