Butter Oil Emulsion Research Articles

Ultrasonic processing of butter oil (ghee) into oil-in-water emulsions

Butter oil (ghee) derived from cow or buffalo milk is in semi-solid form at room temperature and contains >99% of lipids. Apparent high viscosity and water immiscibility – owing to the hydrophobic nature of lipid components hinder the applicability of butter oil for formulations. Here, we have employed ultrasonic processing technique to create oil-in-water emulsions of butter oil. We show that the butter oil is capable of self-stabilizing an emulsion at low concentration while higher concentrations could be kinetically stabilized using pluronic stabilizer. We were able to modulate water contents of emulsions in the range of 80%–95% and maintain the particle size in submicron range. Reported butter oil emulsions retain hydrophobic properties of the original butter oil within cores of dispersed particles, overcome a problem of butter oil-water immissibility, display fluid consistency, and are stable for several months. These properties are highly suitable for developing food, pharmaceutical, and cosmetic formulations. Practical applications Ultrasonic processing of butter oil improves its miscibility with water and increases its fluidity thereby enhancing its capability to be used as or to derive formulations for various applications. Further advantage of the reported butter oil emulsions is that they can be loaded with ‘polar’ in addition to ‘non-polar’ active molecules, which was hardly possible with formulations merely based on butter oil. This is because an aqueous phase of the butter oil emulsion contains 80%–95% water where polar molecules can easily be solvated. These emulsions, prepared from quite an abundant and economical source, can potentially act as alternatives to the emulsions that usually involve highly expensive lipid components whose extraction or synthesis are rather tough tasks. The ultrasonic processing of butter oil, presented here, could be easily scaled-up using continuous processing modes.

Stability and rheological properties of corn oil and butter oil emulsions stabilized with texturized whey proteins by supercritical fluid extrusion

Texturized whey protein powder (tWPC) produced by supercritical fluid extrusion process was used to stabilize butter and corn oil emulsions. The stability of emulsions prepared at various oil concentrations and storage temperatures was investigated. Emulsion morphology was observed by CLSM and quantified for size distribution of oil droplets while rheological properties were examined to establish their stability. All corn oil-based emulsions were stable against droplet coalescence during storage. However, the stability of butter oil-based emulsions was significantly influenced by storage temperatures and oil concentrations. Emulsions with higher elasticity were obtained by raising the oil concentration. Corn oil emulsions were far less sensitive to variations in storage temperature than emulsions based on butter oil. tWPC have a potential for uses in a very large set of food emulsions from low to high fat content and from Newtonian consistency to elastic, solid like materials such as salad dressings, light mayonnaises, fillings, sandwich spread and spreadable butter.

Characterization and acid-induced gelation of butter oil emulsions produced from heated whey protein dispersions

Whey protein isolate was dispersed at 4% or 8% (w/v) and heated at neutral pH to produce protein polymers. Butter oil, up to 20%, was homogenized in heated whey protein dispersions at pressure ranging from 10 to 120 MPa. Emulsion gelation was induced by acidification with glucono- δ-lactone. Whey protein polymers produced finely dispersed emulsions with fat droplet diameter ranging from 340 to 900 nm. Homogenization pressure was the main factor influencing droplet size. At low fat volume fraction, the emulsions exhibited Newtonian behaviour. As fat content increased, shear thinning behaviour developed as a result of depletion flocculation. Emulsion consistency index increased with protein and fat concentrations. Increasing homogenization pressure had no effect on Newtonian emulsions but promoted flocculation and significantly increased the consistency of high fat emulsions. Protein concentration was the main factor explaining emulsion gel hardness and syneresis. Syneresis decreased with increasing fat content in the gel.

Effect of Temperature of CO2 Injection on the pH and Freezing Point of Milks and Creams

