Preparation and impact of multiple (water-in-oil-in-water) emulsions in meat systems

The aim of this paper was to prepare and characterise multiple emulsions and assess their utility as pork backfat replacers in meat gel/emulsion model systems. In order to improve the fat content (in quantitative and qualitative terms) pork backfat was replaced by a water-in-oil-in-water emulsion (W₁/O/W₂) prepared with olive oil (as lipid phase), polyglycerol ester of polyricinoleic acid (PGPR) as a lipophilic emulsifier, and sodium caseinate (SC) and whey protein concentrate (WP) as hydrophilic emulsifiers. The emulsion properties (particle size and distribution, stability, microstructure) and meat model system characteristics (composition, texture, fat and water binding properties, and colour) of the W₁/O/W₂, as affected by reformulation, were evaluated. Multiple emulsions showed a well-defined monomodal distribution. Freshly prepared multiple emulsions showed good thermal stability (better using SC) with no creaming. The meat systems had good water and fat binding properties irrespective of formulation. The effect on texture by replacement of pork backfat by W₁/O/W₂ emulsions generally depends on the type of double emulsion (associated with the hydrophilic emulsifier used in its formulation) and the fat level in the meat system.     

Stability of Cream Liqueurs Containing Low-Molecular-Weight Surfactants

The effect of adding low-molecular-weight surfactants, commercial glycerol monostearate (GMS) or sodium stearyl lactylate (SSL), on the stability of simulated cream liqueurs (dairy based oil-in-water emulsions containing alcohol) was investigated. The presence of 0.4–0.5 wt % GMS or SSL led to a substantial reduction in creaming at ambient temperature as well as a longer shelf-life at 45°C. A protein analysis of the aqueous phase after emulsion centrifugation showed that added GMS or SSL displaced a significant proportion of caseinate from the surface of the emulsion droplets. Improved stability with respect to creaming appeared to be associated with a change in bulk rheological properties of the emulsion, probably arising from complex formation between low-molecular-weight emulsifier and caseinate, both in bulk aqueous solution and at the surface of the fat droplets.     

Physical Characteristics and Microstructure of Reduced-fat Frankfurters as Affected by Salt and Emulsified Fats Stabilized with Nonmeat Proteins

Functional properties and microstructure of frankfurters containing 1.5% or 2.5% salt and 15% pre-emulsified fat (PEF) stabilized with 2% pea protein, soy protein, or sodium caseinate were studied. With the exception of frankfurters with pea protein and 1.5% NaCl, all the others made with PEF" had greater (p < 0.01) thermal stability than all-meat frankfurters. Frankfurters containing soy protein or sodium caseinate had greater (p < 0.01) shear force than those with pea protein. Reducing NaCl in the frankfurters containing PEF did not influence the shear force. Microstructure examination revealed that many fat globules were entrapped physically within soy protein or sodium caseinate, which stabilized the meat emulsions and contributed to a firmer texture. Key Words: emulsified fat, reduced-fat, low-salt, microstructure, frankfurters     

马铃薯蛋白水解物对不同乳化剂制备O/W乳状液氧化稳定性的影响

用Fenton催化氧化体系模拟氧化,催化剂FeCl3,H2O2,VC的浓度分别为5、5、0.1mmol/L,以脂肪氧化产物丙二醛为指标,考察了马铃薯蛋白和不同乳化剂(非离子乳化剂Tween20、阴离子乳化剂卵磷脂和大分子乳化剂酪蛋白酸钠)共乳化制备得到的乳状液的氧化稳定性,并测定了相应乳状液的乳化稳定性。酪蛋白酸钠和马铃薯水解蛋白作为乳化剂得到的乳状液氧化稳定性较好,而Tween20和马铃薯蛋白水解物作为乳化剂得到的乳状液物理稳定性较高。     

Fat reduction in comminuted meat products-effects of beef fat, regular and pre-emulsified canola oil

The effects of fat reduction (25.0%, 17.5%, and 10.0%) and substituting beef fat with canola oil or pre-emulsified canola oil (using soy protein isolate, sodium caseinate or whey protein isolate) on cooking loss, texture and color of comminuted meat products were investigated. Reducing fat from 25 to 10% increased cooking loss and decreased hardness. Canola oil or pre-emulsified treatments showed a positive effect on improving yield and restoring textural parameters. Using sodium caseinate to pre-emulsify the oil resulted in the highest hardness value. Cohesiveness was affected by fat type and level. The color of reduced fat meat batters was darker for all, except the beef fat treatments. Using canola oil or pre-emulsified oil resulted in a significant reduction in redness. The results show that pre-emulsification can offset some of the changes in reduced fat meat products when more water is used to substitute for the fat and that pre-emulsification can also help to produce a more stable meat matrix.     

