Olympic CITRUS Packing Guide

MEASURING PROCEDURE JUICE / ACID / BRIX: DETERMINATION OF JUICE REQUIREMENTS

JUICE REQUIREMENTS 1. A working sample of at least 12 fruit, drawn at random, from more than one trade unit. 2. Determine gross mass. 3. Cut each fruit in half at right angles to its longitudinal axis. 4. Press out juice of the halved fruit. 5. Strain juice through two thicknesses of muslin into a jug (± 1 litre). 6. Twist muslin into tight ball and squeeze - until only damp pulp remains. 7. When liquid becomes thick and cloudy, stop applying pressure. 8. Determine mass of pressed-out halved fruit and damp pulp in the muslin. 9. Determine mass of juice - subtract the mass of halved fruit and pulp (muslin), above, from mass of Working Sample. 10. Express mass calculated as a percentage of mass of the working sample to determine the juice content. 11. Determine brix, acid and the ratio between brix to acid. If JUICE REQUIREMENTS determined do not comply with the requirements. 1. A further working sample will be determined. 2. The average of both determinations will be calculated and this will represent the juice requirements. IF, DETERMINATION referred to above: 1. Average juice content is less than two percent (2%) below minimum. OR Average ratio between total soluble solids content to acid content is less than 0,4 difference from the minimum or the average Brix content is less than 0,2 below the minimum. 2. Juice requirements of a further working sample, will be determined. 3. Average of all the determinations will be calculated. 4. That average will represent the juice requirements of the consignment. 5. If 66,6 percent of all the working samples comply with the requirements, the consignment will be approved. Although the average does not comply. DETERMINATION OF THE BRIX CONTENT (exluding lemons) 1. Calibrated refractometer (or with automatic temperature correction). 2. Temperature of juice sample must be similar to reading of refractometer (Brix). 3. Refractometer must be properly calibrated, this must be done by an accredited laboratory. 4. prism surface of the refractometer must be clean (wipe prism surface with moistened, soft paper, then dry with a dry cloth). 5. Stir juice sample (thoroughly, that no sediment remains at the bottom). 6. Using a non-metallic spoon, transfer drops of the well-stirred juice onto prism surface, covering it. 7. Take Brix reading on the refractometer. 8. Measure juice temperature if a non-temperature refractometer is used. 9. When refractometer without automatic temperature correction is used, the particulars set out above will be used to convert the figure with due regard to the temperature of the juice. This converted figure will represent the percentage total soluble solids content of the consignment.

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