Dynamics of biologically active compounds and antioxidant activity of coffee during cold extraction at different temperatures

This review summarizes published information concerning the determination of antioxidant activity (AA) in coffee samples by various methods (ORAC, FRAP, TRAP, TEAC, etc.) in vitro and limited data of antiradical activity of coffee products in vitro and in vivo. Comparison is carried out of the AA of coffee Arabica and coffee Robusta roasted at different temperatures as well as by different roasting methods (microwave, convection, etc.). Data on the antiradical activity of coffee is provided. The antioxidant activity of coffee, tea, cocoa, and red wine is compared. At the end of this review, the total antioxidant content (TAC) of coffee samples from 21 coffee-producing countries as measured by an amperometric method is provided. The TAC of green and roasted coffee beans is also compared.

Brewing conditions impact on the composition and characteristics of cold brew Arabica and Robusta coffee beverages

Coffee is one of the most widely consumed beverages in the world, because of its unique sensory properties and physiological properties. Coffee beverages represent a significant source of antioxidants in the consumers' diet and contribute significantly to their daily intake. The aim of this research was to investigate the effect of different roasting degrees on the content of biologically active compounds and antioxidant activity in different quality classes of Arabica coffee. Samples of green Arabica coffee (Rio Minas) of two quality classes from two production batches were used for the research. Roasting was carried out at temperatures of 167, 175 and 171°C. The total phenol content (TPC), total flavonoid content (TFC), flavonol content (FC) and antioxidant activity (DPPH, ABTS) in the coffee extracts was determined. This research shows that TPC was significantly higher (P < 0.05) in green coffee compared to TPC in roasted coffee, and TPC decreases as the roasting temperature increases. TFC and FC were significantly lower (P < 0.05) in green coffee than in roasted coffee. Differences in TPC between the 1st and 2nd classes of Arabica coffee were not significant (P > 0.05), while differences in TFC were significant (P < 0.05) only for green coffee from the second production batch and differences in FC were significant (P < 0.05) for green coffee and for coffee roasted at 175°C. Roasting temperatures have different influences the antioxidant activity (DPPH, ABTS) of coffee and the highest antioxidant activity was determined in coffee roasted at 171°C. An exception was 1st class Arabica coffee roasted at 167°C (ABTS). All samples of 1st class Arabica coffee had higher antioxidant activity (DPPH, ABTS) compared to 2nd class Arabica. This research shows that the bioactive compounds content and antioxidant activity of different quality classes of Arabica coffee are dependent on the degree of roasting. TPC decreases when the roasting temperature increases, while TFC and FC also increase. These results indicate that the antioxidant activity of coffee depends on a variety of bioactive components in coffee beans. Antioxidant activity largely depends on the class of coffee. The coffee samples of 1stclass quality (maximum 8 black beans/300 g from the sample and large bean size) had higher antioxidant activity compared to samples of 2nd quality class (maximum 19 black beans/300 g in the sample and medium-sized beans).

