WO2000021380A1 - Produit laitier en poudre et procede de fabrication dudit produit - Google Patents

Produit laitier en poudre et procede de fabrication dudit produit Download PDF

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Publication number
WO2000021380A1
WO2000021380A1 PCT/US1999/024036 US9924036W WO0021380A1 WO 2000021380 A1 WO2000021380 A1 WO 2000021380A1 US 9924036 W US9924036 W US 9924036W WO 0021380 A1 WO0021380 A1 WO 0021380A1
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Prior art keywords
temperature
lactose
whole milk
shearing
product
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PCT/US1999/024036
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English (en)
Inventor
Gregory R. Ziegler
Ali Bulent Koc
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The Penn State Research Foundation
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Publication of WO2000021380A1 publication Critical patent/WO2000021380A1/fr

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    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23G—COCOA; COCOA PRODUCTS, e.g. CHOCOLATE; SUBSTITUTES FOR COCOA OR COCOA PRODUCTS; CONFECTIONERY; CHEWING GUM; ICE-CREAM; PREPARATION THEREOF
    • A23G1/00—Cocoa; Cocoa products, e.g. chocolate; Substitutes therefor
    • A23G1/30—Cocoa products, e.g. chocolate; Substitutes therefor
    • A23G1/56—Cocoa products, e.g. chocolate; Substitutes therefor making liquid products, e.g. for making chocolate milk drinks and the products for their preparation, pastes for spreading, milk crumb
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23C—DAIRY PRODUCTS, e.g. MILK, BUTTER OR CHEESE; MILK OR CHEESE SUBSTITUTES; MAKING THEREOF
    • A23C1/00—Concentration, evaporation or drying
    • A23C1/14—Concentration, evaporation or drying combined with other treatment
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23C—DAIRY PRODUCTS, e.g. MILK, BUTTER OR CHEESE; MILK OR CHEESE SUBSTITUTES; MAKING THEREOF
    • A23C9/00—Milk preparations; Milk powder or milk powder preparations
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23G—COCOA; COCOA PRODUCTS, e.g. CHOCOLATE; SUBSTITUTES FOR COCOA OR COCOA PRODUCTS; CONFECTIONERY; CHEWING GUM; ICE-CREAM; PREPARATION THEREOF
    • A23G3/00—Sweetmeats; Confectionery; Marzipan; Coated or filled products
    • A23G3/34—Sweetmeats, confectionery or marzipan; Processes for the preparation thereof
    • A23G3/346—Finished or semi-finished products in the form of powders, paste or liquids
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23G—COCOA; COCOA PRODUCTS, e.g. CHOCOLATE; SUBSTITUTES FOR COCOA OR COCOA PRODUCTS; CONFECTIONERY; CHEWING GUM; ICE-CREAM; PREPARATION THEREOF
    • A23G9/00—Frozen sweets, e.g. ice confectionery, ice-cream; Mixtures therefor
    • A23G9/52—Liquid products; Solid products in the form of powders, flakes or granules for making liquid products ; Finished or semi-finished solid products, frozen granules
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23G—COCOA; COCOA PRODUCTS, e.g. CHOCOLATE; SUBSTITUTES FOR COCOA OR COCOA PRODUCTS; CONFECTIONERY; CHEWING GUM; ICE-CREAM; PREPARATION THEREOF
    • A23G2200/00—COCOA; COCOA PRODUCTS, e.g. CHOCOLATE; SUBSTITUTES FOR COCOA OR COCOA PRODUCTS; CONFECTIONERY; CHEWING GUM; ICE-CREAM; PREPARATION THEREOF containing organic compounds, e.g. synthetic flavouring agents
    • A23G2200/12—COCOA; COCOA PRODUCTS, e.g. CHOCOLATE; SUBSTITUTES FOR COCOA OR COCOA PRODUCTS; CONFECTIONERY; CHEWING GUM; ICE-CREAM; PREPARATION THEREOF containing organic compounds, e.g. synthetic flavouring agents containing dairy products

