High-pressure homogenisation of raw bovine milk. Effects on fat globule size distribution and microbial inactivation

Whole raw milk was processed using a 15 L h⁻¹ homogeniser with a high-pressure (HP) valve immediately followed by a cooling heat exchanger. The influence of homogenisation pressure (100–300 MPa) and milk inlet temperature T_in (4°C, 14°C or 24°C) on milk temperature T₂ at the HP valve outlet, on fat globule size distribution and on the reduction of the endogenous flora were investigated. The T_in values of 4–24°C led to milk temperatures of 14–33°C before the HP valve, mainly because of compression heating. High T_in and/or homogenisation pressure decreased the fat globule size. At 200 MPa, the d_4.3 diameter of fat globules decreased from 3.8±0.2 (control milk) to 0.80±0.08 μm, 0.65±0.10 or 0.37±0.07 μm at T_in=4, 14°C or 24°C, respectively. A second homogenisation pass at 200 MPa (T_in=4°C, 14°C or 24°C) further decreased d_4.3 diameters to about 0.2 μm and narrowed the size distribution. At all T_in tested, an homogenisation pressure of 300 MPa induced clusters of fat globules, easily dissociated with SDS, and probably formed by sharing protein constituents adsorbed at the fat globule surface. The total endogenous flora of raw milk was reduced by more than 1 log cycle, provided homogenisation pressure was ⩾200 MPa at T_in=24°C (T₂∼60°C), 250 MPa at T_in=14°C (T₂∼62°C), or 300 MPa at T_in=4°C (T₂∼65°C). At all T_in tested, a second pass through the HP valve (200 MPa) doubled the inactivation ratio of the total flora. Microbial patterns of raw milk were also affected; Gram-negative bacteria were less resistant than Gram-positive bacteria.     

Enrichment of the conjugated linoleic acid content of bovine milk fat by dry fractionation

This study investigated the effect of fat fractionation on the conjugated linoleic acid (cis-9, trans-11-C_18 : 2) content of bovine milk fat. Anhydrous milk fat was fractionated into hard and soft fractions using controlled cooling and agitation. Fractionation of milk fat pre-melted at 60°C using a temperature programme of 33–10°C and a cooling rate of 0.58°C h⁻¹ yielded a soft fraction containing 63.2% more conjugated linoleic acid (2.22 g 100 g⁻¹ FAME), which was also enriched in polyunsaturated fatty acids and vaccenic acid (trans-11-C_18 : 1) compared with the parent fat. Agitation following fractionation was found to have a negative effect on the conjugated linoleic acid content of the soft fraction. Refractionation of the soft fraction did not increase the yield of conjugated linoleic acid. The conjugated linoleic acid and trans fatty acid content of 26 selected food products ranging in milk fat content from 0 to 100% is reported. Conjugated linoleic acid concentrations ranged from 0 to 16.2 mg g⁻¹ fat and were generally lower than the trans fatty acid content which ranged from 0 to 155.7 mg g⁻¹ fat. Spreads containing vegetable oils contained higher trans fatty acid and lower conjugated linoleic acid contents than milk fat-containing products. This study highlights that a milk fat fraction enriched in conjugated linoleic acid may be achieved by dry fractionation.     

Rheological studies on commercial egg white using creep and compression measurements

The gel properties of commercial egg white (EW) with high gelling ability were compared with those of standard type using creep and compression measurements. The effects of heating time, temperature, and protein concentration on gel properties were investigated at pH 7.5. The experimental creep curves were analyzed using four elements of the Maxwell–Voigt model. The difference in rheological properties of the two types of EW was reflected in the values of elastic modulus and viscosity. The experimental stress–strain curves for all EW gels were fitted using the BST equation with high accuracy. This equation contained two fitting parameters, i.e. Young's modulus and the elasticity parameter n_BST. The elasticity parameter n_BST characterized non-linear elastic behavior for large deformation. At 80°C, n_BST of both types of EW gels did not change with increasing heating time. However, n_BST decreased with increasing temperature in a range of 70–85°C.     

