Patent Application
20060240159
The present invention relates to a method for reducing fouling of heat transfer surfaces. More specifically, the present invention relates to a method of using certain cellulose ethers for reducing fouling of heat transfer surfaces of food and beverage compositions containing proteins during pasteurization or sterilization.
Many processed foods and beverages available to the consumer are heat-processed to eliminate microbial contamination and to ensure a suitable product shelf-life. These heat-processed foods have been subjected or exposed to temperatures that would kill disease-causing microorganisms and/or reduce the number of spoilage microorganisms. Heat-processing is used in the production of a variety of food and beverage products, including but not limited to juice, juice products, milk and other dairy products, egg based foods and beverages, and canned condensed soups.
In addition to improving the shelf-life of the food or beverage, heat-processing can also initiate reversible and irreversible changes in the solubility of proteins, fats, and salts that are components of the food or beverage product. The result is the deposition and adsorption of these organic components, e.g., proteins, fat, and other food components, and inorganic components, e.g., calcium phosphates and other salts onto the surface of the processing equipment, producing a surface deposit layer known as a fouling layer on the equipment. The heat exchanger surfaces of the processing equipment are particularly affected.
Fouling and subsequent cleaning of processing equipment, and particularly heat exchangers, is a problem in the food and beverage industry because of its impact on food safety as well as plant performance and production efficiency. Fouling and subsequent cleaning of processing equipment in the dairy industry causes significant increases in capital and operating costs annually. Frequent cleaning of plate heat exchangers (PHE), tubular heat exchangers, equipment used in pasteurization, ultra-high temperature (UHT), and high temperature short time (HTST) treatments, and other heat processing equipment, is needed to remove food and microbiological deposits and to restore PHE heat transfer characteristics, which are reduced by the presence of the fouling layer. In addition, the fouling layer leads to reduced flow rates and pressure buildup in the processing equipment over time, which leads to the need for equipment shutdown and cleanout.
In the prior art, various types of heat exchangers are used in heat-processing of food and beverage products. Indirect PHE are used for processing milk, flavored milk, fermented milk products such as drinking yogurt, as well as cream and coffee whiteners. The indirect tubular-based heat exchanger system is used for processing milk, flavored milk, cream, ice cream mix, evaporated milk, desserts and puddings, cheese sauces, dairy sauces, soups, liquid protein concentrates and preparations. This system is also used for juices, and especially for juices with pulp. Neutral and acidic pH dairy and nondairy beverages can also be processed in this equipment. A wide range of products can be processed in scraped-surface heat exchangers, including milk concentrate, yogurt, processed cheese, whey protein concentrate and quarg products.
Direct steam infusion of a food or beverage product into a steam chamber followed by rapid cooling or direct injection of steam into a food or beverage product followed by cooling with a PHE or tubular heat exchanger are more gentle heat treatments that are also used in food and beverage processing.
In order to remove fouling deposits and operate equipment safely, efficiently, and free from microbial contamination, several cleaning practices have been adopted, including 1) manual cleaning of surfaces using brushes and cloths, 2) spray jet cleaning of tanks and vessels, 3) empirical clean-in-place protocols have been developed in the milk processing industry, using either a) a two stage alkali and/or acid circulation through equipment or b) a single stage formulated detergent containing wetting and/or surface active agents and chelating compounds, and 4) the use of coatings on equipment which are toxic to organisms, i.e., Microban® coatings.
Approaches to reduce the occurrence of a fouling layer in food and beverage processing equipment have been investigated, including mechanical and chemical methods. Studies have shown that fouling during milk pasteurization and sterilization is related to heat denaturation of proteins, especially B-lactoglobulin protein. Milk deposit formation on the heat exchanger surface area when temperatures are less than 90° C. has been directly linked with denaturation of this protein.
