Добірка наукової літератури з теми "Roasting degree"

On this work, the experimental implementation of a cascade control algorithm to regulate coffee roasting degree in a batch spouted bed process is presented. The control algorithm is composed of an inner control loop that regulates the temperature of the hot air inflow used to roast coffee grains inside a spouted bed, while an outer control loop, based on imaging processing techniques, tracks on real time the coffee roasting degree and decides if the inflow air temperature must be modified. To achieve this goal, a colour-matching algorithm is used to compare a colour spectrum obtained from images acquired on real time, from a peephole on the spouted bed, with the colour spectrums of several reference images with different degrees of roasting. Match scores are computed based on the similarity between the colour spectrums. With the match scores, a roasting index is finally calculated to assess the degree of roasting, allowing to automatically track the roasting progress to decide if the batch roasting process has achieved the desired roasting degree. The experimental results show that the control scheme is able to robustly achieve the desired roasting degree with excellent effectiveness.

Introduction: Coffee is one of the most widely consumed beverages in the world. The desired aroma and flavour of coffee are developed duringroasting which is the most important step in coffee processing. Instant Controlled Pressure Drop Process (DIC) technology is controlled hightemperature and short time process which been used successfully to improving the kinetics of drying, extraction, and decontamination of fresh and dried natural products. The main advantages of DIC are that it is a master controlled temperature and time process, the dwell times are short, reducing the chemical degradation, so new products with superior quality attributes may be developed. Materials and Methods: Two coffee beans varieties were investigated by Brazilian and Ethiopian sources. The raw beans were pre-treated using the DIC process under adopted conditions prior to roasting. A two-factor central composite design was used to optimize the settings of roasting time and roasting temperature on response variables of bulk, true and normalized density, and roasting degree. Also, microscopic analysis using Scanning Electron Microscopy (SEM) and kinetics of the roasting processes are included. Results and Discussion: The obtained results confirmed that the roasted DIC treated beans for both varieties have lower densities, higher roasting degree and lower activation energy needed for roasting compared to the raw beans. The physical properties’ magnitude is highly relevant to coffee origin. Roasting time and the temperature seemed to be of significant regarding all the physical characteristics of the beans, however, time was of topmost significance. Besides, treating coffee been by DIC prior to roasting leads to texture modification and conservation of time and energy needed for roasting. Conclusions: The physical properties of the roasted coffee beans are highly affected and changed with the coffee origin, roasting conditions and pre-treatment of coffee beans prior to roasting using the DIC process. The incorporation of the DIC process prior to roasting seemed to achieve more conservation of time and energy needed for roasting compared to the raw untreated beans. The higher degree of roasting and the competitive roasting activation energy of Brazilian coffee beans give aconclusion that more economic roasting process could be achieved with the Brazilian coffee. The pre-treatment by DIC enhances the remarkable reduction in coffee beans density and increasing in the roasting degrees that are in line with the industrial needs of coffee beverages. Response Surface Methodology is an efficient tool for optimization and mathematical modeling of the coffee roasting process.

Coffee roasting is the process of applying heat to green coffee beans to bring out flavors through chemical changes. This study aimed to investigate the effect of roasting degree on the antioxidant capacities of espresso and drip coffee extracted from Coffea arabica cv. Java in Laos. Green coffee beans were roasted under four conditions (Light-medium, Medium, Moderately dark, and Very dark), and espresso and drip coffee were extracted. The contents of total phenolics (TP), total flavonoids (TF), and chlorogenic acids (CGA) decreased as the roasting degree increased, whereas the caffeine content increased. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was lower in the Medium, Moderately dark, and Very dark compared to the Light-medium. The ferric reducing antioxidant power (FRAP) was lower in the Very dark than the Light-medium, Medium, and Moderately dark. Principal component analysis showed that TP, TF, CGA, caffeine, DPPH radical scavenging activity, and FRAP distinguish coffee extracts with various roasting degrees. Therefore, it is concluded that roasting degree is a modifiable factor for the use of coffee as an antioxidant material in the food industry, and TF, TP, CGA, and caffeine contents, DPPH radical scavenging activity and FRAP are good indicators for determining the antioxidant capacity of coffee.

We evaluated the differences in total polyphenol content (TPC) of beverages prepared by three methods (Hario V60, espresso and pour-over coffee) using single-origin beans roasted at four temperatures. The beans were roasted based on the degree of roasting: the lightest roasting had a final temperature of 204 °C (first roasting), a slightly darker roasting had a final temperature of 205 °C (second roasting), a dark roasting had a final temperature of 215 °C (third roasting) and the darkest roasting had a final temperature of 220 °C (fourth roasting). TPC in the beverage was highest for the Hario V60 for all temperatures, ranging from 32.0 to 46.8 mg GAE g–1 (gallic acid equivalent per 1 g of ground beans). The third roasting had the highest TPC, ranging from 34.6 to 46.8 mg GAE g–1 for all methods of preparation, whereas the content for the fourth roasting ranged from 28.6 to 32.3 mg GAE g–1. Our results indicated that the differences in TPC in the beverage depended on the preparation method (P < 0.001) and the degree of roasting (P < 0.001). The most nutritional coffee was prepared using the Hario V60 with the third roasting.

Abstract The demand for specialty coffee has increased over the past few years, and several cafes and coffee roasteries are starting to enter the market. Coffee roasting is considered art rather than science that requires a lot of experience from a master roaster. The key parameters used to identify the roast status of the beans are the initial temperature and roasting time from bean samples. The degree of roasting is often the first consideration for consumers when buying coffee. Some of the flavor attributes used to assess coffee are body, aroma, and acidity. Many studies have been done to evaluate the quality of roasted coffee experimentally using different parameters. However, these techniques could not be implemented in real-time and have their limitations. The current need for roasteries is a method of controlling the quality of roasted coffee through risk and a real-time approach. This paper presents a review carried out the methods used to determine roasting degree on risk perspective. This review has covered recent research on coffee roasting evaluation methods on physical, physicochemical, and chemical composition changes.

