Progress 10/01/01 to 09/30/06
Outputs
Several studies were conducted over the life of this project. Parameters investigated to improve the body and texture of ice cream with the formation of small (more desirable) ice crystals included double homogenization of ice cream mix, addition of whey protein concentrate, variation in fat content of the ice cream mix and addition of stabilizers. Large ice crystals in ice cream are known to reduce palatability and shelf-life. In one study, ice creams were manufactured with two levels of milk fat (11 or 16%), two levels of homogenization (single or double), and two levels of stabilizer-emulsifier blend (0.35 or 0.43%). Texture of ice creams were evaluated at 1 and 10 weeks by direct microscopic examination of ice crystal size and a trained sensory panel. Milk fat level increased ice cream mix total solids and viscosity, and lowered freezing points and draw temperatures. The higher level (16%) of milk fat increased ice crystal size. Large ice crystals in ice cream are
considered to be undesirable. Higher fat improved the texture scores (iciness, coldness intensity, creaminess, and overall texture acceptance), but had no effect on vanilla flavor intensity and overall flavor acceptance of ice creams. Double homogenization reduced ice crystal size and did not diminish over 10 weeks of storage. Use of a commercial continuous pasteurization process followed by homogenization of ice cream mix twice using a two-stage homogenizer at 13.8 MPa (first stage) and 3.5 MPa (second stage) at 60 C would possibly further improve the benefits of double homogenization. Double homogenization may have assisted in modifying the structure formed by the stabilizer-emulsifier blend. Different levels of homogenization or stabilizer-emulsifier blend did not affect the sensory scores of ice creams. Ice crystals grew larger over time and affected the texture scores of ice creams. In a different study, 1% whey protein concentrate substituted for 1% nonfat dry milk in ice cream
mix did not improve the texture of ice cream. In another study, a patent pending approach has been developed and will need to be further optimized that inhibits oxidized off-flavor in milk. In another study, a comprehensive Dairy Foods Curriculum Packet was developed and inservice training were provided to South Dakota high school agricultural education instructors. After curriculum distribution and inservice training, over half of instructors indicated an increase in class time spent on dairy foods instruction. More than one-half of instructors taught a greater variety of dairy foods topics after receiving the curriculum. Over one-third of instructors who increased dairy foods instruction attributed 75% or more of their increase to the Dairy Foods Curriculum Packet and inservice. High school dairy foods education can be enhanced by providing curriculum and training to instructors. Dairy foods education is necessary to ensure high school graduates are educated about dairy products and
exposed to potential dairy science careers.
Impacts
Addition of a stabilizer blend to ice cream mix and double homogenization of ice cream mix reduced ice crystal sizes in ice cream. Ice cream with 16% milk fat had larger ice crystals compared with ice cream with 11% milk fat. Small ice crystals in ice cream are more desirable and increase shelf-life. In another study, development and distribution of a Dairy Foods Curriculum Packet, as well as instructor inservice training made a positive impact on the amount of dairy foods instruction that was taught in South Dakota Agricultural Education classrooms.
Publications
- Kahnke, S. L., R. J. Baer, and M. T. Portillo. 2006. Development and effectiveness of a Dairy Foods Curriculum Packet and inservice and the assessment of barriers to dairy foods education. J. Food Sci. Edu. 1:1-8.
- Henning, D. R., R. J. Baer, A. H. Hassan, and R. I. Dave. 2006. Major advances in concentrated and dry milk products, cheese, and milk fat-based spreads. J. Dairy Sci. 89:1179-1188.
- Patel, M. R., R. J. Baer, and M. R. Acharya. 2006. Increasing the protein content of ice cream. J. Dairy Sci. 89:1400-1406.
