How to Use Sugar Refractometer : Quick and Dirty Guide

Last Updated on October 21, 2020 by marvin v

Sugar refractometer estimates the sugar of liquids. The measure is expressed as ºBrix which means one gram sucrose per 100 ml solution. Therefore, a 23ºBrix reading equates to 23 grams of sugar per 100 ml or simply 23%.

The reading is not accurate, the reason why I said “estimate.” The instrument measures soluble solid content which may include not only sucrose, but also acids and broken sucrose components such as glucose and fructose.

It’s a refractometer, not a monocular

My first encounter with a refractometer was a bit embarrassing. I was not alone though. All of my classmates felt the same as we thought of the same thing. And, that awkward moment turned into laughter.

We all arrived at the conclusion – the small contraption was a monocular. It was a handheld device with an adjustable eyepiece. Except, the lens which supposed to magnify distant images was odd.

It was flat and slanted, forming a prism,  and with a cover. Perhaps, to protect the prism from dirt, scratches, and breakage due to accidental fall.

The eyepiece is indeed adjustable to suit the individual vision. The prism and cover mechanism are for holding the liquid of concern.

How to use a refractometer

Let’s cut to the chase. Using refractometer is simple. Follow the steps.

  1. Wipe the prism and cover clean with a soft cloth.
  2. Carefully drop liquid, enough to cover the prism area.
  3. Slowly lower down the cover to trap the liquid in between and check if the entire platform is covered. Repeat otherwise.
  4. Look through the eyepiece and rotate the adjustment until a clear horizon appears. Record.

How to calibrate the refractometer

Attempt to calibrate reading the Brix of distilled water. Adjust the horizontal line to zero by turning the screw which is usually located near the hinge of the prism cover.

You should be able to adjust the reading to zero. If not, the refractometer in your hand might be in serious trouble.

Troubleshooting the refractometer

Things don’t always go the way you want. It’s time to tinker in case of error.

1. If all that is seen is blue, the sugar concentration exceeds what the instrument can read. Get another that can read higher values. Juice refractometers can read only from 0 to 32 percent.

2. If the sample on hand is honey or heavy syrup, get a refractometer specifically made for honey.

3. Do trial dilutions and compute the sugar content in accordance with dilutions made.

4. For the colored and heavy syrup, sugar estimation might not be possible due to low visibility. Try diluting the sample until the value becomes readable. Then compute.

5.  Seeing a white canvas indicates that something is wrong with the device. Re-calibrate. If unsuccessful, seek technical help.

6. Observing black and other weird images signals a problem probably beyond repair. Bring it to the service center, if there is. Buy a replacement otherwise.

Refractometer buying tip

Do your homework before throwing the hard-earned cash. Read each instrument corresponding specification sheet and look for credible reviews if possible. A functional tool that is not fit for the job is a waste of money.

Often, more expensive brands are more reliable. Talk to a reputable supplier to avoid getting imitation products.

Role of refractometer in the food industry

The instrument plays a big role in the food industry.

Take wine for example. Before grape harvest, you can pick samples and quickly measure sugar content. It is convenient, prevents mistakes, minimizes losses, and leads to a high-quality product.

Another scenario is making syrup for Leche flan. You can test the syrup by dipping in and raising up a spoon. The syrup is ready if a thread-like structure forms.

You don’t have to trouble yourself with traditional tests if a refractometer fitted for the job is in hand. You just need a few drops of liquid.

Refractometer can provide repeatable results

Of course, a winemaker can quickly discern the best quality grapes.  For syrup, anyone could master the preparation after a few trials. But, I’m talking about accurate and repeatable results.

If you’re running a winery or a sweet shop, you and your expert staff are not always there to do the job. Time will come when the job needs to be delegated to someone else.

A quality check without the help of an instrument is always subjective. You and your co-workers are likely to interpret the set standards differently.

Refractometers are not only made for sugar measurement

There are variants for salt and wine. Perhaps other substances too that I haven’t heard of.

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