Technological and functional properties of reduced-salt pork batter incorporated with soy protein isolate after pressure treatment

To investigate the effects of different pressures (0.1–400 MPa), the techno-functional properties, water distribution and mobility of reduced-salt pork batters (1% NaCl) supplemented with soy protein isolate (SPI, 2%) were examined. Compared with the batters treated at 0.1 MPa, those treated at 100–300 MPa showed significantly increased the cooking yield, hardness, springiness, cohesiveness, chewiness, and G′ values of gel and reduced the initial relaxation times of T_2b, T₂₁ and T₂₂, as observed from the results of low-field NMR. Among all samples, those treated at 200 and 300 MPa had the highest L^* value, cooking yield, hardness, springiness, cohesiveness, chewiness and G′ value of gel, with the largest peak ratio of P₂₁ and the smallest peak ratio of P₂₂. Overall, treatments at 200 and 300 MPa improved the gel properties and lowered the water mobility of reduced-salt pork batters supplemented with SPI.     

大豆分离蛋白添加方式对猪肉凝胶特性的影响

大豆分离蛋白是肉制品加工中常用的植物蛋白,能够改善肉制品品质,但添加方式影响肉制品质量。本文研究添加大豆分离蛋白和11S球蛋白变性的大豆分离蛋白乳化猪背膘对猪肉肉糜蒸煮得率、乳化稳定性及猪肉凝胶色差和质构的影响,并应用低场核磁共振技术,研究不同处理猪肉凝胶中水分分布状态和水分迁移特性的异同。与添加大豆分离蛋白相比,添加大豆分离蛋白乳化猪背膘显著提高(P0.05)猪肉肉糜的蒸煮得率和乳化稳定性,提高凝胶的L*-值和b*-值,硬度、弹性、内聚性和咀嚼性等。低场核磁共振结果表明:添加大豆分离蛋白乳化猪背膘的凝胶,T_(2b)和T_(22)弛豫时间较短,说明水分可移动性降低;T_(21)的峰比例增加,而T_(22)的峰比例降低,说明不易流动的水分含量增加,凝胶有较好的保水性。     

Physicochemical, functional and angiotensin converting enzyme inhibitory properties of amaranth (Amaranthus hypochondriacus) 7S globulin

BACKGROUND: Amaranth 7S globulin is a minor globulin component and its impact on the properties of an amaranth protein ingredient depends on its proportion in the variety of amaranth being considered. Some physicochemical, functional and angiotesin I‐converting enzyme (ACE) inhibitory properties of amaranth vicilin were studied in this work and compared with the 11S globulin. RESULTS: Fluorescence spectroscopy results indicated that 7S globulin tryptophans were more exposed to the solvent and, by calorimetry, the 7S globulin denaturation temperature (T_d) was found lower than the 11S globulin T_d, suggesting a more flexible structure. The 7S globulin surface hydrophobicity was higher than that of the 11S globulin, which is in agreement with the better emulsifying properties of the 7S globulin. The solubility in neutral buffer of the 7S globulin (851 ± 25 g kg^?1) was also higher than that of the 11S globulin (195 ± 6 g kg^?1). Bioinformatic analyses showed the presence of ACE inhibitory peptides encrypted in 7S tryptic sequences and peptides released after in vitro gastrointestinal digestion showed a high ACE‐inhibitory capacity (IC₅₀ = 0.17 g L^?1), similar to that of 11S globulin peptides. CONCLUSION: Compared with the 11S globulin, the 7S globulin presents similar ACE inhibitory activity and some functional advantages, better solubility and emulsifying activity, which suits some food requirements. The functional behavior has been related with the structural properties. Copyright © 2011 Society of Chemical Industry     

Effects of combined high-pressure and heat treatment on the textural properties of soya gels

SPI, 7S, and 11S globulin at 12% (w/v) protein concentration, at neutral pH, did not form gels when heat-treated (90 °C, 15 min) or when high pressure-treated (300–700 MPa), except for the 11S, which formed a gel when heat-treated. The combination of heat and pressure (that is heating the solutions in a water bath and then pressure-treating at room temperature or the reverse sequence), led to differences: when heat-treatment was before high-pressure treatment, only the 11S fraction formed a self-standing gel; however, when the solutions were pressurised before heat treatment, all the proteins formed self-standing gels. The textural and water-holding properties were measured on the gels formed with the three different soy proteins.     