Ekstraksi teknik cold brew mulai berkembang dikalangan masyarakat yaitu menggunakan air bersuhu ruang yang didiamkan 6-18 jam. Metode ini digunakan untuk menyeduh kopi atau teh dengan kualitas yang baik tapi membutuhkan waktu yang cukup lama. Oleh karena itu perlu metode ekstraksi yang lebih cepat tanpa mengurangi kualitas produk yang dihasilkan. Salah satunya yaitu Ultrasonic assisted extraction (UAE) merupakan metode ekstraksi berbantu ultrasonik yang dapat menghasilkan ekstrak cukup baik pada suhu ruang dalam waktu yang lebih singkat bahkan mampu menghasilkan ukuran partikel dalam skala nanometer. Untuk itu, dilakukan penelitian ekstraksi teh hijau menggunakan metode UAE dalam temperatur rendah (dibawah suhu ruang). Tujuan Penelitian ini adalah mengetahui pengaruh suhu dan waktu ekstraksi terhadap ukuran partikel menggunakan UAE cold brew serta menentukan waktu dan suhu optimum pengekstraksi untuk menghasilkan berat terekstraksi tertinggi dan melakukan analisis distribusi ukuran partikel ekstrak yang dihasilkan. Proses UAE menggunakan air suhu (10, 15, 20 ºC) dan waktu (5, 10, 30 menit). Sebagai kontrol dilakukan ekstraksi maserasi cold brew menggunakan suhu ruang selama 12 jam didiamkan pada lemari pendingin dan hot brew suhu 70ºC selama 10 menit. Analisis kepekatan warna dilakukan untuk menentukan sample yang akan diuji PSA. Hasil analisis kepekatan warna menunjukan ekstraksi UAE suhu 10ºC dengan variasi waktu 5,15,30 menit yang paling sesuai dengan karakteristik larutan teh hijau. Uji PSA menghasilkan ukuran paling kecil pada suhu 10ºC selama 30 menit dengan rata-rata ukuran 293.64 nm. Waktu dan suhu optimum untuk menghasilkan berat terekstraaksi terbanyak pada suhu 20ºC 30 menit sebesar 0,82 gram dari 6 gram sample teh hijau. Hasil ini menunjukan ekstraksi UAE dapat mempersingkat waktu, meningkatkan berat terekstraksi dan menghasilkan ukuran nanometer.Kata kunci : Cold Brew; Ekstraksi; PSA; Teh Hijau; UAE ABSTRACT The extraction of cold brew techniques has begun to develop among the community, by using room temperature water that is left to rest for 6-18 hours. This method is used to brew coffee or tea with good quality but it takes a long time. Therefore, it needs a faster extraction method without reducing the quality of the product produced. One of them is Ultrasonic assisted extraction (UAE) which is an ultrasonic-assisted extraction method that can produce extracts quite well at room temperature in a shorter time and is even able to produce particle sizes on the nanometer scale. For this reason, a research on green tea extraction was carried out using the UAE method at low temperature (below room temperature). The purpose of this study is to determine the effect of temperature and extraction time on particle size using UAE cold brew and to determine the optimum extraction time and temperature to produce the highest extracted weight and analyze the particle size distribution of the extracts. The UAE process uses water temperature (10, 15, 20 ºC) and time (5, 10, 30 minutes). As a control, the cold brew maceration extraction was carried out using room temperature for 12 hours, left in the refrigerator then hot brew at 70ºC for 10 minutes. Color density analysis is carried out to determine the sample to be tested for PSA. The results of the color density analysis showed that the UAE extraction temperature was 10ºC with a time variation of 5.15.30 minutes which was the most suitable with the characteristics of the green tea solution. The PSA test produced the smallest size at 10ºC for 30 minutes with an average size of 293.64 nm. The optimum time and temperature to produce the most extracted weight were at 20ºC 30 minutes at 0.82 grams from 6 grams of green tea samples. These results showed that the UAE extraction can shorten the time, increase the weight extracted and produce a nanometer size.Keywords : Cold Brew; Extraction; PSA; Green tea; UAE

Study of the effect of microwave roasting method on volatile compounds and some physicochemical attributes and sensory properties of green coffee bean

Coffee has a positive effect on health due to its high content of antioxidant compounds. The potential antioxidant activity of coffee is strongly influenced by its chemical compound profile. This study aimed to analyze the effect of different solvents on the chemical metabolites profile, antioxidant activity, and to determine the relevant chemical functional groups which positively contribute to the coffee’s antioxidant activity. In this study, methanolic extract of coffee samples from robusta and arabica varieties were fractionated by liquid-liquid fractionation method using four solvents with different polarities. ABTS (2,2'-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) and cupric reducing antioxidant capacity (CUPRAC) assays were applied to measure the antioxidant activity of the coffee fractions. Fourier Transform Infrared- Attenuated Total Reflectance (FTIR-ATR) based chemometric approach was used to identify the compound functional groups as the fingerprinting profile of the coffee fractions. Correlation between the FTIR-ATR fingerprinting with the antioxidant activity of the coffee fractions was studied using multivariate data analysis, i.e. Principal Component Analysis (PCA) and Orthogonal Partial Least Squares (OPLS). From this study, a reliable PCA model to evaluate the effect of different solvents to FTIR-ATR fingerprinting profile was produced. The correlation between FTIR-ATR fingerprinting profile with the antioxidant activity and the characterization of the chemical functional groups relevant to its antioxidant activity can be analyzed by a reliable OPLS model obtained. This study suggests that the highest antioxidant potential in coffee is found in ethyl acetate fraction both in robusta and arabica coffee samples, while the relevant chemical functional groups having positive correlation to antioxidant activity of coffee were phenol, carbonyl, cyclohexane, aromatic, amide, phenyl, amino, and alkene groups.

