In this article:

The paper describes an experiment to determine the threshold at which consumers can detect soil contamination in dried grapes.

The results show that for washed dried sultanas to be free from a gritty taste they must not contain more than 20-30mg of a naturally occurring mixture of particles of soil per 100g of dried fruit.

Consumer Detection of Soil Particles on Dried Vine Fruits

1968, Food Technology in Australia, vol 20, issue 11, month 11, pages 537

csiro 114

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