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Brix Index

About BRIX - it's more than just making wine

Shades of Green newsletter:

We mentioned BRIX last month and had a number of readers ask for more information. The BRIX Index is a way of quantifying the amount of sugar in plants' sap. This has long been economically important as a measure of sweetness in everything from peaches and plums to citrus fruit, grapes, and even corn.

Recent research on large acreage indicates another importance of BRIX with the discovery that many damaging insects avoid plants with a high BRIX Index. This naturally leads to many fewer infestations.

So how do we build a high BRIX Index? The first step is to avoid synthetic fertilizers and excessive moisture, both of which cause plants to grow faster than sugars can be produced. Secondly, support the microbial life in the soil with products such as molasses, our organic compost, humates, and mycorrhizal inoculants. Thirdly, enable plants to create carbohydrates by making sure they are receiving adequate sunlight.

Maximizing the BRIX Index is a win-win situation. Through good culture we increase the insect resistance of our plants while improving the flavor and nutrition of edibles, encouraging abundant blooms, and stimulating better overall health and growth.  

          ---Shades of Green, San Antonio, TX

Additional Information:

Wikipedia - Brix

"Degrees Brix (symbol °Bx) is the sugar content of an aqueous solution. One degree Brix is 1 gram of sucrose in 100 grams of solution and represents the strength of the solution as percentage by mass. If the solution contains dissolved solids other than pure sucrose, then the °Bx only approximates the dissolved solid content. The °Bx is traditionally used in the wine, sugar, carbonated beverage, fruit juice, maple syrup and honey industries.

Comparable scales for indicating sucrose content are the degree Plato (°P), which is widely used by the brewing industry, and the degree Balling, which is the oldest of the three systems and therefore mostly found in older textbooks, but also still in use in some parts of the world."

What Is Brix in Wine (and Beer)?

"Brix can be measured using two different instruments: A refractometer or a hydrometer.

A refractometer determines degrees Brix by measuring the refraction of light passing through a liquid sample. Liquids containing sugar are denser than water and cause greater refraction as light passes through. The instrument compares this to the refraction of light through water and provides a Brix value.

Refractometers are the preferred tool of winemakers in the vineyard as they offer results from a very small sample size (i.e., the juice from just one crushed grape).

Hydrometers are used before and after fermentation in both winemaking and brewing. They calculate a liquid’s sugar level by measuring its relative density. The instrument utilizes a weighted, floating glass tube that is placed inside a calibrated test tube containing the liquid sample.

The test tube is calibrated to measure the amount of liquid displaced, and from that, determine how much sugar is present."

Xylem: Let's Solve Water

Refractive Index / °Brix

"When light passes from one medium to another, the speed at which the light travels will change depending on the parameters of the materials. This principle can be seen when looking at a straw in a glass or an oarsman on the river, where the straw or oar appears to be bent at the water/air interface.

The ratio or change in the speed of light is called refractive index and instruments that measure this are called refractometers.
The refractive index of a liquid is related to its concentration and so a refractometer can display the concentration in suitable units, such as °Brix (sucrose), total dissolved solids (TDS), Baume, probable alcohol, sodium chloride, urea and urine specific gravity to name just a few.

Refractometers are simple optical instruments used throughout industry for over 150 years and have now developed in to sophisticated digital instruments capable of measuring the % of dissolved solids to 3 decimal places."

UC Davis

High Brix Grapes and High Alcohol Wine

The Robert Mondavi Institute at the University of California, Davis, is examining the reasons for and ways to work with higher BRIX Index numbers in grapes, both in California and around the world. "Delaying the harvest and other cultural practices can result in riper fruit with more concentrated flavors (which may contribute in an intended fashion to desired quality attributes of the wine), but also a higher sugar concentration (which may be an undesired side-effect, because it results in higher alcohol content of the wine, and makes wine making more difficult). Wineries are developing and applying practices to deal with excess alcohol without compromising the quality of the wine."

