The birth of the breakfast cereal began with granula – not granola – a dry, whole-grain cereal created by baking graham flour and bran together and crumbling it. Invented by Dr. James Caleb Jackson in 1863, granula required about 20 minutes of soaking. Otherwise, it would be too hard to eat. The birth of the breakfast cereal foods industry, however, started with William K. Kellogg, the inventor of the most common and widely-eaten cereal in the world – corn flakes. In 1906, the Kellogg Company was founded, and the rest is, more or less, history.
Today, there are eight breakfast cereal categories commonly found on store shelves. These include flaked cereals, extruded and whole-grain gun-puffed cereals, oven-puffed cereals, extruded expanded cereal, shredded wheats and other whole-grains, extruded and other shredded cereals, and granola. While each of these requires unique manufacturing equipment, all of them go through a process of cooking the grain. This is usually done in combination with other ingredients, such as salt and sugar, other sweeteners, heat-stable nutritional fortifying agents, etc. It’s at this cooking stage when the physical properties are created to develop the final product’s texture. There are, however, several other quality control aspects that cereal manufacturers need to consider for preventing the loss of vitamins and keeping the crunch the cereal is loved for.
Quality Control and Microbial Contamination
Every step of the breakfast cereal manufacturing process needs to be carefully monitored in terms of quality, integrity, and cleanliness. The technologies and equipment used in these food processes need to be made out of stainless steel, which also needs to be cleaned and sterilized on a regular basis. The grain used needs to be inspected for any foreign matter once it arrives at the food production facility. The temperature and moisture content also have to be carefully monitored to ensure proper cooking and shaping. The same thing applies to the mineral and vitamin content so the nutritional values remain accurate.
To maintain accurate shelf life predictions, the quality of stored cereal products needs to be tested on a regular basis. Monitoring cereal freshness requires the cereals to be subjected to higher-than-normal humidity and temperatures to speed up the spoiling process. Special attention needs to be given to the moisture levels found in cereals because moisture provides an opportunity for microbial growth.
● Microbial Growth
Microorganism growth can be stifled during production when heat is applied. However, there is the possibility of post-heat contamination when sweeteners, flavorings, vitamins and minerals, coloring, and other additives and preservatives are added. This post-heat treatment has to be free of any microorganisms to avoid the contamination of the final product. The processing equipment used also needs to be maintained in proper sanitary conditions to avoid this issue.
The problem is most evident during product transfer between the different areas of production and materials processing – from heating and coating to drying and packaging. It’s at this point when the potential of exposure to foreign contaminants and allergens is particularly high. This problem is also exacerbated by the increasingly stringent consumer demand, as well as governmental and industry mandates for maintaining food safety and integrity. Traditionally, cereal manufacturers used bucket elevators, flat-bed conveyors, and aeromechanical, auger, or pneumatic conveyors, among others. However, most of these conveyor systems have issues with cross-contamination, downtime, and long maintenance periods. Tubular drag cable conveyors, on the other hand, were proven to eliminate many of these risks and inefficiencies.
It’s important to keep in mind that low moisture levels in breakfast cereals stop microbial growth, but these microorganisms can still survive. There have been cases of cereal recalls due to Salmonella contamination.
Breakfast Cereal Quality and Integrity Fundamentals
Starch gelatinization is the main purpose behind this cooking stage. This is a textural development needed for expansion or the development of cellularity in cereal, which is an important factor in the product’s organoleptic acceptability. The creation of water vapor, either through oven-puffing or toasting, or a sudden release of pressure when the product is superheated, as is the case with gun- or extrusion-puffing, results in the desired structural development. To survive and respond to this vapor pressure, the cereal mix needs to be tough, elastic, and homogenous enough. The grains and the process used in making different types of breakfast cereals define the integrity of the final product.
● Flaked Cereals
Flaked cereals are made from whole grains or extruded pellets. In the cases of whole grains, the flaked cereal’s finished quality will be dependent on the grain selection. As such, a screening operation may be needed to achieve the right size for the flaking grits. The basic processing steps in flaked cereals include mixing, cooking, tempering, dumping, delumping, drying, flaking, and toasting. For flakes to withstand processing, unmodified corn starch is added to the cereal flakes. A typical flake formula contains a specific mix of ingredients to achieve a 28 to 32% moisture content after cooking.
It’s after the initial cooking, drying, and tempering that the texture and moisture of the final product is controlled. For extruded flakes, this control process happens after extrusion. The optimal moisture rate of cereal flakes is between 1 and 3%. Anything above that reduces the crunch in breakfast cereals, increases toughness, and does not allow them to blister correctly. A moisture level that’s too low causes the flakes to break prematurely, and it also poses problems during the flaking process.