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Progress 01/01/05 to 12/31/05
Outputs
An ultrafiltered retentate that contained 9.2% protein, 1.4% fat, and 16.4% total solids was used to replace 25 or 50% of the protein in ice cream. Ice cream mixes contained 11% fat, 11% milk solids-not-fat, 12% sucrose, and 4% corn syrup solids. One treatment contained no added stabilizer-emulsifier blend, a second treatment contained 0.3% stabilizer-emulsifier blend, a third treatment contained 25% protein replacement with ultrafiltered retentate, and a fourth treatment contained 50% protein replacement with ultrafiltered retentate. Ice crystal sizes in treatments 3 and 4 were larger (72.6 and 76.3 microns, respectively) compared to treatment 1 (65.0 microns) and treatment 2 (67.2 microns). The ultrafiltered retentate did not reduce ice crystal size in ice cream. In another study, a comprehensive Dairy Foods Curriculum Packet and inservice training were provided to South Dakota high school agricultural education instructors. The frame for this study consisted of 77
high school agricultural education instructors. Of the 77 instructors, sixty-eight participated in the study and made up the population that was surveyed. The Dairy Foods Curriculum Packet contained material on historical significance, manufacturing processes, laboratory procedures, marketing, nutrition, and career opportunities. All laboratory procedures were hands-on to allow students to experience relevant science concepts and were selected to use inexpensive, readily available supplies. Three inservices were conducted that increased instructor knowledge and comfort level of dairy foods instruction. Data about barriers to implementation, as well as quantity of dairy foods instruction were obtained through instructor questionnaires. Instructors rated all barriers to teaching dairy foods as small to medium barriers. After curriculum distribution and inservice training, over half of instructors indicated an increase in class time spent on dairy foods instruction. More than one-half of
instructors taught a greater variety of dairy foods topics after receiving the curriculum. Over one-third of instructors who increased dairy foods instruction attributed 75% or more of their increase to the Dairy Foods Curriculum Packet and inservice. High school dairy foods education can be enhanced by providing curriculum and training to instructors. Dairy foods education is necessary to ensure high school graduates are educated about dairy products and exposed to potential dairy science careers.
Impacts
The addition of ultrafiltered retentate to ice cream mix did not reduce ice crystal size in ice cream. The development and distribution of a Dairy Foods Curriculum Packet, as well as instructor inservice training made a positive impact on the amount of dairy foods instruction that was taught in South Dakota Agricultural Education classrooms.
Publications
- Patel, M. R. 2005. Increasing the protein content of ice cream. M.S. Thesis. South Dakota State Univ., Brookings, 47 p.
- Patel, M. R., R. J. Baer, and M. R. Acharya. 2005. Increasing the protein content of ice cream. Institute of Food Tech. Annual Meeting, New Orleans, LA. 71A-56 (Abstr.).
- Ranjan, S., and R. J. Baer. 2005. Effect of milk fat and homogenization on the texture of ice cream. Milchwissenschaft 60:189-192.
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Progress 01/01/04 to 12/31/04
Outputs
Vanilla ice creams were made with two levels of milk fat (11 or 16%), two levels of homogenization (single or double), two levels of stabilizer-emulsifier blend (0.35 or 0.43%), 11% milk solids-not-fat (MSNF), 13% sucrose, and 3% corn syrup solids. Treatments 1, 2, 5, and 6 contained 11% milk fat and treatments 3, 4, 7, and 8 contained 16% milk fat. Treatments 1, 2, 3, and 4 contained 0.35% stabilizer-emulsifier blend and treatments 5, 6, 7, and 8 contained 0.43%. Mixes were made by heating the liquid ingredients (cream and water) at 46 C. Other ingredients were mixed in the order of nonfat dry milk, sucrose, corn syrup solids (36 dextrose equivalent), and stabilizer-emulsifier blend. The stabilizer-emulsifier blend was mixed with sucrose prior to liquefication to ensure proper mixing. Mixes were pasteurized at 71 C for 30 minutes and single homogenized (T1, T3, T5, and T7) at 60 C with 13.8 MPa pressure on the first stage and 3.5 MPa pressure on the second.
