November | December 2009 Feature title: Analytical methods that save money and improve quality
International Aquafeed is published five times a year by Perendale Publishers Ltd of the United Kingdom. All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2009 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1464-0058
The International magazine for the aquaculture feed industry
that save money and improve quality
Stefan Tordenmalm, Business Area Manager - Feed - Perten Instruments AB, Sweden Martin Hallin, Product Manager rheology - Perten Instruments AB, Sweden
years, but it’s only with recent advances that its full potential has been reached. Modern diode array NIR technology makes it possible to analyse samples as they are with no grinding required, and does not need glass cups thus removing the need for cleaning cups between samples. Diode array instruments perform analysis in a few seconds, are robust, and are generally easier to use than previous NIR models. These properties mean that NIR is no longer confined to the lab, but can be used by process operators and placed at the factory floor. The speed and robustness of diode array NIR technology also means it is perfectly suited for on-line use, measuring directly in the process line in real-time. While there have been on-line NIR instruments in the past, they have not been accurate or robust enough to become widely used. In contrast to earlier NIR technologies, diode array technology contains no moving parts in the optics, and is thus robust enough for harsh process environments.
Rapid Visco Analyser (RVA) – an introduction
The Rapid Visco Analyser (RVA) system measures functional characteristics by monitoring changes in viscosity as a sample is put through a series of heating, cooling and mixing steps. For starches it essentially cooks the starch meaning it pushes the starch through gelatinization, pasting and retrogradation. The heating, cooling and mixing steps are repeatable allowing for comparison of performance from one sample to the next. The RVA is used at aquafeed production sites worldwide to verify the starch characteristics. The sample is analysed in an aluminium canister and a plastic propeller shaped paddle measures the change in
he better you know and understand your raw materials and your production process, the more efficient you will be at profitably turning variable ingredients into consistent high quality feed products. Testing nutritional values and functional properties are key for this understanding, and many aquafeed plants have discovered how advanced viscometric equipment and near-infrared spectroscopy (NIR) can save them money. An advanced viscometer, such as the Rapid Visco Analyser (RVA), provides a rapid test for starch characteristics of ingredients and finished feed properties such as water stability and digestibility. NIR instruments determine the composition of ingredients for cost efficient formulation and help you monitor your process to maximise output and save on expensive raw materials. Recent advances have made these tools more accurate and easier to use, making them
Which one ate your feed?
an excellent investment also for smaller plants. Before we discuss their respective applications and benefits, we will explain the basics of the two methods.
Our new RVA, At-line and On-line NIR analyzers improve quality and profitability of your feed. • Save on ingredients & reduce waste • Optimize extruder & dryer efficiency • Improve feed quality & consistency To learn more about our feed analysis systems visit us at www.perten.com
DA 7300 On-Line
DA 7200 determine moisture, protein, fat and more in ingredients and finished feeds. NIR has been used in the industry for
NIR – Introduction and recent advances
Technically, NIR is a molecular vibration spectroscopic technique. In laymen’s terms, it means shining specific wavelengths of light on a sample, measuring how much of the light is absorbed at the specific wavelength, and relating the absorption of light to a constituent (i.e. protein) value. A simple example can be found in the picture of grape juice above. In the glass to the right the darker color is absorbing more light meaning it is higher in concentration. An NIR instrument performs a similar sort of analysis as our eyes in this instance, but in a different portion of the electromagnetic spectrum – i.e. the NIR portion. In this way, NIR can be used to
SPECIALISTS IN QUALITY CONTROL OF GRAIN, FLOUR, FOOD AND FEED
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viscosity while inducing the movement to keep sample mixed and suspended throughout the analysis. Many starches are undigestible until cooked. The RVA provides a tool to monitor the changes of ‘Degree of Cook’ that occurs during extrusion and other manufacturing processes. In addition, it is the starch that provides the structure as opposed to protein in many food/feed products. There are several product goals that can be verified with the RVA. Optimal size, density (float/sink properties) water stability and durability, optimal digestibility, uniformity within and between batches and cost minimisation. A typical standard measurement of a sample starts at 50oC (see red temperature line in graph 1), ramps the temperature up to 95oC, keeps at 95oC for a short while and ramp temperature down to 50oC again for a final period at the lower temperature. The blue line is the measured viscosity during the analysis. From the curve characteristics like cold viscosity, pasting temperature and hot