The main components of fats and oils production are triesters of glycerol and fatty acids. The triesters are named triglycerides. The triglycerides are responsible for the physical properties of manufactured fats and oils as the physical properties are depending on:
In margarine production, fats with mainly unsaturated fatty acids will be liquid, while fats with a high content of saturated fatty acid will be hard. Distribution of the fatty acids on the triglycerides decides whether the consistency is hard, soft or liquid. Thus, some types of fats can only be used for limited purposes. Normally, several fats or oils are used in a shortening oil blend in order to obtain the desired properties with regard to plasticity and consistency of the product.
The process of margarine production is a strong baseline for the production of other fats and oils commercially.
Margarine processing and related products contain a water phase and a fat phase and can thus be characterized as water-in-oil emulsions in which the water phase is finely dispersed as droplets in the continuous fat phase. Depending on the application of the product, the composition of the fat phase and the margarine manufacturing processes are chosen accordingly. Apart from the crystallization equipment, a modern manufacturing facility for margarine and related products will typically include various tanks for oil storage as well as for emulsifier, water phase and emulsion preparation; the size and number of tanks are calculated based on the capacity of the plant and product portfolio. The facility also includes a pasteurization unit and a remelting facility. Thus, the manufacturing process can, in general, be divided into the following sub-processes.
The water phase in margarine production is often prepared batch-wise in the water phase tank. The water should be of good drinking quality. If drinking quality water cannot be guaranteed, the water can be subjected to pre-treatment by means of e.g. a UV or filter system. Apart from the water, the water phase can consist of salt or brine, milk proteins (table margarine and low-fat spreads), sugar (puff pastry), stabilizers (reduced and low fat spreads), preservatives and water-soluble flavors. The major ingredients in the fat phase, the fat blend, normally consist of a blend of different fats and oils. In order to achieve margarine with the desired characteristics and functionalities, the ratio of fats and oils in the fat blend is decisive for the performance of the final product. The various fats and oils, either as fat blend or single oils, are stored in oil storage tanks typically placed outside the production facility. These are kept at stable storage temperature above the melting point of the fat and under agitation in order to avoid fractionation of the fat and to allow easy handling. Apart from the fat blend, the fat phase typically consists of minor fat-soluble ingredients such as emulsifier, lecithin, flavor, color and antioxidants. These minor ingredients are dissolved in the fat blend before the water phase is added, thus before the emulsification process.
The emulsion is prepared by transferring various oils and fats or fat blends to the emulsion tank. Usually, the high melting fats or fat blends are added first followed by the lower melting fats and the liquid oil. To complete the preparation of the fat phase, the emulsifier and other oil-soluble minor ingredients are added to the fat blend. When all the ingredients for the fat phase have been properly mixed, the water phase is added and the emulsion is created under intensive but controlled mixing. Different systems can be used for metering the various ingredients for the emulsion of which two are working batchwise: 1. Flow meter system 2. Weighing tank system A continuous in-line emulsification system is a less preferred but used solution in e.g. high capacity lines where limited space for emulsion tanks is available. This system is using dosing pumps and mass flow meters to control the ratio of the added phases into a small emulsion tank. The above-mentioned systems can all be controlled fully automatically. Some older plants, however, still have manually controlled emulsion preparation systems but these are labor demanding and not recommended to install today due to the strict traceability rules. The flow meter system is based on batch-wise emulsion preparation in which the various phases and ingredients are measured by mass flow meters when transferred from the various phase preparation tanks into the emulsion tank. The accuracy of this system is +/-0.3%. This system is characterized by its insensibility to outside influences like vibrations and dirt. The weighing tank system is like the flow meter system based on batch-wise emulsion preparation. Here the amounts of ingredients and phases are added directly to the emulsion tank which is mounted on load cells controlling the amounts added to the tank. Typically, a two-tank system is used for preparing the emulsion in order to be able to run the crystallization line continuously. Each tank works as a preparation and buffer tank (emulsion tank), thus the crystallization line will be fed from one tank while a new batch will be prepared in the other and vice versa. This is called the flip-flop system. A solution where the emulsion is prepared in one tank and when ready is transferred to a buffer tank from where the crystallization line is fed is also an option. This system is called the premix/buffer system.
