Chitosan-coated paper packaging for specialty coffee beans: Coating characterization, bean and beverage analysis.

Cellulose-based packaging has received great attention due to its characteristics of biodegradability, sustainability, and recyclability. Natural polymer coatings are usually applied to the paper surface to enhance the barriers to water vapour and improve the mechanical properties. A chitosan-based coating for paper packaging was developed in this work to store specialty roasted coffee beans, evaluating two samples of chitosan (Sigma® and molasses chitosan), and following the physico-chemical and microbiological characteristics of coffee beans along a period of 60 days. Sensory tests (Ranking Descriptive Analysis and Preference Test) were applied to the beverage prepared with the roasted and ground coffee beans stored in each packaging. Thin chitosan films provided good coverage and adhesion on the paper. Improved mechanical properties and lower water permeability were observed in the chitosan-coated papers. The physicochemical and microbiological characteristics of the coffee beans were not influenced by the packaging along 60 days of storage. The molasses chitosan coating resulted in slightly darker roasted beans. In sensory evaluation, there is a clear difference between the chitosan samples, so that molasses chitosan-coated packaging had higher scores compared to Sigma® chitosan treatment for flavor and global impression in the preference analysis of the beverage. The molasses chitosan-coated packaging had three to four more consumers attributing the highest scores for the beverage prepared with the roasted beans stored in this type of packaging.

Quality of Arabica coffee grown in Brazilian Savannah and impact of potassium sources.

Located in Brazil's Central Plateau, the Cerrado Savannah is an emerging coffee-growing region with significant potential for the national coffee market. This study investigated the impact of potassium fertilization on Arabica coffee quality in the Cerrado, using three potassium sources (K2SO4, KCl, and KNO3) and five cultivars (Arara, Aranãs, IPR103, Catiguá and Topázio) across two consecutive harvests. We focused on productivity, granulometry, chemical composition, and sensory characteristics. No significant difference in productivity across the cultivars studied or potassium sources as isolated factors were observed. Regarding chemical parameters, potassium sources only affected NO3- and SO42- levels in the grains. Cultivar-specific differences were noted in caffeine (CAF), citric acid (CA), and sucrose (SUC), highlighting a strong genetic influence. K2SO4 improved productivity in Arara (15 %) and IPR103 (11 %), while KNO3 reduced flat grain percentage to 70 % in Catiguá. Sensory evaluation showed that all potassium sources and cultivars produced specialty coffees, with the Arara cultivar treated with K2SO4 achieving the highest SCA score (83.3) while IPR 103 treated with KCl scored the lowest at 78. Only three treatments were below but very close to the threshold (80). Multivariate analysis indicated a trend where specific treatments correlated with higher productivity and quality. Despite the subtle differences in productivity and quality among potassium sources, a cost-benefit analysis may favor KCl due to its affordability, suggesting its viability as a potassium fertilization option in coffee cultivation. Future research is needed to confirm these trends and optimize potassium source selection to enhance coffee quality in the Cerrado.

Is diet related to skin condition? A Mendelian randomization study.

Observational studies have revealed associations between various dietary factors and skin conditions. However, the causal relationship between diet and skin condition is still unknown. Data on 17 dietary factors were obtained from the UK Biobank. Data on four skin conditions were derived from the UK Biobank and another large-scale GWAS study. Genetic predictions suggested that the intake of oily fish was associated with a lower risk of skin aging (OR: 0.962, P = 0.036) and skin pigmentation (OR: 0.973, P = 0.033); Tea intake was associated with a lower risk of skin pigmentation (OR: 0.972, P = 0.024); Salad/raw vegetables intake was associated with a lower risk of keratinocyte skin cancer (OR: 0.952, P = 0.007). Coffee intake was associated with increased risk of skin aging (OR: 1.040, P = 0.028); Pork intake was associated with increased risk of skin aging (OR: 1.134, P = 0.020); Beef intake was associated with increased risk of cutaneous melanoma (OR: 1.013, P = 0.016); Champagne plus white wine intake was associated with increased risk of cutaneous melanoma (OR: 1.033, P = 0.004); Bread intake was associated with increased risk of keratinocyte skin cancer (OR: 1.026, P = 0.013). Our study results indicate causal relationships between genetically predicted intake of oily fish, tea, salad/raw vegetables, coffee, pork, beef, champagne plus white wine, and bread and skin conditions.