Definitions

  • TITLE A DRY MILK PRODUCT AND PROCESS FOR THE MANUFACTURE OF SAME
  • Dry milk powder is used for a variety of purposes.
  • One industry that uses significant quantities of dry milk is the chocolate industry, for example, Chocolate Manufacturers' Association members use 3.5 million pounds of whole milk daily. In 1996 and 1997, production of dry whole milk, mostly for the confectionery industry, was approximately 130,000,000 pounds.
  • Dried whole milk powder ( MP) has generally been prepared by two different processes, roller drying and spray drying.
  • milk fat is entrapped in a glassy matrix composed mainly of amorphous lactose and colloidal protein, such that less than 1% of the fat is extractable with organic solvents at room temperature (about 20-25 °C) .
  • This extractable fat is often called " free fat” .
  • free fat For example, extraction of a commercial whole milk powder containing 28.5% total fat with pentane at room temperature for two hours yielded 0.3% free fat.
  • dry milk powder wherein the fat is entrapped leads to undesirably high viscosity in the final product, requiring a greater amount of cocoa butter or emulsifier to standardize the flow properties.
  • roller-dried milk powder has been preferred for chocolate manufacture, i.e., its greater free fat content.
  • commercial sources of roller-dried product are few, and roller-dried milk powder is susceptible to oxidative rancidity.
  • spray-dried milk powder is most often used. It has previously been shown that crystallization of the lactose in milk powder results in higher free fat (Aguilar and Ziegler, 1993) , and that lactose from spray- dried milk powder crystallizes in the ⁇ form during the process of chocolate conching (Ziegler and Aguilar, 1994) .
  • Conching is a step in chocolate making wherein the initial dried mixture of ingredients is heated, and emulsifiers and more cocoa butter are added to liquify the chocolate and allow the full flavor to develop. The resulting product is smooth and flavorful. Conching is critical to flavor development in ways that are not well understood.
  • skim milk powder non-fat dry milk
  • anhydrous milk fat is still susceptible to flavor deterioration, and the combination of skim milk powder and anhydrous milk fat does not yield the same quality of flavor as whole milk powder.
  • An object of the invention is to provide a dry milk product having lactose in essentially crystalline form and containing fat in the free state.
  • Another object of the invention is to provide a process for producing a dry milk product with the highest free fat content possible.
  • the invention comprises a dry milk product having lactose in essentially the crystalline state and the highest free fat content.
  • the product will contain 20-40% of fat by weight of which 80-100% is in the free state.
  • the invention also comprises a process for producing dry milk product with the desired characteristics.
  • This product typically contains ⁇ 10% moisture, and preferably ⁇ 5% moisture, has lactose in essentially the crystalline state and contains from 20-40% fats by weight of which 80-100% are in the free state.
  • the dry milk is processed at elevated temperature with shear in a mixing or grinding device.
  • the resulting product is beneficial as an ingredient for confectionery, especially chocolate, to reduce viscosity and improve flavor.
  • Figure 1 shows the X-ray diffraction patterns of feed material to the process (a) and converted product (b) .
  • Figure 2 shows the particle size distribution of converted milk paste.
  • Figure 3 shows a response surface plot and three- dimensional view of lactose crystallinity as a function of screw speed and feed rate at process temperature of 71.1 °C (160 °F) .
  • the counter lines with numbers are significantly different at P ⁇ 0.05. Experimental conditions below the diagonal line were not included in the design.
  • Figure 4 is a response surface plot of combined lactose crystallinity and free fat as a function of screw speed and feed rate at 71.1 °C (160.0 °F) .
  • the diagonal line shows the design boundary.
  • the expected free fat is 88.4% and lactose crystallinity spike is at 1271 count per second on x-ray diffraction pattern.
  • Figure 5 is the x-ray diffraction pattern of the unprocessed spray-dried WMP. There is not any characteristic spike. It indicates that the lactose in raw WMP was in amorphous glassy form.
  • Figure 6 is the x-ray diffraction pattern of the processed spray-dried WMP.
  • the spikes in the pattern indicate that the lactose in WMP is crystallized.
  • Figure 7 is the particle size distribution of raw WMP. It is a unimodal distribution with volume based average particle size (D 4 3 ) of 137.29 ⁇ m.
  • Figure 8 is the particle size distribution of processed WMP. It is a bimodal distribution with volume based average particle size (D 43 ) value of 50.27 ⁇ m.
