Hanna HI84533 Formol Number Mini Titrator for Wine and Fruit Juice Analysis

The content of amino-acids and other nitrogen compounds in fruit juices and wines is expressed as total assimilable nitrogen and is determined by the formol method using an acid-base titration. The formol number (also known as formol index) is a parameter used for evaluation of the quality of fruit juices and wines.

In wines, the concentration of alpha amino acid in grapes change as a function of maturity and crop load (yield to vine size ratio). The concentration increases with fruit maturation and decreases with crop load. In the fermentation of wine, there is a minimum amount of amino acid and other nitrogen compounds (eg: 150-200 mg/L of yeast assimilable nitrogen) that has to be present in the must/juice. Too low of an amount will result in a stuck fermentation in which there is not enough nitrogen for the yeast to thrive. Because of the importance of nitrogen in fermentation, it is desirable to determine the nitrogen concentration before fermentation.

In fruit juices, the formol nitrogen number is one of the basic parameters measured to determine quality. Depending on the type of fruit, the number can increase or decrease with maturity. In orange and grapefruit juice, lower values are observed when the fruit is not suitably mature or there has been frost damage. In pineapple juice, a low number could be indicative of over-dilution with water or a disproportionate amount of the core was used. To determine the adulteration of fruit juices, the formol number, along with the chromatography characterization of amino acids, can be used.


Range (as N) Low Range: 2.14 to 28.57 meq/L; 0.21 to 2.85 meq%; 30.0 to 400.0 mg/L; High Range: 21.7 to 71.4meq/L; 2.14 to 7.14 meq%; 300 to 1000 mg/L
Resolution Low Range: 0.01 meq/L; 0.01 meq%; 0.1 mg/L; High Range: 0.1 meq/L; 0.01 meq%; 1 mg/L;
Accuracy (@25ºC/77ºF) ±0.1 mg/L or 3% of reading, whichever is greater
Sample Volume Low Range: 10 mL; High Range: 2 mL
Method acid base titration
Principle endpoint titration, adjustable (pH 8.0 - 8.5 in 0.1 increments)
Pump Speed 10 mL/min
Stirring Speed 600 rpm
pH Range -2.0 to 16.0 pH; -2.00 to 16.00 pH
pH Resolution 0.1 pH / 0.01 pH
pH Accuracy (@25ºC/77ºF) ±0.01 pH
pH Calibration one, two, or three-point calibration, four available buffers (4.01, 7.01, 8.20, 10.01)
Temperature Compensation manual or automatic
mV Range -2000.0 to 2000.0 mV
mV Resolution 0.1 mV
mV Accuracy (@25ºC/77ºF) ±1 mV
Temperature Range -20.0 to 120.0°C; -4.0 to 248.0°F; 253.2 to 393.2 K
Temperature Resolution 0.1°C; 0.1°F; 0.1 K
Temperature Accuracy (@25ºC/77ºF) ±0.4°C; ±0.8°F; ±0.4 K
Logging Data up to 400 ( 200 titrations, 200 pH/mV readings)
Electrode HI1131B glass body, refillable, with BNC connector and 1 m (3.3’) cable (included)
Temperature Probe HI7662-T stainless steel temperature probe with 1 m (3.3’) cable (included)
Environment 0 to 50°C (32 to 122°F); RH max 95% non-condensing
Power Supply 12 VDC adapter (included)
Dimensions 235 x 200 x 150 mm (9.2 x 7.9 x 5.9”)
Weight 1.9 kg (67.0 oz.)
Ordering Information HI84533 is supplied with HI1131B pH electrode, HI7662-M temperature probe, HI7082 electrode fill solution (30 mL), HI84533-50 titrant solution (230 mL), HI84533-44 pump calibration solution (120 mL), HI84533-58 formol base reagent (230 mL), HI84533-59 pH adjustment reagent (30 mL), HI84533-60 additional reagent (30 mL), 100 mL beakers (2), tube set (aspiration tube with titrant bottle cap and dispensing tube with tip), dosing pump valve, 5 mL syringe, 1 mL plastic pipette, cleaning solution sachets for wine deposits and wine stains (2), 12 VDC adapter, instruction manual and quality certificate.
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