Some prior art discuss approaches to reduce fouling in other systems and processes. U.S. Pat. No. 4,929,361 discloses the use of surfactants to control fouling in protein-containing fluids during a corn milling operation. U.S. Pat. No. 5,336,414 discloses the use of lecithin as an additive to control proteinaceous fouling deposits. U.S. Pat. No. 3,483,033 discloses the use of anionic polymers, such as carboxymethylcellulose, as an additive to help control scale formation in evaporators used in the concentration of cane and beet sugar.
Other prior art, such as British Publication No. 2249467 A, discloses a process for pasteurizing or sterilizing a liquid food composition by adding a methyl cellulose ether, a hydroxypropyl methyl cellulose or mixtures thereof to the liquid composition after the temperature of the liquid composition has been raised above the hydration temperature of the cellulose ether.
There remains a need to reduce fouling of heat transfer surfaces during heat processing of food and beverage compositions in order to increase run time of the process, improve cleaning efficiency, and improve product quality.
This invention is directed to a process for reducing fouling of heat exchanger's surfaces by food or beverage compositions containing proteins during a heat treatment treatment of the food or beverage. The process includes the following steps:
a) adding to a food or beverage composition an antifouling agent selected from hydroxypropylcellulose (HPC) having a hydroxypropyl molar substitution of greater than 3.0 and a weight average molecular weight (Mw) as measured by SEC of greater than 350,000 Dalton or a methylhydroxypropylcellulose (MHPC) with a methoxyl content of greater than 17% and a hydroxypropyl content of greater than 3%, methyl cellulose (MC) with a methoxyl content of greater than 17% and a viscosity in water at ambient temperatures at a concentration of 2% of greater than 1,000 cps, or mixtures thereof;
b) heating the food or beverage composition in a first heat exchanger at a temperature between 50 and 100° C. for a time of about 2 seconds to about 30 minutes; and
c) packaging the food or beverage composition
wherein the first heat exchanger is fouled at least 10% by weight less or run-time increased at least 10% as compared to when heat-treating a similar food or beverage composition without the antifouling agent.
The present invention also comprehends a process of sterilizing the food or beverage compositions mentioned above by heat treating the food or beverage composition to a temperature and time sufficient to sterilize the food or beverage composition.
The present invention also relates to a heat treated food or beverage composition that is prepared by the above mentioned processes. This product by process excludes use of HPC alone in creams as the antifouling agent.
It has been surprisingly found that organic and salt deposits that build up on heat exchangers and other processing equipment during the heat-processing of foods and beverages (i.e., pasteurization or sterilization) can be reduced or eliminated by using certain cellulose ethers in a unique process.
The advantages of this unique process is that the heat exchangers are fouled at least 10% by weight less or run-time increased at least 10% as compared to when heat-treating a similar food or beverage composition without the antifouling agent. Other advantages is that the food or beverage properties are improved, such as color, reduced particle size of the discontinuous phase or emulsified or suspended phase, improved mouthfeel, improved thickening, and improved whipping performance, in the form of 20-50% increases in % overrun compared with formulations that do not contain these cellulose ethers and are processed in the unique process of this invention.
This invention encompasses food or beverage compositions including polymers that reduce or eliminate fouling during heat-processing such as the processing used in food and beverage manufacture to achieve pasteurization or sterilization treatment, to eliminate microbial contamination and improve product shelf-life, or to modify the food or beverage product. This invention also encompasses the process of using polymers to reduce fouling during heat-processing of food and beverages by 1) including the polymer in the product prior to heat treatment, 2) heat-processing the product, and 3) cooling the food or beverage product.