Influence of inulin/oligofructose on the acid‐induced cold aggregation and gelation of preheated soy proteins

BACKGROUND: In recent years inulin‐type prebiotics have attracted much attention due to consumers' awareness of the health benefits of functional foods. Currently no information is available about the possible texture‐modifying effect of these non‐ionizable polar carbohydrates in different soy‐based food systems. In this study, the effect of inulin/oligofructose on the cold aggregation and gelation of preheated soy protein isolate (SPI) and its fractions (7S, 11S, and their mixture), induced by glucono‐δ‐lactone (GDL), were evaluated by turbidity (A₆₀₀) and dynamic rheological measurements. RESULTS: Oligofructose significantly delayed the aggregation of all protein samples and decreased the end‐point optical density of 11S fraction and SPI. Inulin, a long‐chain fructan, only delayed the aggregation of 7S globulin and reduced the capacity of aggregation (A₆₀₀) of SPI. While oligofructose showed no significant effect, the addition of 5% (w/v) inulin enhanced the gelation of SPI and the 7S/11S mixture, which was demonstrated by the increase in gel storage modulus up to 13.6% and 10.1% (P < 0.05), respectively. CONCLUSION: Inulin was found to enhance the viscoelastic properties of GDL‐induced cold‐set soy protein gels. It is expected that ‘functional’ cold‐set gel products with improved texture can be prepared from preheated soy proteins and inulin. Copyright © 2009 Society of Chemical Industry     

Roselle (Hibiscus sabdariffa L.) and soybean oil effects on quality characteristics of pork patties studied by response surface methodology

Response surface methodology was used to investigate the effect and interactions of processing variables such as roselle extract (0.1–1.3%), soybean oil (5–20%) on physicochemical, textural and sensory properties of cooked pork patties. It was found that reduction in thickness, pH, L* and b* values decreased; however, water-holding capacity, reduction in diameter and a* values increased, respectively, as the amount of roselle increased. Soybean oil addition increased water-holding capacity, reduction in thickness, b* values of the patties. The hardness depended on the roselle and soybean oil added, as its linear effect was negative at p < 0.01. The preference of color, tenderness, juiciness, and overall quality depend on the addition of roselle and soybean oil. The maximum overall quality score (5.42) was observed when 12.5 g of soybean oil and 0.7 g of roselle extract was added. The results of this optimization study would be useful for meat industry that tends to increase the product yield for patties using the optimum levels of ingredients by RSM.     

Comparative effect of red yeast rice (Monascus purpureus), red beet root (Beta vulgaris) and betanin (E‐162) on colour and consumer acceptability of fresh pork sausages packaged in a modified atmosphere

Fresh pork sausages containing natural colorants, red yeast rice powder (Monascus purpureus; Frame^®) or a crude red beet root (Beta vulgaris) juice or commercial betanin (E‐162), at different concentrations, were packaged in an atmosphere containing 80% O₂ and 20% CO₂ and stored in the dark for 20 days. The following parameters were measured at 4 day intervals: instrumental colour (CIE L*, a*, b*, a*/b*, C* and h*), reflectance spectra, sensory discoloration (trained panel) and acceptability and willingness to purchase (habitual and non‐habitual consumer panels) under two different lighting displays (standard fluorescent and Promolux^® lamp). The use of colorants improved the colour properties of fresh pork sausages. Sausages with red yeast rice, red beet root juice and betanin had lower L* and h* and higher a* and a*/b* values than control samples. The colour properties of sausages with red beet root were the closest to control sausages, while sausages with red yeast rice had significantly lower b* values. Both natural colorants and betanin protected sausages from discoloration and extended acceptability and willingness to purchase by about 4 days, according to evaluation by habitual consumers under two different types of lighting display. Therefore, red beet root juice may be envisaged as the most suitable natural colorant for use in fresh pork sausages. Copyright © 2005 Society of Chemical Industry     

High-pressure treatment effects on proteins in soy milk

Effects of high-pressure treatment on the modifications of soy protein in soy milk were studied using various analytical techniques. Blue shifts of λ_max could be observed in the fluorescence spectra. Spectrofluorimetry revealed that the soy protein exhibited more hydrophobic regions after high-pressure treatment. Electrophoretic analysis showed the change of soy protein clearly and indicated that soy proteins were dissociated by high pressure into subunits, some of which associated to aggregate and became insoluble. High-pressure denaturation occurred at 300 MPa for β-conglycinin (7S) and at 400 MPa for glycinin (11S) in soy milk. High pressure-induced tofu gels could be formed that had gel strength and a cross-linked network microstructure. This provided a new way to process soy milk for making tofu gels.     

