Addition of sodium caseinate to skim milk increases nonsedimentable casein and causes significant changes in rennet-induced gelation,heat stability,and ethanol stability

The protein content of skim milk was increased from 3.3 to 4.1% (wt/wt) by the addition of a blend of skim milk powder and sodium caseinate (NaCas), in which the weight ratio of skim milk powder to NaCas was varied from 0.8:0.0 to 0.0:0.8. Addition of NaCas increased the levels of nonsedimentable casein (from ～6 to 18% of total casein) and calcium (from ～36 to 43% of total calcium) and reduced the turbidity of the fortified milk, to a degree depending on level of NaCas added. Rennet gelation was adversely affected by the addition of NaCas at 0.2% (wt/wt) and completely inhibited at NaCas ≥0.4% (wt/wt). Rennet-induced hydrolysis was not affected by added NaCas. The proportion of total casein that was nonsedimentable on centrifugation (3,000 × g, 1 h, 25°C) of the rennet-treated milk after incubation for 1 h at 31°C increased significantly on addition of NaCas at ≥0.4% (wt/wt). Heat stability in the pH range 6.7 to 7.2 and ethanol stability at pH 6.4 were enhanced by the addition of NaCas. It is suggested that the negative effect of NaCas on rennet gelation is due to the increase in nonsedimentable casein, which upon hydrolysis by chymosin forms into small nonsedimentable particles that physically come between, and impede the aggregation of, rennet-altered para-casein micelles, and thereby inhibit the development of a gel network.     

Influence of oestrus on the heat stability and other characteristics of milk from dairy goats

We examined the heat stability, somatic cell count (SCC), pH, fat, protein and lactose content of milk from goats during the oestrous period, in order to investigate evidence of possible oestrus effects on milk physical and chemical properties. Goats free from mammary infections were ranked on average SCC from three tests so that they could be stratified randomly in pairs to synchronized oestrus or left as unsynchronized non-oestrus controls. The synchronisation consisted of insertion of an intravaginal progesterone-releasing device for 17 d, and introduction of the bucks the day of the device removal (D0). The repeated measurements analysis of variance model included the fixed effects of the experimental group (oestrus or control) and day and the corresponding interaction and also the random effect of doe. Reduced milk-heat stability, increased SCC, increased protein content and reduced pH were found in the milk samples of the oestrus group on D1, 2 and 3. The fat and lactose content of the milk was not affected by oestrus. These data indicate that the milk of goats during the mating period has reduced heat stability and, therefore, that dilution into bulk tanks should be recommended to avoid clotting when milk is intended for high thermal treatment.     

Influence of milk protein concentrates with modified calcium content on enteral dairy beverage formulations: Storage stability

Control of calcium-mediated storage defects, such as age gelation and sedimentation, were evaluated in enteral high-protein dairy beverages during storage. To investigate the effects of reduced-calcium ingredients on storage stability, 2 batches each of milk protein concentrates (MPC) with 3 levels of calcium content were acquired [control, 20% calcium-reduced (MPC-20), and 30% calcium-reduced (MPC-30)]. Control and calcium-reduced MPC were used to formulate 8% (wt/wt) protein enteral dairy beverages. The formulation also consisted of other ingredients, such as gums, maltodextrin, potassium citrate, and sucrose. The pH-adjusted formulation was divided into 2 parts, one with 0.15% sodium hexametaphosphate (SHMP) and the other with 0% SHMP. The formulations were homogenized and retort sterilized at 121°C for 15 min. The retort-sterilized beverages were stored at room temperature for up to 90 d and particle size and apparent viscosity were measured on d 0, 7, 30, 60, and 90. Beverages formulated using control MPC with 0 and 0.15% SHMP exhibited sedimentation, causing a decrease in apparent viscosity by approximately 10 cP and clear phase separation by d 90. The MPC-20 beverages with 0% SHMP exhibited stable particle size and apparent viscosities during storage. In the presence of 0.15% SHMP, particle size increased rapidly by 40 nm on d 90, implying the start of progressive gelation. On the other hand, highest apparent viscosities leading to gelation were observed in MPC-30 beverages at both concentrations of SHMP studied. These results suggested that beverages formulated with MPC-20 and 0% SHMP would have better storage stability by maintaining lower apparent viscosities. Further reduction of calcium using MPC-30 resulted in rapid gelation of beverages during storage.     