Examples of heat-processed foods and beverages as part of this invention include, but are not limited to, neutral and acidic pH dairy and non-dairy beverages and foods, heavy cream, double cream, culinary cream, table cream, half and half, ice cream mixes, flavored milk, milk, fermented milk products such as yogurt, drinking yogurt, yogurt beverages, cream and coffee whiteners, evaporated milk, desserts and puddings, cheese sauces, dairy sauces, acidified dairy beverages, dessert mixes and bases, non-dairy creamers, bases for whipped topping, nutritional supplement beverages, grain beverages, soy milks and beverages, protein beverages, soups, condensed soups, liquid protein concentrates and preparations, juices, juices with pulp, processed cheese, whey protein concentrate and quarg products, guacamole, fruit juices, pourable salad dressings, salsa, poultry products, oil-in-water emulsified foods, foods and beverages containing egg yolks or egg whites, mayonnaise, processed soybeans and soybean food products, coagulated food products such as tofu or the like, fat and oil processed foods such as margarine, creamy foods such as spreads, dips, dressings, sauces, marinades, vegetable toppings, vegetable whipped toppings, pates, fillings for baked goods, soup enhancers, vegetable purees, natural heat-processed vegetables such as tomatoes, tomato-sauce, tomato paste, potatoes and potato products, rice and rice products, processed meat products, injectable brines, processed seafood or fish products, and pet foods.
Examples of the heating apparatus include any indirect heating apparatus, including a heated vessel, a surface heat exchanger, a plate heat exchanger, a tubular heat exchanger, a double pipe heat exchanger, a multi-pipe heat exchanger, a coil heat exchanger, a flat heat exchanger, and a scraped surface heat exchanger; including closed continuous-type scraped-surface heat exchangers, and direct heating apparatuses such as injection types and infusion types of heating apparatuses.
The polysaccharide polymers used in this invention as antifouling agents are hydroxypropyl cellulose (HPC), methyl hydroxypropyl cellulose (MHPC), methyl cellulose (MC). The HPC has a hydroxypropyl molar substitution of greater than 3.0 and a weight average molecular weight (Mw) as measured by SEC of greater than 350,000 Dalton; the MHPC has a methoxyl content of greater than 17% and a hydroxypropyl content of greater than 3%; and the MC has a methoxyl content greater than 17% and a viscosity in water at ambient temperatures and a concentration of 2% of greater than 1,000 cps. Mixtures of these cellulose ethers can also be used in this invention. The amount of the antifouling agent used in the heat treatment process of this invention has an upper limit amount of 0.5 wt % and a lower limit amount of about 0.01 wt %.
In accordance with this invention, packaging out of the pasteurized or sterilized food or beverage composition can be an aseptic packaging in microorganism free containers for either consumer use or further commercial use.
In accordance with the present invention the heat step in the first heat exchanger can be a single heating zone or a plurality of heating zones (2 to 5 zones). This heating step can also include a pre-heating zone where the temperature is raised gradually rather than all at once. The preferred heating method is to heat in the heat exchanger at a temperature between 50 and 100° C. for a time period of from about 2 seconds to about 30 minutes. It should also be understood that this heating step is basically a pasteurization step that can vary slightly depending upon the type of food or beverage or operating conditions of the heat exchanger.
Sterilization occurs in the second heat exchanger that also can be a single piece of equipment or a plurality of pieces of equipment or the heat exchanger can merely have a plurality of heating zones where the food or beverage is moved from one zone to the other. By multiple heat exchangers is meant that there can be either 2 to 5 different pieces of equipment or 2 to 5 zones in a single piece of equipment. Hence, the first and second heat exchangers can be either a single vessel or a serial or plurality of pieces of equipment. By sterilization is meant that the food or beverage is heated to a temperature sufficient to kill most of the microorganisms; the temperature has to be greater than 100° C. at a time between 2 seconds and 80 minutes, preferably greater than 120° C. for a time between about 2 seconds and 30 minutes, with the more preferred temperature being greater than 130° C. for a time between 2 and 30 seconds.
The cooling step in this invention is normally performed before the packaging out of the pasteurized or sterilized food or beverage product. The cooling step is normally at a temperature below the pasteurization or sterilization steps. Hence, the general temperature range for cooling is below 50° C., preferably below 25° C.
In accordance with the present invention, homogenization of the food or beverage composition is optional, in that it can be used to ensure the composition has a uniform consistency for either pasteurization or sterilization. Homogenizers can be used at any step during the process.
