Coffee Manufacturing Research Articles

Modeling Mass and Heat Transfer in Multiphase Coffee Aroma Extraction.

Instant coffee manufacture involves the aqueous extraction of soluble coffee components followed by drying to form a soluble powder. Loss of volatile aroma compounds during concentration through evaporation can lower product quality. One method of retaining aroma is to steam-strip volatiles from the coffee and add them back to a concentrated coffee solution before the final drying stage. A better understanding of the impact of process conditions on the aroma content of the stripped solution will improve product design stages. In this context, we present a multiscale model for aroma extraction describing (i) the release from the matrix, (ii) intraparticle diffusion, (iii) transfer into water and steam, and (iv) advection through the column mechanisms. Results revealed (i) the existence of three different types of compound behavior, (ii) how aroma physiochemistry determines the limiting kinetics of extraction, and (iii) that extraction for some aromas can be inhibited by the interaction with other coffee components.

Environmental and process assessment of a vibratory nanofiltration system for the recovery of water from soluble coffee manufacturing waste

AbstractA case study has been conducted for the recovery of water from complex wastewater at a soluble coffee manufacturing factory. The study has evaluated separation methods for process intervention based on environmental and economic assessments. A novel vibratory field membrane separation was evaluated at the laboratory scale using actual factory wastewater, and was scaled‐up using appropriate design protocols. The recovery of water from an intermediate waste stream proved the most effective, both environmentally and economically. The proposed full‐scale vibratory membrane process recovers 378,541 L of water per day that meets specifications for reuse in the factory cooling tower. The proposed design reduced the daily well freshwater withdrawn by 21% and the amount of wastewater discharged from the factory by 28.5%. Annual operating costs were reduced by 22.5% and total life cycle emissions were reduced by 27.8%. These reductions are mainly the result of the reduced volume of wastewater discharged from the factory and the reduced energy requirement of the on‐site pretreatment processes. Economic assessment showed a net present value after 10 years is $181,100, while the payback time is under 3 years. Overall, the proposed vibratory membrane process used for water recovery presents favorable economics, and significant environmental emission reduction.

Polyol from spent coffee grounds: Performance in a model pour-in-place rigid polyurethane foam system

The objective of this study was to produce a polyol from spent coffee grounds via acid liquification process that meets performance requirements for use in polyurethane applications. The spent coffee grounds based polyol was characterized and evaluated on a fully catalyzed model rigid polyurethane foam system. The pH of the polyol was 6.8, acid value 4.12 mg KOH/g, and hydroxyl value 302.6 mg KOH/g, which are in the range of polyols used in rigid polyurethane foams. The reactivity study confirmed enhanced reactivity of the spent coffee grounds polyol compared to standard sucrose-glycerol initiated polyether polyols, which can be attributed to higher content of primary reactive hydroxyls. Scanning electron microscopy microphotographs of the foams prepared with 10%, 20%, and 30% spent coffee grounds polyol based on total polyols in the formulation revealed a drained dodecahedron type cell structure with intact cell windows as a clear indication of the closed cell structure typical for the rigid polyurethane foams used in thermal insulation applications. Results of this study confirmed the feasibility to produce polyols from spent coffee grounds with performance characteristics suitable for polyurethane application. The fact that spent coffee grounds are readily available industrial waste generated in instant coffee manufacturing, makes this biomass residue a sustainable source of raw materials for scalable production of polyols for polyurethanes.

Mathematical modelling of the steam stripping of aroma from roast and ground coffee

Instant coffee manufacture involves the aqueous extraction of soluble coffee components followed by drying to form a soluble powder. A challenge that arises from the process is the loss of volatile aroma compounds during evaporative drying. One method of retaining aroma is to first steam strip the volatiles from the coffee and add them back to a concentrated coffee solution just before the final drying stage. Understanding the impact of process conditions on the aroma content of the stripped solution offers engineers the ability to target desirable compounds and maximise their yield. This paper presents a multiscale model for aroma extraction that describes: (i) release from the matrix, (ii) diffusion through the coffee grain, (iii) transfer into water and steam, and (iv) advection through the stripping column. Results reveal how aroma physiochemistry determines the limiting kinetics at industrial extraction conditions. The interaction with the soluble matrix can also inhibit extraction, but this effect varies for the different aromas studied.

