Brewing Methods Research Articles

Evaluation of the Brewing Characteristics, Digestion Profiles, and Neuroprotective Effects of Two Typical Se-Enriched Green Teas.

As a functional beverage, selenium (Se)-enriched green tea (Se-GT) has gained increasing popularity for its superior properties in promoting health. In this study, we compared the brewing characteristics, in vitro digestion profiles, and protective effects on neurotoxicity induced through the amyloid-beta (Aβ) peptide of two typical Se-GTs (Enshi Yulu (ESYL) and Ziyang Maojian (ZYMJ), representing the typical low-Se green tea and high-Se green tea, respectively). ESYL and ZYMJ showed similar chemical component leaching properties with the different brewing methods, and the optimized brewing conditions were 5 min, 90 °C, 50 mL/g, and first brewing. The antioxidant activities of the tea infusions had the strongest positive correlation with the tea polyphenols among all of the leaching substances. The tea infusions of ESYL and ZYMJ showed similar digestive behaviors, and the tea polyphenols in the tea infusions were almost totally degraded or transferred after 150 min of dynamic digestion. Studies conducted in a cell model of Alzheimer’s disease (AD) showed that the extract from the high-Se green tea was more effective for neuroprotection compared with the low-Se green tea. Overall, our results revealed the best brewing conditions and digestion behaviors of Se-GT and the great potential of Se-GT or Se-enriched green extract (Se-GTE) to be used as promising AD-preventive beverages or food ingredients.

Does Coffee Have Terroir and How Should It Be Assessed?

The terroir of coffee is defined as the unique sensory experience derived from a single origin roasted coffee that embodies its source. Environmental conditions such as temperature, altitude, shade cover, rainfall, and agronomy are considered the major parameters that define coffee terroir. However, many other parameters such as post-harvest processing, roasting, grinding, and brewing can combine to influence the perception of terroir. In this review, we discuss the contribution of these parameters and their influence on coffee terroir. Assessment of terroir requires defined sensory descriptors, as provided by the World Coffee Research Lexicon, and standardized roast level, grind size, and brew method. The choice of the post-harvest processing method is often environmentally dependent, suggesting that an inclusion into the coffee terroir definition is warranted. Coffee terroir is often not intentionally created but results from the contributions of the Coffea species and variety planted, environmental and agricultural parameters, and both the harvest and post-harvest method used. The unique combination of these parameters gives the consumer a unique cup of coffee, reminiscent of the place the coffee was produced.

Metode penyeduhan terhadap nilai kesukaan dan aktivitas antioksidan seduhan teh meniran (Phyllanthus niruri Linn.)

Meniran is an herbal plant that has many health benefits. Meniran tea contains phytochemicals like teas in general such as saponins, phenolics, flavonoids, and tannins. This study aims to determine the effect of the meniran leaf tea brewing method on the preference value and content of an antioxidant activity. This research was a laboratory experiment with a completely randomized design (CRD). Meniran tea was brewed using the Decoction Brew (DB), Cold Brew (CB), and True Brew (TB) methods with filter and non-filter treatments. The organoleptic test in this study used 30 untrained panelists. Organoleptic test data collection consisting of color, aroma, and taste attributes were assessed using a 9-scale hedonic scale questionnaire. Organoleptic data that had been collected was then tested for normality using Kolmogorov Smirnov, if normally distributed, continued with ANOVA statistical test and then Duncan's further test with 99% CI. Organoleptic test results in the form of attributes of color (p= 0,000), aroma (p= 0,003), and taste (p= 0,000) of panelists preferred tea with the TBF brewing method. Based on the antioxidant activity content of selected meniran tea (TBF) around 2,33 – 2,81 mg/mL. In conclusion, the panelists prefer tea with the TBF brewing method based on the attributes of color, aroma, and taste as well as high antioxidant activity.

Impact of coffee preparation on total phenolic content in brewed coffee extracts and their contribution to the body's antioxidant status.

Although coffee has been reported as a major contributor to antioxidants in the diet, there are limited studies assessing how brewing methods and types of coffee affect antioxidant capacity of coffee consumers. This study was aimed to investigate the impact of coffee preparation on total phenolic content in brewed coffee extracts and their contribution to antioxidant status. We examined how the different brewing methods affect total phenolic content and antioxidant capacity in brewed coffee extracts, then assessed the antioxidant status of coffee consumers after drinking coffee. Results showed that consuming capsule versus French press coffee provides a higher total phenolic content and drinking capsule coffee leads to greater antioxidant status as shown by the higher total antioxidant capacity in urine. Further studies can expand on this by using a broader range of brewing methods to evaluate the contribution of brewing methods of coffee to antioxidant status.