  • Figure 9 is a system diagram for WMP processing of the present invention.
  • Figure 10 is a schematic of a fuzzy logic temperature controller for WMP inputs and outputs which could be added to the process of the present invention.
  • Figure 11 is the fuzzy membership functions for the inputs (a, b, c, d) and output (e) for the controller of Figure 10.
  • the product is a whole milk product with substantially, approaching 100%, free fat and crystalline lactose. Though the form and ratio of crystals ( ⁇ vs. ⁇ ) is not critical, the present product has ⁇ crystals which is not generally found in existing dry milk products.
  • the process involves the application of heat and shear forces to a spray-dried milk powder resulting in crystallization of the amorphous lactose and liberation of entrapped fat, which ultimately results in the desired characteristics of higher free fat content and crystalline lactose.
  • the higher free fat content results in the desired sensory properties of the end product in which the milk powder is used.
  • heat i.e., heating over the glass- transition temperature of the dry milk powder
  • the heat de- vitrifies the glassy matrix and allows the lactose mobility to crystallize. This crystallization liberates entrapped milk fat and reduces the particulate phase volume.
  • the heat should be applied at a level which gives the desired crystallization but does not result in burnt flavors in the product.
  • the heat may be applied extrinsically and/or may be applied intrinsically from the shear (mechanical work input) . Since shear always creates some level of heat, this must be taken into account when applying an extrinsic heat source.
  • the heat may be dry or moist heat .
  • Means of heat control and adjustment of heat depend on the shearing device and/or extrinsic heat source used and are readily known to one of ordinary skill in the art.
  • extrinsic heat sources include jackets around the shearing device or direct heating of the shearing parts.
  • Shear is an action or stress caused by an application of forces that causes two parts of a body to slide on each other. Applying shear to the WMP liberates the entrapped fat and disperses it within the product . The shear also is able to maintain the lactose crystals as smaller particle sizes. Heat alone often causes clumping of lactose crystals. Shear should be sufficient to produce the desired crystal size(s) and the desired level of fat liberation.
  • Suitable shear devices include extruders, high-shear mixers, agitated ball mills, and the like, all of which are readily commercially available and known in the art .
  • PA Readco Manufacturing in York
  • Shear adjustment is based on the device used and is known to one of ordinary skill in the art. Examples of parameters which affect shear are screw speed, energy input, feed rate, and back pressure.
  • Shearing and heat can be controlled manually by an operator or by automatic controls.
  • grinding aid can control overheating and improve the grinding and dispersion of lactose crystals. This results in improved process stability and improved handling properties of the product.
  • commercially spray-dried milk powder at 28.5% fat by weight was processed in either a 2" or 5" Readco Manufacturing Continuous Processor.
  • the Continuous Processor is a high-shear, twin-screw mixing device operating at 100-300 rpm. Dry whole milk was fed into the 2" processor at a rate of 4-35 kg/hr using a dry material feeder.
  • the jacket temperature of the processor was maintained at 80-105 °C, i.e., above the glass transition temperature of the milk powder (-70 °C) .
  • the crystals may grow to sizes greater than 0.5 mm, and at this point, the product looks like wet sand.
  • the processor is capable of grinding these large crystals to produce a paste with particles less than 100 ⁇ m ( Figure 2) . This crystallization and grinding generates a significant amount of heat and, consequently, the jacket temperature may be reduced.
  • the process as described is susceptible to overheating, which may produce burnt off-flavors. However, when controlled, this process can produce caramel -like flavors typical of crumb based chocolates.
  • the overheating can be controlled and the grinding and dispersion of lactose crystals improved by adding a small amount of emulsifier to the process. Adding just 0.3% by weight soy lecithin allowed an increase in throughput from 10 kg/hr to 35 kg/hr while improving the process stability and the handling properties of the product .
  • the process can be carried out using the continuous processor with a number of paddle configurations, and even other devices that provide sufficient mixing/grinding action and allow for some means of temperature control, e.g., twin- screw extruders, high-shear mixers, or agitated ball mills.
