Manufacturing process differences give Keemun black teas their distinctive aromas
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PROVIDER: S-EPMC10534231 | biostudies-literature | 2023 Sep
REPOSITORIES: biostudies-literature
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Project description:The determination of boron by inductively coupled plasma-atomic emission spectrometry has been carried in water-soluble and acid soluble (total content) fractions of 36 samples of traditional black tea and fruit brew. The estimation of the impact of the type of tea on the concentration of boron in water-soluble and acid extracts and potential human health risk from the daily intake of boron was carried out in this study. The levels of boron differed significantly in black and fruit tea types. The mean total content of boron ranged from 8.31 to 18.40 mg/kg in black teas, from 12.85 to 15.13 mg/kg in black tea with fruit flavor, and from 12.09 to 22.77 mg/kg in fruit brews. The degree of extraction of boron in black tea ranged from 8% to 27% and for fruit tea from 17% to 69%. In addition, the values below 25% were of black teas with fruit flavors. The daily intake of B from tea infusions (three cups/day) is still within the average daily intake except for some of the fruit brews which exceed acceptable regulations of the daily intake of total boron by humans. Hence, it may not produce any health risks for human consumption, if other sources of metal contaminated food are not taken at the same time.
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Project description:The approach of ionic gelation was employed at the pilot scale of the 50 kg batch size to manufacture black seed oil (BSO)-loaded alginate (ALG) beads as a natural source supplementing the main bioactive compound of BSO, i.e., thymoquinone (TQ). The BSO-ALG emulsion was prepared by initially emulsifying BSO with alginate solution at the pilot scale in two stages. The final emulsion was then dripped through 12 units of 3D-printed multi-nozzles into a curing bath containing Ca2+. The dripping flow rate was scaled up to 288 mL/min through the 3D-printed multi-nozzles (22-gauge). The characteristics of pilot scale BSO-ALG beads were similar to those produced at the lab scale; the beads were spherical with a size of 1.84-1.94 mm. The mechanical strength and loss on drying ranged from 143.6 to 172 g and 77.85-81.96 %, respectively. The production yield and encapsulation efficiency were 77.53-83.65 % and 95.36-97.9 %, respectively. Furthermore, the emulsification process did not affect TQ stability, while the curing process reduced TQ concentration from 1.51 % to 1.03 % w/w. Additionally, a substantial drop in TQ concentration in the encapsulated BSO was observed after the drying process, where it reached 0.23 % w/w. Finally, the stability of BSO-ALG beads in both wet and dried forms under real-time and accelerated conditions for 3 months revealed that beads were stable in terms of their organoleptic characteristics, size and sphericity, and loss on drying. Findings from this study enable the large-scale manufacturing of encapsulated BSO and similar bioactive compounds in ALG beads for the first time. These findings are valuable for advancing microencapsulation through ionic gelation and enhancing food preservation and safety.
| S-EPMC11462023 | biostudies-literature
Project description:'Baimmaocha' is a distinctive resource for production of high-quality black tea, and its processed black tea has unique aroma characteristics. 190 volatile compounds were identified by comprehensive two-dimensional gas chromatography-olfactometry-quadrupole-time-of-flight mass spectrometry(GC × GC-O-Q-TOMS), and among them 23 compounds were recognized as key odorants contributing to forming different aroma characteristics in 'Baimaocha' black teas of Rucheng, Renhua, and Lingyun (RCBT, RHBT, LYBT). The odor activity value coupled with GC-O showed that methyl salicylate (RCBT), geraniol (RHBT), trans-β-ionone and benzeneacetaldehyde (LYBT) might be the most definitive aroma compounds identified from their respective regions. Furthermore, PLS analysis revealed three odorants as significant contributors to floral characteristic, four odorants related to fruity attribute, four odorants linked to fresh attribute, and three odorants associated with roasted attribute. These results provide novel insights into sensory evaluation and chemical substances of 'Baimaocha' black tea and provide a theoretical basis for controlling and enhancement tea aroma quality.