The food or beverage compositions of this invention contain at least one of the antifouling polymers of this invention and one or more ingredients commonly found in food or beverage products such as proteins, starches, flavors, fats, emulsifiers, coloring agents, opacifying agents, gums, binders, thickeners, preservatives, mold control agents, antioxidants, vitamins, emulsifying salts, sugars, amino acids, fat mimetics, and other ingredients known in the art.
Examples of buffering salts that can also be included in the composition are sodium hexametaphosphate, trisodium citrate, and sodium tripolyphosphate.
The following Examples are merely set forth for illustrative purposes, but it is to be understood that other modifications of the present invention within the skill of an artisan in the industry can be made without departing from the spirit and scope of the invention. All percentages and parts are by weight unless specifically stated otherwise.
Whipping cream is a food product known to present difficulty in heat processing. The protein, high fat content, and viscosity tend to promote burn on, also known as fouling, in the heat processing equipment. Product burn on constricts flow, increasing back-pressure on the equipment. In addition, product is not heated sufficiently, due to the burned on layer, and the heat sensors summon more heat as the product within the equipment does not reach desired temperatures.
During processing of whipped cream, as a result of fouling, two product streams enter the holding tube section just after the plate heat exchanger. One stream is cooler than the desired heat treatment temperature as it runs over the burned on product on the interior of the heat exchanger. The other stream is very hot as it is exposed to the maximum heat the plate heat exchanger is reaching as it tries to accommodate the call for heat. The hold tube has two sensors, picking up temperatures as the cream enters and exits the tube. The time in the holding tube allows for mixing of product, therefore, product temperatures may be uniform upon exit. Differences in these temperatures indicate problems with proper heating in the heat exchanger, as a result of fouling.
Polymers such as Klucel® hydroxypropylcellulose and methylhydroxypropylcellulose have been used in the formulation of nondairy whipped toppings. More recently, Klucel hydroxypropylcellulose has been added to dairy whipping cream. In dairy whipping cream, the benefits of hydroxypropyl cellulose are realized after the cream has been whipped. These benefits are shorter whipping times, foam stiffness, and foam stability. In addition, hydroxypropyl cellulose allows the formulation of whipping creams with lower fat content, from the traditional 35-40% to as low as 24% fat. Other polymers such as carrageenan and products that contain mixtures of polymers and emulsifiers, such as Aertex® cream stabilizer (Food Specialties, Mississauga, ON, Canada), which contains a blend of carrageenan, guar, locust bean gum and emulsifiers, have been added to whipping cream to achieve other functional benefits.
It has been unexpectedly found that in addition to improving the properties of whipped cream, the presence of hydroxypropyl cellulose in a dairy whipped cream formulation or its use as a processing aid reduces fouling typically observed in the heat processing equipment used to sterilize or pasteurize the product. Similar reductions in fouling are expected in other dairy products, and other foods and beverage products undergoing heat treatments or heat-processing to effect pasteurization, sterilization, or simple heating of the food or beverage product.
Incorporation of MHPC, or MC or blends thereof into creams, half creams, and reduced fat whipping cream formulations, milks or other dairy compositions that have been subjected to thermal processing, such as pasteurization, High Temperature Short Time (HTST), or Ultra High Temperature (UHT) treatments, produces a stable cream with desirable rheology, fat globules of small particle size, and good emulsion stability. On whipping these creams, the MHPC or MC improves the overrun or amount of foam delivered on whipping the cream, and the stability and texture of the whipped foam is improved. Additional improvements in physical characteristics and texture of the whipping creams are also observed on blending of MHPC or MC with other hydrocolloids such as carrageenan or hydroxypropyl cellulose, and on including emulsifiers into the composition.
In addition, it has been found that incorporation of methyl hydroxypropyl cellulose or methyl cellulose into dairy formulations reduces the buildup of fouling materials normally observed on heat exchangers during thermal processing of the dairy product leading to longer run times and easier cleaning of the heat exchangers.