Migraine incidence and coffee consumption among child-bearing age women: the Korea Nurses' Health Study.

This longitudinal study aimed to identify factors that influence migraines in Korean women nurses using data from the Korea Nurses' Health Study. Among those who participated in Survey 1 (2013-2014) and the follow-up survey (2015-2019), we selected 2605 participants for Cox proportional hazard regression analysis, 521 participants who were newly diagnosed with migraine and 2084 controls using a 1:4 incidence density sampling approach. Consuming coffee (≥ 3 cups: RR = 1.666; 95% CI = 1.175-2.362, < 3 cups: RR = 1.439; 95% CI = 1.053-1.966), being obese (BMI ≥ 25: RR = 1.341, 95% CI = 1.003-1.793), and engaging in vigorous physical activity (RR = 1.010; 95% CI = 1.000-1.019) increased the risk of developing a migraine. Nurses with an annual salary greater than $3500 were less likely to develop migraines (RR = 0.786, 95% CI = 0.631-0.979). The results imply that lifestyle factors, such as the amount of coffee consumption, BMI level, and degree of physical activity could be considered when formulating treatment plans for women who have newly developed migraines.

Color Stability of Bioactive Restorative Material vs Nanohybrid Resin Composite: An In Vitro Study.

AIM: This study aimed to assess the color stability of bioactive restorative materials vs nanohybrid resin composites after 3 months of immersion in three frequently consumed beverages. MATERIALS AND METHODS: Thirty disk-shaped specimens of Giomer dental restorative material (Shofu, Japan) and nanohybrid resin composite (Tokuyama, Japan) were performed using a Teflon mold. Super-Snap system (Shofu, Japan) was utilized to finish and polish the specimens to be preserved for 24 hours in distilled water at 37°C. The samples had been divided into three subgroups (Coffee, tea, Pepsi) (n = 5). The initially displayed color measurements of the samples were performed using a spectrophotometer (VITA Easyshade® V). After 7 days, 30 days, and 90 days, color measurements were repeated, and the E of each sample was estimated. E of each sample was calculated. RESULTS: The Giomer group showed statistically significant higher E values than the nanohybrid resin composite where the p-value was ≤0.0001. Tea subgroup showed the highest statistically significant E values in both groups where the p-value was ≤ 0.0001. The highest statistically significant color change was recorded at 3 months. CONCLUSION: The color of bioactive restorative material is less stable if compared with nanohybrid resin composite. CLINICAL SIGNIFICANCE: As tea and coffee are popular beverages, particularly in Middle Eastern nations, dentists must advise patients about the color change of resin restorations. Patients are advised to brush their teeth immediately after consuming these beverages. How to cite this article: Saber EH, Abielhassan MH, Abed YA, et al. Color Stability of Bioactive Restorative Material vs Nanohybrid Resin Composite: An In Vitro Study. J Contemp Dent Pract 2024;25(3):221-225.

Chemical composition and sensory profiling of coffees treated with asparaginase to decrease acrylamide formation during roasting.