The applicability of chloridizing roasting for removal of copper from the sulphide copper smelting waste slag of the ”Karabashmed'” copper-smelting plant is investigated. Calcium chloride CaCl2 was used as chlorination agent. It is established that the chlorinating roasting of the initial slag presented by fayalite 2FeO∙SiO2, hasn't led to noticeable removal of copper. Considerable degree of removal of copper (more than 90 %) has been reached as a result of the chlorinating of preliminary oxidized slag in which fayalite was oxidized to form Fe2O3 and SiO2. Using a fractional factorial experiment 23–1, dependence of degree of copper removal from preliminary oxidized slag upon temperature of the chlorinating roasting, time of isothermal roasting period and content of CaCl2 was established. It is found that increase of temperature and of CaCl2 content leads to increase in degree of copper removal. The influence of time of isothermal roasting period in the studied interval (2–4 h) is statistically insignificant.

An effect of a processing method (dry and wet) and a degree of roasting (light, medium, and dark) of 15 coffee (Coffea arabica) samples on the content of caffeine, chlorogenic acid (CQA), total polyphenols (TPP), acrylamide (AA), and on the colour parameters L*, a*, and b* was evaluated. Neither processing nor roasting affected caffeine content (p > 0.05). The degree of roasting accounted for 46% and 72% of explained variability of the CQA content and AA content, respectively (p < 0.05). AA content was in the range from 250 (wet-processed, light-roasted samples) to 305 µg·kg−1 (wet-processed, dark-roasted coffees), but the dark roasting only tended (p > 0.05) to increase AA content. Wet-processed, dry-roasted coffee had higher (p < 0.05) TPP content (48.5 mg·g−1) than its dry-processed, dry-roasted counterpart (42.5 mg·g−1); the method of processing accounted for 70% of explained variability of TPP. Both the method of processing and the degree of roasting affected the L*, a*, and b* values (p < 0.01), but the lower values (p < 0.05) of these parameters in the dark-roasted samples were found only within the wet processing. A negative correlation between the AA content and lightness (L*) was established (r = −0.39, p < 0.05). It was concluded that from the consumers’ viewpoint, the results of the present study indicate relatively small differences in quality parameters of coffee irrespective of the method of processing or degree of roasting.

Taking high nitrogen aluminum dross as the research object, the effects of the additives sodium carbonate and cryolite and the roasting process on the denitrification effect of aluminum dross were studied. The principle of additive denitrification was studied by XRD, SEM and TG-DSC. The experimental results show that sodium carbonate and cryolite can quickly reduce the content of aluminum nitride in aluminum dross. The optimum denitrification process parameters were also obtained simultaneously. When the mass ratio of cryolite to aluminum dross was 0.4, the roasting temperature was 900 °C, and the roasting time was 3 h, the denitrification degree could reach 96.19%. When the mass ratio of sodium carbonate to aluminum dross was 0.8, the roasting temperature was 1000 °C, and the roasting time was 4 h, the denitrification degree could reach 91.32%. This study provides a reference for the non-harmful treatment of high nitrogen aluminum dross.

Drinking coffee has become part of our everyday culture. Coffee cultivation is devoted to over 50 countries in the world, located between latitudes 25 degrees North and 30 degrees South. Almost all of the world's coffee production is provided by two varieties, called ‘Arabica’ and ‘Robusta’ whereas the share of Arabica is 70% of the world's coffee harvest. Green (raw) coffee can not be used to prepare coffee beverages, coffee beans must first be roasted. Roasting coffee and reaching a certain degree of coffee roasting determine its flavor and aroma characteristics. In the present study the fate of sucrose, chlorogenic acid, acetic acid, formic acid, lactic acid, caffeic acid, total phenolic compounds and 5-hydroxymethylfurfural was studied in coffee (Brazil Cerrado Dulce, 100% Arabica) roasted in two ways (Medium roast and Full city roast). It has been found that almost all sucrose has been degraded (96 – 98%) in both roasting ways. During Medium roast 65% of chlorogenic acid contained in green coffee was degraded while during Full city roast it was 85%. During both Medium and Full city roasting, the formation of acetic acid but especially formic and lactic acid was recorded. The highest concentration of organic acids was recorded at Full City roasting at medium roasting times (3.3 mg.g-1 d.w. acetic acid, 1.79 mg.g-1 d.w. formic acid, 0.65 mg.g-1d.w. lactic acid). The amount of phenolic substances also increased during roasting up to 16.7 mg.g-1 d.w. of gallic acid equivalent. Highest concentrations of 5-hydroxymethylfurfural were measured at medium roasting times at both Medium (0.357 mg.g-1 d.w.) and French city (0.597 mg.g-1 d.w.) roasting temperatures. At the end of roasting, the 5-hydroxymethylfurfural concentration in coffee were 0.237 mg.g-1 d.w. (Medium roast) and 0.095 mg.g-1 d.w. (Full city roast).

<em>Quality and techno-economic improvement is important to increase export value of coffee in Indonesia. Complex roasting is one excellent method in increasing the added value of coffee, such as Coffea arabica var. Sigarar Utang which is the best coffee variety in Indonesia. The study was carried out at The Indonesian Industrial and Beverage Crops Research Institute (IIBCRI), Sukabumi, West Java, from January to November 2020 which aimed: (1) to evaluate the effect of initial temperature and roasting degree on the quality of Sigarar Utang coffee bean, and (2) to evaluate the mass balance and economic feasibility of the best roasting treatment. This study was designed in a factorial completely randomized design, using 2 factors, and 2 replications. The first factor was the initial temperature which consisted of 2 levels (185 ^oC dan 210 ^oC), and the second factor was the roasting degree which consisted of 2 levels (light-medium and medium-dark). The variables observed were the water content, ash content, bulk density, brix, titratable acidity, pH, radical scavenging (antioxidant) activity, and caffeine content. The results showed that the complex roasting method with an initial temperature of 210 ^oC and mild-moderate roasting degrees generated a quality of Sigarar Utang coffee originating from Gunung Putri, IIBCRI, closest to the quality I of SNI 01-3542-2004. The roasted coffee beans have a special taste (score 86.51) which is a high added value. The production economic value is feasible to be adopted by small-medium scale coffee industry.</em>

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第19019号
農博第2097号
新制||農||1029(附属図書館)
学位論文||H27||N4901(農学部図書室)
31970
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 近藤 直, 教授 清水 浩, 准教授 小川 雄一
学位規則第4条第1項該当