From the buffer tank the emulsion is normally continuously pumped through either a plate heat exchanger (PHE) or a low pressure scraped surface heat exchanger (SSHE), the GS Consistator®, or high-pressure SSHE, the GS Kombinator or GS Perfector, for pasteurization prior to entering the crystallization line. For full-fat products, a PHE is typically used. For lower-fat versions where the emulsion is expected to exhibit a relatively high viscosity and for heat-sensible emulsions (e.g. emulsions with high protein content) the GS Consistator® system as a low-pressure solution or the GS Kombinator as a high-pressure solution is recommended. The pasteurization process has several advantages. It ensures inhibition of bacterial growth and growth of other microorganisms, thus improving the microbiological stability of the emulsion. Pasteurization of the water phase only is a possibility, but pasteurization of the complete emulsion is preferred since the pasteurization process of the emulsion will minimize the residence time from pasteurized products to filling or packing of the final product. Also, the product is treated in an in-line process from pasteurization to filling or packing of the final product and pasteurization of any rework material is ensured when the complete emulsion is pasteurized. In addition, pasteurization of the complete emulsion ensures that the emulsion is fed to the crystallization line at a constant temperature achieving constant processing parameters, product temperatures and product texture. In addition, occurrence of pre-crystallized emulsion fed to the crystallization equipment is prevented when the emulsion is properly pasteurized and fed to the high-pressure pump at a temperature 5-10°C higher than the melting point of the fat phase. A typical pasteurization process will after preparation of the emulsion at 45-55°C include a heating and holding sequence of the emulsion at 75-85°C for 16 sec. and subsequently a cooling process to a temperature of 45-55°C. The end temperature depends on the melting point of the fat phase: the higher the melting point, the higher the temperature.
The emulsion is pumped to the crystallization line by means of a high-pressure piston pump (HPP). The crystallization line for the production of margarine and related products typically consists of a high-pressure SSHE which is cooled by ammonia or Freon type cooling media. Pin rotor machine(s) and/or intermediate crystallizers are often included in the line in order to add extra kneading intensity and time for the production of plastic products. A resting tube is the final step of the crystallization line and is only included if the product is packed. The heart of the crystallization line is the high-pressure SSHE, the GS Nexus, the GS Kombinator or the GS Perfector, in which the warm emulsion is super-cooled and crystallized on the inner surface of the chilling tube. The emulsion is efficiently scraped off by the rotating scrapers, thus the emulsion is chilled and kneaded simultaneously. When the fat in the emulsion crystallizes, the fat crystals form a three-dimensional network entrapping the water droplets and the liquid oil, resulting in products with properties of plastic semi-solid nature. Depending on the type of product to be manufactured and the type of fats used for the particular product, the configuration of the crystallization line (i.e. the order of the chilling tubes and the pin rotor machines) can be adjusted to provide the optimum configuration for the particular product. Since the crystallization line usually manufactures more than one specific fat product the GS Nexus, GS Kombinator or GS Perfector often consists of two or more cooling sections or chilling tubes in order to meet the requirements for a flexible crystallization line. When producing different crystallized fat products of various fat blends, flexibility is needed since the crystallization characteristics of the blends might differ from one blend to another. The crystallization process, the processing conditions and the processing parameters have a great influence on the characteristics of the final margarine and spread products. When designing a crystallization line, it is important to identify the characteristics of the products planned to be manufactured on the line. To secure the investment for the future, flexibility of the line, as well as individually controllable processing parameters, are necessary, since the range of products of interest might change with time as well as raw materials. The capacity of the line is determined by the cooling surface available of the GS Nexus, GS Kombinator or GS Perfector.Different size machines are available ranging from low to high capacity lines. Also various degrees of flexibility are available from single tube equipment to multiple tube lines, thus highly flexible processing lines. After the product is chilled in the GS Nexus, GS Kombinator or GS Perfector it enters the pin rotor machine and/or intermediate crystallizers in which it is kneaded for a certain period of time and with a certain intensity in order to assist the promotion of the three-dimensional network, which on the macroscopic level is the plastic structure. If the product is meant to be distributed as a wrapped product it will enter the GS Nexus, GS Kombinator or GS Perfector again before it settles in the resting tube prior to wrapping. If the product is filled into cups, no resting tube is included in the crystallization line.
Various packing and filling machines are available on the market and will not be described in this article. However, the consistency of the product is very different if it is produced to be packed or filled. It is obvious that a packed product must exhibit a firmer texture than a filled product and if this texture is not optimal the product will be diverted to the remelting system, melted and added to the buffer tank for re-processing. Different remelting systems are available but the most used systems are PHE or low-pressure SSHE like the GS Consistator®.