Effect of milk protein genetic polymorphisms on rennet and acid coagulation properties after standardisation of protein content

The effects of milk protein genetic polymorphisms on the rennet and acid coagulation properties of milk after protein standardisation were investigated. Skim milk samples were adjusted to a protein concentration of 6.07 ± 0.06% by ultrafiltration (UF) before evaluating rennet coagulation and acid coagulation properties. Only the β-lactoglobulin (β-LG) genotypes influenced the rennet-clotting time before standardisation for the total protein concentration by UF; however, this effect was confounded with the β-LG concentration. After UF-concentration, a similar protein concentration between the samples was achieved in the retentate, then the rennet clotting time and rennet curd firmness at 30 min were significantly influenced by both the κ-casein (κ-CN) and β-LG genotypes. κ-CN genotypes significantly influenced the acid coagulation properties of both skim milk and retentate. Variations in the concentration of milk proteins (mostly α_S2-CN-12P) explained most of the differences in the rennet and acid coagulation properties of milk after protein standardisation by UF.     

Influence of protein content and storage temperature on the particle morphology and flowability characteristics of milk protein concentrate powders

Milk protein concentrate (MPC) powders are widely used as ingredients for food product formulations due to their nutritional profile and sensory attributes. Processing parameters, storage conditions, and composition influences the flow properties of MPC powders. This study investigated the bulk and shear flow properties of 70.3, 81.5, and 88.1% (wt/wt, protein content) MPC after storage for 12 wk at 25 and 40°C. Additionally, the morphological and functional changes of the MPC powders were investigated and correlated with flowability. After 12 wk of storage at 25°C, the basic flow energy values significantly increased from 510 to 930 mJ as the protein content increased from 70 to 90% (wt/wt). Flow rate index was significantly higher for samples with high protein content. Dynamic flow tests indicated that MPC powders with high protein content displayed higher permeability. Shear tests confirmed that the samples stored at 25°C were more flowable than samples stored at 40°C. Likewise, the higher-protein content samples showed poor shear flow behavior. The results indicated that MPC powders stored at 25°C had less cohesiveness and better flow characteristics than MPC powders stored at 40°C. Overall, the MPC powders had markedly different flow properties due to their difference in composition and morphology. This study delivers insights on the particle morphology and flow behavior of MPC powders.     

Effect of manufacture and reconstitution of milk protein concentrate powder on the size and rennet gelation behaviour of casein micelles

Samples of raw skim milk, ultrafiltration/diafiltration retentate, concentrated retentate and milk protein concentrate powder (MPC80) from a single commercial production run were analysed using photon correlation spectroscopy. Measurements revealed insignificant differences in casein micelle size between the samples. In addition, there was no discernable difference between raw skim milk and MPC powder dissolved at 60 °C in the amount of casein remaining in supernatants from centrifugation at either 25,000 × g or 174,200 × g. Casein micelles did not appear to be altered during manufacture of MPC. The rennet gelation behaviour of reconstituted MPC was compared with raw skim milk. Reconstituted MPC did not coagulate unless supplemented with approximately 2 mm calcium chloride, which was attributed to the mineral removal during ultrafiltration/diafiltration. Addition of sufficient calcium could restore rennet coagulation kinetics and gel strength of reconstituted MPC to approximately that of raw skim milk.     

Structure and shelf stability of milk protein gels created by pressure-assisted enzymatic gelation

In this work, pressure-assisted enzymatic gelation was applied to milk proteins, with the goal of enhancing the structure and stability of pressure-created milk protein gels. High-pressure processing (HPP) at 600 MPa, 3 min, and 5°C was applied to milk protein concentrate (MPC) samples of 12.5% protein concentration, both in the absence and in the presence of calf chymosin [up to 60 IMCU (international milk-clotting units)/kg of milk] or camel chymosin (up to 45 IMCU/kg of milk). Gel hardness, water-holding capacity, and degree of proteolysis were used to assess network strength and shelf stability. The processing trials and all measurements were conducted in triplicate. Statistical analyses of the data were performed by ANOVA, at a 95% confidence level. After HPP treatment, we observed significant structural changes for all samples. Pressurization of MPC, with or without chymosin addition, led to extensive protein aggregation and network formation. The strength of HPP-created milk protein gels without chymosin addition, as measured by the elastic modulus (G′), had a value of 2,242 Pa. The value of G′ increased with increasing chymosin concentration, reaching as high as 4,800 Pa for samples with 45 IMCU/kg of camel chymosin. During 4 wk of refrigerated storage, the HPP and chymosin MPC gels maintained higher gel hardness and better structural stability compared with HPP only (no chymosin) MPC gels. The water-holding capacity of the gels without chymosin remained at 100% during 28 d of refrigerated storage. The HPP and chymosin MPC gels had a lower water-holding capacity (91–94%) than the HPP-only counterparts, but their water-holding capacity did not decrease during storage. Overall, these findings demonstrate that controlled, fast structural modification of high-concentration protein systems can be obtained by HPP-assisted enzymatic treatment, and the created gels have a strong, stable network. This study provides insights into the possibility of using HPP for the development of milk-protein-based products with novel structures and textures and long refrigerated shelf life, along with the built-in safety imparted by the HPP treatment.     