  • twin- screw extruders e.g., twin- screw extruders, high-shear mixers, or agitated ball mills.
  • the sugar composition (ratio of sucrose : lactose) in each fraction was analyzed by HPLC (Table 2) .
  • sucrose Prior to conching, particles ⁇ 45 ⁇ m had a higher proportion of sucrose (less lactose) than particles >45 ⁇ m, consistent with observations that sucrose undergoes abrasion (surface erosion) during the roll refining process, producing a larger number of particles.
  • the ratio of sucrose : lactose was nearly the same in all size ranges, i.e., lactose was now distributed evenly through all particle sizes.
  • X-ray diffraction patterns revealed the presence of ⁇ -lactose in conched, but not in unconched samples, and scanning electron micrographs showed fine crystalline material adhering to the surface of what appeared to be sucrose particles (Ziegler and Aguilar, 1994) .
  • WMP Spray-dried whole milk powder
  • the powder was purchased from Agri-Dairy Products, Inc. (Purchase, NY).
  • Typical composition of the raw WMP was as follows:
  • a 2" twin-screw co-rotating continuous processor manufactured by Readco Manufacturing, Inc. (York, PA), was used to process the spray-dried WMP.
  • a control panel displayed the thermocouple sensors' readings and the power consumption on the processor barrel.
  • An AccuRate" gravimetric single screw powder feeder fed the WMP to the processor.
  • the control of the feeder was accomplished using a microcontroller provided with the feeder.
  • a circulating water heater manufactured by Mokon Inc. (Buffalo, NY) , was used to warm the components up and control the process temperature.
  • the continuous processor is a twin-shaft co-rotating mixer. It provides homogenous mixing, shearing, kneading, and crystallizing of one or more dry materials with one or more liquid materials.
  • the shafts are driven by a 3.728 kW (5 hp) electric motor.
  • the mixing, shearing, kneading, and crystallizing are accomplished with the help of paddles or the processing elements positioned on the shafts in the processor.
  • paddles There are three types of paddles: forward helix, reverse helix, and flat. Forward helix paddles have conveying, reverse helix paddles have mixing and shearing, and flat paddles have shearing and mixing effects on the material being processed.
  • the paddles and feeding screws were configured in such a way that lactose crystallization could take place in a uniform manner while providing stable processing conditions (Table 4) .
  • the discharge gate position is at paddle numbers 1-3, and the powder enters at paddles numbered 25-27. Table 4. Paddle configuration inside the continuous processor barrel
  • L CIELAB lightness value
  • a* CIELAB redness value
  • b* CIELAB yellowness value
  • Free fat content was determined suspending 2 g of sample in 15 mL of HPLC grade pentane for 2 hrs . The suspension was stirred until all insoluble particles were well dispersed. After initial suspension, every 30 min. the solution was stirred for 15 sec. by shaking the flask. After two hours, 12 mL solution was placed in Pyrex ® centrifuge tubes and centrifuged until the solid parts were separated from the liquid. Using a pipet, 2 mL of clear supernatant were taken and placed in weighed and labeled aluminum cups and dried in a convection oven at 80 °C (176 °F) for 2 hrs. The cups with fat were weighed at room temperature. From the known total fat content of the WMP and the weight of the extracted fat, the free fat content was determined as a percentage of the total fat content.
  • Lactose crystallinity X-ray diffraction patterns of the samples were determined between 10° and 30° (Aguilar and Ziegler, 1994) using an automated x-ray diffractometer (Rigaku Denki , Co. Ltd., Tokyo, Japan) .
  • Particle size distribution The MasterSizer laser light-scattering particle size analyzer was used to determine the particle size distribution of the products. The analyzer had a MS 15 sample presentation unit and 300 mm lens (Malvern Instruments Ltd. , Malvern, England) .
  • the processed WMP was dispersed in isobutanol (Fisher Scientific, Pittburg, PA) at room temperature until the obscuration value was reached to 0.2, corresponding to a volume concentration of 0.03-0.05% (Aguilar and Ziegler, 1994) .
  • Mechanical stirring and ultrasonic dispersion 50 W at 27 kHz for 2 min. were applied for dispersing the particles independently.
  • Color The CIELAB L* , a*, b* (lightness, redness, and yellowness) values were determined using reflectance spectrometry (Minolta Spectrophotometer, CM-3500) .
  • Moisture contents of the processed and raw WMP were determined drying 2 g samples at 50 °C in an oven for 14 hrs. Similar analyses on raw milk powder samples were also conducted to compare the processed and raw WMP properties (Table 6) .
