Natural versus Saccharomyces boulardii self-induced anaerobic coffee fermentation: Effects on physicochemical properties and microbial ecology, and their influence on volatile profiles and sensory attributes across roast levels.

Modulation of the volatile and non-volatile profiles of coffee fermented with Yarrowia lipolytica: II. Roasted coffee

Coffee is one of the leading plantation commodities in Indonesia. High-quality coffee has a higher price than low-quality coffee. The quality of coffee is determined by the method of selecting planting materials, handling during harvest, and processing. Coffee that is processed naturally, will be dried in the form of fruit/cherry so that coffee will decrease in quality. The quality of coffee beans can be improved if the roasting process is carried out using the right roasting temperature and time. With a variety of treatments in post-harvest processing methods and roasting levels will produce different coffee quality so that appropriate treatment is needed to determine the final result of coffee with the best quality. This study used the Complete Randomized Design (CRD) method with 2 factors, namely differences in coffee types (robusta coffee and arabica coffee) and roasting levels (light roast, medium roast, and dark roast). The research variables observed were seed weight, camba density, water content, and caffeine content. The data obtained will be analyzed using analysis of variance. If there is a significant difference between treatments, then further tests will be carried out using the Duncan Multiple Range Test (DMRT) at the 5% failure level.

Arabica Yellow Caturra, a newly cultivated coffee variety in Indonesia, exhibits an unbalanced flavor profile that diminishes its consumer appeal. To enhance its competitiveness in both domestic and international markets, appropriate post-harvest processing techniques are essential. This study investigated the impact of carbonic maceration - a fermentation method involving CO₂ gas injection on the physicochemical and sensory properties of coffee powder. Analyses included physicochemical properties (colour, moisture, ash content, pH, caffeine, total acidity) and sensory attributes. Results indicated that CO₂ injection intensity significantly influenced colour characteristics, pH levels, and caffeine content (p< 0.05). In contrast, the roasting level significantly affected colour, moisture content, ash content, caffeine concentration, total acidity, and the sensory attributes of body and uniformity (p< 0.05). The optimal treatment, identified by the highest Cupping Test score (81.88), involved CO₂ injection at the initial stage of fermentation combined with light roasting.

Coffee is one of the refreshing plants that can provide a stimulating effect for consumption. Two types of coffee that are popular among the public are Arabica and Robusta. Coffee contains caffeine. Consumption of large amounts of caffeine can have an impact on human health. The development of research so that development is carried out by determining caffeine from different roasting levels which are Light, medium and Dark. This study aims to determine the caffeine content in Arabica and Robusta coffee at different roasting levels using the HPLC (High-Performance Liquid Chromatography) method. The samples used as much as 5 grams. The method used is the determination of caffeine using HPLC (High-Performance Liquid Chromatography). Then taken to be injected into a 1.5 ml vial and ready to be injected into the HPLC device using HPLC Agilent 1260 Infinity II, C18 and UV Vis detector with a wavelength of 275 nm. The mobile phase used was distilled water and methanol with a flow rate of 1 ml/min. The results of this study determined caffeine levels in Arabica with roasting levels of light 0.0779, medium 0.0893, and dark 0.0909 mg/g. While Robusta Coffee contains caffeine at a roasting light level of 0.1399, medium 0.1432 and dark of 0.2115 mg/g.

The effect of variations in temperature and roasting time on the physical properties of coffee beans originating from the Gayo highlands with Arabica and Robusta types have been studied in this paper. Physical properties measured include weight loss, true density, porosity, and water content. The measurement procedure follows Standard Nasional Indonesia (SNI) 01-2907-2008. Three roasting levels were used in this study, i.e., Light Roast (159 -164 °C), Medium Roast (211 - 215 °C), and Dark Roast (above 232 °C) by an oven. The result showed that the weight loss for Arabica and Robusta coffee beans is from 11 - 19% and 14 - 29%, respectively. The true density for Arabica and Robusta coffee beans ranged from 0.905 - 1.085 g/cm3 and 0.950 - 1.156 g/cm3, respectively. The difference in porosity changes before and after roasting was 23 - 73% for Arabica and 33 - 68% for Robusta coffee beans. Meanwhile, the water content of Arabica and Robusta coffee beans after roasting is 0.7 - 5% and 0.6 - 6%, respectively. The value of the weight loss, true density, and water content of Arabica is lower than that of the Robusta coffee bean, while the porosity value of Arabica is higher than that of the Robusta coffee bean.