paste viscosity is extracted. Pasting temperature and peak viscosity will have an impact on the mixing properties of the feed and will help the operator to set up the process. As an example a higher pasting temperature means that more heat energy needs to be added to the process to achieve the required starch characteristics modification of the mix. Final viscosity can be used to predict the end product characteristics. A high final viscosity in raw material helps to get a more stable end product. products, it is critical to monitor also the qualitative characteristics of the ingredients. The characteristics of primarily the high starch ingredients will highly influence the production and the final product and verifying incoming material will secure that production will run smoothly. The starch in the ingredients will determine the binding and expansion of the mix in the process and also the size, density, durability and water stability of the final product. It will also highly influence the nutritional digestibility of the final product. When new loads of e.g. wheat or rice arrives, running them in the RVA verifying pasting temperature, peak and end viscosity and other parameters from the RVA will give the correct information to be able to design the right mixes. When new harvests are out on the market, or a new supplier is used, the confirmation of the viscometric parameters is extra important. In graph 2 the RVA pasting profile of different types of rice provides an example of the variation between different sources of raw material. As can be seen there are significant differences between, for example Mochi, Basmati and Century Patna rice and this variation seen in the RVA would give clear rheological differences in aquafeeds produced with these rice types. In the Mochi variety with a low pasting temperature and an early peak, the starch would be transformed to a higher degree in the process than, for example the Century Patna or Pelde varieties. In the final product using the Mochi variety would lead to higher digestibility but if the Degree of Cook becomes too high the feed may disolve too fast in the water. Figure 1
actual composition of produced feeds is often not known until a day or two has passed. This makes it impossible to react and make changes. Modern NIR instruments provide the information in seconds, but only when a sample has been taken out and analysed. With on-line NIR the measurements are done in real-time and operators will always know the exact current composition. The most obvious money saver is controlling moisture to stay as close as possible to the upper limit. Increasing average moisture content by one percentage point means that production volume increases by one percent at no extra cost. At a plant with 100,000 ton per year production volume this means 1000 extra tonnes and hundreds of thousands of dollars in profit increase. Protein and fat also offer substantial potential for savings and product improvements. One rule of thumb suggests that decreasing protein content by one percentage point will save two Euros per tonne of feed. Much of these savings can be realised when using a modern bench-top NIR instrument, but on-line analysis brings additional benefits. Consider figure 1 to the left, which comes from a factory where on-line NIR had been installed but not yet connected to the control system. It shows fat content over time in multiple batches of one recipe, and makes it very clear that while the average is close to target, the product is highly inconsistent. If only one sample had been taken for analysis, it would almost certainly have been at least slightly misleading, and if taken during the peak it would have given a very incorrect picture of fat content. With the detailed information on-line NIR provides, the problem is seen and it’s possible to start investigating.
Where and how to save money Buying the right ingredients
Many users of NIR instruments have saved back the investment simply by monitoring suppliers and make claims when specifications are not met. When a shipment arrives, it is tested for compliance before it’s even unloaded. If it’s out-of-spec it can be rejected immediately, and immediate rejections tend to be more effective than rejections when wet chemistry results are available the next day. As modern NIR instruments don’t require grinding even for analysis of grain or pellets, much labor is saved on grinding of samples. Due to the importance of the rheological performance of the mix in both the production process and the final
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properties will, so it is important that the pasting properties of the mix match the production process settings. To secure that the process will be set up correctly for each product mix and will run smoothly the final mix/dough going to the extrusion process can be confirmed with the RVA. With correct moisture content and pasting properties of the mix the final product will become the correct one. In graph 3 it can be seen how the characteristics is considerately changed from the raw mix to the dough prepared for the extruder, and further into the final expanded end product. The raw mix before treatment has a completely unmodified starch structure, in this case with a high final viscosity. Modified in the process the mixture transforms via the dough prepared for the expander into the final expanded prod-
uct where e.g. the cold viscosity achieved will let the feed dissolve in a proper pace when put into water.