The objectives of this study were to measure the impact of CO2 injection temperature (0°C and 40°C) on the pH and freezing point (FP) of (a) milks with different fat contents (i.e., 0, 15, 30%) and (b) creams with 15% fat but different fat characteristics. Skim milk and unhomogenized creams containing 15 and 30% fat were prepared from the same batch of whole milk and were carbonated at 0 and 40°C in a continuous flow CO2 injection unit (230 ml/min). At 0°C, milk fat was mostly solid; at 40°C, milk fat was liquid. At the same total CO2 concentration with CO2 injection at 0°C, milk with a higher fat content had a lower pH and FP, while with CO2 injection at 40°C, milks with 0%, 15%, and 30% fat had the same pH. This indicated that less CO2 was dissolved in the fat portion of the milk when the CO2 was injected at 0°C than when it was injected at 40°C. Three creams, 15% unhomogenized cream, 15% butter oil emulsion in skim milk, and 15% vegetable oil emulsion in skim milk were also carbonated and analyzed as described above. Vegetable oil was liquid at both 0 and 40°C. At a CO2 injection temperature of 0°C, the 15% vegetable oil emulsion had a slightly higher pH than the 15% butter oil emulsion and the 15% unhomogenized cream, indicating that the liquid vegetable oil dissolved more CO2 than the mostly solid milk fat and butter oil. No difference in the pH or FP of the 15% unhomogenized cream and 15% butter oil emulsion was observed when CO2 was injected at 0°C, suggesting that homogenization or physical dispersion of milk fat globules did not influence the amount of CO2 dissolved in milk fat at a CO2 injection temperature of 0°C. At a CO2 injection temperature of 40°C and at the same total CO2 concentration, the 15% unhomogenized cream, 15% vegetable oil emulsion, and 15% butter oil emulsion had similar pH. At the same total concentration of CO2 in cream, injection of CO2 at low temperature (i.e., <4°C) may produce a better antimicrobial effect during refrigerated shelf life due to the higher concentration of CO2 in the skim portion of the cream.

A method to determine free fat in emulsions

Small amounts of free (non-emulsified) fat in food emulsions can lead to an unacceptable appearance and product rejection. Most methods of analysis available for emulsions neglect this bulk scale heterogeneity and there is no generally accepted protocol to determine the amount of oiling-off. A new technique to determine free fat in emulsions was developed based on the principle that a lipid dye solution added to an oil-in-water emulsion will be diluted by the free fat but not by the emulsified fat present. The change in dye concentration (as measured from the decrease in absorbance) could then be used to calculate the amount of non-emulsified fat originally present. Oil Red O, a lipid soluble dye, diluted in corn oil was selected for this study. First it was shown the dye does not partition into typical aqueous food surfactant systems (2wt% whey protein isolate, sodium caseinate, and polyoxyethylene sorbitan monolaurate) or emulsions (20wt% corn oil) stabilized with the same surfactants. Corn oil spikes added to each of these emulsions, to represent different amounts of free fat, was quantitatively determined by this method. Finally the destabilization of the butter oil emulsion in ice cream mix during freezing was measured by dye dilution and compared to other methods (solvent extraction and turbidiometry).

Direct determination of the total fat content of butter and edible oil emulsions — an international collaborative study

Abstract A standard operating procedure for the direct determination of fat in butter and edible oil products involved the extraction of the fat from the sample, separation of the solvent–fat phase from the serum phase and transfer of the solvent–fat phase to a fat-collecting vessel. The solvent was removed by distillation or evaporation and the mass of extracted matter was determined gravimetrically. This method was studied collaboratively involving 13 laboratories and eight samples to determine precision estimates. Estimates of repeatability and reproducibility were 0.23 g per 100 g and 0.45 g per 100 g, respectively. The method is recommended for adoption as an international reference method.

Influence of adsorbed milk protein type and surface concentration on the quiescent and shear stability of butteroil emulsions

Abstract Understanding of the relationship between adsorbed milk protein layer characteristics and stability of butteroil emulsions may be applied to create emulsions with specific properties such as ice cream emulsions (quiescently stable, destabilizing under shear) formulated without chemical surfactant. Emulsions created from butteroil (25%) with skim milk powder (SMP) (0.2–0.7%), whey protein hydrolysate (WPH) (1.6–2.1%), whey protein isolate (WPI) (0.2–0.7%) and sodium caseinate (0.2–0.7%) were characterized for particle size distribution, protein surface concentration and relative stability when whipped. The SMP emulsions destabilized immediately after formation, possibly because of bridging flocculation. The levels of WPH required for quiescent stability prevented whipping-induced partial coalescence. At levels above 0.3% both WPI and sodium caseinate produced quiescently stable emulsions. Destabilization during whipping decreased as protein concentration increased. Whey protein isolate at a level of 0.3% was found to be the most suitable for producing an emulsion with the properties of an ice cream emulsion.

Determination of protein surface concentration for emulsions containing a partially crystalline dispersed phase

This study was undertaken to determine the effect of dispersed phase crystallinity on the determination of protein surface concentration. Butteroil (25%) or soya oil (25%) was emulsified with whey protein isolate (1%) or sodium caseinate (1%). The emulsions were centrifuged at several temperatures (5, 20, 40°C) and speeds (5000, 10 000, 15 000 g) for a variety of times (20, 40, 60 min) and the protein surface concentration determined for the isolated fat droplets. The isolated fat phase was also resuspended and the particle size distribution determined by light scattering. For the soya oil emulsions no difference was seen in the protein surface concentration or particle size distribution for any of the centrifugation conditions. For the butteroil emulsions the speed and time of centrifugation had little effect but the temperature appeared critical. When centrifuged at 5°C the butteroil emulsions underwent pronounced destabilization in the centrifuge and the resulting protein surface concentrations determined were very low. Centrifugation of an emulsion for protein surface concentration determination should be conducted at a temperature which eliminates the solid fat content of the dispersed droplets.