Optimization of heat and ultrasound assisted extraction of bioactive compounds from Echinacea purpurea using response surface methodology

The optimal conditions for extracting phytochemical from plant materials is a critical step in herbal medicine industry. In the present study, the optimal conditions for extracting the maximum amount of E. purpurea chicoric acid, total phenolics, and antioxidant activity were obtained by response surface methodology (RSM). A D-optimal design of extracting factors including temperature (25–75 °C), sonication time (0–60 min), solvent concentration (0–100%), and solvent types (methanol and ethanol) was generated. Results showed that solvent concentration, solvent types, temperature and sonication times are respectively the most significant factors when all responses were considered. The optimal extraction conditions were found as follows: 75 °C temperature, 51.8 min sonication, and 41.70% methanol with a desirability of 0.982. The optimum condition was repeated five times and the average amount of chicoric acid, total phenolics, and antioxidant activity were 26.09 mg/g, 47.31 mg/g, and 56.94%, respectively, which were in accordance with the optimized predicted values (p < 0.05). In comparison with the optimal conditions obtained in this research, traditional brewing methods cause the loss of more than 50% of bioactive compounds.

Effect of Different Brewing Methods on Some Physicochemical Properties of Green Tea (Camellia sinensis)

Different brewing methods can lead to changes in the physicochemical properties of green tea. In this study, the physicochemical properties of green tea brewed with different amounts (5, 7.5 and 10 grams) and times (5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 minutes) were investigated. Green tea produced by Çaykur was used in the study. Mineral analysis of green tea samples was performed with ICP-OES, and color analysis was performed with Minolta Spectrophotometer. The antioxidant activity was assessed using the DPPH method and the total phenolic content was determined using the Folin–Ciocalteu method. In terms of mineral content, it was determined highest levels of mineral content (mg/kg) for Al, Ca and Mg (10 g-25 minutes); Fe, Mn and Na (10 g-25 minutes); and B (10 g-50 minutes) as 16.005, 4.099, 24.075, 0.120, 13.855, 1.320 and 0.164, respectively. It was determined lowest levels of mineral content (mg/kg) for Al, Ca, Mg, and Mn (5 g-5 minutes); B and Fe (5 g-10 minutes), and Na (5 g-15 minutes) as 2.756, 1.193, 3.324, 1.23, 0.025, 0.002 and 0.48, respectively. In terms of color, it was determined that the lowest and highest L* values are 39.97 (10 g-45 minutes) -54.23 (5 g-35 minutes), lowest and highest a* values are -2.24 (5 g-5 minutes) (-4.70) (7.5 g-35 minutes) and lowest and highest b* values are 4.91 (5 g-5 minutes)- 23.98 (10 g-60 minutes). The antioxidant activity value (inhibition %) in green tea was found to be the range of 28.51 % (5 g, 45 minutes)- 47.95 (10 g- 40 minutes), and the total phenolic content (mg GAE/mL) was found to be the range of 15.99 (5 g, 5 minutes)- 35.61 (10 g, 15 minutes). The findings determined that green tea brewed with different amounts and times showed statistical differences in terms of color, mineral content, antioxidant activity, and total phenolic content.

Use of electrochemical techniques for determining the effect of brewing techniques (espresso, Turkish and filter coffee) and roasting levels on total antioxidant capacity of coffee beverage

In this study, we determined how roasting levels (light, medium, and dark) of Arabica coffee seed and three brewing techniques—decoction methods (Turkish coffee), infusion method (filter coffee), and pressure methods (Espresso)—affect the total antioxidant capacity in a cup of coffee beverage by electrochemical methods such as square wave stripping voltammetry (SWSV), differential pulse stripping voltammetry (DPSV), and cyclic voltammetry (CV). The highest antioxidant capacity was found in espresso coffee prepared with light roasted coffee seeds, as equivalent of rutin and caffeic acid at 9.4 ± 0.2 g/L and 19.7 ± 0.7 g/L, respectively with SWSV on a carbon paste electrode (CPE). The antioxidant capacity of coffee beverages was influenced by the roasting degree, extraction time, and brewing methods, significantly. SWSV, DPSV, and CV voltammetric methods, fast, reliable, fully validated and without any pretreatment, are alternatives to conventional analytical methods for evaluation of antioxidant values in coffee brews. Practical applications This research will contribute to the literature considerably since we have established that the antioxidant capacity can be measured by electrochemical methods rapidly with high reliable results. According to the study, the brewing method and roasting temperature significantly affected the antioxidant capacity, and thus, it is important to know how brewing methods, roasting temperatures, and other conditions changes the coffee quality. The results can be used to prepare healthy coffee beverages.