Hydrogen Production from Coffee Mucilage in Dark Fermentation with Organic Wastes

One of primary issues in the coffee manufacturing industry is the production of large amounts of undesirable residues, which include the pericarp (outer skin), pulp (outer mesocarp), parchment (endocarp), silver-skin (epidermis) and mucilage (inner mesocarp) that cause environmental problems due to toxic molecules contained therein. This study evaluated the optimal hydrogen production from coffee mucilage combined with organic wastes (wholesale market garbage) in a dark fermentation process. The supplementation of organic wastes offered appropriate carbon and nitrogen sources with further nutrients; it was positively effective in achieving cumulative hydrogen production. Three different ratios of coffee mucilage and organic wastes (8:2, 5:5, and 2:8) were tested in 30 L bioreactors using two-level factorial design experiments. The highest cumulative hydrogen volume of 25.9 L was gained for an 8:2 ratio (coffee mucilage: organic wastes) after 72 h, which corresponded to 1.295 L hydrogen/L substrates (0.248 mol hydrogen/mol hexose). Biochemical identification of microorganisms found that seven microorganisms were involved in the hydrogen metabolism. Further studies of anaerobic fermentative digestion with each isolated pure bacterium under similar experimental conditions reached a lower final hydrogen yield (up to 9.3 L) than the result from the non-isolated sample (25.9 L). Interestingly, however, co-cultivation of two identified microorganisms (Kocuria kristinae and Brevibacillus laterosporus), who were relatively highly associated with hydrogen production, gave a higher yield (14.7 L) than single bacterium inoculum but lower than that of the non-isolated tests. This work confirms that the re-utilization of coffee mucilage combined with organic wastes is practical for hydrogen fermentation in anaerobic conditions, and it would be influenced by the bacterial consortium involved.

On the Dual Nature of Transparency and Reliability: Rethinking Factors that Shape Trust in Automation

Prior literature has found that increasing system reliability and transparency can positively impact operators’ trust of automated systems; however, these factors are typically confounded. In the present study, we separated these factors by manipulating different stages of automation. Participants engaged in a simulated coffee manufacturing task using an interface with differing levels of reliability (65% or 95%) and transparency (one line or multiple lines of system display). The Human Computer Trust Scale (HCTS) and the Trust in Automated Systems Scale (TAS) were used to measure trust. When examining scores on TAS items with a positive-valence, we novelly observed that transparency interacted with reliability, such that high transparency and low reliability negatively impacted trust in the system. Alternatively, trust was not negatively affected by poor reliability when transparency was low, due to trivial cost of corrective behaviors that compensated for poor reliability and lack of system history understanding by the operators.

인스턴트커피 제조를 위한 커피추출조건 최적화

인스턴트커피 제조를 위한 커피추출조건 최적화

Membrane-based Water Recovery in Coffee Manufacture

Membrane-based Water Recovery in Coffee Manufacture

Rapid Classification of Coffee Products by Data Mining Models from Direct Electrospray and Plasma-Based Mass Spectrometry Analyses

In coffee manufacture, analytical methods with high-throughput and cost efficacy are required for process development and quality control. Thus, we investigated the applicability of direct mass spectrometry methods to distinguish coffee products according to species, geographic origin and processing. We tested the performance of the established method direct-injection electrospray mass spectrometry (DIESI-MS) and the emerging method low-temperature plasma ionization mass spectrometry (LTP-MS). Both methods are capable of classifying coffee products, but DIESI-MS and LTP-MS yield complementary information about the chemical composition of the samples. DIESI-MS shows a broad molecular weight range of compounds. In contrast, LTP-MS detects mainly low molecular weight compounds, which correspond to quality-related ingredients, such as caffeine and purines. LTP-MS displays a high potential for rapid quality control measurements and online monitoring, because no sample processing is required. Data mining methods support the discovery of ‘important’ compounds, which are responsible for the discrimination between sample groups, and reveal associated chemical processes.

Electric Motors in São Paulo, Brazil 1900–1950

The engineering achievements and milestones in the application, repair, design and manufacture of electric motors in São Paulo from 1900 until 1950 are described in the economic and technological contexts of the time. The application of electric motors in the State of São Paulo began at the same time as its industrialization, which was driven by the reinvestment of capital accumulated from coffee exports and manufacturing activities, most notably in the textile industry. Both railways and electricity utilities were a source of training for skilled labour, and an outstanding school of engineering was founded to support industrialization. Immigrants established the first motor repair shops. With the import restrictions imposed by WWII some of them became manufacturers, often in association with either equipment manufacturers or importers seeking local suppliers. A lack of materials and parts, which were previously imported, demanded ingenuity from the new manufacturers in order to develop viable alternatives and modify design criteria. These processes were supported by the Polytechnic School and its associated Institute of Electrotechnics.