Doutoramento em Bioquímica
Os polissacarídeos são os componentes maioritários dos grãos de café verde e torrado e da bebida de café. Os mais abundantes são as galactomananas, seguindo-se as arabinogalactanas. Durante o processo de torra, as galactomananas e arabinogalactanas sofrem modificações estruturais, as quais estão longe de estar completamente elucidadas devido à sua diversidade e à complexidade estrutural dos compostos formados. Durante o processo de torra, as galactomananas e arabinogalactanas reagem com proteínas, ácidos clorogénicos e sacarose, originando compostos castanhos de alto peso molecular contendo nitrogénio, designados de melanoidinas. As melanoidinas do café apresentam diversas atividades biológicas e efeitos benéficos para a saúde. No entanto, a sua estrutura exata e os mecanismos envolvidos na sua formação permanecem desconhecidos, bem como a relação estrutura-atividade biológica. A utilização de sistemas modelo e a análise por espectrometria de massa permitem obter uma visão global e, simultaneamente, detalhada das modificações estruturais nos polissacarídeos do café promovidas pela torra, contribuindo para a elucidação das estruturas e mecanismos de formação das melanoidinas. Com base nesta tese, oligossacarídeos estruturalmente relacionados com a cadeia principal das galactomananas, (β1→4)-Dmanotriose (Man3), e as cadeias laterais das arabinogalactanas, (α1→5)-Larabinotriose (Ara3), isoladamente ou em misturas com ácido 5-Ocafeoilquínico (5-CQA), o ácido clorogénico mais abundante nos grãos de café verde, e péptidos compostos por tirosina e leucina, usados como modelos das proteínas, foram sujeitos a tratamento térmico a seco, mimetizando o processo de torra. A oxidação induzida por radicais hidroxilo (HO•) foi também estudada, uma vez que estes radicais parecem estar envolvidos na modificação dos polissacarídeos durante a torra. A identificação das modificações estruturais induzidas por tratamento térmico e oxidativo dos compostos modelo foi feita por estratégias analíticas baseadas principalmente em espectrometria de massa, mas também em cromatografia líquida. A cromatografia de gás foi usada na análise de açúcares neutros e ligações glicosídicas. Para validar as conclusões obtidas com os compostos modelo, foram também analisadas amostras de polissacarídeos do café obtidas a partir de resíduo de café e café instantâneo. Os resultados obtidos a partir dos oligossacarídeos modelo quando submetidos a tratamento térmico (seco), assim como à oxidação induzida por HO• (em solução), indicam a ocorrência de despolimerização, o que está de acordo com estudos anteriores que reportam a despolimerização das galactomananas e arabinogalactanas do café durante a torra. Foram ainda identificados outros compostos resultantes da quebra do anel de açúcares formados durante o tratamento térmico e oxidativo da Ara3. Por outro lado, o tratamento térmico a seco dos oligossacarídeos modelo (individualmente ou quando misturados) promoveu a formação de oligossacarídeos com um maior grau de polimerização, e também polissacarídeos com novos tipos de ligações glicosídicas, evidenciando a ocorrência de polimerização através reações de transglicosilação não enzimática induzidas por tratamento térmico a seco. As reações de transglicosilação induzidas por tratamento térmico a seco podem ocorrer entre resíduos de açúcares provenientes da mesma origem, mas também de origens diferentes com formação de estruturas híbridas, contendo arabinose e manose como observado nos casos dos compostos modelo usados. Os resultados obtidos a partir de amostras do resíduo de café e de café instantâneo sugerem a presença de polissacarídeos híbridos nestas amostras de café processado, corroborando a ocorrência de transglicosilação durante o processo de torra. Além disso, o estudo de misturas contendo diferentes proporções de cada oligossacarídeo modelo, mimetizando regiões do grão de café com composição distinta em polissacarídeos, sujeitos a diferentes períodos de tratamento térmico, permitiu inferir que diferentes estruturas híbridas e não híbridas podem ser formadas a partir das arabinogalactanas e galactomananas, dependendo da sua distribuição nas paredes celulares do grão e das condições de torra. Estes resultados podem explicar a heterogeneidade de estruturas de melanoidinas formadas durante a torra do café. Os resultados obtidos a partir de misturas modelo contendo um oligossacarídeo (Ara3 ou Man3) e 5-CQA sujeitas a tratamento térmico a seco, assim como de amostras provenientes do resíduo de café, mostraram a formação de compostos híbridos compostos por moléculas de CQA ligadas covalentemente a um número variável de resíduos de açúcar. Além disso, os resultados obtidos a partir da mistura contendo Man3 e 5-CQA mostraram que o CQA atua como catalisador das reações de transglicosilação. Por outro lado, nas misturas modelo contendo um péptido, mesmo contendo também 5-CQA e sujeitas ao mesmo tratamento, observou-se uma diminuição na extensão das reações transglicosilação. Este resultado pode explicar a baixa extensão das reações de transglicosilação não enzimáticas durante a torra nas regiões do grão de café mais ricas em proteínas, apesar dos polissacarídeos serem os componentes maioritários dos grãos de café. A diminuição das reações de transglicosilação na presença de péptidos/proteínas pode dever-se ao facto de os resíduos de açúcares redutores reagirem preferencialmente com os grupos amina de péptidos/proteínas por reação de Maillard, diminuindo o número de resíduos de açúcares redutores disponíveis para as reações de transglicosilação. Além dos compostos já descritos, uma diversidade de outros compostos foram formados a partir dos sistemas modelo, nomeadamente derivados de desidratação formados durante o tratamento térmico a seco. Em conclusão, a tipificação das modificações estruturais promovidas pela torra nos polissacarídeos do café abre o caminho para a compreensão dos mecanismos de formação das melanoidinas e da relação estrutura-atividade destes compostos.
Polysaccharides are the major components of green and roasted coffee beans, and coffee brew. The most abundant ones are galactomannans, followed by arabinogalactans. During the roasting process, galactomannans and arabinogalactans undergo structural modifications that are far to be completely elucidated due to their diversity and complexity of the compounds formed. During the roasting process, galactomannans and arabinogalactans react with proteins, chlorogenic acids, and sucrose, originating high molecular weight brown compounds containing nitrogen, known as melanoidins. Several biological activities and beneficial health effects have been attributed to coffee melanoidins. However, their exact structures and the mechanisms involved in their formation remain unknown, as well as the structure-biological activity relationship. The use of model systems and mass spectrometry analysis allow to obtain an overall view and, simultaneously, detailed, of the structural modifications in coffee polysaccharides promoted by roasting, contributing to the elucidation of the structures and formation mechanisms of melanoidins. Based on this thesis, oligosaccharides structurally related to the backbone of galactomannans, (β1→4)-D-mannotriose, and the side chains of arabinogalactans, (α1→5)-Larabinotriose, alone or in mixtures with 5-O-caffeoylquinic acid, the most abundant chlorogenic acid in green coffee beans, and dipeptides composed by tyrosine and leucine, used as models of proteins, were submitted to dry thermal treatments, mimicking the coffee roasting process. The oxidation induced by hydroxyl radicals (HO•) was also studied, since these radicals seem to be involved in the modification of the polysaccharides during roasting. The identification of the structural modifications induced by thermal and oxidative treatment of the model compounds was performed mostly by mass spectrometry-based analytical strategies, but also using liquid chromatography. Gas chromatography was used in the analysis of neutral sugars and glycosidic linkages. To validate the conclusions achieved with the model compounds, coffee polysaccharide samples obtained from spent coffee grounds and instant coffee were also analysed. The results obtained from the model oligosaccharides when submitted to thermal treatment (dry) or oxidation induced by HO• (in solution) indicate the occurrence of depolymerization, which is in line with previous studies reporting the depolymerization of coffee galactomannans and arabinogalactans during roasting. Compounds resulting from sugar ring cleavage were also formed during thermal treatment and oxidative treatment of Ara3. On the other hand, the dry thermal treatment of the model oligosaccharides (alone or when mixed) promoted the formation of oligosaccharides with a higher degree of polymerization, and also polysaccharides with new type of glycosidic linkages, evidencing the occurrence of polymerization via non-enzymatic transglycosylation reactions induced by dry thermal treatment. The transglycosylation reactions induced by dry thermal treatment can occur between sugar residues from the same origin, but also of different origins, with formation of hybrid structures, containing arabinose and mannose in the case of the model compounds used. The results obtained from spent coffee grounds and instant coffee samples suggest the presence of hybrid polysaccharides in these processed coffee samples, corroborating the occurrence of transglycosylation during the roasting process. Furthermore, the study of mixtures containing different proportions of each model oligosaccharide, mimicking coffee bean regions with distinct polysaccharide composition, subjected to different periods of thermal treatment, allowed to infer that different hybrid and non-hybrid structures may be formed from arabinogalactans and galactomannans, depending on their distribution in the bean cell walls and on roasting conditions. These results may explain the heterogeneity of melanoidins structures formed during coffee roasting. The results obtained from model mixtures containing an oligosaccharide (Ara3 or Man3) and 5-CQA and subjected to dry thermal treatment, as well as samples derived from spent coffee grounds, showed the formation of hybrid compounds composed by CQA molecules covalently linked to a variable number of sugar residues. Moreover, the results obtained from the mixture containing Man3 and 5-CQA showed that CQA acts as catalyst of transglycosylation reactions. On the other hand, in the model mixtures containing a peptide, even if containing 5-CQA and subjected to the same treatment, it was observed a decrease in the extent of transglycosylation reactions. This outcome can explain the low extent of non-enzymatic transglycosylation reactions during roasting in coffee bean regions enriched in proteins, although polysaccharides are the major components of the coffee beans. The decrease of transglycosylation reactions in the presence of peptides/proteins can be related with the preferential reactivity of reducing residues with the amino groups of peptides/proteins by Maillard reaction, decreasing the number of reducing residues available to be directly involved in the transglycosylation reactions. In addition to the compounds already described, a diversity of other compounds were formed from model systems, namely dehydrated derivatives formed during dry thermal treatment. In conclusion, the identification of the structural modifications in coffee polysaccharides promoted by roasting pave the way to the understanding of the mechanisms of formation of melanoidins and structure-activity relationship of these compounds.