  • the process conditions providing the desired spikes on x-ray diffraction patterns showing the lactose crystallinity were found to be 13.8 kg/hr (30.5 lbs/hr) feed rate, 266 rpm screw speed, and 71.1 °C (160 °F) process temperature.
  • the temperature had a significant linear effect on the lactose crystallinity (P ⁇ 0,01).
  • Screw speed and feed rate also showed significant quadratic effects on lactose crystallinity at P ⁇ 0.05.
  • the response surface plot of lactose crystallinity as a function of screw speed and feed rate at 71.1 °C (160 °F) is shown in Figure 3.
  • Screw speed and feed rate interaction and quadratic term of screw speed showed significant effects on product moisture content at P ⁇ 0.05. Linear effects of screw speed and feed rate on power consumption were significant (P ⁇ 0.001). Feed rate and temperature interaction also showed a linear effect on power consumption at P ⁇ 0.05.
  • the maximum torque and the screw speed that the electric motor could provide were 3.728 kW (5 hp) and 320 rpm, respectively. Taking these limits into account and from preliminary experiments, the maximum feed rate and screw speed were determined to be 18.1 kg/hr (40 lbs/hr) and 290 rpm, respectively. Exceeding these limits resulted in machine failure.
  • Spray-dried WMP increased the free fat content from less than 10% to over 95%.
  • Spray-dried WMP with high free fat content would reduce cocoa butter addition during conching. This would result in reduction in production costs since the cocoa butter is the most expensive ingredient in chocolate.
  • Particle size distribution of the WMP was improved with processing.
  • the particle size distribution of the processed and raw WMP are shown in Figure 7 and Figure 8.
  • Particle size distributions of the raw WMP samples show unimodal distributions with volume based average particle size (D 43 ) values of 137.29, 140.28, 139.45 ⁇ m (Table 6).
  • processed WMP showed a wider and close to a bimodal particle size distribution, with smaller D 4 3 values.
  • Preprocessing not only reduced the average particle size of the WMP, it also provided a bimodal particle size distribution which is preferable for chocolate manufacturing (Stauffer, 1998) . Having a bimodal particle size distribution helps to reduce the cocoa butter use.
  • the color analyses of the raw and processed milk powders were also conducted using reflectance spectroscopy .
  • the three color-reflectance values, CIELAB L* , a*, and b* were obtained for both the processed and raw WMP (Table 5 and 6) . After processing, the color of WMP turned to bright light yellow.
  • Spray-dried WMP with minimum 28% total fat content and less than 3% moisture content was processed.
  • a 2" diameter, 5 hp, pilot-scale co-rotating twin-screw continuous processor was used to process the WMP.
  • a gravimetric powder feeder was used to feed the powder into the continuous processor.
  • the maximum capacity of the powder feeder was 36.2 kg/hr (80 lbs/hr) .
  • a circulating water heater was used to provide heating and cooling for the processor barrel.
  • a peristaltic pump was used to inject lecithin into the processor.
  • ECHIP ECHIP Inc., Hockessin, DE
  • the designs provided the minimum number of the combinations of four control variables. There variables were the process temperature, processor screw speed, powder feed rate, and lecithin injection. Two separate experimental designs were conducted. For both designs, the same control variables in different ranges were used. The first experimental design served as a screening design. The ranges of the control variables for the two designs are shown in Table 7.
  • the two separate experimental designs provided 54 combinations of the four control variables. For each combination of the control variables, experiments were conducted and samples were collected. Steady state was considered to be reached when the control variables remained constant at the desired conditions. The collected samples were analyzed to determine the product free fat content, average particle size distribution and lactose crystallinity, CIELAB L*, a*, and b* values, and moisture content. Free fat content of the product was determined by suspending 2 g of processed WMP in 15 mL of HPLC grade pentane for 2 hrs. Every 30 min. the solution was stirred for a few seconds. The solutions were centrifuged to separate the solid parts from the solution.
  • the CIELAB L* , a*, and b* (lightness, redness, and yellowness) values were determined using reflectance spectrophotometry (Minolta Spectrophotometer, CM- 3500d) . moisture contents of the processed WMP were determined drying 2 g of samples at 50 °C in an oven for 14 hrs .
  • the neural network analysis was conducted using NeuroShell 2 commercial software (Ward Systems Group, 1993) on an IBM computer with a Pentium processor.
  • the four control variables of the powder feed rate, processor screw speed, process temperature, and amount of lecithin injection were used as the network inputs.
