No dry coating process for sugar-coated food products

The present invention encompasses a coating method and apparatus used for this purpose, and more particularly a method of coating food products which allows for skipping the intermediate or pre-coating chilling procedure and apparatus used and significantly reducing processing time for top coating such as food sweetening coating. The coating method and apparatus are particularly useful for forming the surface coating of food products such as cereal products and the like.

TECHNICAL LEVEL

Currently, consumers are offered a variety of foods that can be prepared and / or processed in a variety of ways due to motifs such as convenience, appearance, storage stability, and most importantly organoleptic motifs such as taste or feel during chewing. Sweetened foods such as cereals, biscuits, pasta, snacks, nuts, roasted nuts and sweets can be long-lasting. Such products often contain surface-sweeteners which may have different appearance, ie glazed, frosted or powdered.

Top or surface sweetening of food products is generally accomplished by a sweetener solution (U.S. Patent No. 4702925). The sweetener may be a natural sweetener such as sugar, or it may be an artificial sweetener such as potassium acsulfame or aspartame, the N-methyl ester of 3-amino-N- (α-carboxyphenethyl) succinic acid (U.S. Patent No. 3,492,131).

Sugar, usually sucrose, is the most important ingredient in a sweetener. Other commonly used sugars are dextrose, glucose, fructose, corn syrup, saccharin and other well-known natural (honey) and artificial sweeteners.

However, surface sweetening of foods requires a number of different processing steps, each requiring further processing of the food and capital and operating costs for additional apparatus, control systems and their maintenance. Each process step or operation is an introduction to a potentially weak point in production that may be interrupted by both the apparatus and the control system in operation. Each stage is also a potential source of production for non-sorted products, which, as part of an overall system, rejects its proper functioning. As it is very important for food manufacturers to constantly control the quality of the products, including taste, smell and appearance, it is highly desirable to avoid or minimize the possibility of producing non-sorted products.

The coating process also has an economic impact as it can lead to an increase in the cost of any given product in the production stage series. Thus, there are many good reasons, including production and quality control, to have as few process steps as possible when trying to consistently produce products that meet technical requirements and subjective criteria.

THE SUBSTANCE OF THE INVENTION

The present invention is in the field of coating techniques, which allows the formation of crystals to be controlled, thereby enabling manufacturers to choose the appearance of the coating. The method of the present invention eliminates the need to cool hot products prior to coating using apparatuses that consume energy during those stages and the operating mode of the apparatus and the mechanical difficulties associated therewith.

The process of the invention eliminates intermediate processes and advantageously utilizes the energy contained in the product in combination with a conditioned sweetener solution. The method of the invention reduces the number of product processing cycles and significantly reduces product coating time and makes them suitable for storage or packaging.

The method of the invention also makes it possible to avoid the separate drying apparatus and its handling after the coating step.

The features of novelty which characterize the present invention are reflected in the specification which forms a separate part of the description of the invention. For a better understanding of the invention, specific usage descriptions will be given below, with reference to the drawings and a description of the invention, illustrated in the preferred embodiments of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a typical prior art technological scheme used for sugar coating food;

FIG. 2 is a schematic diagram illustrating a technological scheme of the embodiment of the present invention.

DESCRIPTION OF THE IMPLEMENTATION OF THE METHOD

FIG. 1 presents a general typical known scheme of the technology used for sugar coating cereals. The grains may be rice, wheat, psyllium, oats, barley, sorghum, maize, bran or any mixture of cereals and may take any form such as flakes, chips, muffins, loops, nougat, puffed balls or any other suitable form. . The cereal (10) is placed in the furnace (12), which may be a multi-zone furnace in which the cereal is roasted at 288-360 ° C and exited at 154-176 ° C. The roasted product (14) leaving the furnace (12) has a relatively low moisture content of 2-4%. The product is then transported to a refrigerator where it is cooled to less than 38 ° C. A frozen product has less energy but higher moisture. The chilled product (18) is then placed in a conditional coating drum (20).

The volumetric reservoir (22) is filled with an aqueous sugar sweetener solution having a 67 wt% sweetener concentration. This solution is transferred to a concentrator (26) which, when heated, turns the water into steam (30) and the concentrated sweetener solution (24) takes the form of a syrup (28) having a sugar concentration of 82 brix. The syrup (28) is removed from the concentrator (26) at a temperature of 109-111 ° C under normal atmospheric pressure. The syrup (28) is then pumped by a pump (32) into a coating drum (20) where the chilled product (18) is coated with syrup. When the product is exposed, the moisture content rises again. The coated product (34), which is still about 38 ° C, is transferred to a dryer (36) where the coated product is heated with additional thermal energy, the vapor (38) is removed and the coating is dried. The heated dry product (40) is about 105 ° C and is transferred to a refrigerator (42) where it is cooled to a temperature of at least 38 ° C.

