剪切时间对肉糜中微粒分散特性的影响

为形成乳化性良好的肉糜,研究不同剪切时间对肉糜中脂肪微粒粒径的影响。实验以猪背最长肌和背膘为原料肉,在3000r/min剪切速率下分别斩拌1、3、5、7min制成生肉糜,利用激光粒度分析仪测定不同剪切时间下肉糜中脂肪微粒大小和粒度分布特点。结果显示：剪切5min和7min条件下,肉糜中脂肪微粒粒径比较小、粒度分布集中,且无显著性差异。     

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。     

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。     

脂肪类型对乳化肉糜中蛋白膜形成情况的影响

研究脂肪类型对乳化层中蛋白膜形成的影响,包括对乳化液乳化特性、微粒大小、Zeta电位以及脂肪微粒吸收蛋白量等测定。结果表明,乳化液乳化活性表现为背膘组黄油组豆油组,而乳化稳定性则是黄油组背膘组豆油组。背膘组的微粒大小显著较小,而乳化体系破坏后得到的背膘脂肪微粒显著大于另外2组。从Zeta电位值看出肌肉蛋白溶液的稳定性要高于原乳化液。此外,黄油组中表面吸收蛋白总量和单位界面膜吸收蛋白量均高于另外2组。总之,肌肉蛋白质可以较好地乳化背膘和黄油改善乳化液的乳化活性并且提高乳化稳定性,而乳化体系破坏后,黄油可以提高脂肪吸收蛋白量,由此得出黄油可以有效地形成蛋白膜,有利于提高乳化液的稳定性。     

斩拌时间和pH值对牛肉凝胶特性的影响

主要研究pH值和斩拌时间对牛肉糜凝胶特性及颜色的影响 ,确定最佳的斩拌条件。结果表明 ,当肉糜的酸碱度由酸性向中性靠拢时 ,牛肉糜制品的凝胶硬度、弹性、粘聚性均逐渐增大 ,牛肉糜制品的硬度、弹性、粘聚性随着斩拌时间的增加先增大后减小。在斩拌2 0min时达到最高值     

脂肪剪切乳化和蛋白基质对肉糜乳化稳定性的重要作用

完全粉碎肉制品由肌肉蛋白质、脂肪颗粒、水、盐和碳水化合物等物质组成。在肉糜生产过程中,脂肪被剪切成形状和大小不同的固态脂肪颗粒或液态脂肪滴,如何防止脂肪和水分从产品中分离成为挑战。在过去几十年里,涌现出两种学说用于解释肉糊乳化稳定性：水包油型乳化学说和蛋白基质物理镶嵌固定学说,前者强调脂肪球周围形成界面蛋白膜作用,后者强调蛋白基质对脂肪的固定作用。本文讨论了支持这两个研究方向的成果,并在此基础上提出几点建议。     

蛋清蛋白乳化香肠的加工工艺研究

以新鲜猪肉、蛋清蛋白为主要原料制作乳化香肠,主要研究了腌制时间、乳化搅拌时间和肉糜斩拌时间对乳化香肠品质的影响。通过感官评价、剪切力、系水力三个指标进行正交分析确定最佳加工工艺,实验结果表明,腌制时间、乳化搅拌和肉糜斩拌都对乳化香肠品质均有不同程度的影响,通过正交试验得到乳化香肠的最佳加工工艺条件为腌制时间4d、乳化搅拌时间5min,乳化肉糜斩拌时间5min,在此最佳加工工艺条件下,乳化香肠的品质较佳。     

乳化型香肠生产原理和常见问题分析

主要探讨了乳化型香肠的加工原理以及斩拌和乳化时的温度、p H、脂肪颗粒大小、可溶性蛋白的数量和类型、乳化物的粘度等因素对肉糜乳化物稳定性的影响 ,并对如何控制这些因素、生产高质量的产品进行了分析。     

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.     

