共查询到20条相似文献,搜索用时 15 毫秒
1.
David J. Wright Ian B. Leach Peter Wilding 《Journal of the science of food and agriculture》1977,28(6):557-564
Rabbit muscle and its constituent proteins were investigated by differential scanning calorimetry (d.s.c.). Post-rigor muscle yielded a complex thermogram comprising at least three endothermic transitions with Tmax values of 60, 67 and 80°C. Comparison with the purified proteins or fractions indicated that these transitions corresponded to denaturation of myosin, sarcoplasmic proteins and actin respectively. In addition to these endothermic transitions, pre-rigor muscle produced a single large exotherm of Tmax 54°C. The evidence suggested that this transition was closely linked with the process of contraction. 相似文献
2.
B. K. HOWELL A. D. MATTHEWS A. P. DONNELLY 《International Journal of Food Science & Technology》1991,26(3):283-295
The variation in myofibrillar protein thermostability was compared for various fish species, using differential scanning calorimetry. The tropical fish, catfish ( Clarius gariepinus ), carp ( Cyprinus carpio ), Nile perch ( Lates niloticus ), red snapper ( Lutianus sebae ), red mullet ( Parpeneus barberinus ), sea bream ( Gymnocranius rivalatus ), and cold-water reared trout ( Salmo gairdneri ) and cod ( Gadus morhua ) were analysed. Onset temperature of myofibrillar protein denaturation occurred at up to 11°C higher for tropical species (43.5°C, catfish), than cod (32.6°C) at pH 7 and low ionic strength (I). As pH (6.0-8.0) and I (0.05-1.00) were increased, thermal denaturation temperatures of myosins from tropical, but not cold-water, species decreased. Enthalpies of myofibrillar denaturation decreased for all species with increasing pH and I. Only one thermal transition was detected for myosin at pH 6 and low I, increasing to three as pH and I were increased. Changes in thermal characteristics of myosin subunits over iced and frozen storage suggest more rapid deterioration in cold-water than in tropical fish. The differences in myofibrillar stability of fish from different habitat temperatures have implications for the processing and storage of tropical fish. 相似文献
3.
差示扫描量热仪可以测定多种热力学和动力学参数,如比热容、反应热、转变热、相图、反应速率、结晶速率、高聚物结晶度及样品纯度等。该仪器具有使用温度范围宽(-175~500℃)、分辨率高和试样用量少的优点。本文论述了差示扫描量热仪的特点、目前我国与差示扫描量热法相关的标准以及方法的未来发展趋势。未来在聚合物的结晶性研究和相变材料的热焓变化测量方面,差示扫描量热法(differential scanning calorimetry,DSC)会有更广泛的应用。在物质的鉴别方面,熔点的精确测量也会起到很重要的辅助作用。未来期待温度范围更宽的DSC仪器的出现,同时,红外-气相-差式扫描联用技术及热重-差式扫描量热联用仪器的更进一步发展会使得联用技术在未来得到更多的重视。 相似文献
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David J. Wright Donald Boulter 《Journal of the science of food and agriculture》1980,31(12):1231-1241
Two thermal transitions were observed in soya bean meal by differential scanning calorimetry (DSC) and on the basis of previous data were ascribed to the denaturation of the 11S globulin, glycinin, and the 7S globulin, β-conglycinin. Three DSC transitions were apparent in Vicia faba meal; one was associated with starch gelatinisation, and was absent from thermograms of soya bean because the latter stores oil rather than starch. The remaining two transitions were identified with the 11S globulin, legumin, and a 7S globulin, vicilin. The denaturation parameters of legumin and glycinin were very similar, in contrast to those of vicilin and β-conglycinin. From this it was concluded that legumin and glycinin probably represent homologous proteins, whereas the two 7S proteins possess intrinsically different structures to one another. Cowpeas (Vigna unguiculata) and dry beans (Phaseolus vulgaris) afforded two major transitions which were assigned to 7S globulins and starch. From its DSC profile, the 7S globulins of cowpea appeared heterogeneous, but nevertheless possessed denaturation characteristics similar to those of vicilin of V. faba. In contrast, the thermal behaviour of the 7S globulin of dry beans (glyco-protein II) was distinct from that of any of the other 7S globulins investigated. Three protein transitions were observed in the three lupin species examined. As in the case of soya bean, no starch transition was present. On the basis of the correspondence in transition temperature, one of the protein transitions was assigned to the 11S globulin component. Overall, this study indicates the potential of DSC as a means for obtaining data on seed protein homology from whole meals rather than the extracted proteins. 相似文献
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《Journal of dairy science》2022,105(9):7230-7241