Artisanal fortified beers: Brewing, enrichment, HPLC-DAD analysis and preliminary screening of antioxidant and enzymatic inhibitory activities

In this study an artisanal “Porter style” beer has been enriched with diverse natural bioactive substances, following all-grain brewing method. Common beer generally contains a poor content of phenolic acids which confers a low antioxidant power and nutritional value, also due to the presence of ethanol. However in this work we aimed to enrich beer with different flavonoids and other food supplements like taurine, resveratrol and caffeine, thus enhancing its nutritional value and energizing properties. A series of flavonoid/phenol-enriched artisanal beers have been prepared, then sample of each has been tested in vitro to evaluate antioxidant activity, chelating power and enzymatic inhibition capacity. Beer samples were also analysed with HPLC-DAD system to determinate flavonoid and phenol contents. Results show increased nutritional values and significant antioxidant properties in comparison with not-fortified beer as control.

Total polyphenol content and antioxidant properties of cold brew coffee extracts as affected by ultrasound treatment and their application in low fat pork sausage

ABSTRACT The total phenolic content and antioxidant activities of the organic spent coffee ground obtained from different brewing methods were investigated. Among various brewing methods, the organic spent coffee ground showed the highest total phenolic content (TPC) and antioxidant activities and was selected as raw material for extracting phytochemicals using ultrasound assisted extraction (UAE) with different temperature, time, and solvent ratios. In terms of extraction time, the TPC and antioxidant activities were continuously increased until the extraction time reached to 40 min and then dramatically decreased indicating the appropriate extraction time. The extract with highest TPC (78.85 mg garlic acid equivalent/ml antioxidant crude extracts) and antioxidant activities was obtained when extracted with UAE at 50 °C, solvent ratios of 1:20 g/ml and 40 min. The assays of 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ATBS) and ferric reducing antioxidant power (FRAP) were detected at 717.11 µM Trolox/antioxidant crude extracts, 711.23 µM Trolox/antioxidant crude extracts, and 2401.90 µM Ammonium ferrous sulfate/antioxidant crude extracts, respectively. When applied the antioxidant crude extracts from organic cold brew spent coffee ground into low fat pork sausage at 1.00%, the improvement of TPC and antioxidant activities was obtained. After storage for 14 days, the TPC and DPPH scavenging activity was increased to 18.07 mg garlic acid equivalent/100 g pork sausage and 159.76 µM Trolox/100 g pork sausage, respectively, while the 2‐thiobarbituric acid reactive substance values were reduced to 9.18 g malondialdehyde/100 g pork sausage. The rancidity of the sausage was ceased, and the shelf-life was prolonged when the extract was added.

Ultrafast cold-brewing of coffee by picosecond-pulsed laser extraction

Coffee is typically brewed by extracting roasted and milled beans with hot water, but alternative methods such as cold brewing became increasingly popular over the past years. Cold-brewed coffee is attributed to health benefits, fewer acids, and bitter substances. But the preparation of cold brew typically needs several hours or even days. To create a cold-brew coffee within a few minutes, we present an approach in which an ultrashort-pulsed laser system is applied at the brewing entity without heating the powder suspension in water, efficiently extracting caffeine and aromatic substances from the powder. Already 3 min irradiation at room temperature leads to a caffeine concentration of 25 mg caffeine per 100 ml, comparable to the concentrations achieved by traditional hot brewing methods but comes without heating the suspension. Furthermore, the liquid phase’s alkaloid content, analyzed by reversed-phase liquid chromatography coupled to high-resolution mass spectrometry, is dominated by caffeine and trigonelline and is comparable to traditional cold-brewed coffee rather than hot-brewed coffee. Furthermore, analyzing the head-space of the prepared coffee variants, using in-tube extraction dynamic head-space followed by gas chromatography coupled to mass spectrometry, gives evidence that the lack of heating leads to the preservation of more (semi-)volatile substances like pyridine, which provide cold-brew coffee its unique taste. This pioneering study may give the impetus to investigate further the possibility of cold-brewing coffee, accelerated by more than one order of magnitude, using ultrafast laser systems.