Synergistic effects of polyglycerol ester of polyricinoleic acid and sodium caseinate on the stabilisation of water–oil–water emulsions

The inherent thermodynamic instability of water–oil–water (W/O/W) emulsions has restrictions for their application in food systems. The objective of this study was to develop a food grade W/O/W emulsions with high yield and stability using minimal concentrations of surfactants. Emulsions were prepared using soybean oil, polyglycerol ester of polyricinoleic acid (PGPR) alone or in combination with sodium caseinate (NaCN) as emulsifier(s) for primary water-in-oil (W/O) emulsions and NaCN as the sole emulsifier for secondary W/O/W emulsions. Increasing the concentration of PGPR (0.5–8%w/v) had no effect on the droplet sizes of the resulting W/O/W emulsions. However, significant increases in droplet sizes of W/O/W emulsions were observed when the concentration of NaCN in external phase was reduced from 0.5 to 0.03% (w/v) (p<0.05). Percentage yields of emulsions (using a water-soluble dye) improved when PGPR concentration in the inner phase was increased from 0.5 to 8% (w/v). A stable W/O/W emulsion with a yield >90% could be prepared with 4% (w/v) PGPR alone as primary hydrophobic emulsifier and 0.5% (w/v) NaCN as external hydrophilic emulsifier. The concentration of PGPR in the inner phase could be reduced to 2% (w/v) without affecting the yield and stability of the W/O/W emulsion by partially replacing PGPR with 0.5% (w/v) NaCN, which was added to the aqueous phase of the primary W/O emulsion. The results indicate that a possible synergistic effect may exist between PGPR and NaCN, thus allowing formulation of double emulsions with reduced surfactant concentration.     

Characteristics of Sodium Caseinate- and Soy Protein Isolate-Stabilized Emulsion-Gels Formed by Microbial Transglutaminase

ABSTRACT:  Protein-stabilized emulsion gels were prepared via microbial transglutaminase (mTGase) catalysis, and their physicochemical characteristics were examined. Emulsion oil droplet size and interfacial protein load were measured. The sodium caseinate and soy protein isolate emulsion gels exhibited different microstructures and physical properties. The emulsion gels improved the storage stability of aroma compounds. Rheological measurements of the emulsion gels revealed interesting strength, gelation kinetics, and thermal sensitivity properties. The mTGase-induced emulsion gels comprised a fine network which led to less release of aroma compounds upon storage than did emulsions. These results suggest that emulsion gels may be used to improve the texture of food emulsions and to control release of food aromas.     

STABILITY OF OIL-IN-WATER EMULSIONS. 2. Effects of Oil Phase Volume, Stability Test, Viscosity, Type of Oil and Protein Additive

SUMMARY –Stability of oil-in-water emulsions stabilized in sodium caseinate, gelatin and soy sodium proteinate was found to be increased by either an increase in the aqueous phase protein concentration (0.5–2.5%) or oil phase volume (20–50%). Both factors were significantly interrelated. Emulsions stabilized by soy sodium proteinate were generally higher in stability as compared to those stabilized by gelatin or sodium caseinate. With emulsions containing gelatin, greater stability occurred when the stability testing temperature was increased from 37–70°C and when the time interval was decreased from 24 hr to 90 min. Maximum relative viscosities of emulsions stabilized by gelatin and sodium caseinate were 2.0 and 2.5, respectively. Emulsions stabilized by soy sodium proteinate were quite viscous, with relative viscosity from 1.5–30 depending on both protein concentration and oil phase volume. Interchanging the emulsified oil among corn, soybean, safflower and peanut oils did not alter emulsion stability when examined at three concentrations of soy sodium proteinate. Changing the oil to olive oil significantly increased emulsion stability at each soy sodium proteinate level with oil phase volumes of 30, 40 and 50%.     