Ionic conditions affect the denaturation and gelling of whey proteins, affecting the physical properties of foods in which proteins are used as ingredients. We comprehensively investigated the effect of the presence of commonly used emulsifying salts on the denaturation and gelling properties of concentrated solutions of β-lactoglobulin (β-LG) and whey protein isolate (WPI). The denaturation temperature in water was 73.5°C [coefficient of variation (CV) 0.49%], 71.8°C (CV 0.38%), and 69.9°C (CV 0.41%) for β-LG (14% wt/wt), β-LG (30% wt/wt), and WPI (30% wt/wt), respectively. Increasing the concentration of salts, except for sodium hexametaphosphate, resulted in a linear increase in the denaturation temperature of WPI (kosmotropic behavior) and an acceleration in its gelling rate. Sodium chloride and tartrate salts exhibited the strongest effect in protecting WPI against thermal denaturation. Despite the constant initial pH of all solutions, salts having buffering capacity (e.g., phosphate and citrate salts) prevented a decrease in pH as the temperature increased above 70°C, resulting in a decline in denaturation temperature at low salt concentrations (≤0.2 mol/g). When pH was kept constant at denaturation temperature, all salts except sodium hexametaphosphate, which exhibited chaotropic behavior, exhibited similar effects on denaturation temperature. At low salt concentration, gelation was the controlling step, occurring up to 10°C above denaturation temperature. At high salt concentration (>3% wt/wt), thermal denaturation was the controlling step, with gelation occurring immediately after. These results indicate that the ionic and buffering properties of salts added to milk will determine the native versus denatured state and gelation of whey proteins in systems subjected to high temperature, short time processing (72°C for 15 s). 相似文献
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Differential scanning calorimetry (DSC) was used for the direct analysis of melting properties in porcine subcutaneous, intermuscular, and kidney leaf adipose tissue by heating at a constant ratio of +5 °C/min from 4 to 90 °C. Melting curves for adipose tissues as well as fat extracted from the associated tissues by chloroform–methanol were generated using DSC. Major peaks in DSC curves were similar among types of adipose tissue but the temperatures of the melting peak and conclusion point differed among types of adipose tissues. From the visual appearance of fat samples it appeared that the major DSC peak corresponded to phase transition of the fat. The direct DSC analysis of porcine adipose tissues may be useful to determine melting properties. 相似文献
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Properties, translucence, and microstructure of Pacific white shrimp treated with mixed phosphates as affected by freshness and deveining 总被引:1,自引:0,他引:1
Rattanasatheirn N Benjakul S Visessanguan W Kijroongrojana K 《Journal of food science》2008,73(1):S31-S40
ABSTRACT: Effects of freshness and deveining on some properties, translucence, and microstructure of Pacific white shrimp ( Litopenaeus vannamei ) soaked in 2.5% NaCl containing different phosphates were studied. Shrimp soaked in all solutions had increases in weight gain and cooking yield with lowered cooking loss, compared with the control ( P < 0.05). However, efficacy of mixed phosphates in quality improvement of ice-stored shrimp was lower than fresh shrimp. Deveining resulted in increased weight gain and yield ( P < 0.05). Nevertheless, samples treated with phosphates became more translucent. Shrimp stored in ice for 7 d and treated with mixed phosphates were generally more translucent than fresh counterparts ( P < 0.05). Shrimp soaked in 2.5% NaCl containing 0.875% sodium acid pyrophosphate (SAPP) and 2.625% tetrasodium pyrophosphate (TSPP) were generally less translucent and had high weight gain and cooking yield along with low cooking loss. The microstructure study revealed that the muscle fibers were less attached with the loss of Z-disks after being treated with mixed phosphates. Cooked meats of fresh shrimp and ice-stored shrimp had more compact fiber arrangement with the shrinkage of sarcomere compared with raw samples. Disintegration was observed at the M-line in ice-stored shrimp treated with mixed phosphates after cooking, while such a phenomenon was not found in the cooked fresh sample treated with phosphates. T max and enthalpy of both myosin and actin peaks shifted to lower values when shrimp were treated with mixed phosphates ( P < 0.05). Those changes were generally more pronounced in ice-stored shrimp. Therefore, freshness and deveining process had an impact on the quality of Pacific white shrimp treated with phosphates. 相似文献
10.