Scientific Journals

Journal of Entomology

Chlorophyll and brix in sweet sorghum genotypes and their correlation with stem borer Chilo partellus damage

Abstract: A field experiment was carried out at Akola during kharif 2018 in randomized block design to ascertain eight sorghum genotypes for their brix and chlorophyll variation and their reaction to stem borer Chilo partellus (Swinhoe). The results revealed that the leaf injury rating, deadhearts and stem tunneling were: 1.33–2.33, 1.93–7.14% and 0.00–14.51%, respectively. Minimum leaf injury rating was scored in IS-2205 and with SPV 2600 and SPV 2604; significantly least deadhearts were in resistant check IS 2205 which was statistically at par with four other genotypes; and maximum deadhearts was observed with Swarna, while CSV 24 SS showed no tunneling and least tunneling was in resistant check IS 2205, and maximum tunneling was in Swarna. The least chlorophyll index was in IS 2205, with brix index varying significantly in the evaluated genotypes with the least (2.80) being with IS 2205. The chlorophyll index and brix index had significant positive effect on the deadhearts and stem tunneling. The sweet sorghum genotypes SPV 2604 and SPV 2605 tolerate the feeding by stem borer larvae and limit the tunneling.

Keywords: Sorghum, Genotypes, Chilo partellus, Leaf injury, Deadhearts, Tunneling, Brix index, Chlorophyll, IS 2205, Swarna, Correlation coefficients.

Article DOI:  
(Current journal contents:

IEEE Photonics Technology Letters

Smartphone-Based Critical Angle Refractometer for Real-Time Monitoring of Brix Value

We demonstrate the first smartphone-based critical angle refractometer for monitoring refractive index and Brix value in real time. The principle design of an optical coupler is based on the total internal reflection of incident light from the phone screen. The images acquired from the front-facing camera are directly analyzed on the smartphone using a custom developed application, to detect the shift of gradient peak position corresponding to the refractive index and Brix value. Calibrations are carried out using nine water-sucrose solutions providing a linear response in the refractive index range of 1.3330-1.3575 RIU (R 2 = 0.9984) with the sensitivity and the resolution of 2778.1 pixel/RIU, and 3.6 × 10 -4 RIU, and a linear response in the Brix value of 0-16.25 °Brix (R 2 = 0.9968) with the sensitivity and the resolution of 4.239 pixel/°Brix and 0.24 °Brix. We also successfully determined the sugar content in six fruit juices with the absolute error from standard refractometer at less than 0.21 °Brix.

DOI: 10.1109/LPT.2019.2892898

Published in: IEEE Photonics Technology Letters ( Volume: 31 , Issue: 4 , Feb.15, 15 2019 )

Proceedings of the Second Intl. Conference on the Future of ASEAN (ICoFA) 2017

The Influence of Root Zone Temperature Manipulation on Strawberry Yields in the Tropics

The study was conducted to assess the quality of strawberry (Fragaria x Ananassa) cultivated in tropical areas. There are two treatments set up in this study. The root zone temperature (RZT) in Treatment 1 was controlled around 25 °C (±2 °C), while Treatment 2 was left to experience fluctuating RZT varying between 27 and 30 °C. Both treatments were left to experience fluctuating ambient temperature, varying from 21 to 34 °C. Samples of fruit from tropical highland areas were obtained and used as a Control Treatment in assessing the quality of strawberry produced. Though the Control Treatment obtained better results in terms of fruit size, lowering the RZT in Treatment 1 significantly increased the fruit’s diameter and weight up to 8.85 and 21.60%, respectively, compared to Treatment 2. About 70.00% of the strawberries produced in Treatment 1 were of marketable size (>5 g) compared to 46.67% of the strawberries produced in Treatment 2. Treatment 1 and Treatment 2 produced strawberries that were significantly sweeter compared to those produced in Control Treatment. More than 70.00% of the strawberries produced in both treatments were above the average sweetness of the Festival variety (Brix index: >8°Brix), compared to approximately 50.00% of the strawberries produced in the Control Treatment. In conclusion, lowering the RZT was found to produce better fruit yield for strawberry cultivation in the tropics, thus may provide an alternative solution that can comply with the growing strawberry demand.

Root zone temperature manipulation RZT Strawberry Tropics





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