Fractionation of Anhydrous Milk Fat by Superficial Carbon Dioxide

Milk fat was fractionated with supercritical CO₂ (SC-CO₂) into 8 fractions at temperatures of 50° and 7O°C, over a pressure range of 100–350 bar. Two fractions (L1 and 2) were liquid, 3 fractions (11–3) were semi-solid and 3 fractions (Sl-3) were solid at 20°C. The peak melting temperature progressively increased (9.7° to 38.3°C) from fraction L1 to S3. The concentration of short chain (C24-C34) triglycerides decreased from fraction L1 to S3 while that of long chain (C42-C54) triglycerides increased gradually. The medium chain triglycerides were more concentrated in fractions L2 and 11–3. The proportion of short (C4-C8) and medium (ClO-C12) chain fatty acids decreased and that of long (C14-C18) chain fatty acids increased gradually from fraction Ll-S3. The weight average molecular weights and geometric mean-carbon number of milk fat fractions were in the range from 625.6 to 805.0 and 34.2 to 47.6, respectively, in comparison to 729.3 and 41.O, respectively, for native milk fat, suggesting SC-CO₂ effected a fair degree of molecular weight separation.     

Crystallization kinetics of palm oil in blends with palm-based diacylglycerol

Crystallization kinetics of palm oil (PO) in the presence of different concentrations (2, 5, 10, 30 and, 50% w/w) of palm-based diacylglycerol (PB-DAG) were investigated over different ranges of crystallization temperatures. Addition of 30 and 50% (w/w) of PB-DAG (high concentrations) increased significantly (P < 0.05) the melting point and crystallization onset while addition of 2 and 5% PB-DAG did not have significant (P > 0.05) effect. PO and PO blends with 2 and 5% of PB-DAG showed crystal transformation at crystallization temperatures (T_Cr) of 26, 26, 26.5 °C, respectively as reflected in corresponding changes of the Avrami parameters at below and above these T_Cr. This was especially evident for the blends containing 2 and 5% of PB-DAG. Individual comparison of induction time (T_i), Avrami exponent (n), Avrami constant (k) and half-time of crystallization (t_1/2) of blends classified under various supercooling ranges based on the supercooling closeness (± 0.1 °C), showed that addition of 5% of PB-DAG in most of the supercooling ranges significantly (P < 0.05) reduced nucleation rate as well as crystal growth velocity of PO. This was reflected in the significantly (P < 0.05) higher T_i and t_1/2 and lower k. Although the presence of 2% of PB-DAG was found to have inhibitory effect on PO crystallization, this effect was not significant (P > 0.05). Mode of crystal growth attributed to n was changed significantly only in presence of 5% of PB-DAG. Furthermore, presence of 10% PB-DAG showed ??'-stabilizing effect on PO. On the other hand, high concentrations of PB-DAG were found to significantly (P < 0.05) reduce T_i as well as t_1/2 and also increase k suggesting their promoting effects on nucleation and crystallization rate of PO even with the close supercoolings. In addition, they changed crystal growth mode of PO. Amongst the different concentrations of PB-DAG investigated, blend containing 50% of PB-DAG as compared to PO, not only, have healthier benefits but also, may have greater potential applications in plastic fat products due to its unique physical properties.     

Modeling the combined effect of high hydrostatic pressure and mild heat on the inactivation kinetics of Listeria monocytogenes Scott A in whole milk

The survival curves of Listeria monocytogenes Scott A inactivated by high hydrostatic pressure were obtained at four temperatures (22, 40, 45 and 50 °C) and two pressure levels (400 and 500 MPa) in UHT whole milk. Elevated temperatures substantially promoted the pressure inactivation of L. monocytogenes. A 5-min treatment of 500 MPa at 50 °C resulted in a more than 8-log₁₀ reduction of L. monocytogenes, while at 22 °C a 35-min treatment was needed to obtain the same level of inactivation. Tailing was observed in all survival curves, indicating that the linear model was not adequate for describing these curves. The log-logistic model consistently produced best fits to all survival curves and the modified Gompertz model the poorest. The Weibull model produced fits as good as the log-logistic model at the temperature range of 40–50 °C. The Weibull model provided reasonable predictions of inactivation of L. monocytogenes at temperature levels other than the experimental temperatures; however, the log-logistic model was found to be inferior at predicting inactivation.     