Impact of Packaging Characteristics on Consumer Purchase Intention: Instant Coffee in Refill Packs and Glass Jars

AbstractThe study of food packaging is important as packaging represents the first contact between consumer and product. Attributes of interest in the study of instant coffee were initially determined by a focus group study. Subsequently, eight images of instant coffee packages were developed for the quantitative study, separately, for glass jars and refill packs (24−1 design, eight images, each). The package images were evaluated by a total of 206 coffee consumers for purchase intention. Two main groups of consumers were formed and characterized for each study in the conjoint analysis. For refill packs, purchase intention increased with the presence of photo depicting coffee cup with foam and coffee beans and additional information; for glass jars, lower price and shape. Brand was not emphasized as impacting in purchase intent of instant coffees, a positive finding for manufacturers of lesser known brands: improving packaging attributes may encourage product sales.Practical ApplicationsThese results are relevant to sensory scientists and instant coffee manufacturers interested in how packaging characteristics can impact on the purchase intention by consumers. Although coffee represents a significant source of income worldwide, there is less information in the literature about the effect of nonsensory parameters, such as packaging characteristics, in consumers' acceptance and purchase of instant coffee. The study showed that brand was less important than price and packaging attributes, such as additional information, adequate illustration (for refill packs) and package shape (for glass jars). Therefore, these results should hopefully help coffee manufacturers develop their packages and improve their sales, mainly those of lesser known brands, new brands or brands less associated with instant coffee.

SOCIAL INTERACTION IN CONTEXT OF MULTILINGUALISM: FROM THEORY TO PRACTICE

During the last decade, research interest in multilingualism has increased immensely. As a result, the present paper explores certain aspects of growing understanding and commitment to the linguistic diversity, which are considered to be some of the factors that underlie a successful interaction in a multilingual society nowadays. The theoretical framework of the study is designed considering the latest contributions of sociolinguistic ethnography in the area of multilingualism, relating the notion of multilingualism to the notion of multicompetence. The current situation demonstrates that multilingualism having developed from sociolinguistically-bound research distinguishes its own social, institutional and individual dimensions. They are associated with the practices that are linked to the use of the language for instrumental purposes in order to communicate with confidence in a socially and culturally diverse society. Consequently, researching multilingualism moves away from the analysis of coexisting language systems to a more critical approach that situates appropriate language practices in relevant social and/or political contexts. The empirical part of the study investigates one example of pop-culture, i.e., the language originated, used and constantly updated by the Starbucks – world famous coffee manufacturing industry. The study concludes that the language users are expected to possess multilingual competence to interact appropriately in social settings nowadays. DOI: http://dx.doi.org/10.7220/2335-2027.6.5

Microalgae-based agro-industrial wastewater treatment: a preliminary screening of biodegradability

The potential of algal–bacterial symbiosis for the removal of carbon, nitrogen and phosphorus from five agro-industrial wastewaters was investigated in enclosed batch biodegradation tests using a mixed microalgae consortium and activated sludge as model microorganisms. The target wastewaters were obtained from potato processing (PW), fish processing (FW), animal feed production (MW), coffee manufacturing (CW) and yeast production (YW). The initial C/N/P ratio of the agro-industrial wastewater was correlated with its biodegradability. Thus, the highest removals of total organic carbon (TOC) and nitrogen were recorded in two fold diluted FW (64 ± 2 % and 85 ± 1 %, respectively), while the maximum P-PO4 3− removal achieved was 89 ± 1 % in undiluted PW. The biodegradable TOC was in most cases the limiting component in the treatment of the wastewaters evaluated. This study confirmed the potential of coupling carbon and nutrient recovery from agro-industrial effluents with the production of a valuable algal–bacterial biomass, despite their poor biodegradability.

Optimization of Roasting Conditions for High-Quality Robusta Coffee

Central Composite Design (CCD) was used to optimise temperature and time of Robusta coffee beans roasting. Current method of roasting was able to give good quality beans in term of flavour but the formation of acrylamide was not studied. In this study, optimization was based on high quantity of flavour compounds (pyrazines) with low level of acrylamide resulted in roasting temperature and time of 180°C and 26minutes, respectively. The coffee beans produced using the optimized conditions have the following characteristics: colour; L* 10.47-15.45, a* 2.78-4.69and b* 6.11-10.95; flavour compounds: 2,3,5 trimethyl pyrazine (0.832mg/100g), 2,3 dimethyl pyrazine (1.69mg/100g), 2 methyl pyrazine (0.49mg/100g) and 2,5 dimethyl pyrazine (0.62mg/100g) and low concentration of acrylamide (0.23mg/100g). This proposed roasting condition will be very useful for coffee manufacturers in order to produce high quality coffee beans.

