Use of a Water-in-Oil-in-Water (W/O/W) Double Emulsion to Simulate the Full-Fat Cheese Physical Properties in a 30% Reduced-Fat Cheese
Reduced-fat cheese have greater hardness and elasticity than full-fat cheeses because of the reduction in number of fat particles that can interrupt long-range interaction within the casein protein matrix structure of cheese. Our objective was to produce a water-in-oil-in-water (W1/O/W2) double emulsion as the carrier for butterfat that when used in the manufacture of cheese would provide similar physical properties to a full-fat cheese but have 40% less fat. The W1/O/W2 emulsion was made by making a 1% (wt./vol.) solution of inulin in boiling 0.5% (wt./vol.) NaCl solution, and adding this solution in a 40:60 ratio into anhydrous milk fat (containing 8% (wt./wt.) polyglycerol polyricinoleate) at 50°C using low shear. This formed the primary W1/O emulsion. The W1/O emulsion was then mixed with high shear (5,000 rpm for 1 min) in a 20:80 ratio with a 2% (wt./wt.) aqueous solution of whey protein concentrate to form the W1/O/W2 emulsion. A single oil-in-water emulsion was prepared as a control using milkfat emulsified into the whey protein solution and designated as O/W2. Immediately after emulsion preparation, the control (O/W2) and double (W1/O/W2) emulsions were added separately (in triplicate) into pasteurized skim milk at 31°C and then made into cheese FFCON and WOW32, respectively) using a standard procedure for full fat Cheddar cheese. Mean (±SE) composition for FFCON cheeses was 354 (±3) g/kg moisture, 333 (±3) g/kg fat, 17.2 (±.5) g/kg salt and pH 5.37 (±.02), while for the WOW32 cheese it was 424 (±6) g/kg moisture, 228 (±2) g/kg fat, 17.6 (±0.7) g/kg salt and pH 5.30 (±.02). Rheological properties (at 25°C) were analyzed after one month of storage. Storage modulus (G’) and loss modulus (G”) for both cheeses were linear over the range of 10-3 to 10-1 percent strain. The WOW32 cheese was slightly softer(p<0.1) than the FFCON cheese with mean G’ between 0.1% and 0.01% strain of 112 kPa and G” of 33 kPa compared to G’ and G” of the FFCON cheese of 177 and 52 kPa, respectively. This softening of the WOW32 cheese compared to the FFCON cheese was considered beneficial as normally a 30% fat reduction causes cheese to become firmer. We successfully produced a cheese with 30% less fat and similar (slightly softer) properties to a full fat cheese, with the extra moisture in the WOW32 cheese attributed to moisture coming from the W1phase of the W1/O/W2 double emulsion.
Keywords: Cheese Reduced-fat Emulsion