The improvements observed on incorporation of MHPC and methyl cellulose (MC) into whipping creams is also expected to be observed in the stability, whipping characteristics (per application), and texture of other creams, milks, and cream products and dairy products into which the cream or milk containing the MHPC or MC is incorporated.
The invention is demonstrated by the Examples in Tables 1 and 2. The whipping cream formulations are shown in Table 1. Formulation Examples 3, 4, 7, and 8 contain hydroxypropyl cellulose.
The whipping cream in Table 1 was formulated and processed with light homogenization and ultra high temperature (UHT) treatment. UHT treatment is used to produce commercially sterile products for the optimum shelf life. Batches were formulated with skim milk and double cream to obtain the desired fat levels of 31% and 24% in the final cream. Ingredients were added to study the impact of no hydroxypropyl cellulose (HPC), HPC without an emulsifier present and HPC with emulsifier. Emulsifiers are often added to UHT treated whipping cream to aid in foam creation. All formulations contained carrageenan, a common ingredient in heat treated cream to aid in the prevention of the coalescence of fat during storage and prior to whipping. Table 1 contains formulation information; batches were 28 kg.
In all processes the target temperatures preheat to 75° C. and final heat to 133° C. with a holding time of 17 seconds. Two stage cooling was used to achieve chill temperatures of <8° C. (typically 6-7° C.). Pre-process 2-stage homogenization was provided to all products at a value of 50/20 bar (725/296 psi) using a Rannie Homogenizer. The homogenizer also tightly controls the feed rate of the plant to 70 l/hr.
In Table 2, data on processing is presented for the formulations in Table 1. In batches containing carrageenan only (Examples 1,5) or carrageenan and emulsifier (Examples 2,6), the large temperature difference upon entering the hold tube and upon exit indicates buildup of a fouling layer.
In addition to the hold tube temperature data, observations are included in the table. Examples 3, 4, 7 and 8 processed with reduced back pressure (<1 bar), and temperature control was “better sustained”, indicative of little to no fouling layer buildup. The worst fouling, indicated by higher back-pressures and poorer temperature control, was observed in Examples 1 and 2.
These results demonstrate the antifouling performance of polymers such as hydroxypropyl cellulose in a heat-processed dairy application.
AeroWhip ® 630 is a trademark of Hercules Incorporated under which a food grade of hydroxypropyl cellulose is marketed.
Grinsted PK22Lactem ® lactic acid esters of mono&diglycerides from Danisco, and Satiagel ® ACL 15 carrageenan from Degussa were used in this work.
In order to quantify improvements in the quality or performance of the process and the products produced by the processes in Examples 9-56, we measured the methoxyl and propoxyl substitution levels on the MHPC polymers by a sealed tube Zeisel method, and the molecular weight of the cellulose ether polymers was measured by size exclusion chromatography (SEC) and expressed as Mw, the weight average polymer molecular weight. We also monitored the effect of the cellulose ethers and the process on the particle size of the fat phase in the cream or milk, and the effect of the cellulose ether and the process on product viscosity.
In addition, we quantified whipped cream performance by measuring the amount of air incorporated into the cream on whipping, expressed as % overrun. The stability of the whipped creams was also quantified by measuring the % syneresis, or separation of a serum phase from the whipped cream foam. The reduction in particle size in creams, improvement in % overrun, reduction in % syneresis, and visual assessment of whipped cream stability and stiffness over time are shown in the comment sections in Table 3 for heat sterilized creams, and in Tables 5 and 6 for pasteurized creams. These measurements were performed according to the following procedures.
Whipping creams were whipped using a Kitchen Aide® mixer at high speed for 3 minutes and the overrun was obtained.