Treatments 2, 4, 6, and 8 were homogenized twice (double homogenized) at 13.8 MPa and 3.5 MPa. Mixes were aged overnight at 3 C, frozen with a soft serve freezer, and hardened at -25 to -27 C. Texture of ice creams were evaluated at 1 and 10 weeks by direct microscopic examination of ice crystal size and a trained sensory panel. Milk fat level increased ice cream mix total solids and viscosity, and lowered freezing points and draw temperatures. The higher level (16%) of milk fat increased ice crystal size. Large ice crystals in ice cream are considered to be undesirable. Higher fat improved the texture scores (iciness, coldness intensity, creaminess, and overall texture acceptance), but had no effect on vanilla flavor intensity and overall flavor acceptance of ice creams. Double homogenization reduced ice crystal size and did not diminish over 10 weeks of storage. Use of a commercial continuous pasteurization process followed by homogenization of ice cream mix twice using a two-stage
homogenizer at 13.8 MPa (first stage) and 3.5 MPa (second stage) at 60 C would possibly further improve the benefits of double homogenization. Double homogenization may have helped in modifying the structure formed by the stabilizer-emulsifier blend. Different levels of homogenization or stabilizer-emulsifier blend did not affect the sensory scores of ice creams. Ice crystals grew larger over time and affected the texture scores of ice creams.
Impacts
A high level of milk fat increased ice crystal sizes in ice cream. It improved the texture and had no effect on the vanilla flavor intensity and overall flavor acceptance of ice creams. Double homogenization of ice cream mixes favorably reduced ice crystal sizes in ice cream.
Publications
- Kahnke, S. L., and R. J. Baer. 2004. Accessing barriers to dairy foods education and the effectiveness of a Dairy Foods Curriculum Packet and inservice. Institute of Food Technologists Technical Program. p. 158 (Abstr.).
- Kahnke, S. L. 2004. Effectiveness of a Dairy Foods Curriculum Packet and inservice and the assessment of barriers to dairy foods education. M.S. Thesis, South Dakota State University, Brookings, 73p.
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Progress 01/01/03 to 12/31/03
Outputs
Several parameters are being evaluated to improve the body and texture of ice cream. Large ice crystals in ice cream and most frozen desserts are considered undesirable as they will cause a product to be too cold for sensory evaluation and can reduce shelf life. A better understanding of how various parameters affect ice crystal size and growth in ice cream will ultimately assist in control of ice crystal size. The use of a stabilizer blend in 11% milk fat ice cream mix increased flow time. Double homogenization lowered ice cream mix flow time in the presence of stabilizer but not in the absence of stabilizer. One percent whey protein concentrate substituted for 1% nonfat dry milk in ice cream mix had no effect on mix flow time. Mix freezing points ranged from minus 2.45 to 2.49 degrees C and were similar among treatments. No differences were seen among treatments for overrun, which ranged from 90.3 to 96.3%. Draw temperatures ranged from minus 3.08 to 3.54 degrees C
which is in the normal range for ice cream from a batch freezer. Whipping time of the ice cream mixes were similar and ranged from 7.17 to 7.28 minutes. The process of double homogenization of ice cream mix with the addition of stabilizer lowered the mean ice crystal size of ice cream in some treatments; however, sensory evaluation found no difference between ice cream that had been double homogenized and the control. Also, no improvement in texture was seen by double homogenizing ice cream mix without added stabilizer when comparing ice crystal size measurements with sensory evaluation, these two methods are making slightly different comparisons. Direct counting of ice crystals is an excellent method to objectively quantify the texture of ice cream; however, it does not consider all aspects of sensory perception. The texture of ice cream is influenced by the lubricating effect of milk fat as it melts on the pallet. The use of stabilizer and to a lesser degree double homogenization
affected the texture of ice cream as determined by mean ice crystal size and ice crystal distribution, but these differences may become blurred when evaluation is done by sensory perception due to the multitude of factors involved in this process. One percent whey protein concentrate substituted for 1% nonfat dry milk in ice cream mix did not improve texture of ice cream. This may have been due to an inadequate whey protein concentrate usage rate. Generally, the percentage of ice crystals under 45 microns decreased and the percentage of ice crystals over 106 microns increased between storage for 10 days and 18 weeks, portraying the recrystallization process and the increase in icy defect of ice cream over time. Ice cream mix that was processed by double homogenization had a higher percentage of ice crystals under 45 microns and a lower percentage of ice crystals over 106 microns at both periods than did the control. Less growth of ice crystals was seen in the texture of ice cream that
had added stabilizer at both 10 days and 18 weeks of storage.
