剪切时间对脂肪微粒大小和肉糜品质的影响

为研究剪切时间对肉糜中脂肪微粒大小和品质的影响,研究分别测定4种不同剪切时间(1、3、5min和7min)下肉糜中脂肪微粒粒径大小和粒度分布特点、乳化稳定性和凝胶强度大小。结果表明,剪切时间为5min和7min的肉糜中脂肪微粒比较小、粒度均匀,乳化稳定性好,凝胶强度大,但这两处理组间差异并不显著(P>0.05)。因而,试验研究认为3000r/min剪切速度下剪切5min就可制成品质好的肉糜。     

剪切条件下制备的肉糜中脂肪微粒的微观结构特点

研究在剪切条件下制备的肉糜中脂肪微粒分布规律及微观结构特点。以猪背最长肌为原料,绞碎斩拌3min后再加入背膘斩拌5min。分别用光学显微镜和电子显微镜对肉糜和凝胶进行电镜观察。结果表明：在剪切过程中,背膘被剪切成大小形状各不相同的液态脂肪滴和固态脂肪颗粒,有的脂肪滴和脂肪颗粒能够聚集形成脂肪微粒簇。其表面都包被着一层蛋白膜,或单独地或相互交联分散在蛋白基质中。     

以乳清蛋白为基质的脂肪替代品的微粒化研究

研究了以乳清蛋白WPC-80为基质制备脂肪替代品的微粒化工艺。用组织捣碎机分别设定不同的微粒化时间和强度组合对乳清蛋白热凝胶进行微粒化处理。粒径分布分析发现微粒化处理后,50%的颗粒在10μm左右,超微结构分析发现,微粒化处理后的蛋白质凝胶表面变得光滑、柔软,可以模拟脂肪的特性。乳清蛋白脂肪替代品的最佳微粒化工艺条件为转速12 000 r/min,处理时间为5 min。     

创新组方肠内营养乳剂制备的工艺参数研究

目的:初步确定初乳制备工艺参数的范围,为下一步肠内全营养脂肪乳产品的工艺研究提供参考。方法:用D50和跨距的平均值为工艺参数评价指标,固定油相和乳化剂用量,用不同的剪切转速、剪切时间和剪切温度进行实验,初步制备脂肪乳初乳,用激光衍射的方式得到初乳的粒径和粒度分布。结果与结论:当剪切转速在2 500~3 500r/min,剪切时间在10~20min,剪切温度在25~30℃时,粒径较小,而且粒度分布集中。     

NaCl浓度和pH对肉糜中脂肪微粒蛋白吸收量及凝胶特性的影响

研究了不同浓度（0．2mol／L和0．6mol／L）NaCl和pH（6．0和6．5）对肉糜中脂肪微粒表面蛋白吸收量、乳化稳定性、凝胶硬度和微观结构的影响。研究结果表明,高浓度（0．6mol／L）NaCl能够显著提高肉糜中脂肪微粒表面蛋白吸收量和单位界面膜蛋白吸收量,有效地改善肉糜乳化稳定性、凝胶硬度和微观结构等指标（P〈0.05）。但在相同浓度（0．2mol／L和0．6mol／L）NaCl条件下,较大pH（6．0和6．5）对脂肪微粒表面蛋白吸收量、单位界面膜蛋白吸收量、乳化稳定性、凝胶硬度和微观结构等指标无作用效果（P〉0．05）．因此．本实验认为0．6mol／L NaCl（pH6．0和6．5）的提取条件下能够充分剪切肌肉蛋白和脂肪,肉糜乳化性能好.     

