Results from the lipase experiment
You can see that tubes 1, 3 and 5 have changed colour - no longer pink.
They changed from pink to whitish as acid was produced by the action of lipase on fats in the milk , and the indicator phenolphthalein goes colourless below pH 9.
Oddly the tubes above are not numbered as in the results table, but they show the colour changes.
The fastest colour change is in fact with lipase and bile salts, and 37 ° C.
Lipase with no bile salts and 37 ° C results in a slower conversion.
Lipase with bile salts and a lower temperature results in a slower conversion.
The other 2 tubes are still pink in colour so no acid has been produced.
So lipase alone, and bile salts alone, do not cause colour change. Nor does the control with neither.
This page relates to a BioTopics unit on ENZYMES AND DIGESTION - Action of lipase on fats