In Italy tomato is one of the most interesting matrix for the alimentary industry since around the 85% of production is destined to industrial transformation.

Tomato composition is conditioned by different factors: cultivar, environmental conditions and ripening period.

Once the ripening is completed, tomato is of a vivid red colour More than the 96% of it can be eaten since only the skin and the seeds (and the wooden part) can not be assimilated.

Normally 100 g of tomato are composed of 93% of water, 2,9% of carbohydrates, 0,2% of fats, 1% of proteins and 1,8% of fibres. The sugar present is mostly glucose and fructose (reductive sugar) in almost similar proportions and constitute the 40-60% of the dry residual. Saccharose quantity naturally present in tomato is practically negligible.

The determination of sugar that is present in tomato is usually done using Feeling method, based on the titration method.

CDR innovative test simplifies the official procedure using micro-quantities of sample diluted in water and single use cuvettes pre-filled with the reagent. The glucose present in the sample reacts with a phenolic derivate if the peroxidase enzyme is present. It forms a coloured compound that is detectable at 545 nm.

Materials:
· FOODLAB instrument
· Pre-filled single use cuvettes
· Small bottle containing the starter reagent
· 5 mL micropipette
· Scale
· Container for diluting
· Distilled water

The sample preparation is very simple: dilute 1 gr of sample into 20 mL of distilled water in a container and agitate. With the specific pipette add into the cuvette 5 mL of diluted sample and 1 drop of starter reagent.
After 3 minutes the instrument prints the results expressed as g/ 100 g of glucose.
Using this value, with mathematical calculation is determined the concentration of fructose and that of reductive sugar.

Comparative tests between the standard method (Fehling) and Foodlab method have been done in a SINAL certified laboratory.

The two methods have a good correlation.

Repeatability tests have been done in CDR laboratory using 3 different samples of tomato. The results are good.

CONCLUSIONS

Foodlab method for glucose, fructose and reductive sugar analysis on tomato is very simple, rapid and reliable. It is a very good answer to the need of monitoring tomato quality in all production phases, from the reception to the final packaging phase.