Apparent Specific Heat of Chicken Breast Patties and their Constituent Proteins by Differential Scanning Calorimetry 总被引:2,自引:0,他引:2
Chicken breast meat yielded three endothermic transitions, with peak transition temperatures of 53,70, and 79°C. Comparison with the purified protein fractions indicated that these transitions corresponded to denaturation of myofibrillar (53°C) and sarcoplasmic (70 and 79°C) proteins. The apparent specific heat profile of chicken breast meat was successfully modeled as a weighted average of the apparent specific heat of the constituent proteins. The specific heats of sarcoplasmic protein, myofibrillar protein, and chicken breast meat were strongly influenced by temperature; however, the specific heat of stromal protein was nearly constant across the temperature range considered (i.e., 10 to 100°C). 相似文献
11.
Isabel M. N. Sousa John R. Mitchell Dave A. Ledward Sandra E. Hill M. Luisa Beir?o da Costa 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1995,201(6):566-569
Differential scanning calorimetry (DSC) was used to study the 7S and 11S globulin fractions extracted from lupin seed (Lupinus luteus) flour. In agreement with previous work on other lupin species, the isolate showed three denaturation peaks compared to the two observed with soy. By comparison with the isolated globulin fractions, the denaturation peaks at the two higher temperatures in the lupin isolate were assigned to the 11S and 7S globulins. The denaturation temperature of the lupin 7S globulin was about 10 K higher than that for the corresponding soy globulin, whereas the values for the 11S globulin were similar. All globulins displayed increasing thermal stability with decreasing moisture contents. Possible reasons for the differences in behaviour of soy and lupin protein isolates are discussed. 相似文献
12.
Bjorg Egelandsdal Berit K Martinsen Kristen Fretheim Marianne Pettersen Ole Harbitz 《Journal of the science of food and agriculture》1994,64(1):75-85
The aim of this study was to elucidate the functional performance of the most abundant protein component in meat, ie myosin, which is recognised as important for binding in meat products. As several genetic variants of skeletal myosin exist, myosins from two bovine muscles of different fibre type composition, M masseter and M cutaneus trunci were compared with respect to filament forming properties and denaturation characteristics. The principal methods used were turbidimetric measurements, which were used to monitor filament formation, calorimetry and rheology. The myosin systems were examined at two different salt levels (0.2 and 0.6 M NaCl) and at pH 5.5–7.0. The method of preparing myosin suspensions/solutions was also examined. Differences in the filament-forming process for the two myosins were detected. Measurements of turbidity revealed that at conditions of low pH and low ionic strength white myosin had a higher ultimate turbidity compared with red myosin. Early in the transition from low to high turbidity, red myosin had a higher turbidity than white myosin corresponding to reduced solubility. The turbidity increased with time of storing the myosin suspensions/solutions. This change was attributed to formation of filaments and further association of filaments. White myosin had a smaller apparent enthalpy of denaturation than red myosin. The calorimetric measurements recorded in 0.2 M NaCl suggested that the head and the rod of white myosin were less stable than the corresponding parts of red myosin. However, exceptions to this rule were found at pH 6.0. In 0.6 M NaCl the identification of the transitions for red myosin was more difficult. The method of preparing myosin suspensions affected calorimetric and rheological measurements. In 0.6 M NaCl and pH 6.0 calorimetric thermograms of both myosins were affected by the preparation method. At pH 5.5 this change was interpreted as caused by denaturation promoted by the dilution/rapid titration technique compared with dialysing the systems to pH 5.5 from pH 7. Differences in the filaments formed might, however, also contribute to the variations seen in the calorimetric ther-mograms. The gelling properties of white myosin were most sensitive to the preparation method used. Systems prepared by dialysis gave stronger heat-induced gels than those prepared by ‘dilution’. White myosin always produced stronger gels than red myosin independent of the preparation technique. The rheological properties (at 80°C) of red myosin were less affected by the preparation method than were those of white myosin. At lower temperatures, however, there was more variation in the shapes of the rheological thermograms (? versus temperature) for red myosin than in the corresponding thermograms of white myosin. 相似文献
13.