Association between espresso coffee and serum total cholesterol: the Tromsø Study 2015–2016

BackgroundCoffee raises serum cholesterol because of its diterpenes, cafestol and kahweol, and the effect varies by brewing method. Population-based research on espresso coffee’s impact on serum cholesterol is scarce. Our...

Bioactive diterpenes (cafestol and kahweol) in Turkish coffees: Impact of roasting

While the cholesterol-raising effect of coffee has been ascribed to the presence of diterpenes, they have also been shown to present favourable health effects. Boiled-type coffees show slightly higher levels of diterpenes than those made with other brewing methods. However, there is considerable controversy regarding the effect of roasting on the contents of the diterpenes cafestol and kahweol. Therefore, the aim of the present work was to measure the contents of these diterpenes in Turkish coffees, and to determine how they are influenced by roasting. The samples used were 16 roasted and ready-ground Turkish coffees sold in supermarkets in the Turkish Republic of Northern Cyprus. The cafestol and kahweol contents of the coffee samples were analysed using liquid-liquid extraction followed by HPLC-DAD. The lipid contents of commercially roasted and ground Turkish coffee samples varied in the range of 14.32 ± 0.09 to 15.60 ± 0.09 g/100 g. The lipid contents of brewed Turkish coffee samples varied from 318 ± 2.00 to 571 ± 4.30 mg/100 mL. When compared within each commercial brand, dark roasted ground Turkish coffee samples had higher lipid contents. The average diterpene content in one cup of Turkish coffee sample was between 2.69 ± 0.28 and 13.58 ± 0.88 mg. The ranges of cafestol and kahweol contents in a cup were 1.4 ± 0.21 - 6.9 ± 0.65 mg and 1.28 ± 0.07 - 6.68 ± 0.28 mg, respectively. Within products of the same brand, the highest amount of oil was observed in dark roasted Turkish coffee beverages, and no significant differences were found in total diterpene, cafestol, and kahweol contents in coffee beverages among the different roasting levels. It is recommended that future studies perform more detailed investigations of the effect of roasting on the diterpene contents in Turkish coffees, and the impact of preparation parameters, as well as the presence of diterpene-derived compounds.

Air Pollution Exposure Duration and Its Correlation with Triglyceride, HDL, and Atherogenic Index in Online Motorcycle Drivers

Background: The most restoration material used currently in dentistry was composite resin. The newest generation of composite resin was bulk-fill composite resin. The bulk-fill composite resin had advantages of lower polymerization contraction and a more straightforward and faster restoration technique. One of the factors which could affect the hardness of composite resin was the consumption of acidic drinks. The acidic beverage that people often consumed is coffee. A few coffee brewing methods were espresso and drip brewing.Objective: This research aimed to identify the effects of coffee soaking through espresso and drip brewing methods on bulk-fill composite resin's hardness.Methods: his research was experimental research, with a post-test control group design and a total sample of 27 samples. The soaking process was taken for seven days at a temperature of 37˚C on artificial saliva, espresso, and drip brewing coffee methods. The hardness of bulk-fill composite resin was measured after seven days by using Vickers hardness. The statistic test exerted One-Way ANOVA.Results: This research found a significant difference in bulk-fill composite resin's hardness among all groups, p-value = 0.00 (p&lt;0.05). The result of the post-hoc LSD test showed a significant difference in the change of bulk-fill composite resin hardness between the artificial saliva group and espresso group (p=0,00) and no significant difference found between the artificial saliva group and drip brewing group (p=0.85).Conclusion: Soaking with espresso coffee has the smallest hardness value compared to soaking with drip brewing coffee and artificial saliva, so soaking with espresso coffee is the most influential on the hardness of the bulk fill composite resin.