Magnetically modified spent coffee grounds for dyes removal

Large amounts of spent coffee grounds are discharged from food industries, for example, during the instant coffee manufacture. Although part of them is reused as compost and animal feed, most of the coffee grounds are burned as a waste. However, this material can be used as a biosorbent for xenobiotics removal. Spent coffee grounds were magnetically modified by contact with water-based magnetic fluid. This new type of magnetically responsive biocomposite materials can be easily separated by means of commercially available magnetic separators or strong permanent magnets. Magnetic coffee grounds can be used as an inexpensive magnetic adsorbent for the removal of water-soluble dyes. Seven dyes (crystal violet, malachite green, amido black 10B, Congo red, Bismarck brown Y, acridine orange and safranin O) were used to study the adsorption process. The dyes adsorption could be described with the Langmuir isotherm. The maximum adsorption capacities reached the value 73.4 mg of dye per g of dried magnetically modified coffee grounds for acridine orange; it corresponds to 276.6 μmol g−1. This adsorbent can also be used for magnetic solid-phase extraction of crystal violet from extremely diluted solutions. To conclude, magnetic modification of spent coffee grounds resulted in the formation of a new, promising adsorbent for selected xenobiotics removal.

Life cycle assessment of spray dried soluble coffee and comparison with alternatives (drip filter and capsule espresso)

This paper aims to evaluate the environmental burdens associated with spray dried soluble coffee over its entire life cycle and compare it with drip filter coffee and capsule espresso coffee. It particularly aims to identify critical environmental issues and responsibilities along the whole life cycle chain of spray dried coffee. This life cycle assessment (LCA) specifically uses foreground data obtained directly from coffee manufacturers and suppliers. Aside from energy consumption and greenhouse gases emissions, water footprint is also studied in detail, including regionalization of water impacts based on the ecological scarcity method 2006. Other impact categories are screened using the IMPACT 2002+ impact assessment method. The overall LCA results for a 1 dl cup of spray dried soluble coffee amounts approximately to 1 MJ of primary non-renewable energy consumption, to emissions of 0.07 kg of CO 2-eq, and between 3 and 10 l of non-turbined water use, depending on whether or not the coffee cultivation is irrigated and wet treated. When considering turbined water, use can be up to 400 l of water per cup. Pouch – and to a lesser extent metal can packaging alternatives – show lower environmental burdens than glass or sticks. On average, about one half of the environmental footprint occurs at a life cycle stage under the control of the coffee producer or its suppliers (i.e., during cultivation, treatment, processing, packaging up to distribution, along with advertising) and the other half at a stage controlled by the user (shopping, appliances manufacturing, use and waste disposal). Key environmental parameters of spray dried soluble coffee are the amount of extra water boiled and the efficiency of cup cleaning during use phase, whether the coffee is irrigated or not, as well as the type and amount of fertilizer used in the coffee field. The packaging contributes to 10% of the overall life cycle impacts. Compared to other coffee alternatives, spray dried soluble coffee uses less energy and has a lower environmental footprint than capsule espresso coffee or drip filter coffee, the latter having the highest environmental impacts on a per cup basis. This study shows that a broad LCA approach is needed to help industry to minimize the environmental burdens directly related to their products. Including all processes of the entire system is necessary i) to get a comprehensive environmental footprint of the product system with respect to sustainable production and consumption, ii) to share stakeholders responsibility along the entire product life cycle, and iii) to avoid problem shifting between different life cycle stages.

A GC method for simultaneous analysis of bornesitol, other polyalcohols and sugars in coffee and its substitutes

A GC method has been developed for the determination of polyalcohols and sugars in aqueous extracts from green coffee beans, ground roasted coffee beans submitted to either conventional or torrefacto processes, coffee blends and soluble instant coffees. Bornesitol was detected in aqueous coffee extracts for the first time. Mannitol, myo-inositol, mannose, fructose, galactose, glucose and sucrose have also been determined. Results seem to indicate that coffee manufacturing processes, such as roasting or decaffeination, do not affect the polyalcohol content. Coffee substitutes based on cereals, carob or chicory, have also been studied. The possibility to characterize their presence in coffee extracts was evaluated.

