3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
P92 uSING OF hyDROCOLLOIDS FOR DELAyNG
STALING OF bAKERy PRODuCTS
ZLATICA KOHAJDOVá, IVAnA ŠIMOnOVá and
JOLAnA KAROVIČOVá
Institute of Biochemical and Food Technology, Department
of Food Technology, Slovak University of Technology
Radlinského 9, 812 37 Bratislava, Slovak Republic
zlatica.kohajdova@stuba.sk
Introduction
One group of the most extensively used additives in the
food industry are the hydrocolloids 1 . The most well know
and applied in the industry polymers included in this kind
of substances are alginates, carrageenans, agar, guar gum,
arabic gum, methyl cellulose and carboxymethyl cellulose 2 .
These compounds used in food products and processing can
serve as processing aids, provide dietary fiber, impart specific
functional properties or perform a combination of these
roles. Guar and xanthan gums, for instance, have been used at
7 % and 2 % levels, respectively, in bread to provide dietary
fiber for therapeutic purposes. At a lower level of incorporation,
gums have served as additives to improve the quality
of bread 3 .
In the baking industry, hydrocolloids are of increasing
importance as bread improvers as they can induce structural
changes in the main components of wheat flour systems along
the breadmaking steps and bread storage 1 . The hydrocolloids
are added to bakery products for control water absorption
and consequently dough rheology 4 , improving their shelf life
by keeping the moisture content and retarding the staling 5 . It
is well known the effect of hydrocolloids on starch pasting
properties 5,6 . These starch properties, that include gelatinization
temperature, paste viscosity and retrogradation of the
starch, affect baking and final quality and staling behaviour
of baking products 6 .
The present study was done to examine the effect of different
hydrocolloids on retarding the staling process of baked
goods.
Experimental
A wheat flour T650 (containing 11.20 ± 0.2 % of proteins,
0.68 ± 0.001 % of ash in dry matter and 31.55 ± 0.4 %
of wet gluten in dry matter) and wholemeal spelt flour (containing
17.30 ± 0.3 % of proteins, 2.21 ± 0.002 % ash in dry
matter and 40.99 ± 0.5 % of wet gluten in dry matter) and of
local origin was used in the study. Blend flour was obtained
mixing of wheat and wholemeal spelt flours in ratio 85:15.
The hydrocolloids used were: guar gum, gum arabic,
xanthan gum and methyl 2-hydroxyethyl celullose. The
dough was prepared according to formulation, which was
100 % blend flour, salt 2 %, sugar 1 %, yeast 4 %, sunflower
oil 2.5 %, hydrocolloid 1 % on flour weight basis and water
to farinographic consistency 400 BU (Brabender Units).
All raw materials were procured from the local market in
Slovakia.
s785
The ingredients were mixed during 6 minutes in farinographic
mixing bowl. After 20 min fermentation, the dough
was divided into 100 g loaves, formed on dough former, proofed
45 min and baked in an electric oven during 12 min at
230 °C. Baking trials were performed in triplicate.
D e t e r m i n a t i o n o f C r u m b H a r d n e s s
Crumb hardness was measured on freshly baked loves
(2 h after baking) and on loaves that were stored for 24, 48
and 72 hours at ambient temperature using a manually operating
penetrometer AP 4/1 when 1 penetrating unit represented
0.1 mm.
Results
Bakery products have a very short shelf life and their
quality is highly dependent on the period of time between
baking and consumption 7 .
Firming of bread crumb during storage is a common
phenomenon and leads to a crumbly texture, and lower consumer
acceptance. Staling of bakery products is generally
defined as an increase in crumb firmness and a parallel loss in
product freshness 8 . Firming is the preferred parameter used
to evaluate staling development 9 .
In this study, the anti-staling potential of various hydrocolloids
was investigated. We concluded that all from applied
hydrocolloids expect methyl 2-hydroxyethyl cellulose reduced
firmness during 72 h storage period, given softer crumb
than control samples (without hydrocolloids). The reason
for the softer texture with gum treatments might be that the
hydrophylic gums were holding more water, which led to
higher moisture content in the final baked product and as a
consequence, retrogradation of the starch and bread firming
is retarded 10 . Guar gum had the greatest effect in decreasing
crumb hardness (see Fig. 1.). This hydrocolloid has a
softening effect due to a possible inhibition of the amylopectin
retrogradation, since guar gum preferentially binds
to starch 11 . Effect addition of different concentration of guar
gum (from 0 to 2 %) on shelf life of baked products was also
Fig. 1. Effect hydrocolloids on crumb penetration (S-control
sample, × – xanthan gum, A – gum arabic, G – guar gum, M-
methyl 2-hydroxyethyl celullose