Effects of high hydrostatic pressure on enzymes, phenolic compounds, anthocyanins, polymeric color and color of strawberry pulps

BACKGROUND: Changes in activity of polyphenol oxidase (PPO), peroxidase (POD) and β‐glucosidase, individual phenolic compounds other than anthocyanins, total phenols, monomeric anthocyanins, polymeric color and instrumental color of strawberry pulps were assessed after high hydrostatic pressure (HHP) (400–600 MPa 5–25 min^?1) at room temperature. RESULTS: β‐Glucosidase was activated by 4.7–16.6% at 400 MPa 5–25 min^?1 and inactivated by 8.0–41.4% at 500 or 600 MPa. PPO and POD were inactivated at all pressures, the largest reduction in activity being 41.4%, 51.5% and 74.6%, respectively. The individual phenolic compounds and total phenols decreased at 400 MPa, but total phenols increased at 500 or 600 MPa. However, the monomeric anthocyanins, polymeric color and redness (a*) exhibited no change. HHP induced a decrease in lightness (L*) and an increase in yellowness (b*) at 400 MPa, but no significant alteration in L* value and b* value at 500 or 600 MPa was observed; this was attributed to higher residual activity of PPO, POD and β‐glucosidase at 400 MPa. Total color difference (ΔE) was ≥ 5 at 400 MPa and ?3 at 500 or 600 MPa. CONCLUSION: HHP effectively retained anthocyanins, phenolic compounds and color of strawberry pulps, and partly inactivated enzymes. Copyright © 2011 Society of Chemical Industry     

Effects of supercritical carbon dioxide treatment against generic Escherichia coli, Listeria monocytogenes, Salmonella typhimurium, and E. coli O157:H7 in marinades and marinated pork

This study was conducted to evaluate the effects of supercritical carbon dioxide (SC-CO₂) treatment on soy sauce and hot-pepper paste marinades, as well as in marinated pork products, for the inhibition of generic Escherichia coli, Listeria monocytogenes, Salmonella typhimurium, and E. coli O157:H7. SC-CO₂ was more effective at destroying foodborne pathogens when it was applied to the marinades than the marinated products. SC-CO₂ treatment at 14 MPa and 45 °C for 40 min resulted in a greater reduction in soy sauce (2.52–3.47 log CFU/cm²) than in hot-pepper paste marinade (2.12–2.72 log CFU/cm²). In the case of the marinated pork, when SC-CO₂ was applied at 14 MPa and 45 °C for 40 min, the reduction levels of L. monocytogenes were 2.49 and 1.92 log CFU/cm² in soy sauce and hot-pepper paste marinated pork, respectively. The results should be useful in the meat industry to help increase microbial safety and assure the microbial stability of marinades and marinated products.     

Formation of Transparent Gels of Sesame 13S Globulin: Effects of Fatty Acid Salts

The physicochemical properties of sesame 13S globulin gels containing fatty acid salts (FAS) were investigated. The softness, water-holding ability and transparency of the gels markedly increased in the presence of sodium oleate (NaCl_18:1) or sodium linoleate (NaC_18:2) at a 75 molar ratio to a molecule of the 13S globulin. The effect was not observed by the addition of sodium caprylate (NaC_8:0). Scanning electron microscopy showed that a very fine network structure was formed in the gel with 75 molar ratio of NaC_18:2. The addition of a suitable amount of FAS having a moderate length and an unsaturated carbon chain could improve the water-holding ability and transparency of the 13S globulin gel.     