酒精对酪蛋白酸钠溶液及O/W乳状液的影响

介绍了酒精对酪蛋白酸钠溶液及酪蛋白稳定的O/W乳状液性质的影响 .试验表明酒精在一定程度上可以降低酪蛋白酸钠的溶解度 .界面张力的测定则表明酒精的存在在很大程度上可以降低油—水界面和油—酪蛋白溶液界面的界面张力 .含酒精的乳状液体系的粘度会由于酒精的存在而提高 ,在酒精体积分数达 3 0 %时 ,乳状液体系的粘度会突然大幅度升高 .通过O/W乳状液的分层稳定性测定可发现 ,低浓度的酒精可以提高酪蛋白稳定的乳状液的分层稳定性 ,但酒精质体积分数超过 3 2 %时 ,乳状液的分层稳定性会受到破坏 .含酒精的O/W乳状液体系中油相含量的提高在一定范围内可以提高乳状液的稳定性 ,但高分散相浓度的含酒精的乳状液体系中由于连续相中酒精浓度的提高使乳状液体系稳定性下降 .     

Emulsification of Commercial Dairy Proteins with Exhaustively Washed Muscle

The addition of dairy proteins to exhaustively washed chicken breast muscle improved the emulsion stability in heated cream layers (emulsions) containing whey protein concentrate (WPC) or whey protein isolate (WPI). The initial weight of the heated cream layers made with WPC or WPI was heavier than those for sodium caseinate (CNate) or milk protein isolate (MPI). The addition of CNate or MPI resulted in decreased emulsion stability and increased inhibition of myosin heavy chain and actin participation in the emulsion formation compared to WPC or WPI.     

一种水包油包胶型乳液的制备及其在乳化肠中的应用

以结冷胶和无水氯化钙为内水相凝固剂,酪蛋白酸钠为外水相乳化剂,制备一种水包油包胶（S/O/W）型 乳液。以多重乳液粒径和分布为指标,研究酪蛋白酸钠添加量对S/O/W型多重乳液加工适应性的影响。结果表明： 正交试验得到S/O型单重乳液最佳制备条件为：内水相中结冷胶添加量0.2%、无水氯化钙添加量0.5%;内水相乳化 剂聚甘油蓖麻醇酯添加量2.5%;油相为精炼猪油,油水体积比3∶2;剪切速率17 500 r/min,剪切时间1.5 min。将制 得的S/O型单重乳液与不同添加量酪蛋白酸钠混合制得S/O/W型多重乳液。当酪蛋白酸钠添加量0.1%时,S/O/W型 多重乳液粒径符合加工要求,且贮藏、热处理、剪切稳定性较好。以多重乳液替代猪脂肪制备的低脂乳化肠与高脂 （精炼猪油含量20%）乳化肠外观不存在明显差异;微观结构观察结果表明,多重乳液在乳化肠中包裹良好、分布 均匀。     

Influences of Gums, Soy Protein Isolate, and Heating Temperatures on Reduced-Fat Meat Batters in a Model System

Effects of incorporation of iota-carrageenan, sodium alginate (AL), and soy protein isolate (SPI) in comparison with control (CONT) on the textural and physicochemical properties of reduced-fat (15%) meat emulsions heated to various internal temperatures were investigated. Lower percent fat and water losses for treatments containing gums or soy protein isolate than those of CONT indicated that addition of gums and soy protein isolate could improve emulsion stability. AL had the greatest water-holding capacity at the higher endpoint temperatures (76.7 °C and 82.2 °C), which was possibly due to the formation of a heat-stable alginate gel. The SPI had the highest concentration of salt-soluble protein in either raw or cooked meat batter.     

Influence of xanthan gum on the formation and stability of sodium caseinate oil-in-water emulsions

Studies have been made of the changes in droplet sizes, surface coverage and creaming stability of emulsions formed with 30% (w/w) soya oil, and aqueous solution containing 1 or 3% (w/w) sodium caseinate and varying concentrations of xanthan gum. Addition of xanthan prior to homogenization had no significant effect on average emulsion droplet size and surface protein concentration in all emulsions studied. However, addition of low levels of xanthan (≤0.2 wt%) caused flocculation of droplets that resulted in a large decrease in creaming stability and visual phase separation. At higher xanthan concentrations, the creaming stability improved, apparently due to the formation of network of flocculated droplets. It was found that emulsions formed with 3% sodium caseinate in the absence of xanthan showed extensive flocculation that resulted in very low creaming stability. The presence of xanthan in these emulsions increased the creaming stability, although the emulsion droplets were still flocculated. It appears that creaming stability of emulsions made with mixtures of sodium caseinate and xanthan was more closely related to the structure and rheology of the emulsion itself rather than to the rheology of the aqueous phase.     

