Titratable acidity of fruit juices is an important parameter in determining fruit maturity and sour taste in citrus fruits. The maturity of fruit is one of the most important factors to determine how well fruit will store and how it will taste. For some fruits, governmental quality standards (based on titratable acidity or the ratio of total soluble solids (°Brix) to titratable acidity) are in place to protect consumers. Immature fruit will normally have a low sugar to acid ratio as compared to mature fruit that will have a high sugar to acid ratio.
The HI84532U-01 measures the concentration of titratable hydrogen ions contained in fruit juice samples by neutralization with a strong base solution to a fixed pH. This value includes all the substances of an acidic nature in the fruit juice including free hydrogen ions, organic acids, and acid salts. Titratable fruit acidity is expressed as g/100 mL of the predominant acid. The predominant acids in fruit depend on the type of fruit being tested and include citric acid, tartaric acid, and malic acid.
| Fruits, Juices | Titratable acidity (g/100 mL) | Predominant acid |
| Apple, pear | 0.36-0.80 | Malic Acid |
| Cranberry | 1.6-3.6 | Citric Acid |
| Grapefruit | 1.2-2.0 | Citric Acid |
| Lemon | 4-6.2 | Citric Acid |
| Mango | 0.34-0.84 | Citric Acid |
| Orange | 0.8-1.4 | Citric Acid |
| Peach, nectarine, sweet cherry | 0.24-0.94 | Citric Acid |
| Pineapple | 0.7-1.6 | Citric Acid |
| Plum, sour cherry | 0.94-1.64 | Malic Acid |
| Strawberry | 0.6-1.1 | Citric Acid |
| Table Grape | 0.4-0.9 | Tartaric Acid |
| Tomato | 0.34-1.00 | Citric Acid |
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Double Junction pH Electrode
The HI84532U-01 is supplied with the HI1131B refillable, double junction, combination pH electrode. By design, the HI1131B has a spherical tip for use in aqueous or liquid solutions. This versatile electrode provides a wide surface of contact with a sample and is ideal for direct measurements or titrations in the beverage industry.
Custom pH Calibration
According to AOAC International, the titration endpoint for fruit products is pH 8.1. The HI84532U-01 uses a custom calibration point of pH 8.20. The preprogrammed pH 4.01 and pH 8.20 calibration points allow for calibration of the meter that brackets the pH readings.
Good Laboratory Practice
The HI84532U-01 offers comprehensive GLP information including date and time of the last pH electrode and dosing pump calibrations. Tracking calibrations are critical to have confidence in the results obtained from titrations. The GLP data is stored along with any logged readings.
Piston Driven Dosing Pump
The heart of the HI84532U-01 is the piston-driven burette pump. This type of dosing system uses a motor in which each dose is very precisely controlled and the volume dispensed is accurately determined. This titrant is dynamically dosed, where titrant is delivered in larger doses at the start of the titration and smaller doses near the endpoint. With larger doses at the beginning of the titration, the speed of the titration is increased, where smaller doses near the endpoint allow for more time for the titrant and analyte to react. Smaller doses also prevent the over titration of a sample and a more accurate determination of titrant volume used.
Automatic Stirrer
The built-in stirrer is automatically maintained at a speed of 600 rpm, regardless of the viscosity of the solution being titrated.
| Specification Name | Detail |
|---|---|
| sku | HI84532U-01 |
| Range | Low Range: g/100 mL as citric acid: 0.10 to 2.00% CA; g/100 mL as tartaric acid: 0.11 to 2.35% TA; g/100 mL as malic acid: 0.10 to 2.09% MA High Range: g/100 mL as citric acid: 1.00 to 10.00% CA; g/100 mL as tartaric acid: 1.17 to 11.72% TA; g/100 mL as malic acid: 1.05 to 10.47% MA |
| Resolution | 0.01% |
| Accuracy (@25ºC/77ºF) | ±0.02% or 3% of reading CA whichever is greater |
| Sample Volume | 5 mL |
| Methods | acid base titration |
| Principle | endpoint titration: 8.1 pH |
| 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) | ±1.0 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; 0.1K |
| 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 | HI84532 is supplied with HI1131B pH electrode, HI84532-50 low range titrant (100 mL), HI84532-51 high range titrant (100 mL), HI84532-55 calibration standard (100 mL), HI7662-T temperature probe, HI7082 electrode fill solution (30 mL), 100 mL beakers (2), 20 mL beaker, tube set (aspiration tube with titrant bottle cap and dispensing tube with tip), dosing pump valve, 5 mL syringe, 1 mL plastic pipette, stir bar, power adapter, instruction manual and quality certificate. |
| Warranty | 2 years |
