Nutritional and Volatile Characterisation of Milk Inoculated with Thermo-Tolerant Lactobacillus bulgaricus through Adaptive Laboratory Evolution
| Autor: | Michelle J.Y. Yoo, Brent Seale, Jiahui Liang, Gianpaolo Grazioli |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Health (social science)
Plant Science TP1-1185 Health Professions (miscellaneous) Microbiology chemistry.chemical_compound Lactobacillus Food science Lactose Lactobacillus bulgaricus Aroma adaptive laboratory evolution volatiles amino acids Methionine biology Chemical technology food and beverages MRS agar biology.organism_classification Diacetyl Lactic acid chemistry Bacterial cellular morphologies Food Science |
| Zdroj: | Foods, Vol 10, Iss 2944, p 2944 (2021) Foods; Volume 10; Issue 12; Pages: 2944 |
| ISSN: | 2304-8158 |
| Popis: | In this study, thermo-tolerant strain of Lactobacillus bulgaricus (L. bulgaricus) was developed using gradual increase in temperature to induce Adaptive Laboratory Evolution (ALE). Viable colony count of 1.87 ± 0.98 log cfu/mL was achieved at 52 °C, using MRS agar supplemented with 2% lactose. Changes in bacteria morphology were discovered, from rod (control) to filament (52 °C) to cocci after frozen storage (−80 °C). When milk was inoculated with thermo-tolerant L. bulgaricus, lactic acid production was absent, leaving pH at 6.84 ± 0.13. This has caused weakening of the protein network, resulting in high whey separation and lower water-holding capacity (37.1 ± 0.35%) compared to the control (98.10 ± 0.60%). Significantly higher proteolytic activity was observed through free amino acids analysis by LC-MS. Arginine and methionine (237.24 ± 5.94 and 98.83 ± 1.78 µg/100 g, respectively) were found to be 115- and 275-fold higher than the control, contributing to changing the aroma similar to cheese. Further volatile analysis through SPME-GC-MS has confirmed significant increase in cheese-aroma volatiles compared to the control, with increase in diacetyl formation. Further work on DNA profiling, metabolomics and peptidomics will help to answer mechanisms behind the observed changes made in the study. |
| Databáze: | OpenAIRE |
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