Assessment of the production of Bacillus cereus protease and its effect on the quality of ultra-high temperature-sterilized whole milk

Bacillus cereus is one of the most important spoilage microorganisms in milk. The heat-resistant protease produced is the main factor that causes rotten, bitter off-flavors and age gelation during the shelf-life of milk. In this study, 55 strains of B. cereus were evaluated, of which 25 strains with protease production ability were used to investigate proteolytic activity and protease heat resistance. The results showed that B. cereus C58 had strong protease activity, and its protease also had the highest thermal stability after heat treatment of 70°C (30 min) and 100°C (10 min). The protease was identified as protease HhoA, with a molecular mass of 43.907 kDa. The protease activity of B. cereus C58 in UHT-sterilized whole milk (UHT milk) showed an increase with the growth of bacteria, especially during the logarithmic growth phase. In addition, the UHT milk incubated with protease from B. cereus C58 at 28°C (24 h) and 10°C (6 d) were used to evaluate the effects of protease on the quality of UHT milk, including protein hydrolysis and physical stability. The results showed that the hydrolysis of casein was κ-CN, β-CN, and α_S-CN successively, whereas whey protein was not hydrolyzed. The degree of protein hydrolysis, viscosity, and particle size of the UHT milk increased. The changes in protein and fat contents indicated that fat globules floated at 28°C and settled at 10°C, respectively. Meanwhile, confocal laser scanning microscopy images revealed that the protease caused the stability of UHT milk to decrease, thus forming age gelation.     

Microencapsulated Iron for Food Fortification

Lipid microcapsules of FeSO₄, alone or with ascorbic acid, and FeCl₃, were developed to fortify cheese and other high moisture foods with iron. Varying lipid coat composition and amount of core iron solution optimized their stability. A high melting fraction of milk fat (m.p. 43.5°C) was oxidized by iron and was thus unsuitable as coat material. Microcapsules made with cottonseed stearine (m.p. 62.8°C) had good oxidative stability and retained more iron under rapid stirring at 39°C than those made with hydrogenated milk fat (m.p. 49.0°C). Microcapsules having good oxidative stability and low leakage of iron were coated with stearine and had a ratio of 0.10g Fe solution/g lipid coat. Microencapsulation may allow fortification of cheese and other iron sensitive foods.     

Melting and Solidification Properties of Palm-Based Diacylglycerol,Palm Kernel Olein,and Sunflower Oil in the Preparation of Palm-Based Diacylglycerol-Enriched Soft Tub Margarine

Many studies have been conducted to deliver more healthy alternatives to full fat products. Incorporation of a high proportion of diacylglycerol oil as a functional oil into the plastic fat products through development of blend formulation is considered as one such attempt. Ternary mixtures containing sunflower oil (SFO), palm kernel olein (PKOL), and palm-based diacylglycerol oil (POL-DAG) with certain proportions were designed using mixture design. The corresponding physical properties such as solid fat content (SFC) as well as deviation from SFC (DSFC) using nuclear magnetic resonance and melting and crystallization properties using differential scanning calorimetry were studied. Ternary phase behavior was analyzed with isosolid diagrams. The eutectic behavior was observed along the binary line of PKOL/POL-DAG at temperature ranges of 5–20 °C. This was reflected in the lower heat of crystallization (ΔHc) as well as higher DSFC for 50/50 mixture of PKOL and POL-DAG in contrast with PKOL and POL-DAG. No eutectic interaction was observed along the binary lines of SFO/PKOL as well as SFO/POL-DAG despite showing DSFC within temperature ranges of 5–25 °C. Addition of 0%, 33.33%, 66.66%, and 100% of POL-DAG to 50/50 mixture of SFO/PKOL increased ΔHc, crystallization onset (T _O), and SFC (at all temperatures studied) of the blends and showed no eutectic behavior. However, addition of the same amounts of PKOL to equi-mixture of SFO/POL-DAG reduced T _O while ΔHc increased and showed minor eutectic behavior. Therefore, PKOL was indicated to be less compatible with POL and SFO. Palm-based DAG-enriched soft tub margarine containing SFO/PKOL/POL-DAG [35/15/50, (w/w)] was optimally formulated through analysis of multiple isosolid diagrams and was found to have quite similar SFC profile as well as SMP but also lower saturated fatty acid as compared with commercial soft tub margarine.     