碩士
國立虎尾科技大學
工業工程與管理研究所
102
The coffee bean roasting process not only involves frying beans, but also involves catalyzing the flavor and aroma of coffee beans through the roasting process under high temperatures. Other than “country of origin” and “brewing method”, the key lies in the bean roasting and heating process. Through varying degrees of temperature control, even the same kind of beans will produce greatly varied flavors after brewing. The purpose of this study was to construct an evaluation model for determining the coffee characteristic performance and explore which factors experts use as the focus of coffee performance evaluation. The research content covers three different types of candidate heating procedural combinations during roasting. According to established roasting model, actual roasting was performed. Through the electronic temperature measurement module, parameters such as temperature and time were collected. The actual roast samples were divided into “light roast”, “medium roast”, and “dark roast” groups for follow-up assessment and taste testing. The fuzzy delphi method’s (FDM) key evaluation factors for coffee selection and the fuzzy analytic hierarchy process (FAHP) were adopted to explore the factor’s degree of importance. The fuzzy synthetic decision making was used for performance evaluation and testing. Finally, the fuzzy performance coupled with the fuzzy weights of the factors’ degree of importance, FAHP were used for weighted calculations and defuzzification, thereby obtaining the candidate sample group with the best degree of coffee bean roasting. After performance measurement of the three sample sets, “dark roasting” received the highest rating. Additionally, in terms of degree of importance, FAHP analysis results show that “smoothness”, “Acidy”, and “Flavor” rank the top three, thus indicating the factors the experts will focus on when experiencing the taste of coffee. The findings shall serve as a basis for relevant organizations, stores, or individuals when roasting and evaluating coffee; they shall also serve as a research reference for follow-up research or survey.