Partial Characterization of the Action of An A. niger Lipase on Butteroil Emulsions

ABSTRACTA commercially available lipase (A. niger, APF‐12) was employed to hydrolyze an emulsified butteroil substrate. HPLC analyses of the reaction products indicated that short chain fatty acid residues (e.g., butyric acid) were preferably hydrolyzed at pH 5 whereas the overall rate of hydrolysis for all major fatty acids showed a pH optimum between 6 and 7. This indicated the possibility of directing the selectivity of lipolysis in butteroil to enhance production of short‐chain fatty acids associated with flavor development. The optimal temperature was ca. 35°C. Different cations also affected rate of hydrolysis.

In vitro model for lipase-catalyzed lipophile release from fats

A simple method was developed to study the release and dispersion of lipophilic substances into the aqueous phase from an edible oil emulsion and to estimate their potential availability for transport across the intestinal lumen. The rates of cholesterol release and dispersion from butter oil-cholesterol and from butter oil fatty acid based sucrose polyester-cholesterol emulsions were compared when both systems were exposed to lipoprotein lipase or bile-pancreatic fluid, under conditions that simulated in vivo hydrolysis. The cholesterol lipophile remained associated with the oil phase in the butter oil emulsion until appreciable hydrolysis had taken place. Results clearly indicate that cholesterol release is intimately linked to the extent of lipolysis likely via cholesterol entrapment in the micelles as they are formed. No detectable lipolysis took place in experiments with sucrose polyester-cholesterol emulsions and no cholesterol was released. The method provides a facile technique for in vitro measurements of lipophile release, and the results obtained conform to in vivo hypotheses of lipid transfer and absorption.

Heat Resistant Bacterial Lipases and Ultra-High Temperature Sterilization of Dairy Products1,2

Properties of a heat resistant lipase produced by Pseudomonas spp. MC50, a psychrotroph isolated from raw milk, were studied to determine if such enzymes could interfere with successful production of ultra-high temperature sterilized dairy products. In milk MC50 lipase was extremely heat resistant at 100 to 150°C and would be expected to suffer little inactivation during recommended ultra-high temperature processes of 121 to 149°C for .5 to 8s. The optimum temperature for MC50 lipase activity in butter oil emulsion was 40°C, and activity at 20 to 25°C was 27 to 41% of maximum. The optimum pH was pH 8.5 with only 8.3% of maximum activity at pH 6.5 but 43% of maximum activity at pH 7. Lipase activity was greatest in 5% butter oil emulsions, but activity was never less than 65% of maximum over the range of 1 to 10% butter oil. The pH may be the most critical factor in influencing lipase activity in ultra-high temperature sterilized dairy products. Of five batches of normal whole milk and four batches of normal 10% half-and-half subjected to one of three ultra-high temperature sterilization treatments, all exhibited evidence of lipase activity during subsequent storage at room temperature and 40°C. Changes in acid degree values during storage suggested that hydrolytic rancidity could develop in these products in 1 to 7 mo, depending on the ultra-high temperature process and storage temperature. Heat resistant lipases may be common to raw milk and will survive readily most ultra-high temperature sterilization treatments. Although pH may be inhibitory, other factors are suitable to allow lipase activity in dairy products leading to development of rancidity.

PRODUCTION AND PROPERTIES OF PENCILLIUM ROQUEFORTI LIPASE

SUMMARY: A Penicillium roqueforti strain produced maximal amounts of lipase when grown in 0.5% casitone‐1% Proflo broth, pH 5.5, at 27°C. Addition of butteroil, com oil or olive oil to the growth medium inhibited the lipase production. Under pH stasis the partially purified lipase of P. roqueforti had an optimum pH of 8.0 and an optimum temperature of 37°C. Maximum lipolytic activity occurred with 5% butteroil emulsion as the substrate. Manganese chloride and magnesium chloride stimulated the enzyme activity. Calcium, sodium and potassium sale had no appreciable effect on lipolysis; silver, mercury and zinc salts were inhibitory. The lipase was thermolabile, being inactivated completely within 10 min at 50°C. The lipase hydrolyzed tributyrin, tricaprylin, tricaprin, tripropionin and triolein in decreasing order.