Determination of the Crystallization Behavior of Lipids by Temperature Modulated Optical Refractometry

This study was conducted to examine if the new temperature modulated optical refractometry (TMOR) method is applicable to study the phase behavior of alkyl-based components. n-Hexadecane, palmitic acid, and glycerol tripalmitate were used as model components. TMOR was benchmarked against differential scanning calorimetry (DSC) and polarized light microscopy (PLM). For all substances, a good agreement of the DSC data with TMOR was found. For n-hexadecane, a difference of 2.2 °C for the crystallization and 2.6 °C for the melting temperature was found. Considering palmitic acid, the crystallization temperature differed by 3.3 °C while the melting varied by 2.8 °C. The crystallization temperature of tripalmitate identified by TMOR was 2.7 °C higher, and the melting temperature 2.3 °C was lower compared to the DSC. The crystallization temperature for TMOR was always higher, and the melting temperature was always lower if related to DSC. This leads to the conclusion that TMOR is more accurate and direct. In addition, the transition peaks identified by TMOR were narrower compared to the DSC peaks. This is due to slower heating and cooling rates leading to a smaller temperature range of phase transition and less thermal lag. The study showed that TMOR is an appropriate method to determine the phase transition temperatures for the three examined substances. The results were comparable to the DSC data in both melting and crystallization behavior. Since the accuracy of TMOR is better at lower heating and cooling rates, it could be a reasonable extension of the well-known DSC method in the studies of melting and crystallization.     

Simultaneous HPLC–DAD quantification of vitamins A and E content in raw,pasteurized, and UHT cow’s milk and their changes during storage

An improved extraction and HPLC method for the simultaneous extraction and quantitation of retinol, α-tocopherol, α-tocotrienol, and β-carotene was developed to analyze commercial whole/semi-skim/skim samples of raw/pasteurized/UHT milk in transparent plastic/glass bottles and Tetra Brik? containers. The sample preparation method required prior saponification at 40 °C for 15 min followed by n-hexane extraction. An isocratic acetonitrile/methanol (65:35 v/v) mobile phase, C₁₈ analytical column, and UV detector were chosen for HPLC quantification. The liposoluble vitamin content in raw, pasteurized conventional/organic, and UHT milk ranged 0.055–5.540 (retinol), 0.135–1.410 (α-tocopherol), and 0.040–0.850 mg/L (β-carotene). No significant differences (p > 0.05) were observed on losses of retinol, α-tocopherol, and β-carotene content in UHT whole milk after 5 days at 4 °C in the dark. After 14 days at 4 °C in the dark, the contents of retinol, α-tocopherol, and β-carotene remained higher in milk with higher fat content and were higher in unopened containers. In UHT whole milk, samples containing 0.02 % NaN₃, retinol (33 %), and α-tocopherol (11 %) but not β-carotene (2 %) decreased significantly (p < 0.05).     

The cooling rate effect on the microstructure and rheological properties of blends of cocoa butter with vegetable oils

The elasticity (G′) and yield stress (σ¹) of blends of cocoa butter (CB) in vegetable oils (i.e., 30% CB/canola and 30% CB/soybean oil) crystallized at temperatures (T_Cr) between 9.5 °C and 13.5 °C and two cooling rates (1 °C/min and 5 °C/min) were determined, evaluating their relationship with parameters associated with the formation and structural organization of the crystal network [i.e., solid fat content (SFC), Avrami index, crystallization rate, fractal dimension (D)]. The results showed that T_Cr and cooling rate had a different effect for each blend on the three-dimensional organization of the crystal network, and on the proportion and size of β′ and β crystals. Thus, under low supercooling conditions at both cooling rates, the crystallized CB/canola oil blend was formed by a mixture of small β′ and large β crystals that provided high G′ and σ¹ at low SFC (i.e., 20.5–20.9%) and D (i.e., 1.66–1.72) values. The CB/soybean oil blend achieved similar G′ and σ¹ independent of cooling rate only at high supercooling. In this case, the crystal network was formed mainly by small β′ crystals with SFC (i.e., 25.4–26.3%) and D (i.e., 2.86–2.79) values higher (P < 0.05) than in the CB/canola oil blend at low supercooling.     

Adsorption and Desorption of Cholesterol in Continuous Supercritical Fluid Processing of Anhydrous Milk Fat

The adsorption breakthrough volume of adsorbent for cholesterol reduction of anhydrous milk fat (AMF) was determined by passing supercritical carbon dioxide (SC-CO₂) phase through an adsorption column with magnesium silicate at 40°C/241 bar. The breakthrough quantity for 76% cholesterol reduction was 2.0g fat/g adsorbent. With in-line adsorption on magnesium silicate, the cholesterol reduction in the extracts was 80 to 86%. Magnesium silicates saturated with cholesterol were regenerated with 10% ethanol in CO₂ at 40°C and 64°C/241 bar. The adsorption capacity of the magnesium silicate regenerated with 10% ethanol in SC-CO₂ at 40°C/241 bar was close to its original value. Its behavior was described by the Langmuir isotherm.     