大豆蛋白稳定乳液油凝胶的制备及其在肉糜中的应用

以大豆蛋白为稳定剂,葵花籽油为油相,通过高速剪切乳化技术制备乳液油凝胶,研究载油量、大豆蛋白浓度和热处理时间对乳液油凝胶的影响,并将乳液油凝胶应用于肉糜中替代动物脂肪。结果表明：大豆蛋白颗粒可以承载体积分数达70%的油相,且在大豆蛋白浓度超过1%的条件下,能形成稳定的乳液油凝胶,其粒径随着大豆蛋白浓度的增加而略微变小。乳液油凝胶经80 ℃热处理后,粒径大小随加热时间基本不变,显示良好的热稳定性。流变分析表明乳液油凝胶的黏度随剪切速率升高而下降,不同加热时间下的储能模量均比损耗模量高,表明乳液形成了弹性的类凝胶网络,且加热处理45 min 的乳液油凝胶黏弹性最为突出。肉糜经高温蒸煮后,肉糜蒸煮得率随乳液油凝胶替代比例的升高而提高,当乳液油凝胶完全替代猪油脂时,油脂和水分的渗出率明显降低。     

纳米ATO导电粉的分散性

针对纳米ATO导电粉在水中均匀分散性差的问题,以平均粒径和沉降率为指标,探讨分散剂种类和用量对纳米ATO水浆分散效果的影响。以pH值、高速剪切作用时间以及超声波作用时间为影响因素,采用单因素试验和正交试验法研究纳米ATO水浆的分散工艺。结果表明:当分散剂SPP用量为纳米ATO导电粉的2.0倍,pH值为7,高速剪切作用时间为40 min,超声波作用时间为15 min时,纳米ATO水浆分散效果最好。在最优分散工艺条件下,通过粒径分析得纳米ATO水浆中ATO导电微粒的粒径主要分布在60～80 nm。     

计算机视觉技术预测肉糜斩拌终点的初步研究

利用计算机视觉技术研究肉糜斩拌终点的判定方法,防止斩拌过程中斩拌不足或斩拌过度而引起的产品质量下降。本研究以猪后腿肉和背膘为主要原料,按照肥瘦比3/7添加比例进行斩拌,分别于第6、7、8、9、10、12、14、16和18min取样,测定肉糜颜色和加工特性指标。结果表明:斩拌时间对肉糜的颜色、蒸煮损失、脂肪损失、硬度、弹性、Purge损失以及贮能模量(G’)均有影响,肉糜HSL颜色空间变量中亮度值(L)与蒸煮损失、脂肪损失、硬度等加工特性指标之间的相关性显著。因而,利用计算机视觉技术测定的肉糜亮度值用于预测肉糜斩拌终点是可行的。     

人参淀粉微粒的制备工艺及性质

为了探究人参淀粉微粒的制备工艺及性质,采用醇沉法制备人参淀粉微粒。利用单因素试验分析淀粉质量浓度、无水乙醇体积、搅拌速度等工艺条件对人参淀粉微粒性质的影响;利用扫描电子显微镜和激光粒度分布仪研究人参淀粉微粒的形貌、粒径尺寸及粒度分布情况,研究发现,人参淀粉微粒是表面具有块状结构的不规则的形貌,其粒径尺寸及粒度分布受淀粉质量浓度、无水乙醇体积和搅拌速度的影响;当淀粉质量浓度增加或无水乙醇体积减少时,均会导致人参淀粉微粒粒度增加及粒度分布不均匀的现象;搅拌速度对人参淀粉微粒粒度分布的影响不是单一的。以人参淀粉微粒质量浓度为2%、无水乙醇体积为40倍、搅拌速度为150 r/min的工艺条件制得的人参淀粉微粒具有相对较小的粒径尺寸,粒径主要集中在1～4μm,粒度分布均匀,适合作为食品原料进行加工使用。     

捶打时间对牛肉凝胶品质的影响研究

为探究捶打工艺对牛肉凝胶品质的影响,以打浆工艺制作的牛肉凝胶为对照组,通过测定不同捶打时间的牛肉凝胶色差、肌原纤维蛋白氧化程度、蒸煮损失率、脂肪渗出率、质构特性,并测定牛肉凝胶的肉糜粒径、蛋白质二级结构及微观结构的变化,了解捶打时间对牛肉凝胶品质的影响机理。结果表明,捶打时间在15~40 min之间时,随着捶打时间延长,肉糜L*值与W值先降后升,a*值和b*值先升后降;肌原纤维蛋白氧化程度不断增加,总巯基不断减少,羰基值及溴酚蓝结合量不断增加;蒸煮损失率与脂肪渗出率先减少后增加;凝胶质构中硬度、咀嚼性逐渐增加,弹性、内聚性与回复性先增加后减少,以30 min为分界点,捶打30 min以内凝胶品质呈上升趋势,超过30 min呈下降趋势。30 min前凝胶品质上升原因为肉糜粒径减小及蛋白质二级结构β-折叠增多;30 min后凝胶品质下降原因为蛋白质氧化程度加深及凝胶微观结构的改变。试验结果表明传统捶打方式能提高肉糜品质,但过度捶打会引起肉糜品质劣变。     