Comparing the heat stability of soya protein and milk whey protein emulsions

The heat stability of emulsions stabilized by WPC or SPI or mixtures of the two are compared by following the change in oil droplet number during heating, and applying kinetic rate equations to calculate the rate constant (k) for destabilization. SPI emulsions were found to be unstable to heat at pH around the pI, whilst being stable at pH further from the pI. This is related to the pH dependent solubility of soy proteins. This determined that a pH close to the pI (pH 4.5) be used for further studies so as to give a heat labile emulsion. Both WPC and SPI emulsions showed a weak dependence of k on protein concentration at pH 4.5, and an increasing k as the temperature increased. Arrhenius plots for emulsions made with WPC were bilinear, whilst those for SPI followed a single straight line. The change in slope of the Arrhenius plots for the WPC emulsions occurred around 70 °C, lower than would be expected from the denaturation temperature of β-lactoglobulin, the protein that dominates the thermal behaviour of WPC. The activation energies for WPC and SPI emulsions calculated from the slopes of the Arrhenius plots are slightly lower for WPC and considerably lower for SPI than the equivalent values in the literature for these proteins in solution. This, and the apparent lower denaturation temperature of β-lactoglobulin in emulsions, we explain by hypothesizing that the WPC and SPI proteins are already partially denatured by surface adsorption when they are heated, and thus require less energy to denature, and unfold at lower temperatures than native non-adsorbed proteins.     

Free amino acid content of goat's milk cheese made with animal rennet and plant coagulant

BACKGROUND: Enzymes present in the flowers of Cynara cardunculus (cyprosins) are used in the production of some traditional Spanish and Portuguese cheeses, replacing animal rennet. The aim of this work was to study the changes that take place in free amino acids during the ripening of a goat's milk cheese (Murcia al Vino) manufactured with plant coagulant (PC) or animal rennet (AR). RESULTS: The total free amino acid (TFAA) concentration increased during ripening, with Ile, Val, Ala, Phe, Gaba, Arg and Lys representing more than 50% of the TFAA content at 60 days in both types of cheese. The TFAA concentration was significantly higher in cheeses made with PC (854 mg 100 g^?1 total solids (TS)) than those made with AR (735 mg 100 g^?1 TS). The concentration of most free amino acids, especially His, Ser, Gln, Thr, Ala, Met and Ile, was higher in the PC cheese. CONCLUSION: Cheese made using PC as coagulant presented higher contents of free amino acid throughout the ripening period than cheese made using AR. Therefore we can conclude that the use of PC to produce Murcia al Vino goat's cheese would accelerate the ripening process as a result of increased cyprosin proteolytic activity. Copyright © 2011 Society of Chemical Industry     

Influence of fat, heat treatments and species on milk rennet clotting properties and glycomacropeptide formation

The influence of species, fat and heat treatment (70 °C for 30 min) of milk on rennet clotting time, k₂₀ value (time as the curd is firm enough to be cut) and glycomacropeptide formation was studied. Rennet clotting properties were affected by the three studied factors. The results obtained could indicate that the fat and the heat treatment have a different influence in the rennet clotting properties of cow's, ewe's and goat's milks; however, those differences, although significant, are not high and its influence in cheese manufacture perhaps have not a great importance. The slope of the glycomacropeptide formation as a function of the incubation time of milk with rennet was calculated applying a linear regression analysis. The slope decreased significantly when whole or skim cow's milk was heated indicating a slower glycomacropeptide formation. Fat and heat treatments had no significant influence on glycomacropeptide formation of ewe's and goat's milk. The results obtained indicate that the fat concentration and the fat globule membrane could influence the initial aggregation of the destabilised casein micelles.     