碩士
輔仁大學
食品營養學系
87
Light-roasted, medium-roasted and dark-roasted coffees from Brazil, Colombia, Mandehling, Panama, Indonesia and Thailand were used to study the inhibition of superoxide anion radicals produced in xanthine/xanthine oxidase system. Different regional coffees, degree of roasting and their interaction significantly (p<0.05) influenced the inhibition of xanthine oxidase activity. Chlorogenic acid, caffeic acid and caffeine were able to inhibit xanthine oxidase activity. After heating at 205℃, 215℃ and 225℃ for 15 min, the three compounds reduced their inhibition ability with increasing temperature. The influence of Brazilian, Colombian, Mandehling and Thai coffees with three degrees of roasting on removing hydroxyl radicals was also investigated. Different regional coffees, degree of roasting and their interaction were significant on scavenging radicals (p<0.05). Light-roasted Brazilian and Colombian coffees, medium-roasted Mandehling and dark- roasted Thai coffees showed better removing abilities. Both roasted and ground coffees packed in aluminum-foil bag had the same effect on the removal of hydroxyl radicals during 14-day storage. The scavenging ability was greatly influenced by storage time rather than storage temperature. Pure chemicals of chlorogenic acid, caffeic acid and caffeine showed strong abilities to scavenge radicals. However, after heating at 205℃,215℃ and 225℃ for 15 min, chlorogenic acid and caffeic acid became prooxidant and caffeine decreased scavenging ability. Storage conditions had no effect on the properties of heated chlorogenic acid. Compared to temperature, storage time of caffeic acid and caffeine had greater effect on the scavenging ability. The inhibition abilities of linoleic acid ethyl ester (LAEE) oxidation by the above four coffees with three degrees of roasting were significantly different (p<0.05). All light-roasted coffees showed strong antioxidant activities and followed by medium-roasted and dark-roasted. Both roasted and ground coffees packed in aluminum-foil bag had the same antioxidant activities during 14-day storage. Storage time showed greater effect than temperature on antioxidant activity. Pure chemicals of chlorogenic acid, caffeic acid and caffeine had ability against LAEE peroxidation. After heating at 205℃,215℃ and 225℃ for 15 min, chlorogenic acid and caffeic acid increased antioxidant activity, whereas caffeine decreased. Storage of these heated compounds at 4℃and 25℃ had no effect on their antioxidant abilities. However, the antioxidant ability of chlorogenic acid and caffeic acid increased after 7- and 14-day storage, and that of caffeine decreased with time.

碩士
國立臺灣大學
食品科技研究所
102
Depression is a prevailing psychiatric disease, which would cause socio-economic burden. WHO have predicted that unipolar depressive disorder will be the ranking 1st of the burden and disability disease by the year 2030. However, current therapies for depression cause many side effects. Hence it is imperative to look for an alternative preventive remedy. In my study, I aim to evaluate the neuroprotective effects of coffee extract at different roasting degrees on cell viability of corticosterone-induced differentiated and undifferentiated PC12 cells. Also I analyzed the contents of active compounds of coffee extract at different roasting degrees and investigated the relationship between antioxidant activity and neuroprotective effects. To further investigate the effects of coffee on neuroplasticity, I analyzed the average neurite length of damaged differentiated PC12 cells treated with coffee extracts. With increase in roasting degree, the antioxidant activity of coffee extract would rise slightly then decrease in ABTS assay. The contents of chlorogenic acid, ferulic acid, quercetin and rutin would decrease；caffeine and caffeic acid would rise then decrease with increase in roasting degree. The second crack coffee could increase cell viability for both differentiated and undifferentiated PC12 damaged by corticosterone. The neuroprotective effect of coffee extract may partially be related to the activity of lipophilic antioxidant such as chlorogenic acid lactones, but the underlying mechanism is still be investigated. Furthermore, coffee at all roasting degree could inhibit the neurite shortening of differentiated PC12 damaged by corticosterone, indicating the coffee at all roasting degree have the potential to improve neuroplasticity. In conclusion, coffee may have the possibility to prevent or delay the incidence of depression by its neuroprotective effect and improving neuroplasticity.

