NANUA J. N, OSORIO L. R, McGREGOR J. U., TRAYLOR
S.
Abstract
A study was conducted to find out the contribution of free fatty acids (FFA),
glycerol and monoglycerides to milk foaming. Laurie acid and glycerol were added
to skim and whole milk at a molar concentration of 0.005, 0.010 and 0.015 lauric
acid and 0.011, 0.021 and 0.032 M glycerol. Monoglycerides were added to the
milk at the rate of 0.1, 0.2 and 0.3 % (m/v) instead of glycerol. Steam frothing
value (SFV) of the milk was determined using a Expresso machine. Other milk
samples were also stored for 15 days at 3+ 0.5° C and SFV determined after
0, 5, 10 and 15 days. Addition of FFA significantly reduced the SFV of the milk.
Mean SFV for whole and skim milk was 21.7% and 29.5% respectively and was reduced
to 4.0% and 6.3% on addition of 0.015 M lauric acid. Adding 0.1% Monoglycerides
reduced the SFV to 5.8% and 8.5% for whole and skim milk respectively. Glycerol
had no effect on the SFV. Storing milk for 15 days at 3° C caused a slight
decrease in the SFV of whole milk but caused an increase on the SFV of skim
milk. This work indicates that only monoglycerides and FFA affect milk frothing.
Control of milk fat hydrolysis can be used to influence the foaming properties
of milk pro ducts.
Key Words:
Steam frothing value, Milk, Fatty acids, Monoglycerides, Glycerol, Cappuccino,
Abbreviation: SFV, FFA