White Paper. Dry Ingredient Chilling for Bakery Manufacturers.

Transcription

1 White Paper. Dry Ingredient Chilling for Bakery Manufacturers.

2 02 Dry Ingredient Chilling for Bakery Manufacturers. Abstract Bakery manufacturers know that controlling dough temperature in the mixer is one of the principal challenges in bakery operations, especially when they are producing products that require high proportions of flour content or have short mixing times. The quality and characteristics of dough handling and, ultimately, the quality of the final product hinge on the proper balance of ingredients, temperature, and mixing time. Controlling the temperature of the ingredients is the ideal way to achieve the optimal mixing time and produce the highest quality product. Traditionally, bakers have used a variety of cooling techniques in the mixer, which can result in inconsistencies in dry ingredient temperatures and variances in dough quality from batch to batch. However, Linde has developed a Dry Ingredient Chilling System that chills flour (or other dry ingredient) in the transfer line, adding only the precise amount of cryogen needed to obtain the desired temperature. The use of cryogenic liquid in conjunction with a conventional pneumatic conveying system instantly cools the dry ingredient to a predetermined ideal temperature while it is conveyed to the mixer.

3 Dry Ingredient Chilling for Bakery Manufacturers. 03 Precise Temperature Control Improves Dough Quality Typical desired temperatures of dough might range from 80ºF (27ºC) down to 40ºF (4ºC), depending on the product being mixed. If dough temperatures are not controlled, the texture and consistency of the dough will be adversely affected, which will in turn affect the way the dough behaves during later processing. In the limited time available for temperature control under ideal mixing conditions, the cooling system must offset heat from three major sources: 1. Friction created when the dough is kneaded. 2. The hydration that takes place when the dry ingredients absorb water. 3. The temperatures of incoming ingredients, especially the flour, which during the summer months and in generally hot climates may reach well above 100ºF (38ºC) in silos. Uniform blending and optimum mixing of ingredients are essential to creating repeatable batch-to-batch dough quality. It is not just the quality of the dough that is affected, however; the productivity of a baking operation also depends on having the dough achieve the ideal formulated texture and handling characteristics. The dough temperature during and after mixing affects all these factors. Warm dough may stick during dividing, rounding, and molding. It may not proof up as anticipated, or it may over-bake or under-bake in the ovens. The net result can be low-quality dough, wasted product, and reduced plant output. A Better Way to Control Ingredient Temperature The most common cooling techniques in the bakery include mechanical refrigeration of the mixer bowl itself, the use of chilled ingredient water, and even the less precise practice of adding water ice to the dry ingredients during mixing. The problem with each of these methods is that there is no predictability in the production process and could lead to extreme variances in the quality of the end product. Another cooling technique is to pre-chill the dry ingredients before they enter the mixer. Historically, this method has been implemented with flour, because it is usually the most abundant ingredient with the highest temperature fluctuation and pre-chilling the flour can significantly contribute to temperature control. An in-line dry ingredient chilling system using liquid cryogenic gases as the refrigerant provides an enhanced option in temperature control. By chilling the incoming dry ingredient and controlling the temperature precisely, a bakery manufacturer saves processing time and improves efficiency; creates repeatable batch-to-batch dough quality; and wastes less dough. In addition, this system eliminates the necessary waiting times for ice melting and product equilibration, which in turn reduces the overall processing time. Finally, an in-line dry ingredient chilling system using liquid cryogenic gases can often be less costly to operate than the use of ice for supplemental refrigeration, considering the cost of purchasing and making ice and the reduced need for labor for scaling and handling the ice.

4 04 Dry Ingredient Chilling for Bakery Manufacturers. Types of Doughs that Benefit Most from Dry Ingredient Chilling In-line ingredient chilling is most beneficial when there is a temperature drop required during mixing that must be accomplished quickly. Bakers already using cryogenic gases for dough chilling, or to refrigerate or freeze finished baked foods, may find dry ingredient chilling especially convenient and may find that they can achieve significant economies of scale. Many doughs for cookies, crackers, and other snack goods, for example, have short mixing times and are exceedingly sensitive to temperature abuse. Bread and roll mixing processes benefit from temperature control in different ways. In the sponge process, temperature control at both states improves texture and handling characteristics. Because of the short mix times of "no time" dough methods, temperature control is essential to prevent over-working the dough. When processing frozen dough, the temperature must be controlled to minimize the time between yeast activation and freezing in order to prevent fermentation and yeast kill during the freezing process. In numerous installations, dry ingredient chilling can achieve more accurate and consistent temperature control that enhances the quality and handling characteristics of the dough. It improves the ability to mix at ideal temperatures and reduces, or even eliminates, the use of supplementary ice cooling, thus ultimately improving product quality.