The instinctive rejection of bitter taste has been crucial to the survival of our species and continues to influence food choices. In fact, the bitter taste receptors have evolved to protect the body from the ingestion of foods potentially harmful to health. However, some foods are widely consumed despite their high intensity of bitterness, for example coffee, one of the world’s most popular beverages. Coffee is drunk for its pleasant flavour and aroma as well as for the stimulatory properties arising from its caffeine content. Such properties, as well as the addition of sugar and/or milk, are most likely responsible for our learned preferences for coffee. The aim of this work was to study the relationship between the preference patterns for coffee and the perception of its bitterness. For this purpose, factors relating to both the product – degree of roasting - and the individual - bitterness perception and caffeine metabolism rate - were studied. First, the effect of the roasting temperature on coffee sensory profile and preference was investigated, initially by describing the sensory properties of coffee brews prepared with both under-roasted (140-165°C) and standard roasted (220°C) beans. In addition, seventy-five coffee consumers rated their liking for unsweetened and freely sweetened under-roasted coffee samples. Increasing the bean processing temperature positively affected both the perceived intensity of some sensory attributes specific to coffee and also consumers’ liking. In particular, coffee processed at temperature higher than 150°C were described by the terms “coffee”, “roasted”, “burnt”. Furthermore, no significant differences in the intensity of these attributes were found between samples processed at temperatures higher than 155°C and samples roasted at the standard temperature. In general, samples processed at temperatures higher than 150°C were preferred. However, a subgroup of subjects who liked the samples roasted at lower temperatures was found. These subjects were on average less neophobic than the others, that is, more inclined to consume unfamiliar/unconventional foods. Later, the effects of bitterness sensitivity and caffeine metabolism rate on perception of, and liking for coffee were examined. One hundred and thirty-five regular coffee consumers participated in the study. Subjects were characterised in terms of bitterness sensitivity (fungiform papillae – FP - number and sensitivity to the bitter compound 6-n-propylthiouracil –PROP-); caffeine metabolism rate (slow and fast metabolizers); attitudes and food behaviour (frequency – number of coffees per day- and modality - black, with sugar, with milk- of coffee consumption; preference for and familiarity with bitter foods; self perceived effect of caffeine intake). Caffeine metabolism was investigated by competitive immuno-enzymatic assay. Subjects provided saliva samples after 12 hours of caffeine abstinence (T0) and at 30 and 90 minutes after ingestion of caffeine (100 mg). The individual caffeine metabolism rate in 90 minutes was expressed as a caffeine metabolism index (CmI), computed as the ratio between the amount of residual caffeine in saliva 60 minutes after the adsorption peak and the amount of caffeine at the adsorption peak corrected with the baseline. Subjects rated their liking for six unsweetened and freely sweetened coffee samples selected on the base of their roasting degree, caffeine content and bitterness. The immersive test technique was applied to evaluate the effect of the context on coffee liking. In particular, just before starting the test, subjects were asked to describe the most preferred situation for consuming coffee (time of the day, place, company, etc.) and to imagine that they were doing coffee tasting in that particular situation. In a separate session, subjects evaluated the sourness, bitterness and astringency in the coffee samples. Psychophysical curves were constructed for caffeine and quinine-HCl over 6 concentrations. No significant relationships were found between the FP number, the PROP taster status and the caffeine metabolism rate. Subgroups of subjects were identified based on these indices and differences in preference and sensory responses were explored independently in the subgroups. Both FP density and PROP taster status affected taste sensitivity for bitter compounds in general (caffeine; quinine-HCl) and the use of sugar in coffee. In particular, subjects with a higher FP number rated the bitterness of caffeine and quinine-HCl solutions and sourness of coffees stronger than subjects with a lower FP number. They also added more sugar to, and gave higher liking ratings for, the coffee samples. While coffee liking was unrelated to PROP taster status, PROP non-tasters added more sugar to the coffee samples than did PROP super-tasters. However, super-tasters rated sourness, bitterness and astringency as stronger than non-tasters, both in coffee samples and in standard solutions. Caffeine metabolism was related to bitterness perception both in coffee samples and in standard solutions of caffeine, but not of quinine-HCl. In particular, subjects with a lower caffeine metabolism index rated the bitterness of coffees and of caffeine solutions as stronger than subjects with a higher caffeine metabolism index. Moreover, they added more sugar in coffees and consumed less coffees daily. In general, the results demonstrate that even in high coffee consuming cultures such as Italy, there are clear sensory variations in the coffees that are consumed. Coffee consumption and preference, in terms of frequency and modality, are influenced both by the sensory properties of coffee and the psychological, physiological and metabolic characteristics of consumers. In the coffee production process, the roasting degree is a crucial step towards the development of the sensory properties affecting consumer preference. Furthermore, both the physiological indices – FP number and PROP taster status – and the caffeine metabolism rate play a significant role in taste sensitivity for bitter compounds in general and also in the preference for coffee with or without sugar.

Masters of Science
Department of Food, Nutrition, Dietetics and Health
Edgar Chambers IV
In today’s market, there is a growing demand for high-quality coffee with distinctive sensory characteristics. An example of such coffees is the cold brew which has become quite popular. Despite the increasing prevalence of cold drip/brewed coffee, little-published research exists on the factors that impact the sensory characteristics of cold brew coffee. The objectives of this study were to determine the impact of a) degree of roasting, b) coffee to water ratio (C2WR) and c) brewing methods on cold brew coffee from d) Ugandan coffee beans. Four distinct coffee samples, sourced from different lowland and mountainous regions in Uganda, were roasted and tested using a factorial design that allowed comparison of all main factors (a-d) and their interactions. The samples were evaluated by a highly trained sensory panel based on 42 attributes from a previously published coffee lexicon. Results showed that all aspects studied (Ugandan variety, roast degree, C2WR, and brewing method) had an impact on most of the attributes. For example, Robusta coffees generally had a more bitter taste than Arabica coffees and the Dark roast samples generally were more bitter than the Medium roast coffees. In addition, coffee samples that were brewed using a higher coffee to water ratio (C2WR) generally were more bitter than the coffees that were brewed using a lower C2WR. However, although most of the main effects had a significant impact, their effects were mitigated by their interaction with other factors. For example, Medium roast Robusta that was slow-dripped with a high C2WR had a more bitter taste than the corresponding Arabica samples however when the Medium roast Robusta was steeped with a high C2WR it had a similar bitter intensity with the corresponding Arabica samples. Thus, although major impacts are critical, individual sample combinations must be considered when evaluating coffee samples for their impact on the sensory characteristics.

碩士
國立臺灣海洋大學
食品科學系
101
The popularity of coffee is increasing around the world because of its role as a significant source of hydroxycinnamic acids, caffeine, and melanoidins. The aim of this work was to study the antioxidant properties of DongShan coffee brews with different degrees of roasting (light, medium, and dark) and their changes when stored at room temperature for up to 2 hours and at low temperature overnight. Brazil was selected as the control group. Antioxidant capacity by colorimetric assays (Total phenol content, Total flavonoids coontent, DPPH and Reducing power assay) and phenolic compounds and caffeine were quantified by using high performance liquid chromtography coupled with photodiode array detection. The coffee beans were roasted at 250oC as follows: light, 15 min; medium, 17 min; and dark, 18 min. The weight loss of DongShan and Brazil green coffee beans ranged from 10-25%. Total phenol content of DongShan coffee brews with different degrees of roasting increased significantly in an hour (light-12.80 mg gallic acid equivalents/g coffee, medium-11.07 mg GAE/g, dark-7.61 mg GAE/g) and for Brazil light- and medium-roasted coffee brews was 13.06 and 10.00 mg GAE/g, respectively. But Brazil dark-roasted coffee brews found the higher TPC in 2 hour (8.43 mg GAE/g). DongShan coffee brews exhibited the highest total flavonoids content was in 0.5 hour (light-2.09 mg QE/g, medium-1.53 mg QE/g, dark-0.71 mg QE/g) and as same as Brazil light- and dark- roasted coffee brews (light-1.94 mg QE/g, dark-0.77 mg QE/g). The highest radical scavenging activity of DongShan variety was in 0.5 (light-98.2%, dark-69.4%) and 2 (medium-96.7%) hour. The DPPH radical scavenging ability of Brazil light- and medium- roasted coffee brews was in an hour (94.3% and 94.5%) and dark- roasted coffee brews was in 0.5 hour (91.8%). It decreased ranged from 7.4-42.1% while storing at low temperature overnight. DongShan light- and dark-roasted coffee brews showed the highest reducing power in an hour (light-41.22 mg vitamin C equivalent capacity/g , dark-22.00 mg VCEC/g) and Brazil variety found in 0.5 hour (light-32.53 mg VCEC/g, medium-28.77 mg VCEC/g , dark-23.71 mg VCEC/g). According to the results of HPLC analysis, the content of polyphenols and caffeine in analysed DongShan varied in a wide range: chlorogenic acid from 106.26 to 160.26 µg/g, caffeic acid from 130.57 to 1491.44 µg/g, coumaric acid from 4.99 to 64.28 µg/g, ferulic acid from 1.00 to 77.63 µg/g and caffeine from 830.73 till 1447.19 µg/g. For Brazil varied in a wide range: chlorogenic acid from 110.88 to 132.87 µg/g, caffeic acid from 316.67 to 1181.21 µg/g, coumaric acid from 9.55 to 60.50 µg/g, ferulic acid from 3.01 to 35.69 µg/g and caffeine from 1049.93 till 1156.13 µg/g.