Fortification of reconstituted skim milk powder with different calcium salts: Impact of physicochemical changes on stability to processing

Reconstituted skim milk powder (RSMP) was fortified with 12.5 mM/L calcium (Ca) using soluble [Ca chloride (CChlor), Ca gluconate (CGluc) or Ca hydroxide (CHyd)] or insoluble [Ca carbonate (CCarb), Ca phosphate (CPhos) or Ca citrate (CCit)] salts. CPhos and CCit decreased heat stability moderately at 140 °C, while CCarb had no effect. Soluble salts had a pronounced destabilising effect at 140 °C due to increased ionic Ca levels. After a laboratory‐scale high‐temperature short‐time heating process, CHyd‐fortified RSMP had a lower viscosity than all other samples. CChlor and CGluc increased sedimentation during accelerated physical stability testing, with CHyd causing greater sedimentation than CChlor or CGluc.     

Comparison of milk protein composition and rennet coagulation properties in native Swedish dairy cow breeds and high-yielding Swedish Red cows

Recent studies have reported a very high frequency of noncoagulating milk in Swedish Red cows. The underlying factors are not fully understood. In this study, we explored rennet-induced coagulation properties and relative protein profiles in milk from native Swedish Mountain and Swedish Red Polled cows and compared them with a subset of noncoagulating (NC) and well-coagulating (WC) milk samples from modern Swedish Red cows. The native breeds displayed a very low prevalence of NC milk and superior milk coagulation properties compared with Swedish Red cows. The predominant variants in both native breeds were α_S1-casein (α_S1-CN) B, β-CN A² and β-lactoglobulin (β-LG) B. For κ-CN, the B variant was predominant in the Swedish Mountain cows, whereas the A variant was the most frequent in the Swedish Red Polled. The native breeds displayed similar protein composition, but varied in content of α_S1-CN with 9 phosphorylated serines (9P) form. Within the Swedish Mountain cows, we observed a strong inverse correlation between the relative concentration of κ-CN and micelle size and a positive correlation between ionic calcium and gel firmness. For comparison, we investigated a subset of 29 NC and 28 WC milk samples, representing the extremes with regard to coagulation properties based on an initial screening of 395 Swedish Red cows. In Swedish Red, NC milk properties were found to be related to higher frequencies of β-CN A², κ-CN E and A variants, as well as β-LG B, and the predominant composite genotype of β- and κ-CN in the NC group was A²A²/AA. Generally, the A²A²/AA composite genotype was related to lower relative concentrations of κ-CN isoforms and higher relative concentrations of α_S1-, α_S2-, and β-CN. Compared with the group of WC milk samples, NC milk contained a higher fraction of α_S2-CN and α-lactalbumin (α-LA) but a lower fraction of α_S1-CN 9P. In conclusion, milk from native Swedish breeds has good characteristics for cheese milk, which could be exploited in niche dairy products. In milk from Swedish Mountain cows, levels of ionic calcium seemed to be more important for rennet-induced gel firmness than variation in the relative protein profile. In Swedish Red, lower protein content as well as higher fraction of α_S2-CN and lower fraction of α_S1-CN 9P were related to NC milk. Further, a decrease in the frequency of the composite β-κ-CN genotype A²A²/AA through selective breeding could have a positive effect on milk coagulation properties.     

Changes in the physical properties,solubility, and heat stability of milk protein concentrates prepared from partially acidified milk

A limiting factor in using milk protein concentrates (MPC) as a high-quality protein source for different food applications is their poor reconstitutability. Solubilization of colloidal calcium phosphate (CCP) from casein micelles during membrane filtration (e.g., through acidification) may affect the structural organization of these protein particles and consequently the rehydration and functional properties of the resulting MPC powder. The main objective of this study was to investigate the effects of acidification of milk by glucono-δ-lactone (GDL) before ultrafiltration (UF) on the composition, physical properties, solubility, and thermal stability (after reconstitution) of MPC powders. The MPC samples were manufactured in duplicate, either by UF (65% protein, MPC65) or by UF followed by diafiltration (80% protein, MPC80), using pasteurized skim milk, at either the native milk pH (~pH 6.6) or at pH 6.0 after addition of GDL, followed by spray drying. Samples of different treatments were reconstituted at 5% (wt/wt) protein to compare their solubility and thermal stability. Powders were tested in duplicate for basic composition, calcium content, reconstitutability, particle size, particle density, and microstructure. Acidification of milk did not have any significant effect on the proximate composition, particle size, particle density, or surface morphology of the MPC powders; however, the total calcium content of MPC80 decreased significantly with acidification (from 1.84 ± 0.03 to 1.59 ± 0.03 g/100 g of powder). Calcium-depleted MPC80 powders were also more soluble than the control powders. Diafiltered dispersions were significantly less heat stable (at 120°C) than UF samples when dissolved at 5% solids. The present work contributes to a better understanding of the differences in MPC commonly observed during processing.     