● Shredded Cereal
For shredded cereals, which are typically made of whole wheat, the critical step for controlling the finished product quality and integrity comes during tempering. The cooked wheat needs to be allowed up to 24 hours to temper before shredding. It’s during this time that the moisture equilibrates and firms up from starch retrogradation. If there is insufficient tempering, the shreds will come out gummy, sticky, and crooked. They will also be more difficult to cut. Shredded biscuits are baked with an initial moisture level of 45% to a final level of around 4%.
● Puffed Cereal
Rice and wheat are the most common grains used in gun-puffing. For this process to work effectively, the grain must be cooked then exposed to a sudden pressure drop. This releases steam from the grain very quickly, forcing it to expand (puff). Temperatures range between 400º and 500ºF, and the pressure is about 200 lbs. psi. The resulting puffed grains will have a moisture level of between 5 and 7%, which requires a drying process to bring them down to between 1 and 3%. It’s important to note that puffed cereal is highly porous and can pick up moisture rather easily. As such, these types of cereal require a layer of coating and proper packaging material to maintain their crispiness.
● Extruded Cereals
Extruded cereals use flour instead of whole grains. They are typically cooked and extruded at the same time. Basically, the twin-screw cooker mixes the flour with the other ingredients, pushing it to the other end in the form of an elongated ribbon. This is then cut into pellets with a rotating knife. General Mills’ Kix cereal was one of the first ones to be made with this technique. By adding modified wheat starch, cereal manufacturers can produce a higher expansion volume, a better film-forming ability that slows down the absorption of milk into the cereal, and low-fat content, which improves the flavor characteristics. After the extrusion process, the moisture levels of the cooked pieces are around 20 to 24%. After two drying steps and gun-puffing, they reach the desired moisture content of between 1 and 3%.
However, such a low moisture content also means that the cereal product is particularly brittle and prone to breakage, especially when moved from one processing station to another. Fortunately, tubular drag conveyor systems will eliminate this risk entirely. The cereal will be moved between disks and be pushed along the enclosed tube. The discs will, in turn, be pulled by a cable and will not smash or thrash the material around as is often the case with aero-mechanical, pneumatic, or vacuum conveyor systems. They will also not be beaten up or crushed by using a chain conveyor or tossed around by bucket elevators. To put it simply, enclosed tubular drag cable and disc systems are ideal when it comes to dry or, otherwise, fragile materials as they ensure both product integrity and eliminate the risk of spillage.
Even though many granola cereals are made entirely of all-natural ingredients, they are no longer just for “natural-food” eaters. Granola is basically a combination of whole wheat or quick oats mixed with a combination of nuts, brown sugar, coconut, malt extract, dried milk, honey, dried fruits, oil, and other spices in a process known as agglomeration. The mixture is cooked at temperatures from 300º to 425ºF to achieve a light-brown color and moisture level of about 3%. Once cooking and drying are complete, the mixture is broken up into chunks. About 5% inulin, together with other carbohydrates, may be added to bind the granola.
Granola and cereal bars, with or without filling or coating, are also considered a ready-to-eat breakfast cereal and are increasing in popularity. They can be made with either flaked, puffed, or extruded grains that are put together using a sugar-based solution and compressed under low pressure.
However, there needs to be more diligence in cereal processing techniques to ensure that all the grains and other food additives are free of microbial contamination. The reason for this is that there is an increased risk since there is no heating step used in the production of cereal bars, which would help with the initial microbial count found in raw materials and cereal grains. The heat used to blend the binding syrup is not enough to reduce the microbial load found in contaminated cereal grain products. An added level of care needs to be given to ensure that cross-contamination does not occur throughout the rest of the manufacturing process, particularly from the processing equipment, personnel, or the surrounding environment. This is one area where processing technology like tubular drag cable conveyors are especially beneficial in ensuring the processing conditions and environment are free of contaminants.
Cablevey’s tubular drag cable and disc systems are enclosed and clean, using brushes, urethane disks, and air knives to mitigate breakage and accumulation of fines. They ensure quality by not breaking the final cereal product. They also ensure the integrity of any cereal blend that has multiple components in the mix. Since the cereal is not blown, as is the case with pneumatic conveyors, not sucked into a vacuum system, and not tossed around in bucket elevators, the final product in a tubular drag cable and disc conveyor will maintain both the quality and integrity of the blend exactly as the food scientist formulated it from the outset.