BRIX

[Millet]

Brix 8:  Trees grafted upon Rough lemon will have lower TSS (total soluble sugars), less acidity, and less juice content compared to trees grafted upon citranges and trifoliate root stock.

[Walt]

TTS means total soluable solids, I think.
Earlier you said BRIX was a reading of sucrose.  40 years ago when I was a tomato breeder, we (tomato breeders) concidered BRIX to be a good substitute for sugar measurement, as it could be done in the field. But it included glucose, and other sugars.  I don't know which sugars are in citrus.   And high BRIX was indeed related to good flavor.  But at least in tomatoes, there were other things in the juice that affected BRIX readings, and these other things could be good or bad.
This is just an observation.  This wouldn't be the first time my experience with other crops might miss lead me when dealing with citrus.

[SeaWalnut]

Its TDS ( total disolved solids).
Fruits contain mostly fructose wich is sweeter than glucose.
Sucrose is a mix of glucose and fructose.

[Ilya11]

Its TDS ( total disolved solids).
Fruits contain mostly fructose wich is sweeter than glucose.
Sucrose is a mix of glucose and fructose.

False again, citrus sucrose content is 2-3 times higher than that of fructose.
Sucrose is not a mix, it is a disaccharide with its physical and chemical properties different from both glucose and fructose. 

[Millet]

Walt thanks for your point.  TSS means Total Soluble Sugars.  The main sugar in citrus is sucrose.

[SeaWalnut]

Its TDS ( total disolved solids).
Fruits contain mostly fructose wich is sweeter than glucose.
Sucrose is a mix of glucose and fructose.

False again, citrus sucrose content is 2-3 times higher than that of fructose.
Sucrose is not a mix, it is a disaccharide with its physical and chemical properties different from both glucose and fructose.

Ive used bad exprimation.
What i wanted to say its that sucrose can be split into glucose and fructose.
Sucrose its @ 50 percent fructose and the rest glucose.
Results that the main carbohidrate is fructose wich is a lot sweeter than sucrose( sugar).

[Millet]

Splits in human blood.

[SeaWalnut]

Splits in human blood.

It splits in all living things ,plants and animals not just humans because we only need the glucose wich is the fuel of life.Fructose isnt the fuel of life .
And sucrose splits easy into glucose and fructose with just a little acid ,its called invertase.
TSS its TDS actually,a measurement of electrical ressistance to guess the ammount of solids wich are conducting electricity.
Since fruits are mostly water ,the TDS is mainly from sugars.

TDS is correct and TSS is incorect because such measurement of density measures all the solids not only the sugars.There are salts and manny otther solids altough in verry small ammounts in the fruits.

Edit: measuring density with electrical devices does not work for sugars because they are non ionised.My mistake ,but still any density measurement for sugars wich is non electric should still be called TDS because its not just sugars that it measures.

[Ilya11]

Fructose isnt the fuel of life .

Fructose is easily converted into glucose in the organism, moreover it is used directly to synthesize fatty acids serving  as  a "fuel of life"

[SeaWalnut]

Fructose isnt the fuel of life .

Fructose is easily converted into glucose in the organism, moreover it is used directly to synthesize fatty acids serving  as  a "fuel of life"

Fructose is as bad as alcohol for the organism.It is converted in the liver and normally the human liver can process 50 grams of glucose per day and for comparison ,40 grams of alcohol.Both ,consumed in excess cause liver damage
Glucose in pure form is readily available or from sucrose by invertase ( acid).
Worker bees fed only with fructose live 12 days while on regular diet they can live up to 80 days.
We say that fructose ,,wears,, the bees.

[Ilya11]

Very original comparisons, both between fructose and ethanol as well as humans and bees. 

[Walt]

The BRIX meter I used in the field measured the change in polarization of light.  Daylight was polarized by a polarizing film, then the light though the juice, then through a polarizing film  mounted so it would turn.  The amount it turned to let through the most, or least light.  Then you looked at the marks on the dial tp read the BRIX.
Sogars give the most rotation of ihgt in tomato juice, though rotiiens and any other molicule that has either a right hand or left hand form will effect the brix reading.  I don't know if this thimg is still used.  But it was easy to use in the field, and it looked like it wouldn't be expebcive to make.  But I never actually bought one.  A local canning company let me use theirs.
This was in Rep. du Niger in 1980, and ordering one would mot have been easy.

[Millet]

Brix 8:  In GENERAL, the higher the brix count, the better the fruit quality, the healthier the tree, and the fewer pests will attack your tree