Black apple is a new elaborated product obtained from whole fresh apple through fermentation at controlled high temperature (60~90°C) and humidity (relative humidity of 50~90%). The appearance, color, texture, and taste of black apple changed dramatically compared with those of fresh apple. In this study, changes in the physicochemical and phytochemical properties, volatile profiles, and antioxidant capacity of apple during the fermentation process were investigated. Results showed that the browning intensity and color difference increased continuously during the whole 65-day fermentation process (p < 0.05). Sugars decreased in the whole fermentation process (p < 0.05), whereas the contents of organic acids increased first and then decreased with prolonged 35 days of fermentation (p < 0.05). Total polyphenol content of black apple showed an increase of 1.5-fold as that of fresh apple, whereas 12 common polyphenolic compounds present in fresh apple decreased dramatically in the whole fermentation process (p < 0.05). The analysis of flavor volatiles showed that high-temperature fermentation decreased the levels of alcohols and esters and resulted in the formation of furanic and pyranic compounds, which are the main products of Maillard reaction (MR). Antioxidant activities of black apple were enhanced compared with those of fresh apple, and results indicated that the enhancement of antioxidant activities was related to the polyphenols and products of MR.

Free amino acids (FAAs) participate in the synthesis of quality characteristic ingredients and taste substances in fermented minced peppers (FMPs), and they can be affected by fermentation method and time. In this study, changes in FAAs of FMP during natural fermentation (NF) and inoculated fermentation (IF) process were characterized by HPLC-MS/MS. The results showed that a total of 20 FAAs were identified, including 8 essential amino acids (AAs), 2 semiessential AAs, and 10 nonessential AAs. Comparing with other FAAs, Gln, Arg, and Asn presented higher content in the whole NF or IF periods. The FAAs content of NF and IF samples showed similar tendency during fermentation process, which first increased and then decreased. The highest content of most FAAs in IF and NF samples was obtained on the 18- and 12-day, respectively. Moreover, the FAA content in IF samples was higher than that in NF ones at the same fermentation time. The taste AAs content accounted for 23.3% to 50.0% in total FAAs, and taste activity value of bitter and umami was higher than sweet and aromatic ones. Based on principal component analysis, comprehensive analysis ranking, and heat map clustering analysis, FMP obtained by IF posed better FAAs quality than NF samples during fermentation process. PRACTICAL APPLICATION: Free amino acids (FAAs) participate in the synthesis of quality characteristic ingredients and taste substances in fermented minced peppers (FMPs), and they can be affected by fermentation method and time. Changes in FAA varieties and level in FMP during natural fermentation (NF) and inoculated fermentation (IF) process were analyzed using HPLC-MS/MS. Then, they were performed by principal component analysis (PCA), and clustered with the heat map. The results showed that FMP obtained by IF posed better FAAs quality than NF samples in the whole fermentation. HPLC-MS/MS was a reliable and effective mean for determining the FAAs and could provide regulation guidelines for improving the quality of FMP during fermentation process.