Crystallization behavior of milk fat obtained from linseed-fed cows

Milk with an increased content of unsaturated fatty acids was obtained by incorporating 60% of extruded linseed into the concentrate of cows. Two groups of Holstein cows (3 animals/group) were fed a concentrate (control or linseed enriched) together with the same roughage diet (ad libitum). After an adaptation period of 3 wk, evening and morning milk samples were collected every 7 d for 3 wk. Milk was decreamed and anhydrous milk fat (AMF) was isolated from the fat fraction by using the Bureau of Dairy Industries method. The objective of this study was to investigate if the crystallization mechanism of milk fat changed when the content of unsaturated fatty acids was increased. Therefore, the crystallization behavior of a milk fat enriched with unsaturated fatty acids was compared with that of a control milk fat. Nonisothermal crystallization was investigated with differential scanning calorimetry, and 1-step and 2-step isothermal crystallization behaviors were investigated using pulsed nuclear magnetic resonance, differential scanning calorimetry, and x-ray diffraction. A higher content of unsaturated fatty acids in AMF resulted in an increased proportion of low melting triglycerides. These triglycerides lowered the solid fat content profile, particularly at refrigerator temperatures. Furthermore, they induced some changes in the crystallization and melting behaviors of milk fat compared with a control AMF, although no fundamental changes in the crystallization mechanism could be revealed. Even though a lower melting point could be observed for milk fat with a higher content of unsaturated fatty acids, a similar degree of supercooling was needed to initiate crystallization, resulting in a shift in onset temperature of crystallization toward lower temperatures. In addition, slower crystallization kinetics were measured, such as a lower nucleation rate and longer induction times, although crystallization occurred in a similar polymorphic crystal lattice. During melting, a shift in offset temperature toward lower temperatures could be observed for the 3 melting fractions of AMF in addition to a higher proportion of low melting triglycerides. These results demonstrate that a higher content of unsaturated fatty acids has some effect on the crystallization behavior of milk fat. This knowledge could be used to produce dairy products of similar or superior quality compared with conventional products by intervening in the production process of dairy products.     

Microencapsulating Properties of Trehalose and of its Blends with Sucrose and Lactose

A low melting fraction of milk fat (LMF), with a dropping point (MDP) of 16.7 °C, was encapsulated by freeze‐drying emulsions formulated with trehalose or its blends with 30 wt% lactose or sucrose as hydrophilic phase, and with a mixed of 50 wt% of the palmitic sucrose esters (SE) β‐170 and β‐1670 as emulsifiers. Trehalose or trehalose/sucrose matrices were very efficient to encapsulate LMF (retention values were 82.8%± 3.2% and 90.5%± 3.7%, dry basis, respectively), whereas trehalose/lactose showed a significant decline in initial retention (42.5%± 2.5%, dry basis). The role of emulsion stability, water content, physical state of the matrix, and particle size distribution on LMF loss was investigated by following retention of LMF with time for the powders stored at water activities (a_w) of 0.11, 0.33, 0.44, 0.54, and 0.76. Trehalose emulsion was the most stable. However, encapsulation efficiency was higher for the trehalose/sucrose blend. Despite the high initial degree of crystallization, retention with time for the trehalose matrix was very high at all a_w. The trehalose/lactose blend had a low efficiency to encapsulate LMF, especially at a_w of 0.54 and 0.76. Retention was determined by the counteracting effects of all these factors and was more closely related to structural changes of the encapsulating matrix than to the physical state (amorphous or crystalline) of it.     

Crystallization Kinetics of Concentrated α,α-Trehalose and α,α-Trehalose/Salt Solutions Studied by Low-resolution 1H-Pulsed NMR

Crystallization kinetics of concentrated trehalose and trehalose/salt solutions were followed by proton ¹H) pulsed nuclear magnetic resonance (¹H p‐NMR). Three concentrations (66,70, and 72.5%) of trehalose and with the addition of ZnCl₂.2H₂O, CaCl₂.2H₂O, and MgCl₂.2H₂O were crystallized at 5,10,15,20, and 25 °C. Supercooling and molecular diffusion determined the crystallization rates. The highest rate of crystallization of 66,70, and 72.5% trehalose occurred at 20 °C, whereas the lowest rate occurred at 25 °C. The maximum solid content was higher at lower temperatures, as expected based on the higher supercooling values. Crystallization was delayed by the addition of salts and especially of CaCl₂.2H₂O.     

