Development of powdered kombucha sourdough starter culture and characterization of kombucha sourdough bread
Sourdough bread has gained consumer interest due to its excellent sensory characteristics and health functions. However, sourdough starter culture preparation for breadmaking is very tedious, and the inconvenience of liquid traditional sourdough starter (LTSS) culture is not preferred in the m...
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| Format: | Thesis |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/98847/1/FSTM%202021%203%20UPMIR.pdf |
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| Summary: | Sourdough bread has gained consumer interest due to its excellent sensory characteristics
and health functions. However, sourdough starter culture preparation for breadmaking is
very tedious, and the inconvenience of liquid traditional sourdough starter (LTSS)
culture is not preferred in the modern lifestyle. Therefore, this research was conducted
to optimise the production of liquid kombucha sourdough starter (LKSS) culture using
Response Surface Methodology (RSM), to evaluate the effect of gum Arabic (GA) on
the properties of encapsulated kombucha sourdough starter (EKSS) culture powder, and
to characterize the properties of sourdough bread prepared using the EKSS culture. RSM
was applied to optimise the incubation temperature (31-37ᴼC) and refreshment time
(every 8-12 hours) of LKSS culture production, to minimise the ripening time (h) and
maximise the leavening rate (mL/h). The LKSS culture produced at its optimum
conditions was compared with the LTSS culture for the microbiological properties and
metabolomics profiling using 1H-NMR based technique. The LKSS culture was
transformed into powder via encapsulation using GA and spray drying. The EKSS
culture properties were evaluated compared to the unencapsulated kombucha sourdough
starter (UKSS/control) culture. The powders were stored at different storage to
investigate the culture viability throughout 3 months of storage. The EKSS culture was
used in breadmaking, and the bread properties were compared with LTSS and baker’s
yeast (BY) bread. RSM optimisation revealed the optimised incubation temperature and
refreshment time for the LKSS culture production are at 34ᴼC and every 7 hours,
respectively. The LKSS culture showed significantly (p<0.05) higher lactic acid bacteria
(LAB) (11.07±0.04 log10CFU/g) and yeast (10.37±0.05 log10CFU/g) counts compared
to LTSS. The 1H-NMR analyses showed the presence of 15 metabolites in LKSS culture.
The major compounds contributing to LKSS culture's differences were alpha-aminobutyric acid, alanine, acetic acid, riboflavin, pyridoxine, anserine, tryptophan,
gluconic acid, and trehalose. GA was found adequate to produce EKSS culture with
significantly (p<0.05) lower moisture content (5.20±0.19%) and water activity (0.32±0.02), higher LAB (9.93±0.10 log10CFU/g) and yeast (9.40±0.15 log10CFU/g)
viability and survival percentage (90.27% for LAB and 89.52% for yeast) after spray
drying compared to control. EKSS culture was stable at 27-29ᴼC as high microbial
viabilities for 2 months of storage were observed. EKSS culture extract also exhibited
high antibacterial activity (>85% inhibition) against pathogenic and spoilage bacteria
used in this study. EKSS culture has produced bread with significantly higher loaf
volume (976.70±25.2mL) and specific loaf volume (4.38±0.12mL/g), lower pH
(5.16±0.02), longer storage life (6 days), and lower crumb firmness (116.07±6.28g) than
BY bread. EKSS culture bread inoculated with spoilage fungi delayed the mycelia
growth to 5–10 days compared to BY bread. EKSS culture bread extract demonstrated
significantly (p<0.05) higher antibacterial activity (50±0.07 to 100±0.00%) than BY
bread extract. EKSS culture bread had significantly (p<0.05) higher taste and overall
acceptability scores than BY bread, indicating this bread was well accepted by
consumers. The findings showed that the EKSS culture promises to produce functional
sourdough bread with extended shelf life and improved quality that could greatly benefit
the bread industry. |
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