Norovirus (NoV) is a symptomatic virus that is the leading cause of gastrointestinal disease. It spreads easily through the fecal-oral route and contact with contaminated food or surfaces. Maintaining a high level of hygiene in food industry settings and refocusing food production on isolating and testing natural compounds that exhibit antimicrobial and antioxidant properties are important elements in preventing NoVs infection. This study evaluated plant extracts prepared by cold brew and cold concentrate techniques for their antioxidant and antiviral activity. The extracts obtained demonstrated high antioxidant activity, with notable variation depending on the plant material, ranging from moderate to very strong levels. Correspondingly, high antiviral potential was observed, reaching the nearly complete inactivation of the virus. Remarkably, the highest virucidal effects were already achieved at relatively elevated, but not maximal, antioxidant activity levels. The results of the study indicate that cold water extraction techniques allow for the obtention of plant extracts showing strong virus-inactivating activity and favorable antioxidant activity.

Cold and hot water extracts (2, 6 and 10%) were prepared from parching green tea and its antioxidant properties studied and potential antioxidant components determined. Yields of hot water extracts (17.53–28.63%) were significantly higher than those of cold water extracts (13.34–16.14%). The half maximal effective concentration (EC50) values in antioxidant activity and reducing power were 2.17–2.75 and 0.22–0.30 mg/mL, respectively. Scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl radicals were comparable. EC50 values in scavenging ability on hydroxyl radicals and chelating ability on ferrous ions were 3.31–4.54 and 1.63–3.09 mg/mL, respectively. Contents of total phenols were 220.52–339.83 mg/g whereas those of total catechins in cold and hot water extracts were 130.22–146.28 mg/g and 136.40–191.33 mg/g, respectively. Based on the results obtained, hot water extracts were more effective in antioxidant activity, reducing power and scavenging ability on hydroxyl radicals but less effective in chelating ability on ferrous ions. PRACTICAL APPLICATIONS Tea is one of popular drinks in the world. The consumption of green tea is especially popular in Asia, mainly for its health benefits. Parched tea is a Chinese style green tea, which is different from the Japanese style steamed tea. Recently, the tea prepared by brewing tea leaves in cold water has become a new choice in Taiwan in addition to traditionally hot water-brewed tea. Results from this research, the cold and hot water extracts of green tea are good antioxidant. Besides, green tea is also reported to reduce serum cholesterol levels and inhibit hypertension, mutagenesis, and tumourigenesis in several experiments in vitro and in vivo. Therefore, the extract of green tea has the potential to be developed into new health foods, and the cold brewing would be a new alternative way to make a tea.

Coffee is one of the most often consumed beverages almost all over the world. The multiplicity of beans, as well as the methods and parameters used to brew, encourages the optimization of the brewing process. The study aimed to analyze the effect of roasting beans, the brewing technique, and its parameters (time and water temperature) on antioxidant activity (determined using several in vitro methods), total polyphenols, flavonoids, and caffeine content. The infusions of unroasted and roasted Arabica beans from Brazil, Colombia, India, Peru, and Rwanda were analyzed. In general, infusions prepared from roasted beans had higher antioxidant activity and the content of above-mentioned compounds. The hot brew method was used to obtain infusions with a higher antioxidant activity, while the cold brew with higher caffeine content. The phenolic compound content in infusions prepared using both techniques depended on the roasting process. Moreover, the bean’s origin, roasting process, and brewing technique had a significant effect on the tested properties, in contrary to brewing time and water temperature (below and above 90 °C), which had less impact. The results confirm the importance of coffee brewing optimization.