Synthesis of extracellular lipase by a strain ofPseudomonas fluorescensisolated from raw camel milk

Ten strains of psychrotrophic bacteria were isolated from raw camel milk and were arranged according to their lipase production. Lipolytic activities ranged between 0.26 to 3.43 meq of palmetic acid 100 g^-;1of bovine milk fat h^-;1.Pseudomonas fluorescensRM₄was the most active strain. This bacterium could grow and secrete lipase over a wide range of temperatures. The optimum temperature for growth was 37°C, and the maximum lipase production was at 25°C. Growth was maximal after 96 h of incubation at 25°C, and lipase activity was maximal at 72 h post-inoculation at 25°C (during the late logarithmic phase). Shaking of the cultures (100 rpm) led to an increase in both growth and enzyme activities. Pseudomonas fluorescensRM₄was able to grow and secrete lipase over a pH range of 5.5-;8.50. Synthesis of the enzyme appeared to be inducible because no enzyme was detected in the absence of organic nitrogen. Supplementation of the basal medium with milk proteins enhanced lipase production. Tryptophan and lysine induced enzyme synthesis most effectively. Addition of 4 g l^-;1of glucose to broth stimulated both growth and production of lipase. Beyond this level of supplementation, lipase activity was considerably depressed.     

Direct measurement of phase transitions in milk fat during cooling of cream—a low-field NMR approach

Low-field ¹H nuclear magnetic resonance (NMR) transverse relaxation (T₂) was measured during cooling (31–4 °C) of cream with low or high content of long-chain fatty acids (FA). Distributed analysis of the T₂ relaxation data revealed marked differences in the T₂ relaxation characteristics of the liquid fat population (10–100 ms), which was ascribed to differences in the size of the fat globules in the two types of cream. Principal component analysis (PCA) of the obtained T₂ relaxation decay data showed clear shifts in NMR relaxation behavior at 17 and 22 °C for cream with low or high content of long-chain FA, respectively. Differential scanning calorimetric measurements on the creams revealed that these shifts took place at the onset of crystallization of fat. Consequently, the present study demonstrated that low-field NMR can be used to measure phase transitions in cream.     

The Effect of Minor Components on Milk Fat Microstructure and Mechanical Properties

ABSTRACT: Although minor polar components affected the kinetics of milk fat crystallization, its structure and mechanical properties remained unchanged. At 5 °C, a granular microstructure was observed, while at 20 °C, a combination of granular and spherulitic microstructures were observed. By 27.5 °C, only spherulites were present after 24 h. There were no differences observed in the fractal dimension (D) determined by microscopy or rheology for anhydrous milk fat, milk fat triacylglycerols and MF‐TAGs with added diacylglycerols at 5 °C. There was, however, a strong temperature effect on D, increasing from 1.87 at 5 °C to 1.98 at 22.5 °C. The yield force and storage modulus were unaffected by removal of minor components.     

Effect of Concentration and Temperature on the Rheological Properties of Oat Milk

The rheological behavior of oat milk (Avena sativa L.) at different concentration (5, 10, 15, and 20 °Brix) was studied in the temperature range of 10, 20, 30, and 40 °C using a controlled stress rheometer. Power law model adequately described the flow behavior of oat milk (0.881–0.987). The value of flow behavior index (n) was less than unity (0.19–0.68) at all temperature and concentration range indicating the shear-thinning (pseudoplastic) nature of oat milk. Consistency index (k) increased with soluble solids concentrations and decreased with temperature. The Arrhenius equation adequately described the effect of temperature on the viscosity. The activation energies for flow of oat milk quantified using Arrhenius equation increased with solid concentration and ranged from 7.43 to 303.64 kJ/mol. The effect of concentration on the viscosity followed the exponential model. The empirical model obtained from the study could well-describe the combined effect of temperature and concentration within the range of the study. It was concluded that temperature and concentration had a significant effect on the rheology of the oat milk.