The following reference question came in by phone to a reference desk at a local public library. "Why do some blueberries float and others sink?" Ideas? Sources? Experiments? Research? Conspiracy theories?
Somebody actually patented a device for "hydroponic blueberry sorting" that is based on this quality:
http://www.freepatentsonline.com/4225424.html
Aside from the apparently common wisdom that ripe blueberries sink and unripe ones float I can't find much. It's definitely not the case for all ripening fruit...
Funny you say that about the ripe and unripe ones, because that was my first, gut response/theory. However, I thought it was the reverse (in the case of blueberries at least, since I hadn't really thought about it in connection with any other fruit before): unripe sink, ripe float. I am not at all sure why I thought this. But then blueberries came down in price and I really started paying attention, and it just ain't so (either way, or so it seems to me). The person with the patent, though, seems to think that the ripe blueberry surface can be made to release gas bubbles, which in turn makes the ripe ones sink, or .... I am not sure I get it. Oh well, they are still yummy to eat, whether they bob or they sink. So how did you find the blueberry sorting patent? Did you google? What were your search terms?
The patent was a google search, yes, for "blueberry buoyancy." It's the second result, and the first reasonable one.
Actually, searching for "blueberries sink float", the second result is a book on blueberry sorting, with abstract, that also relates density to ripeness:
http://www.actahort.org/books/241/241_61.htm
I tried the ISI Web of Knowledge science citation index, for "blueberry buoyancy," "fruit ripening density," and "berry ripening density," but there were no obviously good results, and I haven't taken science since freshman year, so...
Remarkably, there are no conspiracy theories on blueberry buoyancy that I could find =)
The only things that makes something sink or float is the difference in density between the object floating and the medium it is floating in, even where air bubbles and gas are concerned, they are only relevent when they, one way or another, affect the overall density of the object.
Example- the plastics in a straw are more dense than most liquids, so the straw initially sits at the bottom. However, in a carbonated beverage, the air bubbles that adhere to the straw in effect become part of that straw's volume, so theirlow overall density is able to affect the straw's density enough to make it float.
As blueberries are concerned, I would guess that they are most dense when they are young and unripe... most fruits seem to be, and that their ratio of volume to mass changes significantly enough as they mature to make them less dense than water so they float.
Either that, or they are witches. BURN THEM, BURN THEM.
Very interesting, positive and even 'fun,' Probably because thoughtful people are the ones who bother to ask thoughtful questions.
WELL, consider this. Every blueberry is like a little boat ����. Each having an small bowl shaped opening where air can tend to be trapped. Also, the skin is air loving, or water repelling. You can observe this when your blueberries are floating around in a bowl of water. There are little bubbles of air attached to the blueberry and especially under the rim of the tiny bowl in the center of the 'flower.' I was able to sync several of my floating blueberries by making them go under and give up their air bubbles. But, not all of them. So, the query continues.
Future (& current) librarians are you game? Let's stay search-nimble post-ref class: in print and online! The more and more varied the sources (cited/linked,) the better. Because it's all about the search and not the find. That is, do tell how you sought what you found.
Future (& current) librarians are you game? Let's stay search-nimble post-ref class: in print and online! The more and more varied the sources (cited/linked,) the better. Because it's all about the search and not the find. That is, do tell how you sought what you found.
5 comments:
Somebody actually patented a device for "hydroponic blueberry sorting" that is based on this quality:
http://www.freepatentsonline.com/4225424.html
Aside from the apparently common wisdom that ripe blueberries sink and unripe ones float I can't find much. It's definitely not the case for all ripening fruit...
Funny you say that about the ripe and unripe ones, because that was my first, gut response/theory. However, I thought it was the reverse (in the case of blueberries at least, since I hadn't really thought about it in connection with any other fruit before): unripe sink, ripe float. I am not at all sure why I thought this. But then blueberries came down in price and I really started paying attention, and it just ain't so (either way, or so it seems to me). The person with the patent, though, seems to think that the ripe blueberry surface can be made to release gas bubbles, which in turn makes the ripe ones sink, or .... I am not sure I get it. Oh well, they are still yummy to eat, whether they bob or they sink.
So how did you find the blueberry sorting patent? Did you google? What were your search terms?
The patent was a google search, yes, for "blueberry buoyancy." It's the second result, and the first reasonable one.
Actually, searching for "blueberries sink float", the second result is a book on blueberry sorting, with abstract, that also relates density to ripeness:
http://www.actahort.org/books/241/241_61.htm
I tried the ISI Web of Knowledge science citation index, for "blueberry buoyancy," "fruit ripening density," and "berry ripening density," but there were no obviously good results, and I haven't taken science since freshman year, so...
Remarkably, there are no conspiracy theories on blueberry buoyancy that I could find =)
The only things that makes something sink or float is the difference in density between the object floating and the medium it is floating in, even where air bubbles and gas are concerned, they are only relevent when they, one way or another, affect the overall density of the object.
Example- the plastics in a straw are more dense than most liquids, so the straw initially sits at the bottom. However, in a carbonated beverage, the air bubbles that adhere to the straw in effect become part of that straw's volume, so theirlow overall density is able to affect the straw's density enough to make it float.
As blueberries are concerned, I would guess that they are most dense when they are young and unripe... most fruits seem to be, and that their ratio of volume to mass changes significantly enough as they mature to make them less dense than water so they float.
Either that, or they are witches.
BURN THEM, BURN THEM.
Very interesting, positive and even 'fun,' Probably because thoughtful people are the ones who bother to ask thoughtful questions.
WELL, consider this. Every blueberry is like a little boat ����. Each having an small bowl shaped opening where air can tend to be trapped. Also, the skin is air loving, or water repelling. You can observe this when your blueberries are floating around in a bowl of water. There are little bubbles of air attached to the blueberry and especially under the rim of the tiny bowl in the center of the 'flower.'
I was able to sync several of my floating blueberries by making them go under and give up their air bubbles.
But, not all of them. So, the query continues.
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