Biotransformation of gluten-free composite flour mediated by lactic acid bacteria via solid-state fermentation process conducted under different moisture contents
Over the years, the development of staple food products from composite flour is considered a low-cost approach to address the burden of protein-energy malnutrition in developing countries. However, despite the numerous advantages of composite flour, the high amount of anti-nutritional factors typ...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2022
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/113001/1/113001.pdf |
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| Summary: | Over the years, the development of staple food products from composite flour is
considered a low-cost approach to address the burden of protein-energy
malnutrition in developing countries. However, despite the numerous
advantages of composite flour, the high amount of anti-nutritional factors typical
to food derived from plant origin usually impede nutrient bioavailability. Five
strains of lactic acid bacteria (LAB) isolated from Malaysian foods that include
Lactiplantibacillus plantarum RG-14, L. plantarum RI-11, L. plantarum RS5, L.
plantarum IUL-4, and Pediococcus pentosaceus UP-2 have been reported for
their capabilities to produce various extracellular hydrolytic enzymes via solidstate
fermentation (SSF) which can breakdown complex food matrix into smaller
absorbable forms and reduced antinutrients. Therefore, the LAB strains were
employed in this study to biotransform the gluten-free composite flour derived
from rice, sorghum, and soybean. The SSF process was performed under 30-
60% moisture content for 7 days, where samples were withdrawn at 24 h
intervals for various analyses such as LAB cell viability, pH, total titratable acidity,
extracellular protease activity, soluble protein concentration, crude protein
content, and in vitro protein digestibility. The pH of the biotransformed composite
flour showed a significant reduction from the initial range of pH 5.98 - 6.67 to the
final pH of 4.36 - 3.65, corresponding to the increase in the percentage of total
titratable acidity in the range of 0.28 - 0.47% to 1.07 - 1.65% from Day 0-4 and
remained stable till Day 7 of the SSF process. The LAB strains exhibited high
extracellular proteolytic activity (0.63 - 1.35 U/mg to 4.21 - 5.13 U/mg) from Day
0-7. In addition, the treated composite flour soluble protein increased
significantly (p≤0.05) (0.58 - 0.60 mg/mL to 0.72 - 0.79 mg/mL) from Day 0-7,
crude protein content (12.00 - 12.18% to 13.04 - 14.39%) and protein digestibility
(70.05 - 70.72% to 78.46 - 79.95%) from Day 0-4 of SSF. In addition, the
antinutritional factors of the biotransformed composite flour showed a significant
reduction (p≤0.05) in the phytic acid (127.11 – 137.73 mg/100 g to 124.84 - 120.24 mg/100 g) and tannin content (89.48 – 93.92 mg/100 g to 63.51 – 39.84
mg/100g). Since lower moisture content promotes flour quality, 50% moisture
was selected as the most suitable moisture content to have effectively
biotransformed the composite flour, even though a comparable result was
observed at 60% moisture content. Overall, Lactiplantibacillus plantarum RG-14
was ranked the best strain attributed to the general improvement in composite
flour's pH, TTA, protein quality, and antinutritional properties. |
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