To identify chemical parameters that might be used as discriminators, pH, soluble solids, caffeine, trigonelline, total caffeoylquinic acids, 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, 5-O-caffeoylquinic acid, total dicaffeoylquinic acids, 3,4-O-dicaffeoylquinic acid, 3,5-O-dicaffeoylquinic acid, 4,5-O-dicaffeoylquinic acid, total feruloylquinic acids, 3-O-feruloylquinic acid, and 5-O-feruloylquinic acid were measured in Arabica and Robusta coffees submitted to three roasting levels. It was found that the fraction of soluble solids increased with roasting level, being slightly higher in Robusta roasted coffee. The contents of caffeine did not vary significantly between roasting degrees within the Arabica and Robusta samples, respectively, revealing a considerable stability during browning. The contents of trigonelline in Arabica and Robusta coffee decreased significantly with browning intensification. Overall, the levels of chlorogenic acids remained higher in Robusta roasted coffee beans but decreased sharply with roast increase. With roasting intensification, the ratio of total caffeoylquinic acids, total dicaffeoylquinic acids, and total feruloylquinic acids varied markedly in both species, with the proportion of total caffeoylquinic acids and total feruloylquinic acids increasing significantly, whereas the opposite occurred with dicaffeoylquinic acids. One can conclude, through the application of a multivariate analysis, that these chemicals form four clusters, constituting caffeine, trigonelline, total dicaffeoylquinic acids, and total feruloylquinic acids a relevant group for T3 roasting level discrimination, in both coffee species. Additionally, detailing discriminators for roasting intensity in Arabica coffee might be caffeine, trigonelline, 3-O-caffeoylquinic acid, and 4-O-caffeoylquinic acid, whereas in Robusta roasted coffee are trigonelline, 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, 5-O-caffeoylquinic acid, 3,4-O-dicaffeoylquinic acid, 3,5-O-dicaffeoylquinic acid, 4,5-O-dicaffeoylquinic acid, 3-O-feruloylquinic acid, and 5-O-feruloylquinic acid.

Effect of roasting on degradation and structural features of polysaccharides in Arabica coffee beans

This study investigates the effect of harvesting altitude, fermentation time and roasting degree on the volatile profile released by coffee (Coffea arabica, variety Catimor) powder. The analysis of the volatile organic compounds was performed by proton transfer reaction mass spectrometer (PTR-MS). The experimental design consisted of three factors: altitude at two levels (900 m and 1500 m, milder and harsher climate, respectively), four different fermentation times (0, 24, 48 and 72 h) and roasting at three levels (light, medium and dark). Analysis of the released volatile organic compounds (VOCs) revealed that the intensity of m/z 45 and 59 dramatically decreases at a higher harvesting altitude. Longer fermentation times induce a decrease of m/z 61 and 75, probably related to the activity of the isocitrate lyase. Finally, a prolonged roasting degree induces a rise of the m/z 61, 75, 81 and 97. The total count per second measured by PTR-MS was used as an index of “overall coffee aroma intensity” to build a linear regression model. The model was used to predict the total VOCs intensity on the basis of the altitude, fermentation time and roasting level. The validation of the model (adjusted R2 = 0.91 and normalized relative standard deviation in prediction of 7%) reveals that, although the degree of roasting clearly affects the resulting aroma intensity, altitude and fermentation time also play a role in the formation of the volatile profile. Moreover, a significant interaction was observed between the altitude where the bean were grown and the roasting level. These results support the hypothesis that the type of process of the seeds has a strong impact on the resulting coffee’s quality. Furthermore, PTR-MS coupled with linear regression models is a powerful tool for the quality control of coffee process.

The objective of this study was to evaluate sensorially, by professional Q-Grader, the beverage coffee from fermentation natural and fermentation with the use of yeasts and lactic acid bacteria as starter cultures in wet coffee processing. The Arabica coffee was harvested at two different altitudes in Espirito Santo State. Both coffees went through 04 treatments: inoculated with starter cultures Saccharomyces cerevisiae (YML) or Pediococcus acidilactici CCT 1622 (LAF), natural fermentation (NF) (not inoculated) and Control, without fermentation (WF). The coffee was processed by just the wet process. After process and roasting, the sensorial analysis was performed to understand the impact of fermentation processing in the coffee quality, and was performed by 6 Q-Graders, following SCA protocol. The study evidenced that the use of natural fermentation or starter cultures during post-harvest coffee contributed to obtain a quality beverage with pleasurable sensorial characteristics, punctuated by the tasters in the overall score obtained and also by the highsensory scores in attributes such as fragrance, acidity, aftertaste and the different perceived aromas. This work demonstrates for coffee growers that fermentation technology is not intuitive but requires an understanding of the relationship of the microorganisms with the coffee and the environment. In addition to the other chemical aspects of roasting and brew coffee. Key words: Fermentation; Microorganisms; Quality.