The Effect of Espresso and Drip Brewing Coffee Methode to The Hardness of Bulk-Fill Composite Resin

Background: The most restoration material used currently in dentistry was composite resin. The newest generation of composite resin was bulk-fill composite resin. The bulk-fill composite resin had advantages of lower polymerization contraction and a more straightforward and faster restoration technique. One of the factors which could affect the hardness of composite resin was the consumption of acidic drinks. The acidic beverage that people often consumed is coffee. A few coffee brewing methods were espresso and drip brewing.Objective: This research aimed to identify the effects of coffee soaking through espresso and drip brewing methods on bulk-fill composite resin's hardness.Methods: his research was experimental research, with a post-test control group design and a total sample of 27 samples. The soaking process was taken for seven days at a temperature of 37˚C on artificial saliva, espresso, and drip brewing coffee methods. The hardness of bulk-fill composite resin was measured after seven days by using Vickers hardness. The statistic test exerted One-Way ANOVA.Results: This research found a significant difference in bulk-fill composite resin's hardness among all groups, p-value = 0.00 (p&lt;0.05). The result of the post-hoc LSD test showed a significant difference in the change of bulk-fill composite resin hardness between the artificial saliva group and espresso group (p=0,00) and no significant difference found between the artificial saliva group and drip brewing group (p=0.85).Conclusion: Soaking with espresso coffee has the smallest hardness value compared to soaking with drip brewing coffee and artificial saliva, so soaking with espresso coffee is the most influential on the hardness of the bulk fill composite resin.

Exploration of Socio-Scientific Issues through Coffee Brewing Methods to Explore Physics Literacy

The taste of coffee is not only influenced by the type of coffee but also by the brewing methods. The phenomenon of brewing coffee is an interesting scientific phenomenon that can be used as a Socio-scientific Issues (SSI) theme. SSI are social issues that exist in society, contain the basis of science, and in their resolution trigger dialogue, discussion and debate. The purpose of this study is to determine the level of science literacy as an impact of SSI exploration on the phenomenon of coffee brewing methods. This research uses qualitative methods and is conducted at SK Coffee Lab Kediri with baristas as the source of information. Interviews are arranged based on indicators of science literacy with four main components, knowledge of science, the investigation nature of science, science as a way of thinking, and the interaction of science, technology, and society. Based on this research, the results were obtained that baristas at SK Coffee Lab have a sufficient level of physics science literacy with a percentage of 70%. While the descriptions of each indicator are as follows: the indicator of knowledge of science scored 75% with good criteria, the indicator of the investigation nature of science scored 75% with good criteria, on the indicator of science as a way of thinking scored 80% with good criteria and on indicators of the interaction of science, technology and society scored 80% with good criteria.

Feasibility of Ultrasound-Assisted Extraction for Accelerated Cold Brew Coffee Processing: Characterization and Comparison With Conventional Brewing Methods.

A long extraction time for traditional cold coffee brewing considerably reduces the production efficiency of this type of beverage. Herein, a new ultrasound-assisted cold brewing (UAC) method was established. The feasibility of UAC was assessed by comparison with main physicochemical characteristics, non-volatile and volatile compounds in coffee extracts produced by hot brewing and conventional static cold brewing methods. Compared to the static cold brews, the levels of total dissolved solids, total lipids, proteins, and titrated acids of UAC coffee extracts increased by 6–26%, 10–21%, 26–31%, and 12–15%, respectively. Caffeine, chlorogenic acid, and trigonelline concentrations were also determined by HPLC. Based on the volatile profiles obtained by HS-SPME-GC/MS, the aroma compounds in UAC was significantly different (p < 0.05) from hot brews but similar to static cold ones, suggesting that ultrasonication compensated for the time of the static cold brewing, thereby considerably shortening the extraction time (1 h vs. 12 h). This work demonstrated that the combination of ultrasound-assisted with cold brew could produce coffee with good flavor and increase the extraction efficiency, which may provide an option for the acceleration of the cold brew coffee process.

Survival of Salmonella in Tea Under Different Storage Conditions and Brewing Methods.

Salmonella is one of the leading causes of bacterial gastroenteritis. High prevalence of Salmonella in environment is partially due to its ability to enter the “viable but non-culturable” (VBNC) state when they encounter unfavorable conditions. Dried teas are traditionally believed to have a low risk of causing salmonellosis. This study investigated the survival of Salmonella in four types of dried teas under different storage conditions and brewing methods. A method that coupled propidium monoazide (PMA) and quantitative PCR was optimized to quantify VBNC Salmonella cells to assess the risk of Salmonella contamination in teas after brewing. Each tea sample was inoculated with Salmonella at an 8 log CFU/ml concentration and stored at 4, 10, and 25°C. Under three storage conditions, the number of survived Salmonella was highest in teas stored at 4°C and lowest in teas stored at 25°C. After storage of 120 days, culturable Salmonella was detected from all samples ranging from 6–7 log CFU/g (4°C storage) to 3–4 log CFU/g (25°C storage). The effectiveness of brewing methods in inactivating Salmonella was assessed by brewing inoculated teas at room temperature, 55, 75, and 100°C for 10 min. Brewing teas at 75 and 100°C significantly (P < 0.05) reduced the number of viable Salmonella, but VBNC Salmonella formed when brewed at 75°C. Altogether, Salmonella can persist in dried teas for over 3 months at a temperature ranging from 4 to 25°C, and thermal treatment delivered during home brewing may not eradicate Salmonella in teas.