  • the free fat content, lactose crystallinity, average particle size distribution, CIELAB L* , a*, and b*, moisture content, and power consumption were used as the network outputs.
  • a total of 54 patterns of data was obtained from the two experimental designs (Table 8) . Twenty percent of this data was randomly allocated as a test set and 80% was used as training set.
  • a three-layer general regression neural network (GRNN) architecture (Specht, 1991; Caudill, 1993) was used to train the network.
  • Table 8 WMP processing data set used for network training.
  • Training of GRNN includes assigning a neuron for each pattern in the pattern layer.
  • the weights between the pattern layer neurons and the input layer neurons are equal to the inputs of the training patterns .
  • the outputs of the training patterns are assigned as the weights between the pattern layer neurons and the summation layer neurons.
  • the number of neurons in hidden layer in GRNN is equal to the number of training patterns.
  • the number of summation neurons is equal to the number of outputs .
  • City block distance is the absolute difference between the new input and the trained input values .
  • the pattern neurons sum the distances and feed to a nonlinear activation function.
  • the outputs of the pattern neurons are multiplied by the corresponding weights and summed by the summation neurons in the third layer.
  • the summation neuron outputs divided by the sum of the pattern neurons provide values to the output layer.
  • the results of the output neurons are the estimates for the new inputs.
  • the trained network was saved as a file that could be accessed via Dynamic Link Library (DLL) in a Microsoft Excel 97 spreadsheet.
  • DLL Dynamic Link Library
  • This trained network served as the genetic algorithms' fitness function over which the input variables are evaluated to reach the optimal solution.
  • Genetic algorithm search A genetic algorithm was used to search for process conditions providing near optimal free fat content, lactose crystallinity, and average particle size under the constraints.
  • the optimization problem can be summarized as follows .
  • Goal maximum free fat content of the processed WMP
  • the criteria for determining the constraints were based on the visual assessments of the samples from each experiment and the observations made during sample collections.
  • the redness (a*) values greater than 3 were not desirable, since the color of the product was close to undesirable brown color with a burnt smell. Even though the electric motor could provide up to 3.7 kW, the machine was not operating properly above 2.6 kW, so the power consumption was included m the problem as another constraint.
  • the ranges for the inputs that the genetic algorithm search applied were as follows:
  • Powder feed rate 4.35-27.21 kg/hr (10-60 lbs/hr)
  • Lecithin injection 0.058-0.45 kg/hr (0.13-1.0 lbs/hr)
  • the free fat content was represented with a 32 -bit chromosome. Each 8-bit section of the chromosome represented one input variable.
  • An initial population with randomly created 300 chromosomes was assigned. Each individual chromosome m the population provided a solution that may not be the best solution. These randomly assigned chromosomes were decoded to their corresponding decimal numbers and their goodness was evaluated with the fitness function (the trained neural network) . Cross over rate of 0.9, mutation rate of 0.01 and generation gap of 0.98 values were chosen. Generation gap is the percentage of the chromosomes m the current population being m the next generation. Since there were 300 chromosomes in the initial population, only six (300*0.02) of them had a chance to be m the next generation. If the best fitness value was not changed after 50 generations, the search was stopped and the results were displayed. The genetic algorithm search was conducted using GeneHunterTM (Ward Systems Group Inc., Frederick, MD) commercial software .
  • the GRNN training was based on a total of 54 patterns. Eighty percent of the patterns were training and 20% of the patterns were the test patterns.
  • the training provided the coefficient of determination values (R 2 ) (Ward Systems Group, 1993) of 0.71 for free fat, 0.82 for crystallinity, 0.64 for average particle size, 0.91 for L* , 0.76 for a*, 0.88 for b*, and 0.86 for moisture content.
  • R 2 coefficient of determination values
  • the R 2 values for free fat content and average particle size might have been considered to be too low.
  • Echip statistical experimental design software provided the minimum number of experiments. In the experimental design for four control variables, five replications were chosen. The differences in the responses of those replications were quite large, which created large disturbances in the network training .
  • BP backpropagation