碩士
國立中興大學
食品科學系
86
The objects of this research were to investigate the effects of different roasting degrees on the antioxidant properties of water extracts from Cassia tora L. (WECT), and the antioxidant properties of anthraquinones and anthrone, and the effects of WECT on oxidative damage to deoxyribose, DNA and DNA base in vitro.The antioxidant properties of WECT prepared under different degrees of roasting were investigated. The water extracts of unroasted Cassia tora L. (WEUCT) showed 94 % inhibition of peroxidation of linoleic acid at a dose of 0.2 mg/ ml, which was higher than that of a-tocopherol (82%). Water extracts prepared from Cassia tora L. roasted at 175 ℃for 5 min and at 200℃for 5 min exhibited 83% and 82%, respectively, inhibition of linoleic acid peroxidation. This result indicated that the antioxidant activities of WECT decreased with longer roasting time or higher roasting temperature. The IC50 of WEUCT in liposome oxidation induced by Fenton reaction was 0.41 mg/ml, which was higher than that of a-tocopherol (IC50=0.55 mg/ml). WEUCT also exhibited good antioxidant activity in enzymatic and nonezymatic microsome oxidative systems. The water extracts of roasted Cassia tora L. increased with the degree of browning and produced chemiluminescence when compared with the unroasted sample. However, the total polyphenolic compounds of WECT decreased after the roasting process finished. In conclusion, the decreased in the antioxidant activity of water extracts from roasted Cassia tora L. might have been due to the degradation of Maillard reaction products and the decreased of polyphenolic compounds.Anthraquinones are the major compounds found in Cassia tora L. The antioxidant properties of anthraquinones (AQs) and anthrone were evaluated using different model systems. The antioxidant activity of these compounds (200 ppm) on the inhibition of peroxidation of linoleic acid were found to follow the order BHA (96%)≒anthrone (95%)≒alizarin (93%) > aloe- emodin (78%) > rhein (71%) > emodin (36%) > anthraquinone (8%). Chrysophanol accelerated the peroxidation of linoleic acid. Anthrone and alizarin exhibited a reducing power, but the other AQs did not show any reducing power. AQs and anthrone exhibited a weak chelating ability on iron(II). Alizarin completely scavenged hydrogen peroxide at a concentration of 0.2 mg/ml. At a concentration of 0.25 mg/ml, anthrone, aloe-emodin and emodin exhibited 26.2, 16.6 and 41.8% scavenging effects, respectively, on hydroxyl radicals produced by the Fenton reaction. However, anthraquinone, alizarin, chrysophanol and rhein accelerated the production of hydroxyl radicals at the same concentration. These results suggested that the antioxidant mechanism for emodin and aloe-emodin is most likely due to scavenge free radicals. The strong antioxidant activities showed by anthrone and alizarin could be due to their reducing power and scavenging effects on reactive oxygens. The prooxidant activity exhibited by chrysophanol might be due to enhanced the production of free radicals. The effects of WECT on oxidative damage to deoxyribose, DNA and DNA base in vitro were investigated. WECT alone caused a slight strand-breaking of DNA. In the presence of Fe3+/H2O2, WECT accelerated the strand-breaking of DNA under the concentration of 2 mg/ml, but it decreased with an increasing concentration of WECT. WECT inhibited oxidative damage to DNA induced by Fe2+/H2O2, perhaps due to scavenge reactive oxygen species. WECT accelerated the oxidation of deoxyribose induced by Fe3+-EDTA/H2O2 under a concentration of 0.2 mg/ml, but inhibited the oxidation of deoxyribose induced by Fe3+-EDTA/H2O2/ascorbic acid. WECT also caused the oxidation of 2*-deoxyguanosine (2*-dG) to form 8-OH-2*-dG induced by Fe3+- EDTA /H2O2. The prooxidant action of WECT on the oxidation of 2*-dG was in the order of unroasted > roasted at 150℃ > roasted at 200℃> roasted at 250℃. The decrease in prooxidant activity of roasted sample might be due to the reduction of its anthraquinone glycoside content after roasting. WECT exhibited either prooxidant or antioxidant property in the model system that was dependent on the ability of reducing metal ions, scavenging hydroxyl radical and chelating ferrous ion.