Impacts
Double homogenization of ice cream mix lowered flow times in the presence of stabilizer, but not in the absence of stabilizer. Double homogenization of ice cream mix with addition of stabilizer lowered the mean ice crystal size in some treatments. Addition of one percent whey protein concentrate substituted for one percent nonfat dry milk in ice cream mix did not improve the texture of ice cream.
Publications
- Ranjan, S. 2003. Effect of milk fat, homogenization, and stabilizer-emulsifier blend on the texture of vanilla ice cream. M. S. thesis, South Dakota State University, Brookings, 57 p.
- Ruger, P. R., R. J. Baer, and K. M. Kasperson. 2002. Effect of homogenization and whey protein concentrate on the texture of ice cream. J. Dairy Sci.. 85:1684-1692.
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Progress 01/01/02 to 12/31/02
Outputs
In this project a different approach will be taken to improve the textural quality of frozen dairy desserts. Most previous research with frozen desserts involved reduction in size of ice crystals after the freezing part of product manufacture. It is well known that fast freezing or hardening favors the formation of small (more desirable) ice crystals. This research will concentrate on producing small ice crystals in the finished product when the ice cream is still liquid mix. Production of frozen desserts with improved texture should translate into increased frozen dessert sales and consumption. Parameters to be investigated include double homogenization of ice cream mix, addition of whey protein concentrate, fiber powders, fat content, and/or stabilizers. Another factor to be evaluated is mix viscosity, which may affect ice crystal size. Ice cream was made with a mix composition of 11% milk fat, 11% milk solids-non-fat, 13% sucrose, 3% corn syrup solids (36 dextrose
equivalent), 0.28% stabilizer blend or 0.1% emulsifier and vanilla extract. Mixes were high temperature short time pasteurized at 80 degrees C for 35 seconds, homogenized at 141 kg/cm squared and 35 kg/cm squared, and cooled to 3 degrees C. Six treatments were prepared from 4 batches of mix. Mix from batch one consisted of 0.1% emulsifier. Half of this batch, treatment 1 (T1), was cooled to 3 degrees C and the other half, upon exiting the pasteurizer, was heated to 60 degrees C, rehomogenized at 141 kg/cm squared and 35 kg/cm squared (T2), and cooled to 3 degrees C. Mix from batch two consisted of 0.28% stabilizer blend. Half of this batch was used as the control (T3), the other half, upon exiting the pasteurizer, was heated to 60 degrees C, rehomogenized at 141 kg/cm squared and 35 kg/cm squared (T4) and cooled to 3 degrees C. Batch three consisted of 0.1% emulsifier and 1% whey protein concentrate substituted for 1% milk solids-not-fat. It was heated to 60 degrees C, rehomogenized
at 141 kg/cm squared and 35 kg/cm squared (T5), and cooled to 3 degrees C. Batch four consisted of 0.28% stabilizer blend and 1% whey protein concentrate substituted for 1% milk solids-not-fat. It was heated to 60 degrees C, rehomogenized at 141 kg/cm squared and 35 kg/cm squared (T6), and cooled to 3 degrees C. Results showed no difference (P > 0.05) in mean ice crystal size between T3, T4, and T6, however T4 and T6 had a smaller (P < 0.05) mean ice crystal size than T1, T2, and T5. Mix viscosities were tested one day after manufacture. The viscosity of T3 was greater (P < 0.05) than all other treatments and the viscosities of T4 and T6 were greater than T1, T2, and T5. Milk fat and total solids of all treatment mixes were similar (P > 0.05).
Impacts
A goal of this research is to develop recommendations for the dairy industry to use when making ice cream mix to produce ice cream with small ice crystals and improved body and texture. Addition of a stabilizer blend to ice cream mix produced smaller ice crystals in ice cream.
Publications
- Ruger, P. R., Baer, R. J. and Kasperson, K. M. 2001. Effect of double homogenization and whey protein concentrate on the texture of ice cream. J. Dairy Sci. 84:(Suppl. 1):380 (Abstr.).
- Ruger, P. 2001. Effect of double homogenization and whey protein concentrate on the texture of ice cream. M. S. Thesis. South Dakota State University, Brookings, 65 p.
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