  • a three-layer 4-13-8 BP architecture was chosen.
  • the learning rate, momentum, and initial weights were set as 0.1, 0.1, and 0.3, respectively.
  • the network training was stopped when the minimum average error was not changed after 20000 passes.
  • the coefficient of determination values for free fat content, lactose crystallinity, average particle size, L* , a*, b*, and moisture content 0.53, 0.77, 0.48, 0.84, 0.92, 0.74, 0.66, and 0.83, respectively.
  • the R 2 values for free fat from the three-layer BP algorithm was about 20% less than the R 2 values from the GRNN training.
  • the trained GRNN was used as objective function to determine optimal processing conditions providing the highest free fat content, minimum average particle size, and maximum lactose crystallinity while not violating the redness (a*) value. There were little changes in the lightness (L*) and yellowness (b*) values of the processed WMP compared to the raw EMP. Under the constraints discussed in the material and methods, the genetic algorithm resulted in the following optimal processing conditions and the corresponding expected responses .
  • Fuzzy logic controller design Like in the extrusion processes, milk powder processing requires continuous monitoring and control to maintain the operation in these optimal conditions. Variations in the WMP (moisture, density, particle size, etc.) and the interactions between the operating variables make the operation difficult. A human operator usually monitors and makes the decisions of keeping the barrel temperature, screw speed and powder feed rate stable. Among the operating variables, process temperature is the most important variable that is sensitive to the raw material variations. Even small changes in the process temperature affect the product quality and sometimes cause the process to fail.
  • WMP moisture, density, particle size, etc.
  • a fuzzy logic controller is proposed to control the heater and the cooling solenoid valve to maintain the process temperature at allowable ranges.
  • the WMP processing system diagram is shown in Figure 9.
  • the inputs to the fuzzy logic controller will be the temperatures measured at the processor discharge gate and in the middle, optimal temperature and power consumption.
  • the outputs of the controller will be the signals controlling the heater and the solenoid valve for the circulating water.
  • thermocouple sensors indicate that the product temperature is in the allowable range, due to the variations in the raw material, the temperature of the powder on the paddles may be higher than the sensor readings. When the paddle temperature gets too high, the powder burns on them. This increases the friction between the material and the paddles as well as the barrel wall. Increased friction requires more torque to keep the screw speed in the set level so the power consumption increases.
  • the inputs and outputs of the fuzzy logic controller for the temperature control system are shown in Figure 10.
  • the inputs of the controller are the error (E) between the optimal desired temperature and the Temperature 1, change in the error ( ⁇ E) and the difference between Temperature 1 and Temperature 2 ( ⁇ T) .
  • Product temperature at the gate is usually about 4.4 °C (10 °F) less than temperature in the middle of the processor.
  • the fuzzy logic controller of the WMP system design objective is to keep the process temperature as close to the optimal processing temperature of 107.7 °C (226 °F) as possible in spite of the variations in the raw WMP properties.
  • the universe of discourse (range) values for the inputs and outputs of the fuzzy logic controller are shown in Table 9. Table 9. Universe of discourse values for the inputs and out uts ,
  • the fuzzy rule base will be developed using the Combs Method (Combs and Andrews, 1998) .
  • One of the difficulties in fuzzy logic control design is the development of a rule base.
  • the Combs method eliminates relating all the inputs to each other before applying them to the output (Andrews, 1997) .
  • One of the requirements of to apply the Combs method is to have an equal number of membership functions per input and output. Whenever the crisp input values are read from the sensors, with fuzzification the corresponding membership values for every input variable are calculated.
  • the Combs method computes the fuzzy outputs relating each input range to its corresponding output range like P (small) to H (off) , E (small) to H (off) , and so on. Then, the center of gravity method will be used to defuzzify the outputs. Finally, a control signal is sent to adjust the heater position.
  • the process conditions providing the highest free fat content (95.7 %) were determined to be 24.5 kg/hr (54.0 lbs/hr) feed rate, 265 rpm screw speed, 108.0 °C (226.5 °F) , and 0.104 kg/hr (0.23 lbs/hr) lecithin addition.

