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Fruit yoghurt made from hydrolized milk

• I. Jelicic1, K. Tonkovic2, N. Major3, R.
  Božanic1, Lj. Gregurek2
• 1- Faculty of Food technology and Biotechnology,
  Department for Food Engineering, University of
  Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia
  irjelicic_at_pbf.hr
• 2- Probiotik d.o.o., Zagreb, Croatia
• 3- Faculty of Food technology and Biotechnology,
  Department for Food Quality Control, University
  of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia

Sensory evaluation Panel sensory evaluation A
difference panel consisting of 10 members has
been developed according to ISO 39721991 (E)
Sensory analysis - Methodology - Method of
investigating sensitivity of taste. Test persons
who had more than 65 of correct answers were
chosen to enter the panel. Panelists evaluated
sweetness of yoghurts by using the Multiple
paired comparison test where sweetness of all
possible pairs from the existing 12 samples had
to be evaluated. Obtained results were evaluated
by a Friedman-type statistical analysis.
Additionally, panelists conducted an Multisample
comparison test where the sweetness of joghurts
produced from the same milk type had to be ranked
ona a scale from 0 (not sweet at all) to 9
(extremely sweet). Obtained results were
evaluated by comparing standard deviations of
each sample following ANOVA principle with
p5. Electronic tongue analysis Alpha MOS ASTREE
Electronic tongue (Picture 1) was used for
sensory anlysis of all 12 samples. The detection
system consists of 7 liquid sensors and a
reference electrode. 90 mL of every sample was
poured into glasses which were placed into the
automatic sampler. The obtained results were
evaluated by the method of Principal Components
Analysis (PCA).
Introduction
Milk usually contains 4.8 of lactose in a dry
matter which makes it the main sugar in milk.
However, many people suffer from lactose
intolerance or lactose insufficience which makes
them partially or fully unable to digest lactose.
In case of consumption of milk and lactose
containig dairy products this population suffers
unpleasant coseqeuences like cramps, abdominal
pain, abdominal bloating, gas or diarrhea.
Besides that, there is also a risk of suffering
some of the above mentioned symptoms even after
consumption of yoghurt and other fermented dairy
beverages due to the fact that they still may
contain lactose and that their dairy cultures may
no longer be active or may not survive the
conditions in the digestive tract. Nowerdays
there are already products like lactose free milk
on the market, but yet there are no fermented
beverages and/or yoghurt made from hydrolized
milk.
Objectives

• Objectives of this work were to examine
• Whether there is a significant difference in
  sweetness of yoghurts produced from hydrolized
  and from non-hydrolized milk
• Whether there is a significant difference in
  sweetness of these two yoghurts when adding fruit
  base containing artificial sweeteninig agent
  respectively containing sugar
• Whether panel sensory evaluation of fruit
  yoghurts conducted by a panel can be compared
  with results obtained by using electronic tongue
  analysis

Picture 1 Alpha MOS Astree electronic tongue
Results

• Comparing mean values obtained by results from
  Multisample comparison tests among non hydrolized
  milk yoghurt samples it is clearly that in all
  cases yoghurt with fruit base containig
  artificial sweetening agent is sweeter. The same
  results are obtained by comparing mean values
  among hydrolized milk yoghurt samples.
• Comparison of mean values among all 12 yoghurt
  samples showed that hydrolized milk yoghurt
  samples are always sweeter regrdless the fruit
  base they contained.

• From results obtained by Multiple paired
  comparison tests critical values T and ?2
  (a0,05) have been calculated following
  principles of Friedman analysis. Among yoghurt
  samples containing fruit base with sugar,
  comparison of critical values showed that milk
  hydrolized yoghurts are sweeter. The sweetness is
  distributed according to the amount of fruit base
  in yoghurt. Same results were obtained by
  comparing critical values among yoghurt samples
  containing fruit base with artificial sweetening
  agent.

Methods
Yoghurt production

• B- yoghurt from nonhydrolized milk
• BD yoghurts from hydrolized milk
• Indexses 1, 5, 10 amount of fruit base in

Picture 2. PCA analysis of yoghurts with fruit
base containing artificial sweetening agent
Picture 2 showes results of Electronic tongue
analysis of yoghurt samples containing fruit base
with artificial sweetening agent. PCA grouped all
analyzed sample into two gropus. First one was
formed according to whether milk was hydrolized
or not prior to yoghurt production. The other
group was formed according to the amount of fruit
base among each yoghurt type where swetness rises
with the amount of fruit base. Sweetnes intensity
rises in following order BD1 B1 BD5 BD10
B5 B10, where samples BD10 i B5 are most
similar, while samples B1 i BD5 show most
differences.
Conclusions
Fruit yoghurts made of hydrolized milk are
significatly sweeter than yoghurts made of
non-hydrolized milk regardless to the type of the
added fruit base
Aroma intensity of yoghurts rises with the mass
content of the added fruit base
Electronic tongue analysis grouped yoghurt
samples according to the type of raw material
used for their production and according to the
content of the fruit base. These results could
not be exactly compared to the results obtained
by the panel sensory evaluation but point to
similar conclusions.
Fruit yoghurts with addition of fruit base
containing artificial sweetening agent are
significatly sweeter than those with addition of
fruit base containing sugar