A Novel Approach to Improving the Quality of Bittern-Solidified Tofu by W/O Controlled-Release Coagulant. 1: Preparation of W/O Bittern Coagulant and Its Controlled-Release Property

To explore the controlled-release capacity and potential application of water in oil (W/O) emulsions, W/O emulsions with bittern solution as the aqueous phase were prepared with polyglycerol polyricinoleate (PGPR) as the emulsifier. Several factors that influenced the preparation of W/O bittern coagulants were investigated. Optimized conditions were applied as follows: bittern solution/oil phase at 4:6 or 5:5 (w/w), processing temperature at 65 °C, emulsifier concentration higher than 0.6 wt% and high-pressure homogenization at 60 MPa; W/O emulsions that had a good particle size distribution, good rheological properties, good embedding ratio and high stability were prepared. The optimized W/O emulsions also exhibited the expected controlled-release ability, affected by the bath temperature, shear speed and emulsion characteristics. The preliminary results also showed that the application of W/O emulsions has the potential to improve tofu quality by delaying the solidification of soybean protein and creating a much smoother and finer gel structure.     

Development of multiple emulsions based on the repulsive interaction between sodium caseinate and LBG

The stability of oil-in-water, water-in-water and multiple emulsions containing sodium caseinate (Na-CN) and/or locust bean gum (LBG) at pH 5.5 was investigated with different compositions using a visual analysis (creaming and/or phase separation), optical microscopy and rheological measurements. Oil-in-water emulsions (O/W) were produced by high pressure homogenization, which promoted the formation of very small droplets (∼0.4 μm) and hindered the destabilization process. In the second step of this study, a visual phase diagram was constructed in order to identify the concentrations of sodium caseinate (Na-CN) and locust bean gum (LBG) that led to phase separation at pH 5.5. A mixed solution composed of 3% (w/v) Na-CN and 0.3% (w/v) LBG was chosen to produce the water-in-water and multiple emulsions. After centrifugation, the solution was separated into an upper phase rich in polysaccharide (PS) and a bottom phase rich in protein (PR), which were mixed in different proportions (1:3, 1:1, 3:1), forming the water-in-water (W/W) emulsions. The stability, microstructure and rheological properties of the W/W emulsions depended strongly on the composition of the biopolymers. An increase in the polysaccharide concentration in the W/W emulsions led to the production of more viscous and stable systems. Multiple emulsions with different characteristics were prepared and also depended on the biopolymer composition. The system with the highest polysaccharide content was the only one that showed an O/W/W structure, while the others presented the microstructure of an O/W-W/W emulsion.     

Effects of different oils on the properties of soy protein isolate emulsions and gels

The emulsion properties, protein adsorption and visco-elastic properties of heat-treated soy protein isolate (SPI) emulsions containing sunflower oil, soy oil and palm stearin were studied at neutral pH. The rheological properties, textural profile and fat adsorption capacity of subsequently induced glucono-δ-lactone (GDL) gels were investigated. At neutral pH the palm stearin emulsions showed higher stability than the sunflower and soy oil emulsions. The former also showed higher protein adsorption, emulsifying activity index and visco-elastic properties than the latter, indicating a higher denaturation degree for SPI at the oil/water interface of palm stearin emulsions at neutral pH. Acidified SPI-palm stearin emulsion gels were significantly harder than the soy and sunflower oil versions as well as the control (SPI without oil), whereas gels containing the two liquid oils were softer than the control. SPI-palm stearin gels also had higher fat adsorption capacity than SPI-sunflower oil/soy oil emulsion gels.     