影响精细斩拌添加碎冰量的因素——提高火腿肠质量的探讨(四)

灌制火腿肠的肉糜在精细斩拌工序中需要添加一定量碎冰 以降低斩拌温度和调节肉糜稠度,避免因斩拌升温而造成出油、结着力下降,并可改善产品弹性、嫩度,从而提高成品率和质量。然而,斩拌中的碎冰添加量并不是一个常量,要受到生产环境条件、腌制肉馅物化特性、肉糜乳化稳定程度,肥肉添加量、辅料添加量和添加顺序等     

Microstructural changes of starch in cooked wheat grains as affected by cooking temperatures and times

The changes of starch microstructure in soft and hard wheat grains after cooking in a pressure cooker were investigated using a scanning electron microscope (SEM) and a light microscope (LM) in conjunction with image analysis. The conditions studied included variation of the cooking times (20-120 min) at the constant temperature (120 °C) and with variable temperatures (110-140 °C) for constant time (40 min). SEM images showed that steam induced changes in the intact starch granules of cooked wheat grains, with the microstructure becoming more in mud-like structure, with increased cooking time or temperature. The swelling and gelatinization of starch granules could contribute to this change. Suspensions of cooked wheat flour were selectively stained with iodine, for observation using the LM. The image analysis software was used for quantitative analysis of the images captured from the LM, providing both the number and area of the starch granules (determined from the dark-blue spots) per fixed image size. With increased cooking time or temperature, the number of starch granules decreased and the area increased as a result from the swelling and melting of starch granules. This study demonstrated the use of SEM and LM for the investigation of starch granules in cooked wheat grains without prior starch isolation.     

Physicochemical characteristics of mixed colloidal dispersions: Models for foods containing fat and starch

Mixed colloidal dispersions, consisting of starch granules and lipid droplets, were used as model systems to represent commercial food products, such as sauces, desserts, and soups. Colloidal dispersions were prepared by mixing unheated modified starch (3.5 or 5.0 wt%) and lipid droplets (2.5, 5.0 or 8.0 wt% oil) together and then heating (90 °C for 5 min) to promote starch gelatinization. The lipid droplets were stabilized by a food-grade surfactant consisting of a mixture of diacetyl tartaric acid ester of mono-diglycerides (DATEM) and mono-diglycerides. The influence of thermal processing and composition (starch, lipid, surfactant content) on the particle size, microstructure, lightness, and shear viscosity of the model sauces was examined. There was a pronounced increase in shear viscosity upon heating, which was attributed to the swelling of the starch granules leading to a close-packed particle suspension. The shear viscosity and lightness of the colloidal dispersions increased with increasing starch and fat content, with fat droplets dominating lightness and starch granules dominating viscosity. The amount of surfactant present also influenced the rheology of the mixed colloidal dispersions, which was attributed to its ability to modify starch granule interactions. Overall, these results have important implications for designing high quality emulsion-based food products, such as soups, sauces, desserts, and beverages.     

木瓜蛋白酶对猪肉脯嫩化效果的研究

本文首先利用单因素试验得到了木瓜蛋白酶添加于猪肉脯中的用量、作用温度及作用时间的大概范围,再利用正交试验得到了木瓜蛋白酶嫩化猪肉脯的最适作用条件:木瓜蛋白酶用量360U/g、作用温度70℃、作用时间为20min。然后利用扫描电镜,对未处理猪肉和木瓜蛋白酶嫩化后的猪肉微观结构进行了观察,结果发现,木瓜蛋白酶处理过的猪肉的肌肉纤维结构具有明显的断裂痕迹,说明木瓜蛋白酶对猪肉脯确实具有嫩化作用。最后验证了木瓜蛋白酶嫩化后的猪肉脯在嫩度、水分含量、水分活度、成品率、感官指标上的改善情况,结果表明,木瓜蛋白酶处理后的猪肉脯在嫩度和感官得分上均优于未处理样品,并且木瓜蛋白酶处理对产品贮藏不会产生不利影响。     

THERMO-RHEOLOGY,QUALITY CHARACTERISTICS,AND MICROSTRUCTURE OF FRANKFURTERS PREPARED WITH SELECTED PLANT AND MILK ADDITIVES1