Acrylamide is an amide formed in the Maillard reaction, with asparagine as the primary amino acid precursor. The intake of large amounts of acrylamide has induced genotoxic and carcinogenic effects in hormone-sensitive tissues of animals. The enzime asparaginase is one of the most effective methods for lowering the formation of acrylamide in foods such as potatoes. However, the reported sensory outcomes for coffee have been unsatisfactory so far. This study aimed to produce coffees with reduced levels of acrylamide by treating them with asparaginase while retaining their original sensory and bioactive profiles. Three raw samples of Coffea arabica, including two specialty coffees, and one of Coffea canephora were treated with 1000, 2000, and 3000 ASNU of the enzyme. Asparagine and bioactive compounds (chlorogenic acids-CGA, caffeine, and trigonelline) were quantified in raw and roasted beans by HPLC and LC-MS, while the determination of acrylamide and volatile organic compounds was performed in roasted beans by CG-MS. Soluble solids, titratable acidity, and pH were also determined. Professional cupping by Q-graders and consumer sensory tests were also conducted. Results were analyzed by ANOVA-Fisher, MFA, PCA and Cluster analyses, with significance levels set at p ≤ 0.05. Steam treatment alone decreased acrylamide content by 18.4%, on average, and 6.1% in medium roasted arabica and canefora coffees. Average reductions of 32.5-56.0% in acrylamide formation were observed in medium roasted arabica beans when 1000-3000 ASNU were applied. In the canefora sample, 59.4-60.7% reductions were observed. However, steam treatment primarily caused 17.1-26.7% reduction of total CGA and lactones in medium roasted arabica samples and 13.9-22.0% in canefora sample, while changes in trigonelline, caffeine, and other evaluated chemical parameters, including the volatile profiles were minimal. Increasing enzyme loads slightly elevated acidity. The only sensory changes observed by Q-graders and or consumers in treated samples were a modest increase in acidity when 3000 ASNU was used in the sample with lower acidity, loss of mild off-notes in control samples, and increased perception of sensory descriptors. The former was selected given the similarity in chemical outcomes among beans treated with 2000 and 3000 ASNU loads.

Effects of geographical origin and post-harvesting processing on the bioactive compounds and sensory quality of Brazilian specialty coffee beans.

Specialty coffee beans are those produced, processed, and characterized following the highest quality standards, toward delivering a superior final product. Environmental, climatic, genetic, and processing factors greatly influence the green beans' chemical profile, which reflects on the quality and pricing. The present study focuses on the assessment of eight major health-beneficial bioactive compounds in green coffee beans aiming to underscore the influence of the geographical origin and post-harvesting processing on the quality of the final beverage. For that, we examined the non-volatile chemical profile of specialty Coffea arabica beans from Minas Gerais state, Brazil. It included samples from Cerrado (Savannah), and Matas de Minas and Sul de Minas (Atlantic Forest) regions, produced by two post-harvesting processing practices. Trigonelline, theobromine, theophylline, chlorogenic acid derivatives, caffeine, caffeic acid, ferulic acid, and p-coumaric acid were quantified in the green beans by high-performance liquid chromatography with diode array detection. Additionally, all samples were roasted and subjected to sensory analysis for coffee grading. Principal component analysis suggested that Cerrado samples tended to set apart from the other geographical locations. Those samples also exhibited higher levels of trigonelline as confirmed by two-way ANOVA analysis. Samples subjected to de-pulping processing showed improved chemical composition and sensory score. Those pulped coffees displayed 5.8% more chlorogenic acid derivatives, with an enhancement of 1.5% in the sensory score compared to unprocessed counterparts. Multivariate logistic regression analysis pointed out altitude, ferulic acid, p-coumaric acid, sweetness, and acidity as predictors distinguishing specialty coffee beans obtained by the two post-harvest processing. These findings demonstrate the influence of regional growth conditions and post-harvest treatments on the chemical and sensory quality of coffee. In summary, the present study underscores the value of integrating target metabolite analysis with statistical tools to augment the characterization of specialty coffee beans, offering novel insights for quality assessment with a focus on their bioactive compounds.

Mendelian randomization reveals the impact of diet on infertility in men and women.