Maaruf B Abd Ghani Yaakob B Che Man Asbi B Ali Dzulkifly B Mat Hashim 《Journal of the science of food and agriculture》1999,79(14):2001-2009
The effect of sucrose and sodium chloride (NaCl) on sago starch gelatinisation was investigated by differential scanning calorimetry (DSC). The gelatinisation of starch in the presence of low levels of water and high levels of sucrose was studied. The gelatinisation temperature was found to increase in the presence of sucrose, whereas the gelatinisation enthalpy was unaffected. The gelatinisation temperature range was not as broad in the presence of sucrose as without sucrose. Furthermore, the shape of the gelatinisation endotherm was changed by the addition of sucrose. The double endotherm obtained in limited water–starch systems was changed into a single endotherm, similar to the endotherm obtained in excess water–starch systems at higher temperature. DSC was also used to examine the effects of water and NaCl content on the phase transitions of sago starch. Samples were adjusted to starch–water weight ratios of 2:3 and 3:2 in NaCl concentrations from 1 to 5 M . The gelatinisation temperature of sago starch increased and then decreased as the NaCl concentration increased. NaCl created similar effects on the endotherms with excess water content and on the first endotherm with limited water content. © 1999 Society of Chemical Industry 相似文献
14.
Dimuthu Bogahawaththa Rabia Ashraf Jayani Chandrapala Osaana Donkor Todor Vasiljevic 《Journal of dairy science》2018,101(10):8726-8736
In vitro immunogenicity of various native and thermally processed (72°C/15 s and 100°C/30 s) bovine milk protein fractions, their mixtures, whey, and skim milk, was studied by analyzing the immune response of T helper (Th) cells in human peripheral blood mononuclear cells. The secretion of Th type cytokines induced by the protein stimulants was quantified while determining the heat-induced protein denaturation. Purified whey proteins, caseins and whey fraction, and skim milk provoked substantial immune responses at various degrees, indicating their potent immunogenicity. The protein mixtures prepared using the fractionated whey proteins with or without caseins appeared less immunogenic in both native and heat-treated forms, implying their potential of producing less immunogenic dairy products. The 100°C/30 s treatment significantly altered the immunogenicity of most of the potent protein stimulants, which mostly coincided with their levels of protein denaturation. The 72°C/15 s treatment caused the least protein denaturation but altered the immunogenicity of several protein stimulants notably, including heat-stable caseins and α-lactalbumin. 相似文献
15.
F. Speroni M.C. Añón M. de Lamballerie 《Food research international (Ottawa, Ont.)》2010,43(5):1347-1355
The effects of calcium and high pressure (HP) treatment on the thermal properties of soybean proteins were analyzed in soybean protein isolate (SPI), a β-conglycinin-enriched fraction (7SEF), a glycinin-enriched fraction (11SEF), and whey protein concentrate (WPC). For β-conglycinin, the temperature of denaturation (Td) decreased with up to 12.5 mM or 6.2 mM calcium in SPI and 7SEF, respectively. This parameter increased when calcium was more concentrated. The Td of glycinin increased for every assayed calcium concentration. The values of changes in Td (ΔTd) depended on calcium concentration and the proportion of β-conglycinin and glycinin in the samples. Activation energy decreased for glycinin in the presence of calcium. HP treatment promoted denaturation of β-conglycinin and glycinin. Calcium protected both proteins in SPI, 7SEF and 11SEF at 200 MPa, and protected glycinin in SPI and 7SEF at 400 and 600 MPa. Nevertheless, calcium increased the degree of denaturation of β-conglycinin in 7SEF at 600 MPa. In the absence of calcium, partially-HP-denatured polypeptides exhibited the same or lower Td than controls, whereas in its presence, they exhibited higher Tds than their respective controls. 相似文献
16.
