Bleaching earth controls

Treatment of lard with bleaching earth decomposes the peroxides and increases the content of conjugated trienes, which absorb at 268 nm. This characteristic has been the basis of a quality control procedure for determining whether lard has been bleached (66). 

Bleaching Earth. The quantity of earth used is primarily a function of crude oil quality and press efficiency. In both cases, there is already a high degree of problem recognition because of the process and economic implications. Therefore, there will generally not be substantial opportunities to reduce waste earth through process control simply for environmental purposes. Certain brands and types of filter media are better for various crude mixtures and presses however, this is also dictated by process conditions out of necessity. This subject is addressed in more detail elsewhere in other articles. 

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