AOAC Official Method 937.12 Gums in Mayonnaise and French Dressing Qualitative Tests
First Action 1937
Final Action
(Not applicable in presence of starch.)
Caution: See Appendix B, safety notes on trichloroacetic acid.Transfer 100 g test portion to 250 mL beaker, add 35–40 mL hotH2O, and mix thoroughly. Heat to 65–70°C in H2O bath, add 10 mL 50% trichloroacetic acid solution, and maintain at 65–70°C until emulsion shows signs of breaking (never >10 min). Transfer mixture to 250 mL (8 oz) nursing bottle and insert pipet guard [JAOAC 20, 529(1937)] (wide-bore glass tube long enough to reach almost to bottom of centrifuge bottle, with lower end loosely stoppered; tube is held in place by slotted rubber stopper). Centrifuge 15–20 min at ca 1200 rpm. (This should separate mixture into lower aqueous layer and upper oily layer, with layer of curd between. If separation does
not occur, add 30–40 mL toluene, mix, and repeat centrifuging.) Using pipet inserted through pipet guard, remove as much aqueous layer as possible, and filter it into 600 mL beaker. Add 5 volumes alcohol to filtrate and let stand overnight to precipitate gums.