Purified tilapia myosin was digested with α-chymotrypsin and purified to obtain heavy meromyosin (HMM) and light meromyosin (LMM). The thermophysical properties of Tilapia myosin, HMM, and LMM were characterized. Constantly heated myosin, HMM, and LMM samples showed that aggregates began to form around 40 °C as evidenced by the increase of turbidity for all 3 samples (0.25 mg/mL). Beginning turbidity measurements showed differing levels of absorbance for each protein fragment with increasing absorbance values in the following order HMM, myosin, and LMM (0.0026, 0.0282, and 0.052, respectively). Differential scanning calorimetry showed 3 (17.5, 41.9, and 49.9 °C), 2 (43 and 67.1 °C), and 3 (40.4, 51.7, and 69 °C) major peaks for myosin, HMM, and LMM, respectively. Dynamic rheology measurements demonstrated crossover points, which are generally recognized as gelation point, 40.3 °C for myosin and 27 °C for HMM. The results shown for the thermally stable properties of tilapia myosin, HMM, and LMM showed clear evidence that they are all thermal stable at temperatures ranging from 10 °C to approximately 40 °C after which they all are completely denatured. The results also showed that the thermo stability of the myosin and its subfragments were greatly influenced by fish habitat temperature. 相似文献
17.
To measure thermal conductivity of foods, an attachment to a differential scanning calorimeter was constructed. A needle probe with a 40 gauge type-T thermocouple was used to measure the temperature of a cylindrical food sample. The DSC heating pan temperature was maintained at 40°C, and then raised to 50°C. The average thermal conductivities of rutabagas, radish, parsnip, turnip, potato, green apple, and carrot were 0.447, 0.499, 0.392, 0.480, 0.552, 0.405, and 0.564 W/m°C, respectively, for a temperature range between 40–50°C. The DSC method was reliable, precise, and a relatively rapid technique for determining thermal conductivity of foods. 相似文献
18.
James R Bacon Timothy R Noel David J Wright 《Journal of the science of food and agriculture》1989,49(3):335-345
The effect of heat on pea (Pisum sativum L) vicilin has been studied using differential scanning calorimetry (DSC), gel filtrtion chromatography and turbidimetry. By adjusting the variables of pII, ionic strength and protein concentration, two processes could be identified from the DSC thermograms: protein denaturation and protein aggregation. The results are discussed in terms of electrostatic and hydrophobic interactions. A mechanism for the thermal aggregation of pea vicilin is proposed. 相似文献
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Yuanlv Zhang Guishan Liu Qiwen Xie Yanyao Wang Jia Yu Xiaoju Ma 《Comprehensive Reviews in Food Science and Food Safety》2023,22(4):3444-3477
Myofibrillar protein (MP) endows muscle foods with texture and important functional properties, such as water-holding capacity (WHC) and emulsifying and gel-forming abilities. However, thawing deteriorates the physicochemical and structural properties of MPs, significantly affecting the WHC, texture, flavor, and nutritional value of muscle foods. Thawing-induced physicochemical and structural changes in MPs need further investigation and consideration in the scientific development of muscle foods. In this study, we reviewed the literature for the thawing effects on the physicochemical and structural characters of MPs to identify potential associations between MPs and the quality of muscle-based foods. Physicochemical and structural changes of MPs in muscle foods occur because of physical changes during thawing and microenvironmental changes, including heat transfer and phase transformation, moisture activation and migration, microbial activation, and alterations in pH and ionic strength. These changes are not only essential inducements for changes in spatial conformation, surface hydrophobicity, solubility, Ca2+-ATPase activity, intermolecular interaction, gel properties, and emulsifying properties of MPs but also factors causing MP oxidation, characterized by thiols, carbonyl compounds, free amino groups, dityrosine content, cross-linking, and MP aggregates. Additionally, the WHC, texture, flavor, and nutritional value of muscle foods are closely related to MPs. This review encourages additional work to explore the potential of tempering techniques, as well as the synergistic effects of traditional and innovative thawing technologies, in reducing the oxidation and denaturation of MPs and maintaining the quality of muscle foods. 相似文献