Overrun
A constant amount, 237.5 grams of cream, were added to a prechilled stainless steel bowl, and 12.5 grams of 10× powdered confectioner's sugar were added to the cream while stirring at high speed. Mixing was continued for 3 minutes and the overrun was obtained. Percent overrun was measured using a cup by adding the liquid cream to fill the cup and obtaining a weight for the cream. After whipping, the cup was then filled to the rim with the whipped cream and a second weight taken. Percent (%) overrun was calculated according to the following formula:
Foam Syneresis
Foam syneresis was measured according to the following procedure:
Whipped cream was added to the rim of a 60×15 mm Petri dish. The dish was then inverted with foam side down, onto a Whatman No. 41 filter paper circle, on a metal pan. After 1 hour at room temperature, the increase in diameter of the wet circle imprint on the filter paper was measured to obtain the % extension of foam syneresis according to the following equation. A constant diameter of the foam in the Petri dish was measured as 50 mm.
Particle Size Measurement
A Horiba LA-900 laser scattering particle size distribution analyzer is used with a particle sizing method based on an analysis of the angular dependence of light scattered from an optically dilute dispersed phase sample. The measuring instrument consists of a forward scattering angle photo ring diode detector and a number of discrete higher forward and back scattering angle photodiode detectors. The angular dependence of the scattered light is measured at two discrete wavelengths and a particle size distribution is iteratively generated to replicate the measured scattering profile. The specific calculation algorithm to determine the particle size distribution data are proprietary to the instrument vendor.
This method is used to determine average particle sizes (mean, median, mode) and particle size distributions of fluid dispersions. The specific surface area of the material is calculated assuming the particles are solid, homogeneous spheres.
0.1- 0.2 ml of a sample was diluted into a 10-15 ml of suspending solution of 0.25% Tween-20 (wt/vol) in deionized water, filtered with 0.2 μm Nylon membrane filter. After shaking, the particle size was measured.
Molecular Weight Determination by SEC
Molecular weight determinations were performed using size exclusion chromatography, focusing on weight-average molecular weight, Mw.
Methoxyl and Hydroxypropyl Substitution of MHPC and MC Polymers
A standard sealed tube Zeisel method was used to analyze for the wt % methoxyl and wt % hydroxypropyl substitution level on the polymers.
Viscosity of Creams and Milks
The viscosity of the creams and milks were measured on a Brookfield DLV-I viscometer equipped with a small sample adapter, using spindle 18 at a speed of 12 rpm.
The invention is further demonstrated in Table 3 in heat sterilized cream samples. Examples 11-14, 22, and 24 contain HPC. Examples 15-18, 20, and 25 contain MHPC, and Example 19 contains a blend of polymers.
The UHT creams in Table 3 were subjected to a preheat temperature of 75° C. and final heat to 138° C. with a holding time of 8 seconds. Single stage cooling was used to achieve temperatures of <60° C. Prior to the final heat stage, 2-stage homogenization was provided to all products at a value of 750/250 psi using a homogenizer.
After mixing the cream composition, the cream mixture was then heated to 50-55° C. in a water bath and then pumped into a Microthermics Thermal processor at a flow rate of 1.14-1.2 Liters/min. The Microthermics unit was equipped with two sets of plate heat exchangers and a 2-stage pressure homogenization unit. The first set of PHE was used to preheat the cream to a temperature of 75° C. prior to introduction into the 2 stage homogenizer. After passing through the homogenizer, the cream was treated at a temperature of 138° C. for 8 seconds prior to being cooled to 50-60° C., and loaded into sterile Nalgene bottles in an aseptic-fill hood. For Examples 10, a Microthermics thermal processor was used, in a tubular heat exchanger configuration, with an 11.2 second hold time. This example serves as a control demonstrating that fouling in tubular heat exchangers has an induction period that was not exceeded by the run time in this example, and as a result, no fouling was observed.
The reduced fouling for formulations containing HPC, MHPC, and their blend is demonstrated by the longer run time for UHT cream compositions containing HPC and MHPC in Table 3, where the run time is expressed as the time at which the final heater water supply temperature (FHWS) passed 315 degrees F.
