Anhydrous Milk Fat Fractionation with Continuous Countercurrent Supercritical Carbon Dioxide

Effect of Beta Cyclodextrin on the Reduction of Cholesterol in Ewe's Milk Manchego Cheese

Beta-cyclodextrin (β-CD) is a cyclic oligosaccharide consisting of seven glucose units and is produced from starch using cyclodextrin glycotransferase enzymes to break the polysaccharide chain and forming a cyclic polysaccharide molecule. The use of β-CD in food research for reduction of cholesterol is increasing due to its affinity for non-polar molecules such as cholesterol. The aim of this study was to evaluate the feasibility of using β-CD in cholesterol removal from pasteurized ewe’s milk Manchego cheese and evaluate the effect on the main components of the milk, lipids, and flavor characteristics. Approximately 97.6% cholesterol reduction was observed in the cheese that was treated using β-CD. Physicochemical properties (fat, moisture and protein) were not changed by the β-CD treatment, except the soluble nitrogen and non-protein nitrogen that showed slight differences after the treatment. The amount of the different components of the lipid fraction (fatty acids, triglycerides and phospholipids) were similar in cheeses treated and not treated with β-CD. Flavor compound and short chain free fatty acids were not mostly significantly influenced by the effect of the β-CD. β-CD molecules are edible and nontoxic and as a result they can be used safely for cholesterol removal processing in cheese manufacturing. Therefore, the present study suggests that β-CD treatment is an effective process for cholesterol removal from Manchego cheese while preserving its properties.

Milk fat and primary fractions obtained by dry fractionation

The chemical composition and crystallisation properties of milk fat and its primary fractions, obtained by dry fractionation at 21 degrees C, were investigated. The solid fraction (stearin) and the liquid fraction (olein) displayed a different triacylglycerol (TG) composition. Stearin fraction was enriched in long-chain fatty acids, whereas olein fraction was enriched in short-chain and unsaturated fatty acids. Crystallisation properties of milk fat, and both the stearin and olein fractions were studied on cooling at |dT/dt|=1 degrees C min(-1) by differential scanning calorimetry and time-resolved synchrotron X-ray diffraction (XRD) at small and wide angles. Two main types of crystals corresponding to double chain length structures were characterised in the stearin fraction: alpha 2L(1) (47.5 Angstrom) and beta' 2L(2) (41.7 Angstrom). A triple chain length structure was formed in the olein fraction: alpha 3L (72.1 Angstrom). Crystallization of milk fat showed the formation of two 2L (47.3 and 41.6 Angstrom) and one 3L (72.1 Angstrom) lamellar structures with an hexagonal packing (alpha form). A schematic representation of the 3L packing of olein fraction was proposed to explain how a wide diversity of TG can accommodate to form a lamellar structure with a thickness of 72 Angstrom. Furthermore, the sharpness of the small-angle XRD lines associated to the alpha form was explained by the formation of liquid crystals of smectic type.

Melting characteristics of fat present on the surface of industrial spray-dried dairy powders

The melting characteristics of the fat present on the surface (surface free-fat) of two industrial spray-dried dairy powders (cream powder and whole milk powder) were investigated in comparison with those of other milk fat fractions present in the powder, such as free-fat from the interior of the powder particle (inner free-fat) and encapsulated fat. The melting characteristics of the milk fat fractions were studied by fatty acid composition, melting profile and solid fat content profile. The results indicated that all milk fat fractions including surface free-fat contained various triglycerides with melting points ranging from -40 to +40 degrees C. However, some fractionation was observed among the different milk fat fractions. The free-fat fractions (surface free-fat and inner free-fat) had a greater proportion of high-melting triglyceride species than the encapsulated fat. Furthermore, the high-melting triglyceride species present in the free-fat fractions were slightly accumulated at the surface of powder. This phenomenon was observed in both cream powder and whole milk powder and its effect on wetting time was established. This indicates that manipulation of the surface fat content during drying operation may hold the key to functionality improvement.

Short communication: concentration of conjugated linoleic acid from milk fat with a continuous supercritical fluid processing system

A continuous pilot-scale supercritical carbon dioxide system was utilized for the concentration of conjugated linoleic acids (cis-9, trans-11 C18:2) from anhydrous milk fat, which was separated into five fractions (S1 to S5) in the pressure and temperature range of 2.4 to 24.1 MPa (350 to 3500 psi) and 40 to 60 degrees C, respectively. The highest concentration of CLA attained showed an increase of about 89% and occurred in the raffinate fraction (S1) when the solvent to feed ratio was 65. This was followed by a gradual decrease in the concentration of this fatty acid from S2 to S5. This study shows the feasibility of selectively enhancing the CLA concentration in one of the fractions of milk fat with a benign solvent in a one-step process. Other unique attributes of the CLA-rich fraction are also listed.