The food we consume is a complex mixture of 3 major macromolecules carbohydrates, lipids, and proteins. These macromolecules provide a surplus source of nutrition and energy for running the body’s metabolism. The human body is designed to require a proportionate diet where each of these macromolecules is assigned a specific role. And the role of lipids can’t be undermined as they form the most essential layer of all cells; the cell membrane!
While the body can synthesize some lipids, some others can only be supplemented by dietary means. This makes the presence of lipids in our food sources an absolute requirement. The importance of lipids is not just limited to the food domain. It is also important to understand the science behind their synthesis across biological organisms as they serve many more essential roles than we believed they do for a very long time.
The debates and discussions about lipids have become more common in recent years with the mainstreaming of “low-fat diets”. Common people have started talking about good fats, bad fats, trans fats, good cholesterol, bad cholesterol, etc. As the increase in heart disease has gained momentum, people are confused about how what lipids and fats to consume. While omega fats have made their own market in the past 5-10 years, no doubt all of us are aware of multiple brands selling flaxseeds, chia seeds, hemp seeds, and pumpkin seeds with the label of “good fats and lipids”.
This makes authentication and testing for lipids a very important topic. With everyone aware of lipids in our food, the need for biochemical tests at industrial and research levels is necessitated. Such a test is the “Sudan test”. Students introduced to this test often find it difficult to learn its details, underlying principle, and its real-world applications. Even educators dealing with the topic sometimes struggle to deliver the essence of this topic and its crux.
We, at Labster, understand the complexities of this biochemical test. This article can provide some help as it attempts to identify the major issues encountered by students whilst studying this topic. It also lists practical solutions that teachers and educators can incorporate into their next class. By the end, we’ll convince you why a virtual lab simulation will prove useful not only for your students but also for you as an educator to deliver concepts more efficiently.
There are 3 reasons why students dread and get confused about the topic of the Sudan Test. Acknowledging these blocks is the first step toward making the topic more approachable.
This is one of the main reasons why most students don’t understand the working of the Sudan test and other biochemical tests performed for food macromolecules. When the underlying principle is not clear, the test becomes less logical and more theoretical to students. The ‘why’ (reason for performing the test) and ‘how’ (the underlying principle of the test) of each test performed for different macromolecules must be thorough to young learners.
Educators dealing with the Sudan test usually dive into the intricacies of the test without explaining the basic structure of molecules, i.e., lipids. Many students are often oblivious to how polar and non-polar compounds differ. Basic knowledge about lipids, their structure, their types, nature, etc is a prerequisite before one moves on to complex topics like biochemical testing, reagents used for tests, etc.
Learning a technique seems worthless to students when they don’t know how to exploit it in their future research or industry job or businesses. Sudan tests are often taught to students without educating them about their practical utility. This makes the learning journey dull and non-conducive.
To address the issues encountered while teaching this topic, educators can engage the under-listed solutions in their classes. These can decode many different aspects of the Sudan Test. Not only can they make teaching easier for educators like you but they will also make lessons clearer and easier to assimilate for your students.
This is our foremost advice to all the educators dealing with Sudan tests. Designing biochemical tests that exploit the basic biochemistry of lipids at the molecular level necessitates the need for strong core concepts. You can begin with the underlisted examples in your next class.
Different types of food macromolecules (You can use the Introduction to Food Macromolecules simulation from Labster)
Basis of differentiating different food macromolecules
Introduction of lipids
Lipid structure and its types (simple and complex lipids)
Difference between saturated and unsaturated fatty acids
Difference between cis and trans fat
Harmful effects of trans fat
Difference between sterols, triglycerides, and phospholipids.
Usage of confusing terms like amphipathic vs amphiphilic vs amphoteric
Different types of sterols in the biological world (cholesterol, sitosterol, campesterol, ergosterol, and stigmasterol)
Catering to these topics before moving to the explanation of the Sudan test can ease the work for you. Additionally, it will encourage students to raise questions more open-ended manner during classroom teaching sessions related to “basic science”.
The Sudan test is one of the many biochemical tests used in both academic research and the R&Ds of industries. Teaching your students how to scientifically approach a problem can help them reason out “where the Sudan IV test can be applied” and “where it shouldn't be”. This will help them in recognizing the practical applicability of techniques. It will also boost their confidence to translate theory lessons into practical experiments.
There are different types of Sudan dyes like Sudan III, Sudan IV, Sudan Black, etc. While Sudan III and Sudan IV work well for all triglycerides, usually Sudan Black is used for phospholipids and cholesteryl esters. Explaining how Sudan Black works for phospholipids becomes important here. Explanation: Since Sudan Black is slightly basic; it combines with the acidic groups in phospholipids forming a “dye-lipid complex” and eventually staining it.
Such small explanations can help your students in appropriately selecting the Sudan dye variant “as per the lipid in question”.
There are too many biochemical tests for students to learn like Fehling’s test, Benedict’s test, Tollen’s test, Biuret test, etc. Students find it hard to differentiate between this variety due to the focus of classes on the theoretical understanding.
We recommend educators engage students in wet lab handling and empower them with hands-on experience with each of these tests. We understand that it’s not always possible for educators to conduct individual practice sessions for all the experiments. In such cases, we recommend at least demonstrating the experiment. Since the Sudan test is based on a chromogenic change (color change; “orange” to “2 layers; top orange layer formation and lower clear layer), students might find it quite interesting when they observe the color change in front of their eyes.
You can use different food items like milk, butter, mayonnaise, desiccated coconut, sugar, cheese, etc which are rich in lipids to conduct a practical class testing lipids’ presence in them. Watch out for your students as the color changes of the Sudan test engage them in the class!
Additionally, you can increase participation by asking your students to bring a variety of foods from home that they believe to be high in lipids, fats, and oils so that you can include them in the experiment.
Figure: A snippet from the Sudan test simulation by Labster where your students can virtually test for the presence of lipids in different food samples. It is available for School and University/College classes.
Educators must simplify the science behind technical experiments. It's crucial to explain why the color in this experiment changes. If you simplify that for your students, half of the job is done!
Explain the nature of Sudan dye. Sudan dye is a diazo compound. It is lysochromic by nature (fat-soluble).
Explain the role of pH in this staining technique. Fatty acid molecules exist in different states; protonated (ionized) and in the form of soaps. The fatty acids are easily stained on acidification and give bright orange droplets on the Sudan test. While in a controlled pH (~5.6), the staining with the Sudan test is usually variable. And upon alkalinization, no orange droplets are observed on performing the Sudan test.
Explain how the test works. The Sudan dye is lipophilic. When a sample contains lipids, the Sudan dye gets completely incorporated into the lipid micelle.
Figure: (-) is the negative result;(+) is the positive result. Image Source
The Sudan test is a practical technique used for the detection of lipids in food-based research labs and industries. When teachers and educators aren’t able to demonstrate the experiment in their classes, theory lessons can be quite taxing for students.
We at Labster understand the issues faced by both students and teachers. Therefore, we encourage modern-day educators to make the most of the Sudan test simulation. It takes your students into a virtual world where they can understand how the Sudan reagent dyes lipids. They can also learn about the chemical structures of lipids and the differences between saturated, unsaturated, and trans fats by engaging with the gamification elements of the simulation.
As they virtually test for the presence of lipids in different food samples, they can better understand the underlying principle of the Sudan test. With virtual laboratory simulations from Labster, teachers can make more insightful points as students are rendered with better visual options with multiple games and quizzes to keep the class fun-filled. By using this way of active and immersive teaching, our virtual learning platform takes an advent in the field of Science to make the upcoming scientists thorough with the “basics of their respective subjects”.
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