&amp;lt;p&amp;gt;The aim of this paper is to develop specification for the production of roasted coffee with improved nutritional quality. In this sense, the influence of different coffee blends and temperatures of roasting on the antioxidant activity of coffee was examined. Also, the composition of some bioactive components in the analyzed samples was determined. Two Arabica coffees of different quality and Robusta coffee were used for preparation of coffee blends. Experimentally determined green coffee blends B1, B2 and B3 were roasted at 167&amp;amp;deg;C, 171&amp;amp;deg;C and 175&amp;amp;deg;C for 25 minutes in order to establish the effect of temperature roasting on the antioxidant activity and the content of bioactive components in blends. Based on results of DPPH and ABTS test, coffee blends B3 and B2, roasted at 171&amp;amp;deg;C, had the highest (P&amp;amp;lt;0.05) antioxidant activity. Those coffee blends had higher content of Robusta coffee than coffee blend B1. Results of this research can provide opportunities for development roasted ground coffee with improved nutritive quality, which could ensure competitiveness of producers in the target market.&amp;lt;/p&amp;gt;

This study investigated a continuous circulation cold brewing (CCCB) process using a modified single‐serve brewer that allowed recirculation of the brew within the single‐use capsules. The changes of total dissolved solids (TDS), titratable acidity (TA), caffeine and 5‐caffeoylquinic (5‐CQA) concentrations over time during the CCCB process were evaluated using two masses of coffee grounds (10 and 12.5 g). To elucidate the extraction process, Weibull distribution, pseudo‐first order, and pseudo‐second order models were fitted to the extraction kinetics data. The physicochemical quality of the brews produced from the CCCB process were also compared to brews produced though traditional cold brew steeping (separated by gravity and forced filtration) and single‐serve hot brewing processes. Significantly lower (p &lt; 0.05) TDS, TA, and 5‐CQA concentrations than traditional cold brew methods were observed. This observation was due to flow channeling/detachment phenomena in the coffee bed which resulted in localized flow and reduction of coffee‐water contact area. In comparison, the 30 min full immersion processes resulted in approximately 70% of the TDS, TA, and caffeine levels during the first 30 min of brewing, suggesting that cold brewing processes may not have to be &gt;8 h in length if these are the targeted brew quality indices.Practical applicationsThis study examined the kinetics and physicochemical quality of continuous circulation cold brewing of coffee and compared it to traditional full immersion cold brewing methods. The findings in this study indicated that: (1) The brew recirculation method explored was not on par with traditional full immersion cold brewing methods in terms of extraction yield due to flow channeling issues present in single‐use capsules; (2) The extraction time of traditional cold brewing processes can potentially be shortened on the basis of TDS, TA and caffeine content; (3) The choice of filtration mechanism is significant when considering the extraction yield of a brewing process.

The cold brew coffee (CBC) trend is increasing globally; nevertheless, there is limited literature on this popular beverage. Many studies have focused on the health benefits of green coffee beans and coffee brewed by conventional hot water methods. Thus, whether cold brew conveys similar benefits is still unclear. This study aimed to investigate the influences of brewing conditions on physicochemical properties using response surface methodology in order to optimize the brewing parameters and compare the resulting CBC with the coffee from the French Press method. Central Composite Design was used to evaluate the effects and optimize the brewing parameters (i.e., water temperature, coffee-to-water ratio (C2WR), coffee mesh size, and extraction time) on total dissolved solids (TDS). Physicochemical properties, antioxidant activity, volatile compounds, and organic acids were compared between CBC and its French Press counterpart. Our results showed that water temperature, C2WR, and coffee mesh size significantly influenced the TDS of CBC. The optimized brewing conditions were water temperature (4 °C), C2WR (1:14), coffee mesh size (0.71 mm), and 24-h extraction time. At similar TDS, caffeine content, volatile compounds, and organic acids were higher in CBC, while other properties showed no significant difference. In conclusion, this study showed that at similar TDS, CBC has characteristics generally similar to hot brew coffee, except for the caffeine and sensory-related compound content. The model for the prediction of TDS from this study may benefit food services or industries for the optimization of brewing conditions to obtain different characteristics of CBC.

