Dataset Information

Microbial identification of potato taste defect from coffee beans.

ABSTRACT: Coffee is a socioeconomic important plant all over the world due to its exportation and how it provides income to the farmers and the country. However, potato taste defect (PTD) affects the Rwandan coffee quality. The smell is reported to be caused by some bacteria that are responsible for the off-flavor and may also be related to the infestation of Antestia pest which are in its elimination process. The aim of this study was to isolate, biochemically characterize, and identify bacteria producing potato flavor from Rwandan coffee. Five samples were obtained from different regions (Nyamasheke and Nyakizu) of Rwanda. Bacteria were isolated and enumerated in the nutrient agar media followed by culture on nutrient and tryptic soy broth media. Bacteria were also cultured to several carbon sources such as glucose, fructose, sucrose, starch, pectin, and galactose to smell the odor produced by those bacteria. DNA extraction of isolates was done, and the resulting DNA strands were undergone three steps of PCR to be amplified using the forward primer and reverse primer. The identification of bacteria producing potato flavor from Rwandan coffee beans was done through 16S rDNA method followed by sequence analysis using FinchTV software and BLAST. Earthy odor was the mostly produced one for nutrient agar and tryptic soy agar media, and for carbon sources such as sucrose, glucose, pectin, fructose, and galactose. The potato odor was recorded mostly from damaged floaters and hand-sorted damaged coffee beans. However, other odors such as fruity and ferment were found to be produced by bacteria in coffee beans. The study came up by concluding the presence of different kinds of bacteria including Enterobacteriaceae and Pantoea, which are responsible for the formation of 2-isopropyl-3-methoxypyrazine (IMP) in coffee beans and cause the production of potato flavor.

SUBMITTER: Ndayambaje JB

PROVIDER: S-EPMC6341129 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Microbial identification of potato taste defect from coffee beans.

Ndayambaje Jean Bernard JB Nsabimana Antoine A Dushime Sylvie S Ishimwe Florence F Janvier Habinshuti H Ongol Martin P MP

Food science & nutrition 20181120 1

Coffee is a socioeconomic important plant all over the world due to its exportation and how it provides income to the farmers and the country. However, potato taste defect (PTD) affects the Rwandan coffee quality. The smell is reported to be caused by some bacteria that are responsible for the off-flavor and may also be related to the infestation of Antestia pest which are in its elimination process. The aim of this study was to isolate, biochemically characterize, and identify bacteria producin ...[more]

PMID: 30680183

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Project description:The current study investigates the phytochemical composition of coffee plant organs and their corresponding antioxidant capacities compared to green and roasted coffee beans. HPLC analysis indicated that the investigated compounds were present in all organs except mangiferin, which was absent in roots, stems and seeds, and caffeine, which was absent in stems and roots. Total phytochemicals were highest in the green beans (GB) at 9.70 mg g-1 dry weight (DW), while roasting caused a 66% decline in the roasted beans (RB). This decline resulted more from 5-CQA and sucrose decomposition by 68% and 97%, respectively, while caffeine and trigonelline were not significantly thermally affected. Roasting increased the total phenolic content (TPC) by 20.8% which was associated with an increase of 68.8%, 47.5% and 13.4% in the antioxidant capacity (TEAC) determined by 2,2-diphenyl-1-picryl hydrazyl radical (DPPH), 2,2-azino bis (3-ethyl benzothiazoline-6-sulphonic acid) radical (ABTS) and Ferric ion reducing antioxidant power (FRAP) assays, respectively. Amongst the leaves, the youngest (L1) contained the highest content at 8.23 mg g-1 DW, which gradually reduced with leaf age to 5.57 mg g-1 DW in the oldest (L6). Leaves also contained the highest TPC (over 60 mg g-1 GAE) and exhibited high TEAC, the latter being highest in L1 at 328.0, 345.7 and 1097.4, and least in L6 at 304.6, 294.5 and 755.1 µmol Trolox g-1 sample for the respective assays. Phytochemical accumulation, TPC and TEAC were least in woody stem (WS) at 1.42 mg g-1 DW; 8.7 mg g-1 GAE; 21.9, 24.9 and 110.0 µmol Trolox g-1 sample; while herbaceous stem (HS) contained up to 4.37 mg g-1 DW; 27.8 mg g-1 GAE; 110.9, 124.8 and 469.7 µmol Trolox g-1 sample, respectively. Roots contained up to 1.85 mg g-1 DW, 15.8 mg-1 GAE and TEAC of 36.8, 41.5 and 156.7 µmol Trolox g-1 sample. Amongst the organs, therefore, coffee leaves possessed higher values than roasted beans on the basis of phytochemicals, TPC and TEAC. Leaves also contain carotenoids and chlorophylls pigments with potent health benefits. With appropriate processing methods, a beverage prepared from leaves (coffee leaf tea) could be a rich source of phytochemicals and antioxidants with therapeutic and pharmacological values for human health.

Dataset Information

Microbial identification of potato taste defect from coffee beans.

Publications

Microbial identification of potato taste defect from coffee beans.

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