Background: Although studies on the effects of diet on fertility has progressed, some cumulative evidence has piled against popular hypotheses. The aim of our study was to investigate the effects of 31 diets including 23 individual dietary intakes and 8 dietary habits on infertility in men and women. Methods: The datas of diets and infertility were collected from genome-wide association studies (GWAS). Mendelian randomization (MR) methods were used to analyze causal relationships. Multivariate MR (MVMR) adjusted for the effects of other exposures on causality. And MR-Egger, Cochran's Q, radial MR, and MR-PRESSO tests were employed to assess heterogeneity and horizontal pleiotropy. Results: Our study found that coffee intake (OR, 3.6967; 95% CI, 1.0348 - 13.2065; P = 0.0442) and cooked vegetable intakes (OR, 54.7865; 95% CI, 2.9011 - 1030.5500; P = 0.0076) increased the risk of male infertility. For women, beer was a risk factor for infertility (OR, 4.0932; 95% CI, 1.8728 - 8.9461; P = 0.0004); but processed meat was negatively associated with infertility (OR, 0.5148; 95% CI, 0.2730 - 0.9705; P = 0.0401). MVMR demonstrated selenium as a protective factor against female infertility (OR, 7.4474e-12; 95% CI, 5.4780e-22 - 1.0125e-01; P = 0.0314). Conclusion: We found the causal relationships between four diets and infertility. We look forward to more high-quality epidemiologic studies to prove our conclusions.

Effect of fluoride or chitosan toothpaste and at-home bleaching in enamel roughness, tooth color, and staining susceptibility.

PURPOSE: To evaluate how fluoride- or chitosan-based toothpaste used during at-home bleaching affects enamel roughness, tooth color, and staining susceptibility. METHODS: Bovine enamel blocks were submitted to a 14-day cycling regime considering a factorial design (bleaching agent x toothpaste, 2 x 3), with n=10: (1) bleaching with 16% carbamide peroxide (CP) or 6% hydrogen peroxide (HP), and (2) daily exposure of a fluoride (1,450 ppm F-NaF) toothpaste (FT), chitosan-based toothpaste (CBT), or distilled water (control). Then, 24 hours after the last day of bleaching procedure the samples were exposed to a coffee solution. Color (ΔEab, ΔE00, L*, a*, b*) and roughness (Ra, µm) analyses were performed to compare the samples initially (baseline), after bleaching, and after coffee staining. The results were evaluated by linear models for repeated measures (L*, a*, b*, and Ra), 2-way ANOVA (ΔEab, ΔE00) and Tukey's test (α= 0.05). RESULTS: After the at-home bleaching procedure (toothpaste vs. time, P< 0.0001), the toothpaste groups presented a statistically lower Ra than the control (CBT 0.05). After coffee exposure, CBT presented lower ΔEab and ΔE00 values in the HP groups (toothpaste, P< 0.0001), and lower b* and a* values in the CP groups (toothpaste vs. time, P= 0.004). CLINICAL SIGNIFICANCE: Fluoride or chitosan delivered by toothpaste can reduce surface alterations of the enamel during at-home bleaching, without affecting bleaching efficacy.

From cup to clock: exploring coffee's role in slowing down biological aging.

Background: Previous research has proposed that coffee consumption may have potential health benefits, yet the effect of coffee on one's biological age has not been determined to date. The purpose of this study is to investigate the influence of coffee drinking on biological aging. Methods: Participants were chosen from the National Health and Nutrition Examination Survey (NHANES) and had to meet the selection criteria. Coffee consumption was evaluated through two 24-hour dietary questionnaires. Biological age was measured using both the PhenoAge and KDM-BA algorithms. Multiple linear and logistic regression models were adopted to analyze the association of coffee consumption with biological aging. Results: A total of 13 384 participants with an average daily coffee consumption of 1.73 cups were included. Participants with higher coffee consumption tended to be older, male, non-Hispanic white; had a higher educational level beyond high school; were more likely to be married; had better financial status; and were less likely to smoke or engage in excessive drinking. These individuals with higher coffee consumption exhibited a younger biological age in relation to their chronological age, as indicated by lower mean advancements in PhenoAge and KDM-BA scores. Furthermore, coffee intake was found to be inversely related to PhenoAge and KDM-BA progressions, as well as to the chances of accelerated biological aging, both in unadjusted and adjusted models. These associations remained consistent across all age and gender groups. Additionally, some heterogeneity was also observed among body mass index and physical activity categories. Conclusions: Coffee drinking was inversely related to biological age advancements and the likelihood of accelerated biological aging. Moderate coffee consumption may offer substantial benefits in reducing biological aging.