In the known process, after the roasting, the cereal is subjected to at least four separate operations (not including intermediate fattening operations), i.e. first chilling, coating, drying and second chilling until the processed food becomes a sweetened cereal product suitable for storage or packaging. In the prior art, a food product is exposed to a cyclically rising or falling amount of moisture in the same way as the energy added or discontinued. The heating or energy history of a food during the time between removal from the oven and the packaging of the product has a multi-cycle profile of dental floss. Typical processing times for the above system from unloading from the oven to packaging or storage are from 700 to 5000 seconds with an average time of about 900 seconds.

FIG. 2 is a schematic representation of a technological process illustrating a preferred embodiment of the invention. For the sake of simplicity, a description is given of the method of obtaining sweetened cereal products.

The present invention takes advantage of the fact that crystallization rate is a function of crystallization center formation and crystalline growth rate, and that crystal formation in solution can be influenced or controlled by the ratio of solute to solvent, free energy, and presence of crystallization centers. In this way, the size, shape and quantity of predominant crystals determine the quality and appearance of the coating. Balancing variable parameters allows for unique appearance coatings.

The appearance of a food coating is usually determined by the degree of crystallinity of the sweetening agent and the size distribution of the crystals in the coating. If the sweetener on the coating, such as sugar, is in the form of small crystals (50-100 µm), then the coating of the food has a "frosty" appearance. If the sugar is coarse non-crystalline or consists of predominant coarse crystals (<200 pm), the resulting coating will have the appearance of a glaze.

Crystallization is a two-step process. In the first stage, known as the formation of crystallization centers, centers are formed. When suitable materials, such as sucrose, are dissolved, second stage crystal growth occurs. The average crystal size is inversely dependent on the amount of crystallization centers. When only a few centers are formed, relatively large (200 pm) crystals are formed and the resulting coating has the form of a glaze. When there are many crystallization centers, a large number of small crystals (50-100 pm) are formed and the resulting coating has a "frosty" appearance. If too many centers are formed, the appropriate solute, i.e. sucrose, is very finely divided and crystals even smaller than 1 pm do not grow. As a result, it may have the appearance of powdered sugar when forming the coating. Therefore, by controlling the number of crystallization centers and the presence of dissolved material and solvent, the appearance of the resulting coating can be well controlled, since the amount of predominant crystal is what determines the appearance of the coating. For example, if the dominant crystals are large, it is the case that the glaze appearance is obtained and the coating will have that predominant appearance, despite the fact that there are some smaller crystals.

It has been observed that more concentrated solutions can be obtained and used by varying the conditions of the sweetener solution. In the method of the present invention, the sweetener solution is superheated under increased pressure. This step enables the energy content of the solids in the solution to be increased and, if desired, the formation of crystallization centers favorable to the dissolved substance / solvent ratio without changing the physical or chemical properties of the solution. It is understood that the superheat used in the syrup is an additional thermal energy and it is necessary to heat the solution in the liquid state to boiling point under normal atmospheric pressure. The syrup to be reheated is at or near the desired concentration and the additional enthalpy under these pressure conditions does not result in a substantial change in the solids concentration. If desired, a higher sugar solution concentration can be used than conventional techniques such as those shown in FIG. 1, since the use of pressurized superheat allows the use of a high concentration of the solution which maintains the properties of the solution under increased pressure.

One of the achievements of the method is that superheat energy can be utilized advantageously. This is partly because the mass flow rate of the sweetener solution is substantially lower than the mass flow rate of the food to be sweetened, i.e. about 2.3 to 3.4 g of the sweetener solution per 454 g (pound) of food.

In the method according to the invention, the cooling step of the product removed from the oven is omitted before the product is coated. The product is coated when hot or warm by applying solution conditioning, which results in a dry coating without a separate drying step. Another advantage is that concentrated solutions do not undergo any theological changes that would make their controlled characteristics difficult or indefinable. For example, while commercially available corn syrup sweetener concentrations are generally similar to those of Newtonian liquids, higher concentrations often do not reflect Newtonian characteristics, but high concentrations of sucrose in water form mixtures that exhibit glass characteristics.

It has been found that the formation of crystallization centers can be induced during the syrup utilization stage and that certain modifications of the mixtures may accelerate or retard the formation of crystallization centers. In the present invention, when using a pure sucrose-water system, the coating is formed by a large number of centers and has the appearance of a powder of sugar. With the addition of a small amount of fructose-rich corn syrup, i. i.e., 1-10 wt.%, more preferably 2-4 wt.%, it may slightly interfere with the formation of crystallization centers, resulting in small amounts of larger crystals (50-100 µm) and appearance of "frost".