As mentioned above the interaction between the process parameters in the extruder and the mix going into the process determines the final product. The extrusion process with its high shear, high temperature conditions will cook the product and to a certain degree modifies the starch. The degree of cook in the process needs to be controlled for determination of the final product. Too low ‘degree of cook’ may make the final aquafeed less accessible and harder to digest while a too high ‘degree of cook’ may cause the feed to dissolve too quickly in the water. In both cases batches of product may be less valuable or might have to be reworked or discarded. Perhaps the greatest savings in process optimisation are those where the moisture, protein and fat contents are monitored and optimised. Keeping all of them as close to targets as possible is always highly desirable, and new on-line NIR instruments provide completely new opportunities for cost savings. With traditional wet chemistry analysis the
Agricultural products are not uniform and to be able to account for this variability in formulations it’s necessary to have nutritional information for each shipment. As modern NIR instruments can test ingredients in seconds with no grinding required, this information is within reach for the nutritionist and formulations can be more accurate, providing great savings on raw materials at the same time as customers will experience a more consistent product.
Verifying finished product
Before shipping to customers, the finished product needs to be verified against specifications – for nutritional values as well as its functional properties.When NIR is used throughout the production process, it is natural to add a final test before shipping products. With diode array-based NIR instruments this step takes practically no time and serves as a final check-point to prevent any off-grade product from being delivered to customers. Verification of the viscometric quality of the product will confirm that it will give the right performance when used by the aquafarms. To the left (Figure 2) an example of viscometric curves of fish feeds with different ‘degree of cook’.
Determining process conditions
The nutritional values as determined by the formulation would not change in the production process, but the functional
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DA 7300 On-Line on grain intake pipe The higher shear and temperature from the process the higher ‘degree of cook’ of the starch. This is indicated by a lower peak and final viscosity. A higher ‘degree of cook’ leads
Fingerprinting and product development
For development of new products, the RVA works as a mini pilot plant. New formulas can conveniently be mixed and evaluated in the unit using small sample sizes. Another possibility with the RVA is fingerprinting and benchmarking internally or against competing products. In the example are shown viscometric curves of two brands of corn flakes, another type of extruded product. In graph 4 (page 16) there is a clear difference in the early cold viscosity for the two samples. These two products may look the same in the package and may have very similar levels of protein, fibre, fat and other constituents but they will behave very different when put into liquid.The generic will absorb moisture more quickly and get soggy. Similar properties for aquafeed are readily determined using the RVA.
"By using analytical instruments such as the RVA and modern diode array-based NIR, you will be able to use ingredients more efficiently and improve product quality"
to quicker dissolving of the feed in water and higher digestibility.The difference between the four feeds in the graph may be due to different raw material characteristics or different process conditions in the extruder. (Figure 2)
ments such as the RVA and modern diode array-based NIR, you will be able to use ingredients more efficiently and improve product quality. Quality of extruded aquafeed products depends largely on starch transformation that can be measured viscometrically in the RVA for better control of process and product. NIR has taken the leap from the lab to the process. Not only are modern instruments robust and easy enough to use to be placed at the factory floor, they can also be used on-line for real-time monitoring of the processes.
Perten Instruments AB PO Box 5101 Kungens Kurva, SE-141 05 Sweden Stefan Tordenmalm Tel: +46 8 50580927 Fax: +46 8 881210 Email: firstname.lastname@example.org Martin Hallin Tel: +46 9 50580923 Fax: +46 8 881210 Email: email@example.com
An improved understanding of your raw materials and your process unlocks great savings potentials. By using analytical instru-
The solution behind the solution.
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