Online consumer testing beyond central location tests: A case study for brewed coffee.

Due to the constraints of the COVID-19 pandemic, conducting sensory evaluations requiring direct interactions became challenging. In response, researchers have been motivated to devise non-face-to-face testing methods as alternatives. This study aimed to compare two non-face-to-face home-use tests (HUT) with the traditional face-to-face central location test (CLT). Both HUTs involved online recruitment and sample delivery to participants' homes. One HUT provided a written protocol with no direct interaction (contactless HUT; C-HUT), whereas the other included an online meeting with a researcher for live guidance (online HUT; O-HUT). Four coffee samples were evaluated on the basis of liking and sensory and emotional attributes. The comparison between CLT and O-HUT showed RV coefficients of 0.92, 0.93, and 0.98 (P < 0.05) for liking and sensory and emotional attributes, respectively. In addition, based on the RV coefficient, the CLT results showed a significantly greater similarity to those of O-HUT compared to those of C-HUT. The O-HUT also outperformed the C-HUT in its ability to significantly discriminate between samples. Hence, real-time interactions between researchers and participants, as facilitated by O-HUT, may be more suitable in certain scenarios compared to C-HUT, which relies solely on a written protocol. Overall, these findings suggest that C-HUT and O-HUT are suitable methods for collecting sensory data and overcoming geographic and face-to-face contact limitations, providing greater flexibility, and reducing the time and cost associated with traditional sensory evaluations.

Determination of o-quinones in foods by a derivative strategy combined with UHPLC-MS/MS.

As primary polyphenol oxidant products, the occurrence of o-quinone is greatly responsible for quality deterioration in wine, including browning and aroma loss. The high reactivity of o-quinone causes huge difficulty in its determination. Herein, a derivative strategy combined with UHPLC-MS/MS analysis was established with chlorogenic acid quinone (CQAQ) and 4-methylcatechol quinone (4MCQ) as model compounds. Method validation demonstrated its efficiency for two analytes (R2 > 0.99, accuracy 98.71-106.39 %, RSD of precision 0.46-6.11 %, recovery 85.83-99.37 %). This approach was successfully applied to detect CQAQ and 4MCQ, suggesting its applicability in food analysis. CQAQ in coffee was much more than 4MCQ and with the deepening of baking degree, CQAQ decreased and 4MCQ increased. The amounts of CQAQ in various vegetables were markedly different, seemingly consistent with their respective browning degrees in practical production. This study developed an accurate and robust analytical approach for o-quinones, providing technical support for their further investigation in foods.

Color stability and translucency of newly developed composites for splinting teeth.

This study aimed to investigate the colorimetric properties of newly developed composites for dental trauma splints using various staining solutions during the clinical splinting period. The clear shades of G-Fix (GF), Ortho Connect Flow (OC), Light Fix (LF), and Filtek Z350XT (FZ) were fabricated into 96 disk-shaped specimens. Specimens from each composite group were stored in distilled water, coffee, tea, and red wine solutions at 37ºC. CIE values were measured using a spectrophotometer at 24 h after specimen preparation and at 1 day, 1 week, 2 weeks, 3 weeks, and 4 weeks after storage in each solution. Color differences and translucency parameters were calculated using the initial and measured values. Within the experiment period, the color differences of GF, OC, and LF compared to the initial measurement were smaller than that for FZ for all staining solutions except distilled water. There were no significant color differences between the GF, OC, and LF groups.

Whey protein concentrate and skimmed milk powder as encapsulation agents for coffee silverskin extracts processed by spray drying.