It has also been found that overheating of the pressurized solution affects the appearance of the resulting coating. With the increase of superheat, that is, raising the temperature to 110-150 ° C, the possibility of forming a more crystalline coating having a "frosty" appearance increases, while the lower overheating, i.e. below 110 ° C, increases the possibility of obtaining a glaze appearance.

By adjusting the composition of the sweetener mixture by adding invert sugar such as fructose-containing corn syrup or honey, it is possible to obtain a coating having the appearance of "frosted" sugar when the syrup is overheated at 110-150 ° C. At temperatures above 150 ° C, the appearance of the coating can be adjusted by adjusting the amount of fructose-rich corn syrup with larger amounts used at higher temperatures to give a "frosted" or glazed sugar appearance.

From FIG. 2 shows that the cereals (10) are placed in a furnace (12), where they are roasted at a temperature of 154-176 ° C to obtain a roasted product (14). The furnace (12) is a multi-zone operating at 288-360 ° C. The roasted product (14) leaves the oven (12) at a higher temperature and has a relatively low moisture content.

The hot roasted product (14) from the oven (12) may undergo several freezes and / or lose moisture before transferring to the coating apparatus (110). The amount of heat lost will be a function of many variables, including local environmental conditions. It is desirable to minimize heat loss, but some heat loss is inevitable, except when additional heat is added. Thus, removal of the intermediate or pre-coating step of the chilling stage does not affect such heat loss from the product. The desired temperature of the product when placed in the coating apparatus (110) must be at least 110-135 ° C when the coating apparatus (110) is operating at normal local atmospheric pressure. If it is operated at a temperature below local atmospheric pressure, the temperature of the product may be lower. If the apparatus (110) operates above a standard local atmospheric pressure, it is desirable that the product has a temperature of about 110 ° C to allow the coating to dry.

The coating apparatus (110) may be of the conveyor type, such as a transit tube or a liquid system such as a pneumatic transfer apparatus or a "fluidized bed". The coating apparatus (110) is most preferably one in which the weight of the foodstuff is lifted and separated so that the individual food particles, or more precisely the foodstuff in volume form, are actually coated. The time it takes for the food coating machine to be on the machine can range from 15 seconds to a minute. Air-using systems must pre-filter the air to reduce contamination of the food.

In a preferred embodiment of the invention, the coating apparatus (110) is a transit tube. A suitable transit tube is disclosed in U.S. Pat. 4658708. The transit tube has a transfer mechanism such as a pair of rotating actuators for transporting foodstuffs along a tube which is connected to a brush which transmits, lifts and separates foodstuffs, thereby maintaining the coated surface of the foodstuff and allowing improved evaporation of moisture from the surface. Moisture is removed from the coating machine (110) by applying a gentle vacuum, e.g., a column of about 250 mm Hg.

The liquid reservoir (22) is filled with a sweetener solution (in sugar water) (24), which is transferred to a concentrator (26), which removes the water in the form of steam (30) and forms a syrup (28) having a concentration of about 82 brix. Of course, if the concentration of the sweetener solution is close to the desired level, the concentration step is no longer required. To obtain a "frosty" appearance, a small amount of fructose-rich corn syrup is added to the sucrose-water solution in the tank. If the sugar powder coating is to be coated, the corn syrup is not added.

The pump (32) raises the syrup pressure from 2.8 to 14.0 kg / cm² and transferring it to a heater (112) in which the pressurized syrup is heated to 230 ° C, more preferably to 153 ° C, and more preferably to 125-153 ° C. Pressurized overheating maintains the water content of the warm syrup as it maintains the solids concentration or solute / solvent ratio as the solution energy rises.

In a preferred embodiment of the invention, the coating apparatus (110) has a food inlet and a product outlet, and is in the form of an elongated section, preferably consisting of two horizontally oriented, partially overlapping sections that are semicircular or rotating drive spaces.

In operation mode, the furnace unloads the product (14) traveling along the coating apparatus (110). Various speed systems or other transmission devices can be used to control the processing time. In the apparatus, shafts and brushes rotate in opposite directions and move the product along the tube while lifting and separating or flushing the food product.

The heated and pressurized syrup (114) is fed to the coating apparatus (110) to coat the roasted grains (14). The environment in the coating apparatus (110) is generally close to atmospheric pressure, but in some cases lower than that of the pressurized superheated syrup. In the apparatus (110), the syrup is sprayed onto the feed product and forms a hot coated cereal product (116) which exits the apparatus (110) at a temperature of about 93 ° C. Splashes are caused by passing the syrup through the nozzle heads, which causes the pressure to drop, thus contributing to the evaporation of moisture from the syrup. Removal of moisture by rapid evaporation effectively raises the concentration of the dissolved substance in the droplets. The cooling effect of evaporation and the raising of the dissolved substance / solvent ratio in the syrup allow the formation of crystals according to the phase diagram of the sucrose-water system. Evaporation of moisture in the coating apparatus (110) causes a vapor stream (118). Because the product is usually coated as soon as it leaves the oven and there is no intermediate cooling stage before coating, the heat energy contained in the hot product helps to dry the coating.