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Project description:Amino acids contribute to the nutritional value and quality of black tea. Fermentation is the most important stage of the black tea manufacturing process. In this study, we investigated protein degradation and proteinaceous amino acid metabolism associated with enzymatic reactions during fermentation in the black tea manufacturing process. The results showed that the concentrations of both protein and free amino acids decreased during fermentation. We also confirmed that proteins were broken down into free amino acids by artificially synthesized dipeptide benzyloxycarbonyl glutamyl-tyrosine (Z-Glu-Tyr). Metabolites of the amino acid metabolic pathway increased significantly during fermentation. Furthermore, we confirmed that free amino acids were degraded to volatile compounds in a tracer experiment with the isotope precursor. These results provide information that will help black tea manufacturers improve the quality of black tea.
| S-EPMC7022896 | biostudies-literature
Project description:Guangdong black teas have diverse flavors and aromas. To explore the molecular basis of these aromas, we extracted and analyzed the volatile flavor compounds of 31 black tea samples from 7 districts (Yingde, Luokeng, Renhua, Meizhou, Chaozhou, Lianshan, and Heyuan) in Guangdong Province with headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Then, 135 volatile flavor compounds (VFCs) were identified and grouped into 12 classes according to their chemical structure. Notably, alcohols accounted for 31.40-44.43% of total VFCs. The score plot of supervised partial least squares-discriminant analysis (PLS-DA) revealed good discrimination for most black tea samples. Additionally, 64 compounds with variable importance in projection > 1.0 were identified as differential odorants. Through an odor activity value analysis, eight volatile compounds were identified as the key active differential VFCs: linalool, methyl salicylate, phenylethyl alcohol, p-cresol, 3-methyl-butanoic acid, geraniol, benzaldehyde, and benzeneacetaldehyde. Thus, benzeneacetaldehyde and linalool in YJ-Yingde samples, benzaldehyde in Luokeng samples with an almond-like aroma, phenylethyl alcohol in the Heyuan samples, and p-cresol and 3-methyl-butanoic acid in the Chaozhou samples were the key volatile flavor compounds that could differentiate local black teas from other black teas. These findings will enrich the research in tea aroma chemistry and provide a method for identifying the origins of Guangdong black teas.
| S-EPMC10094627 | biostudies-literature
Project description:Lotus leaves combine both edible and medicinal properties and are rich in nutrients and bioactive compounds. In this study, the lotus leaf tea was prepared using a black tea fermentation process, and the functional components and microbial changes during fermentation were investigated. The results indicated that the activity of polyphenol oxidase showed an initial rise followed by a decline as fermentation progressed, peaked at 3 h with 1.07 enzyme activity units during fermentation. The lotus leaf fermented tea has high levels of soluble sugars (20.92 ± 0.53 mg/g), total flavonoids (1.59 ± 0.05 mg GAE/g), and total polyphenols (41.34 ± 0.87 mg RE/g). Its antioxidant activity was evaluated using ABTS, DPPH, and hydroxyl radical scavenging assays, with results of 18.90 ± 1.02 mg Vc/g, 47.62 ± 0.51 mg Vc/g, and 17.58 ± 1.06 mg Vc/g, respectively. The microbial community also shifted during fermentation. Fusarium played a significant role during the fermentation process. This study demonstrated that the black tea fermentation process improved the functional components and biological activity of lotus leaf tea by optimizing the synergistic effect of enzymatic oxidation and microbial fermentation. The findings not only realized the comprehensive utilization of lotus leaf resources but also provided a foundation for developing innovative functional beverages with enhanced bioactive properties.