We tested the hypothesis that milk proteins, through microencapsulation, guarantee protection against bioactive substances in coffee silverskin extracts. Therefore, the aim of this study was to carry out technological, nutritional and physicochemical characterisation of a coffee silverskin extract microencapsulated using instant skim milk powder and whey protein concentrate as wall materials. The aqueous extract of coffee silverskin was spray-dried using 10% (w/v) skim milk powder and whey protein concentrate. The samples were characterised by determining the water content, water activity, particle size distribution, colour analysis and total phenolic compound content as well as antioxidant activity using 2,2-diphenyl-radical 1-picrylhydrazyl scavenging methods, nitric oxide radical inhibition and morphological analysis. The product showed water activity within a range that ensured greater stability, and the reduced degradation of the dried coffee silverskin extract with whey protein concentrate resulted in better rehydration ability. The luminosity parameter was higher and the browning index was lower for the encapsulated samples than for the pure coffee silverskin extract. The phenolic compound content (29.23 ± 8.39 and 34.00 ± 8.38 mg gallic acid equivalents/g for the coffee silverskin extract using skimmed milk powder and whey protein concentrate, respectively) and the antioxidant activity of the new product confirmed its potential as a natural source of antioxidant phenolic compounds. We conclude that the dairy matrices associated with spray drying preserved the bioactive and antioxidant activities of coffee silverskin extracts.

Association of sugary drinks, carbonated beverages, vegetable and fruit juices, sweetened and black coffee, and green tea with subsequent depression: A five-year cohort study.

BACKGROUND & AIMS: Evidence on the impact of beverage consumption on depression is limited in the Asian population. Specifically, there is little information available on vegetable and fruit juices, while whole vegetables and fruits are reportedly protective against depression. Furthermore, evidence is scarce in differentiating the impacts of sweetened and black coffee. We aimed to examine the association of the consumption of total sugary drinks, carbonated beverages, vegetable and fruit juices, sweetened and black coffee, and green tea with subsequent depression in a general population sample. METHODS: We studied individuals without a history of cancer, myocardial infarction, stroke, diabetes, or depression at baseline in 2011-2016, with a five-year follow-up. We used Poisson regression models and the g-formula, thereby calculating the risk difference (RD) for depression. Multiple sensitivity analyses were conducted. Missing data were handled using random forest imputation. We also examined effect heterogeneity based on sex, age, and body mass index by analyzing the relative excess risk due to interaction and the ratio of risk ratios. RESULTS: In total, 94,873 individuals were evaluated, and 80,497 completed the five-year follow-up survey for depression. Of these, 18,172 showed depression. When comparing the high consumption group with the no consumption group, the fully adjusted RD (95% CI) was 3.6% (2.8% to 4.3%) for total sugary drinks, 3.5% (2.1% to 4.7%) for carbonated beverages, 2.3% (1.3% to 3.4%) for vegetable juice, 2.4% (1.1% to 3.6%) for 100% fruit juice, and 2.6% (1.9% to 3.5%) for sweetened coffee. In contrast, the fully adjusted RD (95% CI) was -1.7% (-2.6% to -0.7%) for black coffee. The fully adjusted RD for green tea did not reach statistical significance. The results were robust in multiple sensitivity analyses. We did not find substantial effect heterogeneity based on sex, age, and body mass index. CONCLUSIONS: Total sugary drinks, carbonated beverages, vegetable and fruit juices, and sweetened coffee may increase the risk of depression, whereas black coffee may decrease it.

Unlocking the potential of spent coffee grounds via a comprehensive biorefinery approach: production of microbial oil and carotenoids under fed-batch fermentation.