The moisture evaporated inside the apparatus (110) is removed by a gentle vacuum through the outlet. The coated product is discharged from the tube (110) and enters the refrigerator (120) to cool to a temperature below 43 ° C. The frozen product becomes suitable for storage or packaging. During the summer months, dried products can be placed in a refrigerator to adjust the moisture content of the product.

According to the method of the invention, the average process time from unloading from the furnace to packaging or storage takes from 80 to 120 seconds and on average about 90 seconds.

The spray stage was found to influence the formation of the top coat. Decreasing droplet size and increasing droplet drop time have a crucial effect on crystallization. This is unexpected because conventional wisdom is that conditions for the formation of crystallization centers are better in a large volume of solution.

In the method of the present invention, raising the spray stream over the moving coated food product into the coating apparatus may be varied according to the appearance of the coating desired. Longer drop drop times are obtained by raising the spray nozzle over the food product, resulting in smaller droplets of solution.

In the apparatus (110), the sprayer distributor extends the current for the smallest portion of the tube length and is vertically transported according to the volume of food transported. The sprayer distributor continues to run parallel to the longitudinal axis of the apparatus (110) and is provided with at least one sprayer head. The hot compressed syrup passes into the distributor and is pressed through the nozzles of the sprayer to form a jet of spray which is simultaneously pulverized by compressed air. The shredded droplets fall and cover the raised food particles.

The nozzles of the sprayer are raised so as to form an angle of dispersion which enables the spray solution to be applied to cover the product particles above the cross-section of the apparatus (110). However, raising the nebulizer according to the volume of the food must, in principle, provide a drop-specific period so that the moisture of the concentrated compressed sweetener solution evaporates. In a preferred embodiment, the spray nozzle or assembly is raised from 25 to 50 cm above the volume of the food mass.

It has also been found that the use of a compressed gas stream to crush a spray solution when spraying this solution provides an additional degree of control over crystallization and coating appearance. Improved crystallization results from the use of higher gas pressures. In the absence of compressed gas, the use of low pressure compressed gas or insignificant amount of compressed gas tends to form a coating which gives the appearance of a glaze or has a appearance similar to that of the glazed coating, whereas higher pressures or higher gas flow rates tend to appearance. Well-sprayed or crushed droplets are up to 0.25 cm in size and preferably up to 0.0025 cm in smaller sizes. However, the sprayed solution must not be so finely pulverized that a significant amount of droplets is deposited by the air stream and discharged independently or separately from the coating apparatus (110).

In a preferred embodiment of the invention, the spray sweetener is subjected to external grinding. It can be said that the spray is comminuted when exiting the nozzle nozzle using compressed gas, preferably pure, corresponding to the degree of food air quality. Compressed air is 2.8-4.2 kg / cm² pressure and is from 0.0125 m³ / kg up to 0.0245 m³ / kg, more preferably 0.0187 m³ / kg of sweetener solution by volume. Compressed air may be at room temperature, but in a preferred embodiment is heated. In a most preferred embodiment of the process, the compressed gas is air and is heated to a temperature of 55-125 ° C.

The sprayer nozzle assembly may be part of the sprayer assembly. Suitable spray nozzles with control units for external mixing are used by Spray Systems Co., Wheaton, Illinois. The external application of compressed air can be coupled to a dual nozzle system that compresses a stream of air that comes from a separate but adjacent nozzle, oriented to break current droplets as they exit the syringe nozzle.

Optionally, the apparatus (110) may be connected to a heating enclosure. This design allows the apparatus to warm up, helping to eliminate any energy accumulated on the walls during planned or unplanned heat transfer. As long as the coating apparatus is operating in the desired operating mode without additional heat other than that contained in the food, syrup or compressed gas, heat to assist in drying the food may be provided through the heating hood and / or by supplying heated air to the transfer tube. However, such an embodiment of the method is a compromise to aspects of the invention and does not imply the realization of the idea of ​​full energy utilization resulting from the application of the present invention to preferred embodiments.

In the method of the invention, the food product is subjected to a reduced number of processing steps. Only two (except two intermediate transport) operations of the method affect the product after roasting, ie coating and chilling. In addition, the processing time of the product after leaving the oven is significantly reduced, without sacrificing either the quality or organoleptic attributes of the product.

The terms and expressions used herein are used as a description term and are not limiting or intended to remove any equivalents or portions thereof from the use of such terms and expressions.