高压和食盐对鸡肉肠品质特性的影响

在不同压强条件（0.1、200、400 MPa）下对不同食盐添加量（质量分数0%、1%、2%）的生鸡肉肠加热（60 ℃）处理30 min,测定处理后鸡肉肠的持水力、水分分布、质构特性和微观结构,分析高压和食盐对鸡肉肠热诱导凝胶特性的影响。结果发现：常压下,减少食盐添加量会降低鸡肉肠的保水性和质构特性,但高压处理能降低食盐对鸡肉肠的影响。相比常压组,200 MPa高压处理能显著提高产品的保水性和质构特性（P＜0.05）,而400 MPa的高压处理则显著降低产品的保水性和质构特性（P＜0.05）。高压能促进肉糜中的肌纤维分解,使不易流动水的比例升高,自由水比例下降;200 MPa下能形成致密的凝胶网络,而400 MPa则阻碍凝胶网络的形成。高压结合加热处理可用于提高低盐鸡肉肠的品质特性。     

食盐与超高压对低脂猪肉糜凝胶品质及热特性的影响

以含有0.2%海藻酸钠和1.8%大豆分离蛋白的低脂(≤2.0%)猪肉凝胶(LGPG)为对象,考察食盐添加量(0～2%)和超高压(300MPa)对LGPG品质及肉糜热特性的影响。结果表明:LGPG的蒸煮损失率和L*值随食盐质量分数升高而显著下降(P<0.05),保水率、a*值、b*值、硬度和咀嚼性则显著上升(P<0.05);300MPa处理可显著改善低盐(≤1.5%)LGPG的保水能力、硬度与咀嚼性;添加1.5%的食盐可显著降低肌球蛋白头部和肌动蛋白的变性温度,但会提高肌球蛋白尾部与肌浆蛋白的热稳定性;300MPa处理有降低肌球蛋白、肌浆蛋白和肌动蛋白热稳定性的倾向。     

Thanh法提取7S、11S球蛋白功能特性的研究

以中豆36为原料,分别提取大豆分离蛋白(SPI)、7S、11S球蛋白,系统地比较了它们的功能性质的差异。结果表明:SPI、7S及11S的功能特性之间存在较大差异,11S球蛋白具有较强的凝胶性、吸油性和溶解度;7S球蛋白具有较高的持水性和乳化性。     

Effects of oxygen and antioxidants on the lipid oxidation and yellow discolouration of film from red tilapia mince

BACKGROUND: Generally, biodegradable films from fish muscle protein become yellow after preparation. This discolouration is more likely associated with lipid oxidation and can be prevented by minimising the oxidation in the films. Thus, the effects of oxygen and antioxidants on lipid oxidation and yellow discolouration of film from red tilapia mince during storage were investigated. RESULTS: Both films prepared at pH 3 and 11, and kept under atmosphere containing 100% N₂ had the lowest TBARS value with the concomitant lowest b* and ΔE* values during storage (P < 0.05), when compared with other films kept in air and a 100% O₂ atmosphere. Films prepared at pH 3 and incorporated with antioxidants (Trolox and catechin) at all levels (100, 200 and 400 mg L^?1 film‐forming solution) had the lowest TBARS value, b* and ΔE* values during storage, indicating the retardation of lipid oxidation and yellow discolouration in films. Nevertheless, films prepared at pH 11 had no difference in TBARS values, in comparison with control film, regardless of antioxidant incorporation. Coincidentally, increases in b* and ΔE* values were observed in those films. CONCLUSIONS: Lipid oxidation was the main factor inducing yellow discolouration of film exposed to oxygen and the incorporation of antioxidants in film prepared at acidic pH was able to prevent yellow discolouration of resulting film. Copyright © 2012 Society of Chemical Industry     

Thermally Stimulated Luminescence in Powdered Soy Proteins

Heating powder isolated soy proteins (ISPs) in a N₂ environment produced thermally stimulated luminescence (TSL), in 2 major temperature regions, 50 to 250°C (region R1) and 250 to 350°C (region R2). In soy protein 7S fraction, strong TSL was detected in both regions with glow peak maximum (T_m) at 150 ± 15°C and at 300 ± 10°C. Two additional satellite or shoulder peaks were detected from the ISP and 7S protein fraction within region R1 at T_m = 90°C and T_m = 210°C. The soy protein 11S fraction produced a broad, poorly defined TSL peak in the low‐temperature region. Electron paramagnetic resonance spectroscopy data from the control ISP sample, deuterium sulfide‐treated ISP, ISP stored in either N₂ or O₂, and defatted soy flour, indicated that the trapped radicals present in ISP is associated with the production of the primary TSL peak at 150 ± 15°C. Activation energies required to release the trapped charges (for luminescence to occur) are approximately 0.70, 0.78, 1.50, and 1.8 eV for TSL at T_m = 100, 150, 200, and 300°C, respectively. The reaction mechanism that leads to the release of the trapped charges for TSL to occur followed a mixed order kinetic, between 1.5 and 1.8. The frequency factor varied between 10⁷/s and 10¹⁷/s.     