The purpose of this study was to evaluate substitution of nonmeat proteins for meat protein on the thermo-rheology, quality characteristics, and microstructure of frankfurters. Batters were formulated to contain either 2% sodium caseinate or soy protein isolate, or 3.5% whey protein concentrate or wheat germ flour. The storage modulus (G') of all treatments initially decreased during temperature ramping from 20–50C, then increased rapidly from 60–80C, with all-meat batter exhibiting the highest G' at 80C. Substitution with nonmeat proteins decreased G', shear force, compression force, and red color of meat compared with all-meat frankfurters. Increased protein content, cooking yield, and decreased fat content were obtained with nonmeat protein formulations. Electron micrographs showed that nonmeat proteins were able to bind to the meat protein and fat, forming a protein-fat matrix with less coalescence of fat droplets. Sodium caseinate, soy protein isolate, whey protein concentrate, and wheat germ flour can be used as protein additives in comminuted meat products without adversely affecting their physical characteristics.     

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。     

Creation of reduced fat foods: Influence of calcium-induced droplet aggregation on microstructure and rheology of mixed food dispersions

The impact of calcium-induced fat droplet aggregation on the microstructure and physicochemical properties of model mixed colloidal dispersions was investigated. These systems consisted of 2 wt% whey protein-coated fat droplets and 4 wt% modified starch granules heated to induce starch swelling (pH 7). Optical and confocal microscopy showed that the fat droplets were dispersed within the interstitial region between the swollen starch granules. The structural organisation of the fat droplets within these interstitial regions could be modulated by controlling the calcium concentration: (i) at a low calcium concentration the droplets were evenly distributed; (ii) at an intermediate calcium concentration they formed a layer around the starch granules; (iii) at a high calcium concentration they formed a network of aggregated droplets. Paste-like materials were produced when the fat droplets formed a three-dimensional network in the interstitial region. The properties of fat droplet–starch granule suspensions can be modulated by altering the electrostatic interactions to alter microstructure.     

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。     

氯化钙与高静压处理减钠盐鸡肉凝胶对小鼠生长及消化特性的影响

减钠盐肉制品对机体消化吸收等营养功能的影响,是肉类科技领域值得探究的问题。采用动物模型衡量受压减钠盐（氯化钠含量1.25%）鸡肉凝胶的体内消化特征,研究氯化钙添加量0%＋0.1 MPa处理（C组）、氯化钙添加量0.2%（加入到原料肉糜中）＋0.1 MPa处理（CA组）、氯化钙添加量0%＋200 MPa（10 min、25 ℃）处理（H组）和氯化钙添加量0.2%＋200 MPa（10 min、25 ℃）处理（CH组）4 组减钠盐鸡肉凝胶饲料对小鼠消化特性和生长的影响。结果表明：经过小鼠胃和小肠消化后,与非受压的C组和CA组相比,受压的H组和CH组小鼠食糜中蛋白质降解产物的分子质量和粒径均较大（P＜0.05）,表明200 MPa处理会降低蛋白质的消化降解;2 个受压组的小鼠血清尿素氮含量显著高于非受压组（P＜0.05）,添加0.2%氯化钙的CA及CH组小鼠血清总蛋白含量显著低于对照组C（P＜0.05）,CH组的皮下脂肪质量也显著低于C组（P＜0.05）,表明200 MPa处理和添加0.2%氯化钙具有协同减少小鼠皮下脂肪积累的作用,显示出改善低钠盐凝胶肉制品营养功能的潜力。     

Physicochemical properties and application of micronized cornstarch in low fat cream

With normal cornstarch (CS) as material, micronized starch was prepared first by acid hydrolyzed pretreatment and then ball-milling (HMS). A control sample (MS) was prepared by ball-milling without pretreatment. Particle size and shape of micronized starch were investigated, and its application in low fat cream was studied. The Maltase cross of HMS granules almost disappeared and the particle size clearly decreased. It was evident that acid-lintnerised starch granules were more susceptible to break down upon milling. However, the granules would aggregate with an increase in milling time. Compared with full-fat cream, the apparent viscosity of low-fat cream increased, while fat globules partial coalescence rate, overrun and textural properties decreased with the increasing of the fat replacement rate. The average particle size of whipped cream increased with the increase of whipping time. Results indicate that a 15% fat replacement rate would produce cream with good foaming and storage stability.