Microstructure of Reduced Salt Meat Batters as Affected by Polyphosphates and Chopping Time

Microstructural and textural changes due to salt reduction (2.5% to 1.5%), 0.4% tripolyphosphate (TPP), hexametaphosphate (HMP) or sodium acid pyrophosphate (SAPP) addition and chopping time (40 vs 100 cutter revolutions) were studied in poultry meat batters. Salt reduction significantly increased liquid and fat losses in the long chopping but not in the short chopping treatments. Scanning electron micrographs of reduced salt batters revealed fat globules which lost fat during cooking. HMP and SAPP addition significantly improved emulsion stability. Average fat globule size decreased as chopping time increased and/or salt decreased. Hardness was higher in the NaCl treatments in the short chopping as compared to the long chopping. The opposite was observed when phosphates were added.     

Modelling the yield and texture of comminuted pork products using color and temperature. Effect of fat/lean ratio and starch

Practices to control the processing of finely comminuted meat products are proposed. The objective was to test the practical value of both temperature and light reflection measurements made during emulsification as potential indicators of cooking losses and resulting gel texture in pork sausages emulsified within a wide range of temperatures and starch and fat levels. Prior to cooking, pork batters were chopped for different times to ensure final emulsion temperatures ranging from 5 to 50°C. The effects of the fat/lean ratio (0.25 and 0.67) and starch addition (0.8 and 3.2% w:w) on temperature and optical reflection were also investigated. The chopping increased the temperature and decreased the light reflection of fresh meat emulsion. There was no relevant loss of emulsifying capacity at emulsion temperature below 30°C and lightness values over 70 CIE units. The losses and textural parameters of cooked emulsions could be predicted by means of non-linear regression equations based on the temperature and color of the raw emulsion. The determination coefficients obtained ranged from 0.89 to 0.99. The prediction models needed to be fitted to each batter formulation, especially in the presence of reduced levels of gelation agents (meat protein and starch). Lightness was a better predictor than chromaticity, since it decreased constantly with chopping in the range of final emulsion temperatures studied (5-50°C). This confirms previous studies that lightness could be used for monitoring emulsion stability in meat batters.     

Protein-Protein Interaction and Fat and Water Binding in Comminuted Flesh Products

The possible role of protein-protein interaction in influencing the water and fat binding capacity of comminuted flesh products was studied. Water and fat binding by meat batters diminish when temperatures exceed 16°C during comminution. The loss of binding capacity was partially reversible, and cooling the batters to 0°C by addition of dry ice and rechopping allowed a partial recovery of the fat and water binding capacity. A cause and effect relationship between the change in fat and water binding by meat batters on chopping and protein-protein interaction in actomyosin solutions was demonstrated. Protein-protein interaction results in molecular aggregation and when measured as an increase in light scattering absorbance at 320 nm by a protein solution, the reaction was shown to be reversible between 4 and 30°C. When actomyosin solutions extracted from meat samples showed reduced protein-protein interaction in the temperature range used in chopping, the batters made from these meats also showed the least loss in fat and water binding capacity with prolonged chopping. Controlling temperatures during chopping within a range where protein-protein interaction in actomyosin solutions was found to be minimal, allowed prolonged chopping without loss in fat and water binding.     

