Carlie Peters 6 October 2015 From Seed to Shelf Lab 1 Introduction The objective of this lab was to gain a better understanding of Maillard reactions. Maillard reactions, named for Louis Camille Maillard who discovered these reactions around 1910, are the reactions that occur between a sugar (like glucose or fructose) and an amino acid when heated. Maillard reactions are those reactions responsible for the color and flavor of bread crusts, grilled meats, and cooked potatoes a brown color and complex flavor. The flavor produced by a Maillard reaction is usually more complex and meaty than caramelized flavors, because as described by McGee, the involvement of the amino acids adds nitrogen and sulfur atoms to the mix of carbon, hydrogen, and oxygen, and produce new families of molecules and new aromatic dimensions (McGee 778). In completing this lab, we sought to observe Maillard reactions in potatoes and how certain temperature storage conditions of potatoes can affect the potatoes glucose levels. We also sought to identify how these different glucose levels influence the browning that occurs during the Maillard reaction. Hypothesis I hypothesized that those potatoes stored at higher temperatures (i.e. room temperature) would have higher glucose levels before heating and that after heating, these potatoes would have more browning than the potatoes stored at different temperature (fridge and freezer) and a higher glucometer reading. This was hypothesized because it was believed that the potatoes stored at lower temperatures would take longer to heat up and as a result, less of the Maillard reaction would have occurred in eight minutes. Materials and Procedure Bag of potatoes, sliced and stored in different conditions A glucometer and test strips A cast iron skillet Canola oil Tongs Paper towels Bowls and plates A peeler A blender Potatoes were stored for 1 week at room temperature (~23 C), in the fridge (~8 C), and in the freezer (~1 C). Potatoes in the fridge and freezer were sliced into sticks beforehand and the room temperature potatoes were sliced into sticks the day of the lab. A few (3 or 4 pieces) of each potato category (room temperature, fridge temperature, and freezer temperature) were set aside for testing with the glucometer. These three or four pieces of potato were blended in a blender in order to extract liquid from them. This liquid was analyzed for sugar content using the glucometer. The readings were recorded in Table 1 and averaged. The rest of the potatoes were fried in oil in batches for each temperature category for approximately 8 minutes. The potatoes
were qualitatively evaluated throughout and after the frying process for browning and taste. After cooking, one piece of potato was mixed in a bowl with a tablespoon of water to create a solution. This solution was tested with the glucometer in order to analyze the sugar content of the cooked potato pieces. These readings were recorded in Table 1 and averaged. Data and Results As reported in Table 1, we found that the room temperature potatoes (23 C) before cooking averaged a glucose content level of 101. After cooking (which can be observed in Image 1), the glucose level of the room temperature potatoes was found to be 39. These potatoes were thought to taste the most like French fries and while not the most brown, they were cooked all the way through. The refrigerated potatoes (8 C) before cooked had an average glucose level of 169. After cooking, these refrigerated potatoes averaged a glucose level of 99. These potatoes seemed to soak up more oil, but tasted very good. As seen in Image 2, these potatoes were moderately brown. The frozen potatoes (1 C) averaged a glucose level of 122 before cooking. After cooking, it was found that the cooked frozen potatoes averaged a glucose level of 114. These potatoes were much softer and had less of a potato taste. The refrigerated pre-cooked potatoes had the highest glucose level, with an average of 169. The frozen pre-cooked potatoes had the next highest glucose level with an average of 122 while the room temperature potatoes had the lowest glucose level before being cooked with an average of 101 (Table 1). The frozen potatoes retained the most glucose after cooking with an average glucose level of 114, while the refrigerated potatoes and room temperature potatoes had lower average glucose level readings after cooking (99 and 39 respectively). Table 1: Maillard Reactions in Potatoes & Glucose Content Lab Storage Type Glucose Content () Browning Taste Room 37 (stuck AVERAGES Edges browned Taste like Temperature into Were crispy on French fries (23 C) potato) 101 (averaged second outside, fully cooked Before cooking 112 two) all the way through 89 RT After 36 39 cooking Refrigerated (8 C) Before cooking Refrigerated after cooking Frozen (1 C) Before cooking 41 168 169 Soaking up more oil 175 than RT too 164 Crispy outsides 92 99 96 108 66 We can avg (122) but 138 std dev is going to be Much browner than RT Taste the best Fluffy insides Tastes like cardboard
Frozen after cooking 161 116 111 huge 114 Image 1: Room Temperature Potatoes Cooking in Pan Image 2: Cooked Refrigerated Potatoes Soaked up more oil Very soft on inside Grayish coloring Less potato taste
Image 3: Refrigerated Potatoes Cooking in Pan Image 4: Refrigerated, Room Temperature, and Frozen Potatoes after Frying Discussion/conclusion Unlike my hypothesis, the room temperature potatoes did not have the highest glucose level before cooking and after heating. In fact, the room temperature potatoes had the lowest glucose level. The glucose levels in the potatoes decreased after cooking, which could follow that since glucose had been used during the Maillard reaction, there was less glucose in the potato to read with the glucometer afterwards. While the refrigerated potatoes browned well and tasted the best, perhaps the room temperature potatoes failed to produce a large Maillard reaction effect due to the fact that we cooked the room temperature potatoes first, and it is likely the oil at that point had not heated
enough for a large reaction to occur in eight minutes. Overall, it did not appear the temperature of the potatoes played a role in the browning of the potatoes. Instead, it appears the temperature of the potatoes played a role in the taste of the cooked potatoes, as the frozen potatoes varied more in their taste than in their appearance from the other cooked potatoes. In the future, it would be best and perhaps more reliable to attempt this lab with a glucometer designed to test food products and not blood. Additionally, researching a reliable solution that could be created with the potatoes to accurately test their glucose levels would allow this lab to be more effective. This lab provided a unique method to study and visualize Maillard reactions in a non-traditional environment While this lab had its flaws, it allowed us to understand what is happening between sugars and amino acids when heated and how this can produce an effect on foods we eat, visually and in terms of taste. Bibliography Cuppett, Susan. Irish Potato Products. University of Nebraska-Lincoln Department of Mathematics. Web. McGee, Harold. On Food and Cooking: The Science and Lore of the Kitchen. New York: Scribner, 2004. Print.