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  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Polymers & Plastics (AREA)
  • Confectionery (AREA)

Abstract

L'invention concerne un procédé de fabrication d'un produit laitier en poudre contenant moins de 10 % d'humidité ou, de préférence, moins de 5 % d'humidité, du lactose à l'état sensiblement cristallin, et 20 à 40 % en poids de matières grasses dont 80 à 100 % sont à l'état de repos. Ce produit laitier en poudre est fabriqué par traitement d'un lait en poudre à des températures élevées avec cisaillement dans un dispositif de malaxage ou de broyage. Le produit obtenu est utile comme ingrédient de confiserie (le chocolat, notamment) destiné à réduire la viscosité et améliorer le goût.
PCT/US1999/024036 1998-10-13 1999-10-12 Produit laitier en poudre et procede de fabrication dudit produit WO2000021380A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US10399098P 1998-10-13 1998-10-13
US60/103,990 1998-10-13

Publications (1)

Publication Number Publication Date
WO2000021380A1 true WO2000021380A1 (fr) 2000-04-20

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Application Number Title Priority Date Filing Date
PCT/US1999/024036 WO2000021380A1 (fr) 1998-10-13 1999-10-12 Produit laitier en poudre et procede de fabrication dudit produit

Country Status (1)

Country Link
WO (1) WO2000021380A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6548099B1 (en) * 2000-11-28 2003-04-15 Hershey Foods Corporation Process for crystallizing amorphous lactose in milk powder
JP2017134085A (ja) * 2010-06-13 2017-08-03 株式会社明治 固形乳の溶解性と強度の判定方法及び固形乳の製造方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4871573A (en) * 1985-11-23 1989-10-03 Nestec S. A. Product and process for the production of a milk powder
US5051265A (en) * 1989-02-14 1991-09-24 Nestec S.A. Preparation of crude chocolate powder and products therefrom
US5672373A (en) * 1995-10-16 1997-09-30 Miller; Van Method of producing anhydrous whole milk power having full fat recovery for further use

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4871573A (en) * 1985-11-23 1989-10-03 Nestec S. A. Product and process for the production of a milk powder
US5051265A (en) * 1989-02-14 1991-09-24 Nestec S.A. Preparation of crude chocolate powder and products therefrom
US5672373A (en) * 1995-10-16 1997-09-30 Miller; Van Method of producing anhydrous whole milk power having full fat recovery for further use

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6548099B1 (en) * 2000-11-28 2003-04-15 Hershey Foods Corporation Process for crystallizing amorphous lactose in milk powder
JP2017134085A (ja) * 2010-06-13 2017-08-03 株式会社明治 固形乳の溶解性と強度の判定方法及び固形乳の製造方法

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