Texture and rehydration properties of texturised soy protein: analysis based on soybean 7S and 11S proteins

Soy protein, one of the most commonly used raw materials for texturised vegetable protein, has an important influence on texturised soy protein (TSP) with its 7S and 11S fractions. In this study, soy 7S and 11S proteins were extracted from soybean isolate and added back to the raw material to prepare TSP and analyse the effect of both on the physical properties of TSP. The results showed that the addition of 5% soy 7s or 11s protein increased the water-holding capacity (up to 9.04%) and rehydration rate (up to 25.71%) of TSP. Compared with adding soy 11s protein, adding soy 7s protein has a faster rehydration rate at a lower temperature (30 and 45 °C). After extrusion, the content of free sulphhydryl groups, total sulphhydryl groups, and disulphide bonds was significantly reduced (P < 0.05). The extrusion treatment caused degradation of the protein chains, and the proteins mainly formed insoluble polymers. Electrophoretic analysis revealed that the sodium dodecyl-sulphate (SDS) reducing the extractable rate of the precipitate after SDS non-reduction extraction of the TSP added with 5% soy 7S and 11S proteins were lower than that of the control. The proportion of different soybean protein components in TSP could change its texture, water-holding, and rehydration characteristics of it, which provides a new method for the characteristics design of TSP.     

Differential scanning calorimetry of lupin and soy proteins

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.     

Influence of Gluten-free Flours and their Mixtures on Batter Properties and Bread Quality

Gluten is a major component of some cereals and is responsible for flour technological characteristics to make bakery products. However, gluten must be eliminated from the diet of celiac patients because its ingestion causes serious intestinal damage. The objectives of this study were to assess the effect of different flours and their mixtures on thermal and pasting properties of batters, and to study the quality parameters and staling rate of gluten-free breads. Starch gelatinization temperatures and enthalpies depended on batter composition. Soy flour addition had a higher effect on rice than on corn starch, indicating some differential interaction between starch and proteins. Inactive soy flour incorporation improved all bread quality parameters in both corn- and rice-based breads. Higher batter firmness of formulations with soy addition (extrusion force was doubled in rice/soy and rice/corn/soy batters with regard to rice and rice/corn batters) partially explained higher specific volume (rice breads: 1.98 cm³/g; rice/soy 90:10 2.51 cm³/g, corn/soy 90:10: 2.05 cm³/g, whereas corn/soy 80:20: 2.12 cm³/g), as these batters retained more air during proofing. The staling rate was decreased by soy flour incorporation on rice (staling rate of rice breads with 10% soy diminished 52%, and with 20% of soy addition, 77%, both regarding to 100% rice breads) and corn formulation (the staling rate of corn/soy 80:20 breads was 5.9% lower than corn/soy 90:10) because of the high water-holding capacity of soy proteins and the interactions established with amylopectin that could retard the retrogradation process. Breads made with rice, corn, and soy flours showed the best quality attributes: high volume, good crumb appearance, soft texture, and low staling rate.     

Sarcoplasmic Protein Profile from Drip Loss in Relation to Pork Quality

The aim of this research was to correlate the sarcoplasmic protein profile of the natural drip loss of muscle with the technological and sensory quality of pork meat. Material for analysis was taken from 14 PenArLan pigs. Simple analysis of relationships between the test protein and meat quality traits showed that they adopt a range of from –0.58 to 0.72. It has been shown that the significance of glycolysis expressed as level of glycogen and lactic acid may be 86% (coefficient of correlations, C_R = 0.93), explained by the amount of certain enzymes. The higher relation has been obtained between studied enzymes and value of pH₂₄, L^* and b^* parameters of raw meat (98%; C_R = 0.99). By contrast, L^* and a^* parameters, sour flavor, and tenderness of grilled meat in 79% can be explained based on the content of the enolase, glyceraldehyde‐3‐phosphate dehydrogenase, and phosphoglycerate mutase (C_R = 0.89). The results of the multiple regression showed that amount of lactic acid was related to the quantity of the 3 enzymes: phosphofructokinase, AMP deaminase, phosphorylase b/phosphorylase b kinase (r = 0.88).