Brix scale

Technical articles - Productivity, Nutritional Quality

Forage Refractometer Energy value Soluble solids

The Brix level is a quick indicator of the sugar and other soluble solids content in plant juices. It is used to assess the nutritional quality of forages or estimate the alcoholic potential in viticulture.

Refractometer used to measure the Brix level

Definition

The Brix level (%) measures the soluble solids (sugars, minerals, proteins…) in the juice extracted from a plant. It is obtained with an optical or digital refractometer.

By definition, 1 °Brix = 1 g of sucrose per 100 g of solution.

Measuring the Brix level

1. Harvest fresh grass (standing, ensiled or for grazing).
2. Crush it to extract the juice (with a garlic press or by hand).
3. Place a few drops on the prism of the refractometer.
4. Read the result in °Brix: it reflects the soluble solids present.

Simpler solutions exist to measure the Brix level, such as using the Nutriscope from Senseen, which allows direct reading from the leaf without having to extract the juice.

What is it used for?

The Brix level expresses the proportion of soluble dry matter, mainly sugars, contained in a liquid solution. This value is generally expressed in degrees Brix (°Brix), a conventional notation corresponding to a mass percentage: 10 °Brix means 10 grams of soluble sugars per 100 grams of liquid. The higher the value, the more concentrated or sweet the liquid is. This measurement is widely used in the agri-food sector: fruits, grape musts, jams, juices, confectionery, sorbets. In viticulture, for example, Brix is used to estimate the sugar content of the must and thus the alcoholic potential of the wine.

Why use it in livestock farming?

• Estimate the energy value of forage: a high Brix indicates rich and nutritious grass.
• Quick and economic decision-making: useful for scheduling harvest, grazing or ensiling without laboratory analyses.
• Compare quality between plots or over time, especially in regenerative agriculture.

Limitations to be aware of

• It measures all soluble solids, not just sugars: minerals and proteins can influence the value. That is why °Brix gives a global estimate of concentration but does not allow precise identification of the nature of dissolved substances. In some cases, the Brix measurement can be complemented by other analyses or corrected using empirical models to refine the actual sugar estimate.
• Reliability depends on the plant species: it is suitable for alfalfa, but less relevant for some grasses.
• Conditions (time, weather, preparation) affect results: caution is necessary. Indeed, Brix measurement is more reliable late morning or early afternoon, between 10 a.m. and 2 p.m., when photosynthesis is active and sugars are well distributed in the tissues: the plant has had time to produce sugars without being too stressed by water deficit. Conversely, it is not recommended to measure early in the morning (presence of dew), late in the day (sugar reflux to roots), or during high heat, as water evaporation may distort results by artificially concentrating sugars.