The valorization of renewable feedstock to produce a plethora of value-added products could promote the transition towards a circular bioeconomy. This study presents the development of cascade processes to bioconvert spent coffee grounds (SCGs) into microbial oil and carotenoids employing sustainable practices. The stepwise recovery of crude phenolic extract and coffee oil was carried out using green or recyclable solvents, i.e., aqueous ethanol and hexane. Palmitic acid (43.3%) and linoleic acid (38.9%) were the major fatty acids in the oil fraction of SCGs. The LC-MS analysis of crude phenolic extracts revealed that chlorogenic acid dominated (45.7%), while neochlorogenic acid was also detected in substantial amounts (24.0%). SCGs free of coffee oil and phenolic compounds were subjected to microwave-assisted pretreatment under different irradiations and solvents to enhance subsequent enzymatic saccharification. Microwave/water pretreatment at 400 W, followed by enzymatic hydrolysis with proteases, hemicellulases, and cellulases, at 50 g/L initial SCGs, led to satisfying overall yields of cellulose (75.4%), hemicellulose (50.3%), and holocellulose (55.3%). Mannan was the most extractable polysaccharide followed by galactan and arabinan. SCGs hydrolysate was used in fed-batch bioreactor fermentations with Rhodosporidium toruloides to produce 24.0 g/L microbial oil and carotenoids of 432.9 µg/g biomass.

Polyphenols vs. Caffeine in Coffee from Franchise Coffee Shops: Which Serving of Coffee Provides the Optimal Amount of This Compounds to the Body.

The scientific literature indicates that there is a limited number of data on the content of bioactive components in coffees consumed "on the go". Therefore, this study examined the polyphenol and caffeine content of different types of coffee from franchise coffee shops, and the caffeine/total polyphenol ratio. The five most popular types of coffee purchased in six franchise coffee shops in Warsaw were analysed. A total of 120 coffee samples were tested. A significant positive (r = 0.7407, p < 0.001) correlation was found between the total polyphenol and caffeine content in all coffee types tested. Per unit volume, espresso coffee had the highest significant (p < 0.005) average total polyphenol and caffeine contents (232.9 ± 63.9 mg/100 mL and 198.6 ± 68.3 mg/100 mL, respectively). After taking into account the coffee's serving size, a serving of Americano provided significantly (p < 0.05) the most total polyphenol (average 223.5 ± 81.5 mg), while the highest caffeine content was provided by a serving of ice latte/latte frappe (average 136 ± 57.0 mg). The most favourable ratio of caffeine to total polyphenols (0.56) was found in a serving of Americano coffee; therefore, it seems that this coffee can be considered optimal in terms of the content of both compounds. These findings demonstrate that the polyphenol and caffeine contents of coffees offered in franchise coffee shops are closely related to the serving size.

Isolation, identification, and tolerance analysis of yeast during the natural fermentation process of Sidamo coffee beans.

Yeast, which plays a pivotal role in the brewing, food, and medical industries, exhibits a close relationship with human beings. In this study, we isolated and purified 60 yeast strains from the natural fermentation broth of Sidamo coffee beans to screen for indigenous beneficial yeasts. Among them, 25 strains were obtained through morphological characterization on nutritional agar medium from Wallerstein Laboratory (WL), with molecular biology identifying Saccharomyces cerevisiae strain YBB-47 and the remaining 24 yeast strains identified as Pichia kudriavzevii. We investigated the fermentation performance, alcohol tolerance, SO2 tolerance, pH tolerance, sugar tolerance, temperature tolerance, ester production capacity, ethanol production capacity, H2S production capacity, and other brewing characteristics of YBB-33 and YBB-47. The results demonstrated that both strains could tolerate up to 3% alcohol by volume at a high sucrose mass concentration (400 g/L) under elevated temperature conditions (40 ℃), while also exhibiting a remarkable ability to withstand an SO2 mass concentration of 300 g/L at pH 3.2. Moreover, S. cerevisiae YBB-47 displayed a rapid gas production rate and strong ethanol productivity. whereas P. kudriavzevii YBB-33 exhibited excellent alcohol tolerance. Furthermore, this systematic classification and characterization of coffee bean yeast strains from the Sidamo region can potentially uncover additional yeasts that offer high-quality resources for industrial-scale coffee bean production.