Effect of double homogenization and whey protein concentrate on the texture of ice cream

Ice cream samples were made with a mix composition of 11% milk fat, 11% milk solids-not-fat, 13% sucrose, 3% corn syrup solids (36 dextrose equivalent), 0.28% stabilizer blend, or 0.10% emulsifier and vanilla extract. Mixes were high temperature short time pasteurized at 80degreesC for 25 s, homogenized at 141 kg/cm 2 pressure on the first stage and 35 kg/cm(2) pressure on the second, and cooled to WC. The study included six treatments from four batches of mix. Mix from batch one contained 0.10% emulsifier. Half of this batch (treatment 1), was subsequently frozen and the other half (upon exiting the pasteurizer) was reheated to 60degreesC, rehomogenized at 141 kg/cm(2) pressure on the first stage and 35 kg/cm 2 pressure on the second (treatment 2), and cooled to 3degreesC. Mix from batch two contained 0.28% stabilizer blend. Half of this batch was used as the control (treatment 3), the other half upon exiting the pasteurizer was reheated to 60degreesC, rehomogenized at 141 kg/cm(2) pressure on the first stage and 35 kg/cm 2 pressure on the second (treatment 4), and cooled to 3degreesC. Batch three, containing 0.10% emulsifier and 1% whey protein concentrate substituted for 1% nonfat dry milk, upon exiting the pasteurizer was reheated to 60degreesC, rehomogenized at 141 kg/cm(2) pressure on the first stage and 35 kg/cm(2) pressure on the second (treatment 5), and cooled to WC. Batch four, containing 0.28% stabilizer blend and 1% whey protein concentrate substituted for 1% nonfat dry milk, upon exiting the pasteurizer was reheated to 60degreesC, rehomogenized at 141 kg/cm 2 pressure on the first stage and 35 kg/cm(2) pressure on the second (treatment 6), and cooled to WC. Consistency was measured by flow time through a pipette. Flow time of treatment 3 was greater than all treatments, and the flow times of treatments 4 and 6 were greater than treatments 1, 2, and 5. Flow time was increased in ice cream mix by the addition of stabilizer. Double homogenization lowered ice cream mix flow time in the presence of stabilizer, but no difference in flow time was observed without stabilizer addition. Treatment 4 had a lower mean ice crystal size at 10 d postmanufacture compared with treatment 3; however, overall texture acceptability between treatments 3 and 4 was similar. Mean ice crystal size of treatment 6 was less at 18 wk postmanufacture compared with treatment 3; however, overall texture acceptability for treatments 3, 4, and 6 was similar. Mean ice crystal sizes of treatments 1, 2, and 5 were greater at 10 d and 18 wk compared with treatment 3. Sensory evaluation indicated that treatments 3, 4, and 6 had higher mean scores for icy, coldness intensity, and creaminess than treatments 1, 2, and 5 at 10 d and 18 wk postmanufacture.