Brookfield LFRA Texture Analyzer - Manual (Page 23)

Brookfield Engineering Labs., Inc. Page 3 Manual No. M/05-370-B0507
METHOD: Biscuits approximately 6 mm 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 3 mm. 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:defor-
mation 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 indica-
tion 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 characteristics were consid-
ered to be the result of variations in formulation, composition 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.