EFFECTS OF BACTERIAL EXOPOLYSACCHARIDE ON RHEOLOGICAL PROPERTIES OF ACID MILK CURD AND ITS CORRELATES
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Date
2022-02-01
Authors
Malaka, Ratmawati
Baco, S
Jaya, AK
Vargas Vargas, Maynor Alberto
Journal Title
Journal ISSN
Volume Title
Publisher
AJFAND: African Journal of Food, Agriculture, Nutrition and Development
Abstract
Exopolysaccharide (EPS) is a general term for the forms of bacterial polysaccharides
found outside the cell wall of bacteria. The industrial microbiologist has become
interested in exploiting microbial exopolymer production due to an increasing interest
and need for novel polysaccharides. The use of bacterial EPS in acid milk curd (AMC)
production accounts for a quality improvement of the milk curd in terms of stability
during the normal operations of storage and transportation. On the other hand, EPS
have been used as prebiotic because of its health-promoting effects in human beings.
The objective of this study was to evaluate the rheological properties (RP) and their
statistical correlations in acid milk curd (AMC) samples added with bacterial EPS.
Rheometric properties are suitable parameters to evaluate food quality such as AMC.
Some of the RP normally used in this evaluation include elastic modulus (EM),
hardness (HR), breaking energy (BE), viscosity (VIS) and stress. Correlation between
pairs of these parameters are important to understand in order to predict statistically
other parameters in case they cannot be easily determined. Acid milk curd samples were
formulated using 10, 15, and 20 % of reconstituted skim milk (RSM), to which 0, 0.2,
0.4, 0.6, 0.8, and 1 % level of EPS were added, respectively. Samples were pasteurized
at 60 o Cfor 30 min, and at 85 o
Cfor 30s. Afterwards, AMC samples were tempered to
40 °Cinoculated with Lactobacillus delbrueckii subsp. bulgaricus B-5b, and incubated
at 37 °C for 16 h. Results indicated that viscosity and hardness showed the strongest
and highest correlation among all the parameters evaluated (r=0.9272) and it was
comparable to that between viscosity and breaking energy (r=0.8349) and breaking
energy and hardness (r=0.7694). However, elastic modulus and viscosity showed a
rather low correlation (r=0.5394) and very low correlation (r=0.1830), respectively,
suggesting that estimation of elastic modulus from viscosity values would be
inaccurate. In general, rheometric properties of acid milk curd increased with higher
EPS concentrations until 1 % level of EPS addition. Therefore, it is recommended to
use BE and HR values, and BE and VIS values to predict accurate measurements of
other RP values.
Description
Keywords
Exopolysaccharide (EPS), Acid Milk Curd (AMC), Rheometric Properties (RP), Statistical Correlation (SC)
Citation
https://doi.org/10.18697/ajfand.106.21180