考马斯亮蓝法测定乳与乳制品中蛋白质含量

建立了一种测定乳与乳制品中蛋白质含量的方法。利用6份乳与乳制品作为试验材料,通过考马斯亮蓝比色法测定其蛋白质含量。结果表明,工作曲线在0~0.18 g/100 mL范围内线性关系良好,线性相关系数为0.999 3,平均加标回收率为98.13%,相对标准偏差小于5%,方法的检出限为0.02 g/100 mL,该方法具有操作简便、重现性好、准确可靠等特点。     

Effect of pH and heat treatment conditions on physicochemical and acid gelation properties of liquid milk protein concentrate

Milk protein concentrates (MPC) are typically dried high-protein powders with functional and nutritional properties that can be tailored through modification of processing conditions, including temperature, pH, filtration, and drying. However, the effects of processing conditions on the structure-function properties of liquid MPC (fluid ultrafiltered milk), specifically, are understudied. In this report, the pH of liquid MPC [13% protein (70% protein DM basis), pH 6.7] was adjusted to 6.5 or 6.9, and samples at pH 6.5, 6.7, and 6.9 were subjected to heat treatment at either 85°C for 5 min or 125°C for 15 s. Sodium dodecyl sulfate PAGE was used to determine the distribution of caseins and denatured whey proteins in the soluble and micellar phases, and HPLC was used to quantify native whey proteins as a measure of denaturation, based on the processing conditions. Both heat treatments resulted in substantial whey protein denaturation at each pH, with β-lactoglobulin denatured more extensively than α-lactalbumin. Changes in liquid MPC physicochemical properties were monitored at d 1, 5, and 8 during storage at 4°C. Viscosity increased after heat treatment and also over time, regardless of pH and heating conditions, suggesting the role of whey protein denaturation and aggregation, and their interactions with casein micelles. The MPC samples processed at pH 6.9 had a significantly higher viscosity than those heated at pH 6.5 or 6.7, for both temperature and time conditions; and samples processed at 85°C for 5 min had higher viscosity than those heated at 125°C for 15 s. Particle size analysis indicated the presence of larger particles after 5 and 8 d of MPC storage after heating at pH 6.9. Acid-induced gelation of the liquid MPC led to significantly higher gel firmness after processing at 85°C for 5 min, compared with 125°C for 15 s. Also, gels made from MPC adjusted to pH 6.5 had higher storage moduli, with both time and temperature combinations, demonstrating the role of pH-dependent association of denatured whey proteins with casein micelles in gel network formation. These findings enable a better understanding of the processing factors contributing to structural and functional properties of liquid MPC and can be helpful in tailoring milk protein ingredient functionality for a variety of food products.     

Teat anatomy and its relationship with quarter and udder milk flow characteristics in dairy cows

Anatomical and functional characteristics of the teat are supposed to have considerable influence on milk flow performance. In the present study, various teat and milking characteristics in 148 quarters of 38 cows were analyzed via 3 different approaches. Teat canal length, teat wall thickness, and teat diameter were measured by ultrasound. In addition, the vacuum needed to open the teat canal (VO) was determined and milk flow profiles were measured in each quarter separately.Rear teats were shorter and thicker than front teats, whereas teat canal length and teat wall thickness did not differ according to quarter position. Milk yield and peak flow rate (PFR) were higher in rear than in front quarters. Teat canal length and VO were negatively correlated with PFR and average flow rate (AFR) but no correlations were observed between milkability traits and externally measurable teat characteristics like teat length or teat diameter.Individual milkability at an udder level is a complex characteristic that is determined by the milkability at a quarter level and the distribution of quarter milk yields. The anatomical and functional characteristics of single teats can partly explain the milk flow characteristics of individual quarters.     

