Today I picked a Washington Navel orange and a Gold Nugget mandarin, each from the center of a group of fruits on each tree.
I then measured the Brix from each, calibrating the sensor with ionized water both times. The %s were 10.6 for the orange and 9.8 for the tangerine. These are in the expected range for a digital meter with these fruits.
I also tasted them, and to my pallette it is time to start harvesting. The oranges can be harvested over a month, but the tangerines have less hang time – perhaps 2-3 weeks.
I assume the digital gauge is more accurate? How much off are the analog ones? I had thought the variance from different posts of the same fruit were great enough that most of the inaccuracy on my analog gauge was from that. But that was just my guess without any data.
Scott, I’m not sure if it is a matter of accuracy or scale. Hanna states that this one is “temperature compensated according to the ICUMSA Methods book”. This model is for general field tests of fruits and vegetables. They also make others, e.g. for vintners.
@don1357
The crop analysts I’ve met locally will not use the analog meters, complaining that the results vary too much between units and manufacturers.
Interesting. Do we know if the analog meters make consistent errors in a set of measurements? I mean can one analog meter rank a set of measurements correctly even if the absolute value has errors? If thats true, I am guessing it’ll still be useful for backyard growers, for e.g to see if watering schedule made a difference in brix.
@californicus
I never said they make errors. What I infer from the crop analysts is the analog meters have biases that can vary between manufacturers and individual units. This might be due to lack of temperature compensation. When your clients have million dollar farm operations you need devices with reproducible results.
I can’t find any researched or tested analysis of relative accuracy of various cheap “analog” (quotation marks only because of my own ignorance of how such devices fall into this category… compared to what?) All I find is that they are accurate within .2 of a point if properly adjusted.
For me, within a half point is close enough for all practical purposes when measuring fruit. What I’m interested in is relative sweetness between varieties and seasons, so as long as I’m using the same cheap refractometer I pretty much have the info I need.
I always take other people’s measurements with a grain of salt. A lot of inaccuracy can occur by how you interpret where the line is between blue and white. However, if someone suggests that the brix readings they get from a certain variety are notably higher than others, I take notice. As a general rule, here in the brix challenged world of frequent summer rain and cloud cover, sweeter is better. Of course acid counts too, but in low acid fruit higher sugar is perhaps even more important to my enjoyment in eating it. I hate low-acid peaches at the brix levels I get from them here, but when low-acid nectarines get above about 18 I enjoy them and when they get into the 20’s I think they are special.
Most of us are amateurs here, so requirements of accuracy are different. However, as far as I can tell, most commercial growers are less concerned about eating quality than us amateurs, but I don’t think a $300 digital refractometer is going to help us improve that much.
For me is a brewing thing, I need to know sugars so I can make blending decisions.
While I can go far with just a hydrometer (also known as a saccharometer if you want to geek out about this sort of thing) to measure the specific gravity and thus calculating sugars, a refractometer would go a long way towards me being able to inventory all sorts of apples and fruits in general. During pressing it is easy enough for me to highjack half a cup of juice to see what the hydrometer reading is, but it would be fantastic if I could just measure and track sugars on apples (and fruits) I’m not even juicing. Heck I could even inventory apples from other orchards and keep track of how particular seasons affect apples. Even sugar development over time; Next year I plan on letting Kerr and Franklin apples freeze on the trees; it would be a bit of a pain to juice and test them overtime. A refractometer would make this quick and painless.
@don1357
I’m only familiar with agricultural chemistry test equipment from Hanna Instruments. Here is a list of their products that they believe are applicable to beer: https://www.hannainst.com/beer
