Brookfield LFRA Texture Analyzer - Manual (Page 23)

Brookfield Engineering Labs., Inc. Page 23 Manual No. M/05-370-A1205
PROBE REF: 2mm stainless steel cylinder probe (REF: TA39)
METHOD: Biscuits approximately 6mm thick were located beneath the probe and
clamped to the analyzer bed using low pressure clips. The probe then
penetrated sample to target distance and the profile of characteristics was
recorded through the interface package.
READING:
F
Hardness
(H
1
)
Quantity of Fractures
Calculate mean of all values
(H
AV
)
Distance
Fracture Point Final
H
1 /H A V = Indication of Crispiness
(Crispiness becomes a function of hardness)
Relate the mean value of peaks obtained to the original hardness
value. Empirically our investigations highlighted that higher
values of the ratio were indicative of increased crispiness.
X Y
DISCUSSION: As the probe travels through the sample an initial fracture of the surface is
recorded. This fracture is greater in relation to other peaks within the
chocolate coated sample due to surface characteristics. A range of internal
fractures are then recorded as the probe progresses to the target deforma-
tion of 3mm. The level of peaks within the sample were considered as
being indicative of crispiness e.g. harder samples showed greater fracture
and were thus considered as being more crispy. The overall
force:deformation curve highlights various peaks and troughs as the
aerated structure of the sample is penetrated, peaks may be caused through
the presence of sugar crystals or where the probe makes contact with air
pockets within the dough structure. The overall positive area of the curve
is indicative of sample hardness (as is peak force) and may be taken as a
direct indication of bake conditions imposed e.g. hotter oven or longer
residence time produces a harder biscuit within a sample batch. As two
different varieties of biscuit were evaluated the overall hardness character-
istics were considered to be the result of variations in formulation, compo-
sition and process conditions imposed. Please note that if inclusions such
as chocolate chips or oats are in the biscuit, they will contribute directly to
result fluctuations.
PARAMETER Parameters were calculated within the Load vs. Time Graph after the
COLLECTION cursors had been positioned at start of curve to include as greater range of
peaks as possible. Consistency was taken as total positive area.