Food Science B

[bernard]

Food Science Wiki
Food Science Test Exchange 2017
Past Threads: 2011 (Trial), 2012, 2013, 2016
Past Question Marathons: 2016

[Ri]

This year topic is Food Grain. Any book recommendation.

[SPP SciO]

Any recommendations on where to start with building the calorimeter? The rules are pretty vague; it just has to be non-electric and fit within a 30cm cube. A quick glance at youtube shows devices like this - https://www.youtube.com/watch?v=XjyWr-Mc0-g - basically a flame-shielding can and a water tank. I'm just skeptical about how well it could work; wouldn't an open system like that lose a lot of heat to the environment? And how can you be sure that 100% of the food sample is being burned? It would seem that there are relatively few foods that would be suitable to burn in a student-built device that could produce reasonably accurate results ... Wouldn't students just memorize the calories per gram of those food items (like marshmallows or popcorn etc)?

[Dr BobR]

I agree that there are MANY sources of error in the basic designs on the web for building such a calorimeter. I'm a retired college professor of human nutrition and am serving as a coach in my first Science Olympiad. My part is to oversee the construction of the calorimeter, and I have very serious doubts about the even remotest accuracy of any results obtained. Some, off the top of my head, sources of error using the pop (soda) can design are heat loss from whatever is holding/suspending the food item; convection heat loss of the air coming from the burning food; radiant and convection heat loss from the can holding the water; heat GAIN from whatever source is igniting the food (matches, propane/butane torch, etc); incomplete combustion of the food item; difficulty/inability to suspend food item on a needle stuck in a cork; inaccuracies in measuring water temperature from uneven mixing. Our team has not yet started building their calorimeter, so there may be even more sources of error identified once we get started! Bottom line is that I do not have even the remotest faith in whatever results we, or any other team, come up with.

[SPP SciO]

I'm guessing that since the rules were pretty vague about scoring, the ES will have leeway to ask questions about those sources of error. Calorimetry is worth 15% of the total score, but maybe only 5% is about getting the right number - they could be also scored on energy conversions, procedure writing, errors, etc. I could be wrong though - would be nice to hear from a test writer what to expect though!

[Dr BobR]

I just returned from working with our kids on the pop can calorimeter -- just working on the concept at this time. After trying several versions of the "food holder", we settled on a simple piece of screen as that allowed air (oxygen) to flow upwards to fuel the (insipid) flame. We tried burning several different foods with mixed results. Foods with a low oil content (Rice Chex) do not burn well at all, regardless of the design of the food holder. Hopefully the judges will give a grain-based food with sufficient fat content so that it will actually burn. Lighting foods with matches is NOT the most efficient way to get a nice flame going!

[Jesusfather123]

Hi, please help on how to prepare for food science for 2017. Didn't get the rules manual. Thanks

[Unome]

Hi, please help on how to prepare for food science for 2017. Didn't get the rules manual. Thanks

Step 1: Get the rules manual as soon as possible. If your team's head coach/sponsor/etc. doesn't already have it, then I would suggest either convincing them to get it as soon as they can, or ordering it yourself through the SOinc store.

[retired1]

Not my event, but I find it very hard to believe that this event got out of the summer institute or the California half day events. Specifically, the calorimeter!
To function, it needs to be able to contain all of the heat generated and transfer that to the water. Without electricity for ignition, it can not be a closed system. Without a precharge of oxygen most items will not have complete combustion. If it smokes,(incomplete combustion) the result will be off. What ever method of ignition is used, it will add an unknown amount of heat. Even if alcohol is used, it will have a huge amount of the heat leave an open system due to convection. If it is not completely burned, you can not even effectively measure the residue as it will have char which is not the same wt as the original.

This portion of this event is bad science and should be deleted!!!

A reply by the appropriate national supervisor would be appreciated.

[Dr BobR]

I totally agree with retired1 on the massive sources of error that WILL result from use of such a rudimentary and inefficient device. I worked with my kids on trying to identify all the possible sources of error, and it is massive! The limitations and restrictions that have been put on the construction of this device are not realistic -- even for a middle school level project.