Brix Readings, and What They Tell Us and Why They Matter When Making Jelly!
A Brix reading measures the sugar, mineral and protein content of the fruit. So letting it ripen is really important for both flavor and health!
Brix – A unit of measure used in the refractometer. When the Brix reading is divided by 2 it will be equal to the percent of crude sucrose in the plant tissue.
Refractometer – A device used to measure the refractive index of plant juices in order to determine the mineral/sugar ratio of the plant cell protoplasm.
Refractive Index of Crop Juices are calibrated in percentage of sucrose or degree of Brix.
During the growing season it is possible to check a plant for percent sucrose. A refractometer is easy to use. You will need something like a garlic squeezer for juicing the plant sample. To make a reading, place 2 to 3 drops of the liquid sample on the prism surface, close the cover and point toward any light source. Focus the eyepiece by turning the ring to the right or left. Locate the point on the graduated scale where the light and dark field meet. Read the percent sucrose (solid content on the scale).
The refractometer measures in units called Brix. The Brix equals to the percent of crude carbohydrate per 100 pounds of juice. The higher the carbohydrate in the plant juice the higher the mineral content of the plant, the oil content of the plant, and the protein quality of the plant.
For example, if you were to have 100 pounds of alfalfa that has a Brix reading of 15 it would mean that there would be 15 pounds of crude carbohydrates if the alfalfa was juiced and dried to 0 percent moisture. By dividing 15 by 2 it tells us that the actual amount of simple sugar would be equal to 7.5 pounds.
Crops with higher refractive index will have a higher sugar content, higher protein content, higher mineral content and a greater specific gravity or density. This adds up to a sweeter tasting, more mineral nutritious feed with lower nitrates and water content and better storage attributes.
Crops with higher Brix will produce more alcohol from fermented sugars and be more resistant to insects, thus resulting in decreased insecticide usage. For insect resistance, maintain a Brix of 12 or higher in the juice of the leaves of most plants. Crops with a higher solids content will have a lower freezing point and therefore be less prone to frost damage.
Brix readings can also indicate soil fertility needs. If soil nutrients are in the best balance and are made available (by microbes) upon demand by plants, readings will be higher.
You will find that when the phosphate levels in the soil are not up to what they should be, the sugar in the plants will vary from the bottom of the plant to the top. In other words, the Brix reading at the bottom of the plant will be higher than the top of the plant. The better the phosphate levels in ratio to potassium the more even the Brix reading will be all over the plant. Also the better the phosphate levels in ratio to potassium the less fluctuation there will be in the brix reading in any given 24 hour period.
You will also note that when you are looking into a refractometer you will sometimes be able to see a very sharp line which is very easy to read, while at other times it may be a very hazy line and not well demarcated and so difficult to read. The very sharp and dark and easy to read line means the crop is lower in calcium and higher in acid. A very diffuse and hard to read line tells one that the calcium is higher and the acid is lower in the plant. This is why a lower Brix reading on a plant will actually taste sweeter when there is high calcium than one that may have a little higher Brix reading and a low calcium. The available soluble sugar is what gives taste and sweetness to food. The more calcium in the crop along with the sugar, the sweeter the taste even though the Brix reading will be the same on two samples.
Source: Frontier Labs, Inc; Biologic Ionization as Applied to Farming and Soil Management, Beddoe.
More Jelly 101:
Guess what the FDA determines if you can call your product jelly or jam!
The Food and Drug Administration has “Standards of Identity” which have been in place since 1940 for what constitutes a jam or a jelly.
Interestingly enough, the current standards are based on the housewife’s formula that even pioneer women used when making their own jams and jellies — approximately half fruit and half sugar.
Following are definitions of the terms:
Legally in the USA – jelly is a clear, bright mixture made from fruit juice, sugar and often pectin or acid. No less than 45 pounds of fruit must be used for each 55 lb. of sugar. Must contain at least 65% Brix in the finished product.
High-fructose corn sweeteners are used interchangeably with sucrose due to the benefits each brings to different product formulations. Originally, cane sugar was used exclusively. Its use can be traced back to the 16th century when the Spanish came to the West Indies where they preserved fruit.
And jam is a thick mixture of fruit and sugar (and often pectin) that is cooked until the pieces of fruit are very soft and almost formless — the texture of a thick purée. It is also made with 45 lb. of fruit solids combined with 55 lb. of sugar. Must contain at least 65% Brix in the finished product.
A preserve is almost identical to a jam but preserves can contain large chunks of fruit or whole fruit. It is made with 47 lb. of fruit solids combined with 55 lb. of sugar. Must contain at least 65% Brix.
A conserve is much like a preserve but usually contains more than one kind of fruit and often nuts. No “Standard of Identity” exists.
A marmalade, on the other hand, is also like a preserve but contains some amount of fruit rind, usually from a citrus fruit. No “Standard of Identity” exists.
Fruit spreads such as those that have surfaced over the last 15 years, do not fall under the jelly or jam “Standards of Identity”, hence the generic name “fruit spreads.” These products are usually made with fruit juice concentrates or low-calorie sweeteners replacing all or part of the sugar. No standard of identity exists, and they are less than 65% Brix and legally cannot be called jelly, jam or preserves.
A fruit butter is a spread that is made by cooking fresh fruit with spices until it becomes thick and smooth. Fruit butter has a FDA “Standard of Identity”, and must be five parts by weight of fruit to two parts by weight of sweetener (72% fruit, 28% sweetener). Must contain at least 43% Brix.