Oxidative stability of oil-in-water emulsions with α-tocopherol,charged emulsifier,and different oxidative stress

α-Tocopherol is known to show different activity depending on the concentration and food matrix. Effects of α-tocopherol at the concentrations of 0, 0.1, 0.5, and 1.0 mM were determined in oil-in-water (O/W) emulsions containing anionic, neutral, and cationic emulsifiers under different types of oxidative stress including riboflavin photosensitization, photooxidation, and autoxidation. Headspace oxygen depletion, lipid hydroperoxides, and conjugated dienes were analyzed to determine the oxidative stability of O/W emulsions. α-Tocopherol served as an antioxidant in O/W emulsion with a cationic emulsifier irrespective of oxidative stress. α-Tocopherol acted as an antioxidant in O/W emulsion with a neutral emulsifier at riboflavin photosensitization while a prooxidant at photooxidation. However, in samples with an anionic emulsifier, α-tocopherol activity differed from the concentration and types of oxidative stress. Therefore, cationic transition metals or reactive oxygen species generated from RF photosensitization could play key roles of α-tocopherol in O/W emulsion.     

EFFECTS OF BINDING SUBSTRATE, TYPE OF NONMEAT ADDITIVE AND METHOD OF TENDERIZING ON CURED CHICKEN ROLLS

Chicken rolls were manufactured using ground dark fowl meat or mechanically deboned poultry meat as a binding substrate, sodium caseinate or soya isolate and a meat block that was mechanically tenderized or chunked. Effects of these treatments on yield, chemical composition, sensory and texture profile attributes were evaluated in this study. Inclusion of soya isolate increased the cook yield and improved color over sodium caseinate (P < 0.05). Likewise, rolls containing ground-dark fowl meat were lighter in color than those made with mechanically deboned poultry meat. Rolls made with mechanically deboned poultry meat had greater chewiness, while those made with sodium caseinate had greater cohesiveness. Texture profile analysis indicated that mechanical tenderization was the predominant factor in producing a softer and more springy chicken roll. Sensory evaluation revealed that mechanical tenderization decreased chewiness as compared to cubing (P < 0.05).     

Utilisation of protein fractions from porcine spleen as technofunctional ingredients in emulsified cooked meat sausages

Spleen is a low commercial value meat by-product from industrial slaughterhouses that is mostly underutilised. In this study, porcine spleens were processed to obtain two protein fractions (i.e. soluble and insoluble extracts in sodium citrate buffer 0.1 m pH 5) and the potential of using them to replace functional ingredients in cooked sausages was assessed. Specifically, a pasteurised insoluble protein extract was used as soy protein replacer in mortadella-type sausages, whereas spray-dried soluble proteins were used instead of sodium caseinate in Frankfurt-type sausages. Both splenic extracts performed well as functional ingredients since no differences in proximate composition, emulsion stability, water-holding capacity or texture were found. The only differences were found in the colour of the sausages containing the soluble protein extract, because of the haem and myoglobin content in this ingredient. The results showed that spleens could be a suitable source of non-allergenic functional proteins for meat products.     

超声改性大豆分离蛋白与大豆可溶性多糖复合乳化体系的冻融稳定性研究

本实验针对不同超声功率改性的大豆分离蛋白与大豆可溶性多糖形成的复合乳液的冻融稳定性进行研究, 揭示乳液冻融稳定机理与形成乳液复合物结构特性之间的构效关系。对2 次冻融循环处理前后乳液油滴进行共聚焦 观察,研究等温结晶固脂含量、油脂被乳化量的变化和作为乳化剂的大豆分离蛋白不同超声处理（0、200、300、 400、500 W）下二级结构的变化,进而分析其与乳液冻融稳定性的关系。结果表明：乳液经2 次冻融循环处理后 随着超声功率的增加聚结程度降低,400 W超声处理的大豆分离蛋白与大豆可溶性多糖复合乳液最为稳定;等温 结晶条件下不同乳液固脂含量增加速率不同,但最终平衡时总含量相同;油脂被乳化量发生不同程度的变化;不 同超声处理改变了大豆分离蛋白的二级结构,400 W超声处理的大豆分离蛋白无规卷曲结构含量最高。说明不同 超声改性的大豆分离蛋白与大豆可溶性多糖会形成不同结构的复合物,影响了乳液的冻融稳定性,初步明确了 适当的超声处理能够改善大豆分离蛋白的空间结构,促进其与大豆可溶性多糖分子的键合,进而影响大豆分离蛋 白-多糖界面结构特性和乳化体系的冻融稳定性。