碩士
國立中興大學
食品科學系
87
In the present study, antimutagenicity and the protective effects on DNA damage of water extracts from Cassia tora L. (WECT) treated with different degrees of roasting (unroasted and roasted at 150, 200, and 250℃) were evaluated by Ames test and the Single cell gel electrophoresis assay. No toxicity or mutagenicity to Salmonella typhimurium TA98 and TA100 was found in the WECT at a dose of 0.25-5 mg per plate with and without S9 mix. WECT had a very marked and dose-dependent inhibition effects on the Aroclor 1254-hepatic S9-mediated mutagenicity of benzo[a]pyrene (B[a]P), 2-amino-6-methyldipyrido(1,2-a: 3': 2'-d) imidazole (Glu-P-1), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 3-amino-1,4-dimethyl-5H-pyrido(4,3-b)indole (Trp-P-1). The antimutagenicity of WECT decreased with an increasing roasting temperature in the following order: unroasted＞150℃＞200℃＞250℃. For strain TA98, the IC50 of water extracts of unroasted Cassia tora L. (WEUCT) toward B[a]P, Glu-P-1, IQ and Trp-P-1 were 1.07, 0.57, 0.15 and 0.15 mg/mL; whereas for strain TA100, the IC50 were 0.14, 0.17, 0.48 and 0.2 mg/mL, respectively. Neither the mutagenicity of MNNG nor that of NQNO was suppressed by WECT in TA98 and TA100. WECT had no inhibitory effects toward IQ and B[a]P in the bio-antimutagenic assay. Mutagen-inhibitor interaction (molecular complex formation) could be illustrated by a change in the UV spectrum, suggesting that WEUCT may act as an "interceptor molecule", interacting with mutagens directly and limiting their bioavailability. Methoxy- and ethoxyresorufin-O-dealkylase activities of rat microsomes, linked to cytochrome CYP-450 1A1 and 1A2 monooxygenases catalyzing N-hydroxylation of mutagens, were effectively inhibited by WEUCT (98.0 % and 89.3 %). The NADPH-dependent reduction of cytochrome P-450 activity was similarly inhibited, implying the inhibitory effect on the CYP-450 activity may be, at least in part, due to an impairment of the electron transfer from NADPH to the cytochrome. In addition, WEUCT showed 84.7 % scavenging effect on superoxide anion generated in the activation process of IQ by S9 mix in electron paramagentic resonance (EPR) system. The results presented herein suggest that the antimutagenicity of WECT were due to a desmutagenic action, but not a bioantimutagenic action. WECT exhibited no cytotoxicity to human lymphocytes at a concentration of 0.1-2 mg/mL, the cell viability was greater than 95 %. However, in the COMET assay, WECT caused a different extents of DNA damage in human lymphocytes at a concentration over 0.5 mg/mL, especially the sample of roasted at 250℃ (Tail moment=15). All three types of WECT (unroasted and roasted at 150, and 250℃) presented antigenotoxic effects on DNA damage in human lymphocytes induced by Trp-P-1 and in a dose-dependent manner (P＜0.05). At a concentration of 2 mg/mL, the inhibitory effects were observed in the order of unroasted (75 %)＞roasted at 150℃ (62 %)＞roasted at 250℃ (45 %). It revealed that increasing roasting temperature of the seeds of Cassia tora L. might decrease their antigenotoxic activity both in the Ames test and the COMET assay. Mutagen-inhibitor interaction was identified in spectrophotometry studied, suggesting that WEUCT may produce complexes with Glu-P-1 and Trp-P-1. Using a modified COMET assay procedure, WEUCT exhibited 38.7 % scavenging effect on reactive intermediates of Trp-P-1 generated from metabolism system. Pre-treatment of the human lymphocytes with WEUCT for 30 min resulted in a modest repression of DNA damage (30 %). In contrast, no promotive effect of excision-repair was found during DNA damage expression time in post-treatment scheme. Further, three anthraquinones (AQ): chrysophanol, emodin and rhein were determined from acid hydrolyzed WECT by HPLC. It was found that the amounts of these AQ in WECT all decreased with an increasing roasting temperature. The contents of chrysophanol, emodin and rhein in WEUCT were 0.61, 0.28 and 10.42 mg/g, respectively. Emodin (-S9 mix) and rhein (+S9 mix) exhibited slight DNA damage in human lymphocytes in the COMET assay. However, chrysophanol, emodin and rhein shown 79.0, 63.7 and 37.9 %, respectively, protective effects on DNA damage induced by Trp-P-1. The effects of WECT on B[a]P-induced DNA damage in human hepatoma cell line Hep G2 were investigated in the COMET assay without exogenous activation mixtures (S9 mix). WECT alone shown neither cytotoxic nor genotoxic toward Hep G2 cells under a concentration of 0.1-2 mg/mL. B[a]P-induced DNA damage in Hep G2 cells was reduced by WECT in a dose-dependent manner (P＜0.05). At a concentration of 1 mg/mL, the inhibitory effects on DNA damage were in the order of unroasted (72 %)＞roasted at 150℃ (60 %)＞roasted at 250℃ (23 %). Ethoxyresorufin-O-dealkylase activity of Hep G2 cells, linked to cytochrome CYP-450 1A1 monooxygenases, were effectively inhibited by WECT, and a similar inhibition was observed in the following order: unroasted (63.9 %)＞roasted at 150℃ (41.6 %)＞roasted at 250℃ (17.5 %). The activity of NADPH cytochrome P-450 was also decreased by unroasted and roasted at 150℃ samples (49.5 % and 38.4 %), implying the inhibitory effects on the CYP-450 activity may be, at least in part, due to an impairment of the electron transfer from NADPH to the cytochrome. Furthermore, glutathione S-transferase activity was slightly increased by the treatment with unroasted (1.28-fold) and roasted at 150℃ (1.21-fold) samples at a concentration of 1 mg/mL, compared to the control group. In addition, the contents of antimutagenic AQ in WECT, including chrysophanol, emodin and rhein were decreased with an increasing roasting temperature in the following order: unroasted＞150℃＞250℃. Each of these AQ also demonstrated significant antigenotoxic activity in the COMET assay. The inhibitory effects of chrysophanol, emodin and rhein on B[a]P-mediated DNA damage in Hep G2 cells were 89.4, 85.9 and 71.2 %, respectively. These findings suggested that the decrease in the antigenotoxic activity of the roasted samples might be due to the reduction in its anthraquinones content.

Coffee drying and roasting are usually performed in rotated dryers; therefore, the study of particle dynamics in this equipment is of great relevance to improve their efficiency and hence the quality of the final product. Thus, this work aimed to investigate experimentally and numerically the dynamics of coffee beans in a rotary dryer. The Euler-Euler model was employed to reproduce the particle velocity profile in the rolling regime under different boundary conditions. The results shown that the lower specularity coefficient (0.01), which characterizes the smooth wall and free slip condition, reproduced the bed behavior that most resembled the experimental one. On the other hand, the other coefficients (0.1 and 1.0) showed an increasing deformation in the bed surface, different from the observed experimental behavior. It was also verified that, as the filling degree increases, the bed surface deformation becomes more pronounced. Keywords: coffee; rotated dryer; simulation; specularity coefficient.