SOP: Determination of Screened Pulp

GIFSQ — Global Institute for Food Safety & Quality

Principle

Screened pulp is the coarser pulp material retained on a standard 20-mesh screen; it consists largely of juice-sac material provided by the cut-back juice. The average screened pulp of Florida citrus concentrates is of the order of 1%.

Apparatus required

• 20-mesh screen (12.7 cm diameter and 7.0 cm deep) made of woven stainless wire
• Sieve shaker (or manual shaking)
• Cloth or tissue paper
• Tared dish
• Balance (reading to 0.1 g)

Procedure

Pour the entire sample through the 20-mesh screen and allow to drain for 2 minutes

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Shake the screen vigorously, either manually or using a sieve shaker, for 2 minutes, until the pulp coalesces and lies free on the screen surface

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Wipe off the excess water from the bottom of the screen using cloth or tissue paper

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Transfer the pulp to a tared dish and weigh accurately to 0.1 g

Calculation

Report the results on the basis applicable to the product:

• Bulk juice: weigh the pulp from 1000 ml and report as grams of 20-mesh pulp per 1000 ml
• Chilled juice: use 946 ml (one quart) and report per quart of juice
• Retail concentrate: use a 6-oz can of concentrate, reconstituted to 710 ml of juice, and report per 6-oz can of concentrate
• Bulk concentrate: use 1000 ml of reconstituted juice and report per 1000 ml of reconstituted juice

Precautions

• The screened juice passing through may be used for the determination of suspended solids.
• Shake until the pulp is free on the screen surface; incomplete shaking leaves juice on the screen and inflates the weight.

References

Ranganna, S., Handbook of Analysis and Quality Control for Fruit and Vegetable Products, 2nd edition.