Physicochemical Effects of the Lipid Phase and Protein Level on Meat Emulsion Stability,Texture, and Microstructure

ABSTRACT: The effects of beef fat (25%) substitution with rendered beef fat, canola oil, palm oil, or hydrogenated palm oil at varying meat protein levels (8%, 11%, and 14%) were studied in emulsified beef meat batters. There was no significant difference in fat loss among meat batters made with beef fat, rendered beef fat, or palm oil. Hydrogenated palm oil provided the most stable batters at all protein levels. Increasing meat protein to 14% resulted in high fat loss in batters prepared with canola oil, which did not occur in the other formulations. This indicates that the physicochemical characteristics of fat/oil affect emulsion stability. Cooked batter hardness was higher (P < 0.05) when protein level was raised; highest in hydrogenated palm oil batters when compared at similar protein levels. As protein level was raised springiness values were increased in all the meat treatments. Springiness was higher in the canola oil treatments. Light microscopy revealed fat globule coalescence in canola oil meat batters prepared with 14% protein, as well as the development of fat channels and more protein aggregation; both seem to result in lower emulsion stability. Hydrogenated palm oil batters showed fat particles with sharp edges as opposed to the round ones seen in all other treatments.     

IMPORTANCE OF FAT EMULSIFICATION AND PROTEIN MATRIX CHARACTERISTICS IN MEAT BATTER STABILITY

Finely comminuted meat products are a mixture of proteins, fat particles, water, salt and often carbohydrates. During preparation of the raw meat batter, fat is chopped into tiny particles which are thoroughly mixed within the comminuted lean meat. During cooking, the challenge is to minimize/prevent fat and moisture separation from the product. During the past 3–4 decades two major, but differently oriented, research thrusts have been presented to explain the mechanism(s) by which meat batters are stabilized. They include the emulsion theory and the physical entrapment theory. The first emphasizes the importance of fat emulsification (i.e., forming an interfacial protein film around the fat globules) whereas the physical entrapment theory stresses the importance of the protein matrix in binding the fat. The exact mechanism by which finely comminuted meat batters are stabilized is still uncertain. In this review arguments presented to support both research thrusts are discussed.     

A rapid method based on front-face fluorescence spectroscopy for the monitoring of the texture of meat emulsions and frankfurters

In order to investigate the potential of fluorescence spectroscopy to characterise meat emulsions and frankfurters, a split-plot design comprising three factors at three levels each, i.e. fat/lean ratios (0.25, 0.7 and 1.5), chopping speed (1000, 2000 and 3000 rpm) and chopping time (1, 3 and 7 min), was considered. Principal component analysis and hierarchical ascendant clustering performed on the texture attributes and L(*)a(*)b(*) value data sets for the batters and frankfurters showed that a limited number of clusters can be discriminated, mainly according to the chopping conditions. From the fluorescence spectra of batters and frankfurters, the similarity maps defined by principal components 1 and 2 allowed clear discrimination between formulations with a high fat content from those of low fat content, whereas formulations with an intermediate fat content overlapped. Canonical correlation analysis (CCA) showed strong correlations between the batter texture attributes and the batter fluorescence spectra since the first pairs of canonical variates exhibited squared correlation coefficients of 0.88. Moreover, it was shown by CCA that batter fluorescence spectra and frankfurter texture-attributes were highly correlated (r(2)=0.91) for the first canonical variates suggesting that it may be possible to predict the texture of a frankfurter from a fluorescence spectrum recorded on the batter.     

肉品高效斩拌乳化技术研究进展

在肉制品加工中,斩拌乳化工艺主要起保水和保油作用。斩拌乳化效果主要受工艺参数和原辅料两方面因素的影响。在工艺方面,斩拌温度、斩拌速度、斩拌时间、物料pH等参数是乳化技术的关键参数;在原料方面,原料肉的种类、非肉蛋白、乳化剂、亲水性胶体等因素直接影响乳化效果。本文重点综述了肉品斩拌乳化技术在这两个方面的研究进展。     

Mechanisms of meat batter stabilization: a review.

Comminuted meat products are a complex mixture of muscle tissue, solubilized proteins, fat, salt, and water. The two theories that have been presented to explain meat batters stabilization are reviewed. The emulsion theory explains stabilization by the formation of a protein film around fat globules, whereas the physical entrapment theory emphasizes the role of the protein matrix in holding the fat in place during chopping and subsequent heating. However, some aspects of stabilization cannot be explained adequately by either one of these theories. In this article the role of meat proteins, aqueous phase, and lipid phase are examined in light of past and recent research findings.