Dereje, if the juice sample for which you have the spectrophotometric results is mainly sugars you can estimate what the TSS would have been - you need to convert to g/100 g (not 100 cm3). Most of the sugars have more-or-less the same refractive index, so you are probably OK making a rough estimate. However, it will be an underestimate, because you will not be including other solutes that would also affect the refractive index of the juice. And to be clear, measuring TSS with a refractometer does not measure soluble solids as g/100 g: all it tells you is the concentration (w/w) of a sucrose solution that has the same refractive index as the juice you are measuring - this is still a common mistake and oocurs even in one the pdf files linked to in previous answers. The Brix of a sucrose solution can also be measured using a hydrometer (based on specific gravity) and for pure sucrose solutions the refractometer and hydrometer give the same result, but for fruit juices which are solutions of several solutes, this is not the case.

Hi.

yes. I did.

you can use this paper.

if you have any question, I can help you.

Dear Dereje,

when you talk about "limited sample size", are you referring to small fruit size which do not yield enough juice for the analysis? Or do you mean that you have a very small volume of juice sample (and no means to obtain more?).

If the former, please note that you only need a drop for refractometric analysis. Besides, if necessary (because the same juice is often used for the determination of titratable acidity, for instance, which require more juice volume), you could simply increase the number of fruits of each replicate. You could use, for example, 30 fruit, distributed into 3 replicates of 10 fruit each.

I am not sure to have been of help, but I hope so.

Dear Dereje,

I'm not quite understanding your question. Do you want to measure SSC and TTA using the results from a sugar content obtained from the spectrophotometer? 

I don't think you will be able to measure both parameters using data from sugar content.

Some tips:

The refractometer will measure SSC, but not TTA. 

If you want to know both SSC and TTA, you have to follow the previous comments.

I hope this helps!

 Thank you all for your prompt reply and contributions.

 I don't have problem with measuring them with refractometer and titration, as I have done it several times on tomatoes and peppers. My limitation is I don't have any fruit samples at hand. I sent out all to external lab for analysis of other parameters, including sugar content (%) from analysis of non-structural carbohydrate using Spectrophotometer. My point is, can I use this result (the sugar percentage from Spectrophotometer) to say something about SCC? For example, if there is any conversion factor?  

Thanks

I don't understand your question completely. anyway you can't calculate TSS or SSC from data of fruit sugar content. I hope the attached file help you.

Dear Dereje,

I assume your spectrophotometric results are expressed as glucose or galactose concentration (nM or microM, possibly), but that the value also includes the rest of hexoses, as well as pentoses and other neutral sugars. However, refractometric analyses give SSC values as sucrose equivalents, expressed as % (w/v).

I am not sure that you can convert total sugars that you determined spectrophotometrically into ºBrix. Maybe you could make the assumption that most neutral sugars you determined are hexoses. Since sucrose is composed of two hexoses (glusoce and fructose), and knowing that the molecular weight of a hexose is 180 g/mole, you may be able to establish a relationship between total sugar concentration and ºBrix.

I am however not sure that this is very correct (you would be overrating pentoses and the rest of neutral sugars in your samples), but it is the only idea that came to me. At any rate, I think you can use total sugar content values as determined with the spectrophotometer. It is at least as good as the refractometric values, which are also an estimation.

Best wishes,

Isabel

You need a drop from the sample to measure TSS by pocket refractometer.

Yes, you need just a drop to measure the TSS or the SSC using the pocket refractometer. Refractometric solids indicate the soluble solids such as sugars, acids, etc. You can also measure the Brix value using the Brix meter. If  you can measure  the relationship between the SSC and the Brix value you may roughly estimate corresponding brix value using the refractometer. It will just give you a rough measurement since these food systems are complex.  

Total soluble solids content of a solution is determined by the index of refraction. This is measured using a refractometer, and is referred to as the degrees Brix. Brix is the term used when a refractometer equipped with a scale,based on the relationship between refractive indices at 20°C and the percentage by mass of total soluble solids of a pure aqueous sucrose solution. This tests the solids concentration of a sucrose containing solution. It is widely used during fruit and vegetable processing to determine the concentration of sugar in the products. Sugar concentration is expressed in degrees Brix. At 20°C, the Brix is usually consider equivalent to the percentage of sucrose (sugar) in the solution (60° Brix is equivalent to a sugar content of 60%). The measurement must be made at 20°C to get an accurate value.

Dereje, if the juice sample for which you have the spectrophotometric results is mainly sugars you can estimate what the TSS would have been - you need to convert to g/100 g (not 100 cm3). Most of the sugars have more-or-less the same refractive index, so you are probably OK making a rough estimate. However, it will be an underestimate, because you will not be including other solutes that would also affect the refractive index of the juice. And to be clear, measuring TSS with a refractometer does not measure soluble solids as g/100 g: all it tells you is the concentration (w/w) of a sucrose solution that has the same refractive index as the juice you are measuring - this is still a common mistake and oocurs even in one the pdf files linked to in previous answers. The Brix of a sucrose solution can also be measured using a hydrometer (based on specific gravity) and for pure sucrose solutions the refractometer and hydrometer give the same result, but for fruit juices which are solutions of several solutes, this is not the case.

Hi dear

Since you have no sample in your hand and you wants to know the value of TSS. 

now you can get approx TSS value by adding sugars, ascorbic acid, phenols, acids etc. If you still have doubt than do ask.

www.are food science.blogspot.com

How limited is your sample? Critical angle refractometry only requires a small drop. However there is usually a correction for titratable acidity, which becomes a problem after about 0.2-0.3% citric acid equivalent. Having said that, the measurement of uncorrected TSS is only an approximation when the results are interpreted as sugars, particularly at low values of soluble solids.

Simply, with hand held refrectrometer you can measure the total soluble solids content of the fruit juice.

i measured SSC of grapevine must with hand held refrectrometer (ATAGO)

you can use hand refractometer  to masure of TSS

I've never done it, but I suggest the following: You can make a stain reducing carbon hydrates (eg Fehling or other) of each sample, then measure the intensity of color in a spectrophotometer with the appropriate wavelength. The color intensity is proportional to the concentration of carbohydrate of each sample.

measuring TSS ( Brix  value expressed as ºBrix ) with a hand refractometer (brix meter) gives the value not only for sugar, it includes all solube solids other than sugar i.e. acid, pectin, if add preservatives that also include. Sample size is immaterial. it gives the value for TSS in your Fruit.  In Brix meter there are ranges 0-30 mainly use for fruits and 30-100 mainly use for processed fruit based products as it has more TSS because of adding sugar, acid, pectine, preservatives etc.

 According to the value of TSS get from Brix meter can calculate the TSS as required for any quantity (450 kg) of fruit pulp. for eg 16 ºBrix  in mango to calculate 16/100x 450

We use Palette Series PR 101 α, ATAGO Co, LTD, Japan, a handheld refractometer. You just need destilated water to adjust to zero value. It only need a few drops.