The primary objective of any oilseed processing operation is to squeeze as much oil from the seed as possible by separating the liquid fat from the solid meal. Achieving this requires a complex series of steps and processes along the way, which makes oilseed processing quality control an ongoing priority at every step — not just when sampling your final products.
By paying close attention to quality metrics at each processing phase, processors can take control of their production costs, efficiency, and yields while making strategic adjustments to ensure that the final byproducts meet customer specifications. Understanding how each unit operation impacts the resulting product quality is critical to producing the best oil and meal — not to mention the best profits.
Here are five of the most important oilseed processing quality control practices to consider at every step.
1. Only accept the best raw material
Quality assurance begins before the beans even enter the press. Start by setting strict guidelines for the incoming quality of raw seed material you’ll accept at your plant. The old saying “garbage in, garbage out” is particularly true in this industry because you can’t expect to feed low-quality seeds into your system and end up with anything but low-quality products.
Some initial quality parameters might include:
- A visual check for beans that appear to be off-color, split, sprouting, or damaged by frost, pests, mold, or disease.
- The amount of foreign material, such as sticks, stones, stems, dirt, and other debris in the shipment. The more trash you accept, the more processing time and costs you’ll incur cleaning the beans before storing or processing them.
- The moisture level of the raw seeds, which can interfere with storage, downstream processing, and overall product quality. Buying wet seeds means you’ll spend more processing time and costs drying the material before you can store or process it.
- The oil and protein content of the raw beans. You can’t create more fat or protein during processing, so what you buy is what you get.
Inspect raw seeds from every level of the truckload to ensure that inferior product isn’t buried at the bottom and reject shipments that don’t meet your plant’s minimum standards.
2. Take out the trash
No matter how much foreign material you’re willing to accept in your raw beans, the first pre-processing step involves seed cleaning, or removing as much of this debris as possible.
Read more about the economics of oilseed cleaning and how it impacts your operation.
Monitor how much foreign material enters your seed cleaning system versus how much debris remains after cleaning. You may also want to measure how many good beans are accidentally removed during cleaning to make sure your system isn’t removing more than it should.
3. Monitor moisture
Regardless of the moisture levels of your raw beans, another critical pre-processing step is drying the material to lower the moisture level and prepare seeds for pressing. Soybeans, for example, are typically stored at moisture levels between 11-13%, but mechanical oil presses like the Anderson Expeller operate most efficiently when processing beans with about 5% moisture content.
Oilseed processing quality control requires moisture monitoring throughout the process since various unit operations involve heat treatment that can either be beneficial or detrimental to your final product quality. Soybeans require enough heat to destroy anti-nutritional factors like trypsin inhibitors and urease — but excessive heat could degrade the meal protein quality and increase the likelihood of oxidation in the oil.
Measure the moisture content of beans entering and exiting the seed dryer to ensure you’re handling this important step carefully. Remember that any heating or drying operation can damage the proteins in the bean, create free fatty acids in the oil, and cause other unwanted repercussions downstream. For example:
- Pay attention to the additional heat treatment happening in the extrusion step. A high-shear dry extrusion system like the Anderson Dox ™ Extruder efficiently cooks, dries, and shears seeds like soybeans by generating mechanical heat through friction. This process shortens the traditional cooking time from 20-30 minutes to just 20-30 seconds, which minimizes potential protein damage while deactivating harmful anti-nutritional factors and flash-drying excess moisture. Be sure to measure the temperature and moisture level of soybeans before and after extrusion.
- Likewise, a mechanical screw press like the Anderson Expeller creates additional frictional heat in the process of crushing seeds. Monitor seed moisture and temperature throughout this process to ensure oilseed processing quality control.
4. Size matters
Size matters when it comes to oilseed processing quality control. Oversized seeds (or pulverized seeds with excessive fines) can clog equipment and impede the efficiency of the press. Cracking mills, hammer mills, flakers, or grinders break beans into smaller pieces to make the material easier for the press to process.
By measuring the particle size of seed material leaving the cracking mill and entering the press, processors can better control the efficiency of their system and the quality of the resulting products.
5. Inspect final product quality
In terms of maintaining oilseed processing quality control, the main event happens after the press crushes the beans. At this final stage, processors should gauge how efficiently the press is achieving its mission of separating liquid fat from solid seed material by measuring:
- How much solid residue remains in the pressed oil?
- How much residual oil remains in the solid meal?
Although no extraction method will completely separate every solid particle from each drop of oil, these quality metrics determine the efficiency of your press and the value of your final products.
When paired with the Dox Extruder, the Anderson Expeller has been proven to reduce residual oil (RO) levels to as low as 5%. If you’re not achieving these rates, it might not be the press’s fault because every unit operation upstream can impact the efficiency and yield of the expeller. It’s critical to measure quality at every step throughout the process.
Additional quality control measures for pressed oil typically include:
- Free fatty acid levels
- Phosphorus levels
- Color profile
These factors indicate how much additional processing — such as filtering, degumming, and bleaching — will be required to refine the oil to meet customers’ specifications.
Likewise, additional quality control measures for de-oiled meal might include:
- Fat content
- Moisture content
- Particle size
- Protein quality
As the primary source of protein in most animal diets, soybean meal protein quality can have a profound effect on animal health and performance. This can be measured in multiple ways, including the protein solubility test (KOH), the protein dispersibility index (PDI), and, of course, trypsin inhibitor (TI) activity.
Read more about measuring soybean protein meal quality.
Committed to oilseed processing quality control
Even minor variations in processing methods can significantly impact the resulting product quality and value. By putting checkpoints in place to ensure that your plant maintains quality assurance at every step of the process, you can move closer to your goal of producing the highest quality oil and meal products.
The right oilseed processing system, paired with regular inspection, can help minimize variations and control the factors that impact quality. A high-shear dry extrusion system that combines the Anderson Dox Extruder and Oil Expeller strikes this balance by maintaining the ideal conditions to preserve the value of your byproducts while deactivating harmful enzymes.