Cost Pass-Through in the U.S. Coffee Industry

A rich data set of coffee prices and costs was used to determine to what extent changes in commodity costs affect manufacturer and retail prices. On average, a 10-cent increase in the cost of a pound of green coffee beans in a given quarter results in a 2-cent increase in manufacturer and retail prices in that quarter. If a cost change persists for several quarters, it will be incorporated into manufacturer prices approximately cent-for-cent with the commodity-cost change. Given the substantial fixed costs and markups involved in coffee manufacturing, this translates into about a 3-percent change in retail prices for a 10-percent change in commodity prices. We do not find robust evidence that coffee prices respond more to increases than to decreases in costs.

Production, partial purification and properties of β‐mannanases obtained by solid substrate fermentation of spent soluble coffee wastes and copra paste using Aspergillus oryzae and Aspergillus niger

In order to achieve a higher added value of two galactomannan-containing wastes, copra paste and spent coffee from the soluble coffee industry (SCW), solid substrate fermentation (SSF) was used. Filamentous fungi Aspergillus oryzae and A niger were used to evaluate the feasibility of producing β-mannanase by SSF. A 23 factorial design was used to select the best interaction among the two fungi, the two substrates and two fermentation times. The treatment ‘A niger–copra–2.5 days’ produced a significantly higher (p < 0.05) β-mannanase activity, having five different isoforms of the enzyme, one of which was partially purified to a specific activity of 764 U mg−1 (U = nmol of mannose released per second from a galactomannan substrate). Copra paste had a higher mannose/galactose ratio (14:1) than SCW (6:1), and low oil content, which led to higher β-mannanase production from SSF. A β-mannanase from SSF of copra produced by A oryzae was highly purified using acetone precipitation and cation exchange and size exclusion chromatographies. This enzyme had an MW of 110 kDa, a pI between 3.5 and 4.5 and a specific activity of 1760 U mg−1; purification achieved was 90.7 times. The temperature and pH for optimal activity were 40 °C and 6.0 respectively. The optimal temperature was lower and the optimal pH higher than others previously reported (produced by submerged fermentation), which could be important for viscosity reduction of concentrated coffee extract in instant coffee manufacture. Copra is an interesting alternative for β-mannanase production, since it is readily available in Mexico; moreover, the residue after SSF has a reduced galactomannan content and may be used for monogastric animal feed. © 2000 Society of Chemical Industry

Sensitization to green coffee beans and work‐related allergic symptoms in coffee workers

Background Occupational respiratory allergy to green coffee beans (GCB) and to castor beans (CB) was studied in 112 workers in a modern coffee manufacturing plant of Trieste (Italy), where the process is completely automatic, the environmental conditions are good and where exposure to CB can be considered absent because since 1970, only new sacks have been used for coffee transportation. Methods All subjects were interviewed by a trained doctor using a questionnaire to investigate allergic symptoms and predisposing factors. Sensitization to GCB and to common allergens (pollens, molds, house dust mites) were evaluated by the skin-prick test. The serum of subjects with a positive skin-prick test to CGB or who had symptoms at work was tested for specific IgE (RAST) for GCB and CB. Lung function was evaluated by a Ponigraph spirometer. Results Sensitization to GCB was found in 25.8% of green coffee workers (31 cases), in 2.7% of roasted coffee workers (37 cases) and in 4.5% of the clerks (44 cases), p < 0.01. The evaluation of IgE specific for CB gave positive results only in 3 of 10 subjects sensitized to GCB. A total of 20% of GCB workers (6 cases) complained of work-related respiratory symptoms (asthma and/or rhinitis) compared with only one subject in the roasted coffee group and one in the control group (p < 0.01). Asthma was reported by 2/31 of the green coffee workers and by 1/44 of roasted coffee workers. Conclusions There was a significant correlation between sensitization to GCB and work related symptoms (p < 0.01), common allergic symptoms (p < 0.05) and atopy by prick test (<0.01). These results point to the need to evaluate atopic status in workers and identify the most susceptible subjects, with the aim of informing them of their at-risk status and monitoring their progress. This makes it possible to diagnose sooner those symptoms possibly indicative of a work-related disease, because even in presence of good environmental conditions and even when symptoms are mild, it is almost always the atopic subjects who are affected. Am. J. Ind. Med. 34:623–627, 1998. © 1998 Wiley-Liss, Inc.