5 Dry Ingredient Chilling for Bakery Manufacturers. 05 Mixer Liquid CO 2 RTD Silo Customer control system Control cabinet S S Rotary air lock TS Injector Blower TS: Temperature switch S: Solenoid valve RTD: Resistance temperature sensor How Linde s Dry Ingredient Chilling System Works Linde s dry ingredient chilling system works by injecting liquid cryogen directly into the pneumatic conveying line at a point before the mixer, and cooling the dry ingredient which had been stored outside in a silo and therefore subjected to soaring temperatures. When the liquid cryogen passes through an injection nozzle into the conveyor pipe, it effectively mixes with the conveyed ingredient (e.g., flour). At operating temperatures of less than -100ºF (-78ºC), the release of liquid cryogen causes an almost immediate temperature reduction in the dry ingredient, without adversely affecting its quality. The liquid cryogen gas leaves no residue, and no additional moisture is introduced to the product formulation. Although the method above has been in existence for decades, Linde has effectively used its own related technology and consistently demonstrated its efficiency and economics. Linde's proprietary technology can be used on both pressure and vacuum-type pneumatic conveyor systems and has been implemented in bakeries around the world. System Components and Operation Linde s dry ingredient chilling system consists essentially of: 1. An injection chilling chamber, 2. A temperature sensor, and 3. Electronic and mechanical control panels that regulate the operation of the system. The flour chiller is simple to operate. The liquid cryogen is supplied from an external receiving and storage tank through associated piping. During operation, the only manual adjustment involves choosing the desired temperature of the dry ingredient entering the mixer for that particular batch before activating the system. The system is automatically activated when the rotary valve at the silo is opened and the temperature of the ingredient is above the set point. As the ingredient begins to flow in the pneumatic conveyor line, the control system opens the injector valves, allowing liquid cryogen to flow through nozzles. The cooling rate of the dry ingredient is linked to the injection rate of the cryogenic gas, which is determined automatically and adjusted accordingly. The temperature is regulated to within 1ºF (0.55ºC ). Liquid cryogen is injected into the chilling chamber until either the ingredient temperature reaches the set point or the ingredient flow is discontinued.

6 06 Dry Ingredient Chilling for Bakery Manufacturers. Compatible with both Pressure and Vacuum Systems Linde s in-line dry ingredient chilling system using liquid cryogenic gases works with both pressure and vacuum pneumatic systems. In a pressure system, the pressure builds in the conveying line, usually to an operating level of 8-10 psi. The cryogenic gas system readies itself with a low-pressure (18-20 psi) purge of the cryogen supply line, followed by a high-pressure purge to remove any residual dry ingredient present in the injection nozzles from previous operations. The cryogenic liquid system for a vacuum pump conveyor is identical to a pressure system, except that it does not require the purging cycles. The turbulence created by the dry ingredient passing through the conveyor pipe, combined with the liquid cryogen injection pressure in the injector chamber, ensures uniform mixing of the cryogenic gas and dry ingredient, and leads to virtually instant cooling. Injector

7 Dry Ingredient Chilling for Bakery Manufacturers. Experience and Technology: Working with Linde In the past, dry ingredient chillers have been plagued by high levels of humidity in ambient air. The liquid cryogen injection method in Linde s design is impervious to high humidity levels, which means this system can be used in any geography. Additionally, cryogenic consumption levels for this type of system is relatively low, which results in an efficient and low-cost cooling system. The physical installation work can usually be completed within a few days, depending on the complexity of the pneumatic system. The cryogenic flow control panel, which includes the cryogenic valves and other mechanical regulators, as well as the electronic control panel, can be installed in convenient and protected areas and not necessarily adjacent to the chilling chamber. For the sake of integration, the system can also be linked to existing compatible process control equipment. 07 Linde's Dry Ingredient Chilling System provides consistency and reliability in the dough manufacturing process and eliminates reformulation and waste due to sticky or off-spec dough. However, it is just one of several of Linde's technology solutions for the bakery customer production process. Linde has offers that span the entire bakery operations process-including storage and handling, mixing, chilling/freezing, and packaging-and can provide a great deal of consistency, reliability and repeatability. For more information about how Linde s Dry Ingredient Chilling system can help you improve your bakery production, contact Ed Cordiano, Program Manager of Bakery & Prepared Foods, ed.cordiano@linde.com

8 Getting ahead through innovation. With its innovative concepts, Linde is playing a pioneering role in the global market. As a technology leader, it is our task to constantly raise the bar. Traditionally driven by entrepreneurship, we are working steadily on new high-quality products and innovative processes. Linde offers more. We create added value, clearly discernible competitive advantages, and greater profitability. Each concept is tailored specifically to meet our customers requirements offering standardized as well as customized solutions. This applies to all industries and all companies regardless of their size. If you want to keep pace with tomorrow s competition, you need a leader in industry technology by your side for which top quality, process optimization, and enhanced productivity are part of daily business. Linde will not only be there for you but with you. After all, working together to solve problems forms the core of commercial success. Linde ideas become solutions. Linde North America, Inc. 575 Mountain Ave., Murray Hill, NJ USA Phone , sales.lg.us@linde.com, _0913 Linde North America, Inc. is a member of The Linde Group. Linde is a trading name used by companies within The Linde Group. Linde and the Linde logo are trademarks of The Linde Group. The Linde Group All rights reserved.