During thermal processing, the product burns onto the surface of the heat exchanger, constricts flow, increasing back-pressure on the equipment. In addition, product is not heated sufficiently, due to the burned on layer, and the heat sensors summon more heat as the product within the equipment does not reach desired temperatures. The final heater water supply temperature (FHWS) is a direct measure of fouling as this increase in heat supplied to the heat exchanger is in response to fouling.
Examples containing HPC, MHPC, or their blend in the cream formulation have less fouling as shown by an increase in the length of the UHT process run times for Examples 11,12,15,18,22,24,25 when compared with the control runs in Examples 9,10,21,23. The UHT creams processed for longer times with Examples 11,12,15,18,22,24,25 with greater control over the hold tube temperature and the heating and cooling water temperatures than observed in the control Examples 9,10,21,23. The longer run time is expressed as the time at which the final heater water supply temperature (FHWS) passed 315° F. Less fouling was observed on the plate heat exchangers (PHE) in Examples 11,12,15,18,22,24,25 and the PHE were more easily cleaned after completion of these runs than observed with the control Examples 9, 10, 21, 23.
The products prepared in these Examples 11,12,15,18,22,24,25 also show smaller particle size of the fat phase, better whipping performance as quantified by 20-50% higher % overrun relative to the corresponding control Examples 9,10,21,23, and better foam stability as quantified by 10-40% lower % syneresis than the corresponding control Examples 9,10,21,23. These improvements demonstrate better quality of the products containing the HPC, MHPC polymers and their blends.
Inclusion of lower molecular weight HPC polymers such as Aerowhip 620 HPC in Example 13 or Nisso L type HPC in Example 14 reduced the run time, and appeared to cause more fouling, indicating that higher molecular weight HPC polymers are preferred.
Comparison of the performance of the MHPC polymers in Examples 16, 17, and 18 demonstrates that MHPC polymers having higher methoxyl content and higher hydroxypropyl content (MP943 in Example 17) gives more reduction in fouling.
The invention is further demonstrated in Table 4, in heat sterilized milk, also termed as UHT milk samples. Examples 28, and 32 contain HPC, and Examples 27,29,30,33 contain MHPC.
The UHT milks in Table 4 were subjected to a batch pasteurization temperature of 75° C. fed into a 2-stage homogenization at a value of 750/250 psi using a APV Gaulin homogenizer followed by a final heat to 138° C. in a plate heat exchanger with a holding time of 2-10 seconds. Single stage cooling was used to achieve temperatures of <60° C. The UHT plates were disassembled after cooling with a water rinse, and the plates were air dried with a stream of air, and the amount of foulant on each plate was determined by measuring the weight difference.
As shown in Table 4, the skim milk control run in Example 26 deposited 38 grams of foulant, where the formulation in Example 27 containing MHPC MP1990 deposited les than 18 g foulant. In contrast, MHPC MP843 in Examples 29 and 30 deposited 42 and 43 grams of foulant on the plates. These results again confirm that MHPC polymers having higher methoxyl content and higher hydroxypropyl content (MP1990 in Example 27) give more reduction in fouling than MHPC polymers having lower methoxyl and hydroxypropyl content (MHPC MP843 in Examples 29 and 30). The HPC polymer in Examples 28 and 32 deposited more foulant than the control skim milk on the plates, suggesting that the solubility of this polymer needs improvement in order to perform better in skim milk as an antifoulant in the UHT phase. However, there was significantly less foulant deposited on the surface of the stainless steel pot used for batch pasteurization of the milks in Examples 28 and 32 than when the control skim milk run was pasteurized, demonstrating reduced fouling of skim milk at temperatures less than 100 C when HPC is present in the skim milk.
The smaller mean particle size observed for the milk in Example 27 compared with the control in Example 26 and the conversion of the particle size distribution from bimodal to monomodal also is suggestive of improved milk quality in the presence of the MHPC polymer in Example 27.