Margarine, like other food products, is in many factories today produced under strict traceability procedures. These procedures typically covering the ingredients, the production and the final product result not only in an enhanced food safety but also in a constant food quality. Traceability demands can be implemented in the control system of the factory and the Gerstenberg Schröder GS Logic control system is designed to control, record and document important conditions and parameters concerning the complete manufacturing process. The GS Logic system is equipped with password protection and features historic data logging of all parameters involved in the margarine processing line from recipe information to final product evaluation. The data logging includes the capacity and output of the high-pressure pump (l/hour and back pressure), product temperatures (incl. pasteurization process) during crystallization, cooling temperatures (or cooling media pressures) of the SSHE, speed of the SSHE and the pin rotor machines as well as load of motors running the high pressure pump, the SSHE and the pin rotor machines. During processing, alarms will be sent to the operator if the processing parameters for the specific product are out of limits; these are set in the recipe editor prior to production. These alarms have to be acknowledged manually and actions according to procedures have to be taken. All alarms are stored in a historic alarm system for later view. When the product leaves the production line in a suitably packed or filled form, it is apart from the product name typically marked with a date, time and batch identification number for later tracking. The complete history of all the production steps involved in the manufacturing process is thus filed for the security of the producer and the end user, the consumer.
Clean in Place cleaning plants (CIP = cleaning in place) are also part of a modern margarine facility since margarine production plants should be cleaned on a regular basis. For traditional margarine products once a week is a normal cleaning interval. However, for sensitive products like low fat (high water content) and/or high protein containing products, shorter intervals between the CIP are recommended. In principle, two CIP systems are used: CIP plants which use the cleaning media only once or the recommended CIP plants which operate via a buffer solution of the cleaning media where media such as lye, acid and/or disinfectants are returned to the individual CIP storage tanks after use. The latter process is preferred since it represents an environmentally friendly solution and it is an economical solution in regard to consumption of cleaning agents and hereby the cost of these. In case several production lines are installed in one factory, it is possible to set up parallel cleaning tracks or CIP satellite systems. This results in a significant reduction in cleaning time and energy consumption. The parameters of the CIP process are automatically controlled and logged for later trace in the GS Logic system.
Shortening may be defined as an edible fat used to shorten or tenderize baked products. The hardness or firmness of any plastic shortening/fat is a function of the stress required to cause it to yield and flow. The predominant factor affecting this value is the volume ratio of the solid to the liquid phase. The greater the proportion of solids, the greater the possibility of the particles to touch and interlock and the firmer the material will be.
In general, it is possible to crystallize all types of fats, if the fats are shock chilled with subsequent intensive kneading without cooling. In this way a plastic shortening with smooth appearance, good aeration properties and excellent creaming properties can be produced. This method of crystallization and cooling of shortening mixture is accomplished in a SSHE.
As mentioned above, fat mixtures that are not exposed to shock chilling will form large crystals. This can be compared to the production of grainy ghee. Products with a crystal structure based on large crystals will not possess the plastic properties that are desired in shortening. This is due to a crystal network formed by large crystals being very strong because of forces acting between large particles. If a crystal network of this type is exposed to a deforming force, some of the bindings in the network will be destroyed and not re-established.
During the last decades, low fat spreads have become very popular in the Western World due to an increasing awareness in the population in respect to minimizing the fat intake. Spreads while similar to margarine have strict differences. Margarine contains a minimum of 80% fat, and products with a fat content of less than 80% are called spreads. Low fat spreads have approx. 40% and reduced-fat spreads contain typically 60% fat.
Reduced-fat spreads are usually formulated from the same oil blends as those used for the manufacture of the corresponding soft table margarines, however, these products contain less than 60% fat. For reduced and low-fat spreads, the water phase has a great influence on the finished product in regard to taste and mouthfeel. It mainly consists of water in which the minor ingredients are dissolved. Apart from salt and preservative, whey powder, skimmed milk powder or other types of milk can be added. Due to the high-water content, a stabilizer system is needed in the case of spreads in order to have the necessary stability in the final crystallized product. Water-soluble flavor and color can also be added but are primarily used in low-fat spreads. stable water distribution in order to improve the microbiological keeping properties in the spreads.
In the case of low-fat spreads, the water phase and the oil should have similar temperatures and should be combined slowly when forming the emulsion. Additionally, it is very important that the emulsion is properly agitated to ensure homogeneity. However, care should be taken not to incorporate air during emulsification. SPX Flow Technology has developed special tanks to fulfill these demands. Prior to entering the crystallization equipment, the emulsion is pasteurized, preferably in a scraped surface heat exchanger (SSHE).
In the dairy industry today the majority of the butter is produced on continuous butter making machines using the so-called Fritz method. Initially, the milk is concentrated to cream followed by a pasteurization process. Subsequently, the cream follows a temperature treatment where crystallization takes place. The churning process involves phase inversion of the crystallized cream to butter granules and buttermilk. The butter granules are plasticized by the kneading and mixing process to form the butter.