| S-EPMC11817234 | biostudies-literature
Project description:Morels (Morchella spp.) are valuable medicinal and edible mushrooms. In this study, chemical profiles of aromas and lipophilic extracts of black morel (Morchella importuna) grown in China were analyzed by gas chromatography/mass spectroscopy, along with the evaluation of antioxidant and antimicrobial activities for the lipophilic extracts. Sixty-five compounds in total were identified from the aromas, and 1-octen-3-ol was the main component for aromas of fresh (34.40%) and freeze-dried (68.61%) black morels, while the most abundant compound for the aroma of the oven-dried sample was 2(5H)-furanone (13.95%). From the lipophilic extracts, 29 compounds were identified with linoleic acid as the main compound for fresh (77.37%) and freeze-dried (56.46%) black morels and steroids (92.41%) as the main constituent for an oven-dried sample. All three lipophilic extracts showed moderate antioxidant activities against 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) with the IC50 values ranging 7.56 ∼ 17.52 mg/mL and 5.75 ∼ 9.73 mg/mL, respectively, and no obvious antimicrobial activity was observed for lipophilic extracts. The drying methods affect the chemical profile of black morel, and freeze-drying was favorable for retaining nutrients and morel smell. This is the first report on the aroma and lipophilic extracts of M. importuna grown in China.
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Project description:Many human studies suggest a benefit of tea consumption on bone health. The study objective was to compare the ability of different tea types to promote mineralization. Saos-2 cells underwent mineralization (5 days) in the presence of tea (white: WT, green: GT, black: BT, green rooibos: GR, or red rooibos: RR; 1 μg/mL of polyphenols) or control. Total polyphenol content (TPC, Folin-Ciocalteu's reagent), antioxidant capacity (2,2-diphenyl-1-picrylhydrazyl [DPPH] scavenging), mineralization (Alizarin Red staining), gene expression quantitative reverse transcription PCR (RT-qPCR), and cell activity (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay) were determined. TPC was highest in GT and BT. The ability of each tea to inhibit DPPH also differed (WT, GT > RR) after normalizing for polyphenol quantity. Each tea increased mineralization and differences were observed among types (GT/BT/GR/RR > WT, GT = BT = GR, RR > BT/GT). mRNA expression of alkaline phosphatase (ALP) and ectonucleotide pyrophosphatase/phosphodiesterase (NPP1) remained unchanged, whereas osteopontin (OPN) and sclerostin (SOST) were reduced in cells treated with tea, regardless of type. At 24- and 48-h postexposure to tea, cell activity was greater in cells receiving any of the teas compared with vehicle control. Supplementation increased mineralization regardless of tea type with both rooibos teas and black tea stimulating greater mineralization than WT, whereas green tea is similar to the others. While future study is needed to confirm in vivo effects, the results suggest that consuming any of the teas studied may benefit bone health.
| S-EPMC8403192 | biostudies-literature
Project description:Tea aroma greatly varies with the production date. This study investigated the aroma differences among black teas processed on different dates (March 23rd, April 8th, April 15th, April 27th, and May 7th) in the spring. A sensory evaluation showed that the black tea produced on April 15th had a strong and lasting sweet aroma and the highest score of 93.5. In total, 71 volatile compounds were identified, and alcohols were the predominant category, accounting for 60.98%. From March 23rd to May 7th, the total content of volatile compounds showed a parabolic change trend and reached its maximum on April 15th (715.27 μg/L); the flavor index first peaked on April 8th (23.25) and then gradually decreased. A multivariate statistical analysis showed that 39 volatile compounds were important, differential aroma components. An odor activity value (OAV) analysis showed that the predominant odorants were β-ionone, β-damascenone, linalool, (E)-β-ocimene, and geraniol, all with values larger than 100. The total OAVs of undesirable odorants decreased and reached their minimum (70.4) on April 27th, while the total OAVs of pleasant odorants and the ratio of pleasant/undesirable odorants showed inverse changes and reached their maximum (2182.1 and 31.0, respectively) on April 27th. Based on the significance of differences and OAVs, linalool, (E)-β-ocimene, geraniol, and (E,E)-2,4-nonadienal were considered as the key differential odorants. Combined with the sensory evaluation and the differences in aroma components, it was proposed that black teas produced around April 15th in the Hunan district are more likely to have a strong and lasting sweet aroma. This study will provide scientific guidance for the production of black tea in the Hunan district, China.
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