Modulation of coffee aroma via the fermentation of green coffee beans with Rhizopus oligosporus: II. Effects of different roast levels

ABSTRACTThe consumption of specialty coffee has been growing and attracting an increasing number of enthusiasts both in Brazil and worldwide. Annually, new research is conducted to understand consumer perceptions regarding the nuances of this beverage. This study aimed to explore the sensory perceptions of specialty coffees using the Temporal Dominance of Sensations (TDS) methodology across different roast levels, comparing responses from trained panels and regular consumers. Using samples of Coffea arabica from Minas Gerais in Brazil, the study applied the TDS technique to assess the sensory impact of three distinct roast levels (light, medium, and dark) on both primary (category‐level attributes per the SCA Flavor Wheel) and secondary (sub‐category descriptors) attributes. Coffee samples were analyzed by a panel of trained evaluators based on the Q Grader training protocol and a group of regular specialty coffee consumers. The results revealed distinct sensory profiles across roast levels, with notable differences between trained panelists and consumers. Light roasts were associated with sour and fruity notes, especially by trained panelists, while consumers more often perceived bitter and fermented attributes. Medium roasts showed greater sensory balance, and dark roasts were predominantly bitter for both groups, though trained panelists also identified fermented and alcoholic notes more clearly. Trained evaluators demonstrated greater sensitivity and were able to discern a wider range of sensory attributes. In addition, they spent less time selecting the first sensation and showed higher dominance rates for most attributes compared to the panel of regular specialty coffee consumers for both primary and secondary attributes. This divergence not only emphasizes the role of sensory training in enhancing perceptual acuity but also underlines the importance of aligning coffee sensory claims with consumer expectations and perception.

The effects of 1-methylcyclopropene (1-MCP) on physicochemical properties and sensory characteristics of Fuji apple fruits stored at 2 °C for 9 months in air were investigated. The soluble solid content, titratable acidity (TA), sugars, sorbitol, organic acids, and phenolic compounds were evaluated in this study. We also determined volatile profiles using headspace solid-phase microextraction and gas chromatography–mass spectrometry. Instrumental textural properties and descriptive sensory analysis were also conducted in this study. The correlation coefficients between physicochemical and sensory properties were investigated. In comparison with the untreated apples, those treated with 1-MCP exhibited higher acidity (i.e., higher TA and organic acids), antioxidant total polyphenol content, sum of individual polyphenol content, force linear distance, lower volatile content, b* (yellowness), and fructose and sucrose levels, after long-term cold storage. A significant difference was observed in sensory attributes such as red color of apple peel, textural properties (with peel and without peel), sweet taste, and sour taste between 1-MCP-treated and untreated apples. Sensory attributes related to textural properties (i.e., P_Hardness and Crunchiness) showed positive correlation with instrumental textural properties (force peak and force linear distance) (p < 0.05). A significant positive correlation was observed between red color of apple peels (sensory attribute) and a* (redness) (p < 0.05) and between sour taste and shikimic acid (p < 0.05).

Coffee contains a variety of organic acids (OAs) and chlorogenic acids (CGAs) that contribute to overall sensory properties. Large variations in preparation and measurement methodology across the literature complicate interpretation of general trends. Here, we perform a systematic review and meta-analysis of the published literature to elucidate the concentrations of OAs and CGAs in both Coffea arabica (arabica) and Coffea canephora (robusta), for both green coffee and roasted coffee at multiple roast levels. A total of 129 publications were found to report acid concentration measurements, yielding 8,634 distinct data points. Analysis of the full data set reveals several trends. First, roasted robusta has considerably more acidic compounds than arabica with 2 to 5 times as much total OAs, and much larger amounts of formic and acetic acid. As for CGAs, in both arabica and robusta 5-CQA is the major component, and progressive roasting decreases the concentration of all CGAs. The total amount of CGA present was more dependent on roast level than the type of coffee (arabica vs. robusta). Overall, this meta-analysis suggests that the increases in certain OAs with roast level might play more of a role in the sensory profile of dark roast coffees than previously suspected.