60 rpm
The invention is further demonstrated in Table 5 in pasteurized cream s. Examples 36, 37, 39, 41, 43, and 47-49 contain HPC, and Examples 35,40,44,45, and 46 contain MHPC.
The Examples in Table 5 demonstrate creams containing HPC, MHPC, and MC that have been processed at temperatures less than 100 C. The cream used for Examples 36-49 in Table 5 contained some carrageenan, polysorbate 80, and mono and diglyceride emulsifiers. An additional 0.02% carrageenan was added to the formulations in Examples 34-41. Creams were processed at 75 C for 10 minutes in a stainless steel pot. Exact procedures are noted as a footnote to Table 5.
At a fat content of 10%, in Examples 34-37, none of the formulations whipped to a good foam. Once a fat content of 24% was reached in Table 5, creams containing HPC or MHPC whipped to a stiffer foam, as described in the comments section, and gave improved incorporation of air into the creams, as demonstrated by values of % overrun greater than 120%, indicating improved quality. Similar positive effects on % overrun and syneresis of ice creams are expected when HPC, MHPC, or MC are included in these formulations, or creams prepared according to the processes described in this invention are used to prepare the ice cream or other dairy composition.
Homogenized and Pasteurized Creams Whipping Performance
1. Heat milk to ˜60 C. in microwave.
2. Place on Silverson mixer and begin stirring @ ˜4000 rpm, slowly add all polymers (carrageenan + other polymers).
3. Continue mixing for ˜10 minutes. After ˜10 minutes, place cold water bath under sample to bring room temperature, continue mixing for ˜1
4. Remove and place on overhead Caframo mixer. With stirring at medium speed (dispersion blade).
5. Continue mixing for 45-60 minutes to completely hydrate polymer.
6. Add cream and continue mixing SLOWLY for 10 minutes. (if desired, remove sample and take 15 C. viscosity)
7. Pasteurize @ 75 C. (Samples for −38 were not pasteurized)
8. Homogenize at 750/250 psi 2 stage homogenizer at 75 C. Immediately chill in ice bath to cool.
9. Refrigerate over night and observe for stability at 24 hours. (if desired, remove sample and take 15 C. viscosity)
10. Whip on Kitchen Aide mixer full speed for 3 minutes using bowls and whips placed in freezer. Use 237.5 g of cream + 12.5 g of 10X sugar.
11. Measure % overrun: wt(g) mix before aeration − wt(g) mix after aeration/wt(g) mix after aeration × 100
The invention is further demonstrated in Table 6 in pasteurized cream samples. Examples 54 and 56 contain HPC, and Examples 50, 51, 52, and 55 contain MHPC, and Example 53 contains MC.
Examples 50-56 in Table 6 demonstrate pasteurized milks and pasteurized creams containing HPC, MHPC, and MC polymers prepared by predissolving the polymer and carrageenan in the milk at respective concentrations of 0.4 wt % and 0.067 wt %, then diluting the milk with cold cream to reach final concentrations of 0.12 wt % polymer and 0.02 wt % carrageenan in the cream. No emulsifiers were present in the creams shown in Table 6. The creams and milk containing the polymer and carrageenan were then heated at a temperature less than 100 C for less than 40 minutes. Exact procedures are shown as a footnote to Table 6.
The viscosity of pasteurized creams containing HPC in Examples 54 and 56 in Table 6 decreased as polymer molecular weight, defined as Mw, increased. The inverse relationship of cream viscosity with molecular weight of the HPC polymer was also seen in the extent of fouling for the creams, where creams containing HPC having a Mw value less than 350,000 showed greater and more rapid fouling during thermal processing. The viscosity of creams containing MHPC polymers in Examples 50, 51, 52, 55 and for MC in Example 56 showed a direct relationship of cream viscosity with polymer molecular weight, when expressed as Mw.
This application claims the benefit of U.S. Provisional Application No. 60/662,704, filed Mar. 17, 2005.
| Number | Date | Country | |
|---|---|---|---|
| 60662704 | Mar 2005 | US |