Viability of microwave technology for accelerated cold brew coffee processing vs conventional brewing methods

Production of cold brew (CB) coffee beverages can require 10–24 h of cold-water infusion. Accelerating this process would facilitate its production on a large scale. This study compared hot brewed coffee (HB), CB, heat-treated CB coffee (H-CB), and microwave treated CB coffee (M-CB) over time in terms of four attributes: color measured by L* values, total dissolved solids (TDS), and mg/100 g caffeine and chlorogenic acid (3-CQA). L* decreased over time for both HB and CB (34.98 → 17.19 vs 64.62 → 43.00), while TDS (0.89 → 1.39 vs 0.29 → 0.85), caffeine (48.90 → 84.39 vs 15.23 → 61.42) and 3-CQA (33.60 → 62.85 vs 5.55 → 44.82) increased. H-CB and M-CB attributes remained constant after the heat treatment (L*, 34.46–35.33 vs 29.23–29.29; TDS, 0.80–1.03 vs 1.00–0.94; caffeine, 56.10–62.21 vs 60.88–69.85; 3-CQA, 39.17–46.00 vs 41.39–49.95), were similar to CB samples, but required less preparation time. A brief heat treatment prior to cold infusion accelerates CB production, allowing industry to develop faster, less costly processing methods. • Conventional and microwave processing produced similar/comparable results. • Analysis of physical and chemical changes in coffee over time. • Observed significant separate and interaction effects of time and temperature. • Optimization of rapid cold brew processing method.

Innovative soft beverages made from natural vegetable raw materials

The research made it possible to develop a technology for the production of soft beverages using natural vegetable raw materials. To prepare a non-alcoholic natural drink of direct brewing, the following vegetable raw materials were selected: chamomile, orange, lemongrass, valerian, cinnamon, ginger, rose, karkade, rosehip, honeybush. As a result of the study of the composition of the ingredients, it was found that this raw material is rich in vitamins, macro- and microelements, organic acids, tannins, dietary fibers, flavonols and other functional substances. At the same time, they contain a small amount of calories. Due to the presence of benzoic acid in the composition of rosehip fruits, sorbic acid in the composition of orange, the drink will be stabilized, since they are natural preservatives. Also, orange peel, karkade give the drink a taste and a pleasant aroma. Thus, the considered raw materials are a favorable object to create a soft drink based on them. Beverages based on these natural herbal ingredients will be in demand among people who take care of their health. During the experiment, three experimental blends were made for two beverages, with different contents of chamomile, orange, lemongrass, valerian, cinnamon, ginger and rose, karkade, rosehip, honeybush, lemongrass. According to the organoleptic parameters, one option was selected for each drink. The organoleptic and physico-chemical parameters of the finished product - a natural soft drink of direct brewing - have been studied. Based on the conducted research, a technological scheme for obtaining a soft drink based on the direct brewing method was modeled. Technological documentation for beverages has been developed.

Discrimination for sake brewing methods by compound specific isotope analysis and formation mechanism of organic acids in sake

Organic acids in sake affect its aroma and color and help control the activity of microorganisms. This study used liquid chromatography coupled with isotope ratio mass spectrometry and solid-phase extraction to determine the stable carbon isotope ratios (δ13C) for malic acid, lactic acid, and succinic acid in 49 sake samples. The mean δ13C of lactic acid was −25.6 ± 2.1‰ in kimoto samples and −20.2 ± 2.5‰ in sokujo sample. According to linear discriminant analysis using δ13C of lactic acid, 87.8% of kimoto and sokujo samples were correctly identified. The proportion of brewers’ lactic acid in sake could be calculated from the δ13C value of lactic acid for the first time. The productions of malic acid and succinic acid may be conducted by some kinds of fermentation and the mechanism of the tricarboxylic acid cycle by using δ13C of malic acid and succinic acid.