Coffee is one of the most popular beverages which are rich in sensory attributes. What is the best time for brewing coffee after roasting is important question for consumer. In general, people do not directly brew coffee that has just been roasted. The chemical change which causes sensory changes still continues during the resting time. Enjoying coffee is about taste, everyone has different preferences. Some people prefer bitter coffee; some people like the sour taste and some others consume sweet coffee. Therefore, information about sensory and chemical profile is needed to give several options for consumer to choose their brewing method and brewing time before the coffee has decreased in sensory quality. This current study aims to know sensory and chemical changes of cold and hot brew Arabica coffee at various resting time. The materials were coffee beans Arabica Jawa Gunung Halu obtained from Cibeber, Sidangkerta Village, Mekarsari District, Bandung Regency, West Java. The roasted bean stored at various resting time (1, 3, 5, 7, and 9 days) than brewed in cold and hot brew methods. Sensory evaluation was conducted by 10 trained panelists using quantitative descriptive analysis (QDA). Furthermore, chemical analyses which were evaluated consist of the value of pH, brix and Total Dissolved Solid (TDS). The results showed that longer resting time followed by sensory characteristics changes on aroma, after taste, sweetness that is in line with chemical attributes change in Brix. Moreover color change in line with TDS change. While the different brewing techniques show that hot brew has higher value than cold brew in most all of parameters except Brix value. Keywords — chemical, coffee, panelists , resting time, sensory

Arabica coffee beans exhibit high antioxidant activity, measuring 128.8±18.7 µg TE/mg. Post-harvest processing of coffee beans can influence antioxidant activity, TFC (Total Flavonoid Content), and TPC (Total Phenolic Content) due to the fermentation processes involved. This study aims, firstly, to determine whether there are differences in antioxidant activity across various post-harvest processes of Arabica coffee. Secondly, it seeks to identify the process that yields the highest antioxidant activity in Arabica coffee. Thirdly, it aims to determine the highest TFC in Arabica coffee, and fourthly, to identify the highest TPC in Arabica coffee. The research utilized an experimental method with three replications. The independent variable was the post-harvest processing methods of coffee, while antioxidant activity was measured using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method, TFC was measured using the aluminum chloride (AlCl3) method, and TPC was measured using the Folin-Ciocalteu method. The results showed significant differences in antioxidant activity. Arabica coffee processed using the honey method exhibited the highest antioxidant activity, with an IC50 value of 76.31 ppm, categorized as very strong. Post-harvest processing was found to influence antioxidant activity in honey and civet (luwak) coffee. Civet coffee had the highest TFC, measuring 1.40 mg QE/g extract, while Arabica coffee processed using the full-wash method had the highest TPC, measuring 83.47 mg GAE/g extract. In conclusion, post-harvest processes such as honey and civet significantly affect antioxidant activity, with values of 76.31 ppm and 164.05 ppm, respectively. The honey process produced coffee with the highest antioxidant activity (IC50 76.31 ppm). The post-harvest process for civet coffee resulted in the highest TFC, measuring 1.40 mg QE/g extract.

The acidity and antioxidant activity of cold brew coffee were investigated using light roast coffees from Brazil, two regions of Ethiopia, Columbia, Myanmar, and Mexico. The concentrations of three caffeoylquinic acid (CQA) isomers were also determined. Cold brew coffee chemistry was compared to that of hot brew coffee prepared with the same grind-to-coffee ratio. The pH values of the cold and hot brew samples were found to be comparable, ranging from 4.85 to 5.13. The hot brew coffees were found to have higher concentrations of total titratable acids, as well as higher antioxidant activity, than that of their cold brew counterparts. It was also noted that both the concentration of total titratable acids and antioxidant activity correlated poorly with total CQA concentration in hot brew coffee. This work suggests that the hot brew method tends to extract more non-deprotonated acids than the cold brew method. These acids may be responsible for the higher antioxidant activities observed in the hot brew coffee samples.