Comparison of pressure treatment and heat treatment of skim milk with added starch on subsequent acid gelation of milk

Skim milk with added starch (waxy rice starch or potato starch at levels of 0-1.5 g/100 g) was either pressure-treated (500 MPa, 20 °C, 30 min) or heat-treated (80 °C, 30 min) and subsequently acidified (using glucono-δ-lactone) to form acid milk gels. In the second part of the study, the pH of the skim milk samples was adjusted from the natural condition (pH 6.64) to pH 6.5, 6.6 or 6.9 before the pressure or heat treatment and re-adjusted back to pH 6.64 after the respective treatment. The rheological properties of the samples during acidification and of the final acid gels were studied. The storage modulus, G′, of the final acid milk gels increased as more waxy rice starch was added to milk before pressure or heat treatment. However, acid milk gels made from pressure-treated milk with added potato starch did not show significant changes in the G′ of the final acid gels whereas those made from the heat-treated counterparts showed a marked increase in the final G′ as the potato starch level increased. Waxy rice starch was gelatinised in milk by both pressure treatment and heat treatment whereas potato starch was gelatinised by heat treatment only. Increasing the pH of milk before pressure or heat treatment increased the final G′ of the acid milk gel produced on subsequent acidification of the milk and the final G′ was increased further by the addition of waxy rice starch before the pressure or heat treatment.     

乳制品中肌醇含量的测定及其稳定性的研究进展

肌醇是乳制品中的一种多羟基化合物,是一种重要的母体营养物质,具有多种生理药理活性。本综述对奶粉中肌醇的提取、净化等前处理方法、衍生化方式,目前常用的检测方法包括微生物法,气相色谱法,气相色谱/质谱法,液相色谱法,以及液相色谱-质谱/质谱法等进行了分析和比较,并对乳制品中肌醇的稳定性进行探讨,以期为乳制品中肌醇的检测提供参考依据。     

Abomasal infusion of different exogenous emulsifiers alters fatty acid digestibility and milk fat yield of lactating dairy cows

We evaluated the effects of abomasal infusion of emulsifiers on fatty acid (FA) digestibility and milk production of lactating dairy cows. All emulsifiers examined were polysorbates, nonionic surfactants, consisting of a polyethoxylated sorbitan esterified with FA. The polysorbates tested in this study consisted of the same polyethoxylated sorbitan base but differed by the FA esterified to it. Eight rumen-cannulated multiparous cows (89 ± 13 d in milk) were assigned to a treatment sequence in 4 × 4 Latin squares with 18-d periods consisting of 7 d of washout and 11 d of infusion. Treatments were abomasal infusions of water only (CON) or 30 g/d of different emulsifiers as follows: polysorbate-C16:0 (T40), polysorbate-C18:0+C16:0 (T60), and polysorbate-C18:1 (T80). Emulsifiers were dissolved in water and delivered at 6-h intervals (total daily infusion was divided into 4 equal infusions per day). Cows were fed the same diet that contained (% diet dry matter) 32.1% neutral detergent fiber, 15.7% crude protein, 25.8% starch, and 3.32% FA (including 1.92% FA from a saturated FA supplement containing 34.2% C16:0 and 47.7% C18:0). The T80 treatment increased total FA digestibility compared with CON (5.40 percentage units) and T60 (3.90 percentage units) and tended to increase it compared with T40. Also, T40 tended to increase and T80 increased (4.80 percentage units) 16-carbon FA digestibility compared with CON. The T80 treatment increased 18-carbon FA digestibility compared with the other treatments. The T40 treatment tended to increase and T80 increased total FA absorption compared with CON (53 g/d) and T60 (52 g/d). Both T40 and T80 increased the absorption of 16-carbon FA compared with CON and T60. The T60 treatment did not differ from CON for any digestibility variable. Both T40 and T80 increased the yields of milk fat, 3.5% fat-corrected milk, and de novo, mixed, and preformed milk FA compared with CON. In conclusion, not all emulsifiers increased FA digestibility. Compared with CON, T80 increased the digestibility and absorption of total, 16-, and 18-carbon FA. The T40 treatment tended to increase and T80 increased total FA absorption and the yields of milk fat and 3.5% FCM compared with CON. Milk fat yield was increased by increases in de novo, mixed, and preformed milk FA. In our short-term infusion study, results suggest that the predominant FA present in the polysorbate affects its ability to improve FA digestibility. Overall, FA digestibility and absorption were improved the most when cows received the T80 treatment.