Extraction of coffee diterpenes and coffee oil using supercritical carbon dioxide

Commercial green and roasted coffee beans were used to maximize oil extraction and conditions were studied to obtain the highest and lowest diterpene levels on green and roasted coffee oil, respectively. Thus, operational temperatures (60–90 °C) and pressure (235–380 bar) were optimized for coffee oil extraction. Oil content levels and diterpene oil concentration were compared to the results obtained with the extraction with Soxhlet apparatus, using hexane as solvent. In general, an inverse correlation was observed between the amount of extracted oil and diterpene concentration levels. As a result, different oil contents with different diterpene concentrations could be obtained. The HPLC analysis of cafestol and kahweol in the oil extracted from green coffee beans at 70 °C/253 bar resulted in the highest concentration (453.3 mg 100 g⁻¹), which was 48% lower than in the oil extracted with hexane while in the oil extracted from roasted coffee beans at 70 °C/371 bar, resulted in 71.2% reduction of diterpenes.     

Roasting process affects differently the bioactive compounds and the antioxidant activity of arabica and robusta coffees

The influence of different roasting degrees on the content of bioactive compounds and the antioxidant activity (AA) of arabica and robusta coffees was evaluated. AA was estimated by Folin–Ciocalteau, FRAP and ABTS methods. The results were analyzed by principal components analysis. While the levels of 5-CQA (5-caffeoylquinic acid), trigonelline, furfural and HMF (hydroxymethylfurfural) decreased with the degree of roasting, the level of melanoidins increased. Changes in the levels of the bioactive compounds were more intense that those observed for AA. PC 1 (principal component 1) was mainly correlated with the levels of, furfural, HMF, 5-CQA, trigonelline, and melanoidins. PC2 was mainly correlated with AA and caffeine content. Different compounds contribute to the AA of the coffee and the final result for AA is dependent on the balance of the compounds formed and degraded during the roasting process.     

Heat and mass transfer during the coffee drying process

For a better comprehension of heat and mass transfer during the coffee drying process and optimization of the industrial application transport coefficients and coffee properties were determined. Heat transfer coefficients were measured for different air velocities and were found to follow the known dimensionless equations for the flow surrounding a sphere. Thermal conductivities and effective diffusion coefficients were measured as a function of moisture content as well as volume and densities of the coffee beans. The mentioned properties depend directly on the humidity of the coffee beans rather than on the drying conditions. Sorption behaviour was investigated and temperature dependent parameters for the Guggenheimer–Anderson–deBoer-isotherm (GAB) were determined according to the Arrhenius relationship.     

A numerical approach for the analysis of the coffee roasting process

A numerical model of the coffee roasting process under operating conditions is proposed. This numerical tool is able to simulate the behaviour of all the components of a batch roaster as well as the roasting process of the coffee beans within the drum. The model evaluates the heat and mass transfer between a hot air flow and the coffee beans during the roasting process on the basis of the physical properties of the coffee and the operation of the roasting machine. Different submodels are included in the modelling in order to address particular thermo-physical processes, such as the evaporation of coffee moisture and the heat released or absorbed by the beans due to the roasting reactions.     

Roasting affects phenolic composition and antioxidative activity of hazelnuts (Corylus avellana L.)

The potential effect of skin removal and roasting on individual and total phenolic content, and on antioxidative potential of 6 hazelnut cultivars were investigated. HPLC-MS identification of individual phenolics confirmed the presence of 7 flavan-3-ols (catechin, epicatechin, 2 procyanidin dimers, and 3 procyanidin trimers), 3 flavonols (quercetin pentoside, quercetin-3-O-rhamnoside, and myricetin-3-O-rhamnoside), 2 hydrobenzoic acids (gallic acid, protocatechulic acid), and 1 dihydrochalcone (phloretin-2'-O-glucoside). Flavonols were only detected in whole hazelnut kernels. The content of individual phenolics, with the exception of gallic acid, was always highest in whole unroasted hazelnuts and was significantly reduced after skin removal. Similarly, total phenolic content and antioxidative potential decreased when skin was removed. Roasting had a significant negative effect on individual phenolics but not on the total phenolic content and antioxidative potential of kernels. From a health promoting phytochemical composition of hazelnuts the consumption of whole unroasted kernels with skins should be preferential to peeled kernels either roasted or unroasted. Practical Application: A significant reduction in the antioxidative potential and total phenolic content is detected after hazelnut skin removal but not after roasting, suggesting that hazelnut kernels should be consumed whole. In hazelnut skin, many phenolic compounds are located, which are not present in flesh and, therefore, the health properties of hazelnuts are strongly affected by skin removal. Thermal processing and roasting conditions used in this study had a lesser effect on the individual phenolic composition of the kernel and thus roasted and unroasted hazelnuts without skin contain comparable amounts of health promoting compounds.     

Influence of extraction process on antioxidant capacity of spent coffee

Spent coffee that is produced in tons by restaurants and cafeterias, and consumers at domestic levels, could be a good opportunity to have an important source of natural antioxidants. The main aim of this work was to study the influence of several process factors on the antioxidant capacity extraction from spent coffee. Total phenolic compounds, radical scavenging activity (ABTS and DPPH) and browned compounds (Abs 420 nm) of spent coffee extracts obtained with continuous (Soxhlet 1 h and 3 h) and discontinuous methods (solid–liquid extraction and filter coffeemaker), several solvents (water, ethanol, methanol and their mixtures), successive extractions, and water with different pHs (4.5, 7.0 and 9.5) were carried out. Spent coffee extracts with the highest antioxidant capacity were obtained after one extraction with neutral water (pH 7.0) in a filter coffeemaker (24 g spent coffee per 400 mL water). Furthermore, spent coffee defatting and extract lyophilization allowed us to obtain spent coffee extracts powder with high antioxidant capacity that can be used as an ingredient or additive in food industry with potential preservation and functional properties.     

Changes in carbohydrates during the production of coffee substitute extracts,especially in the roasting process

The changes in the content of starch, dextrin and reducing sugars in rye and barley, and inulin and fructose in chicory roots, during the roasting process, were investigated. The analysis of carbohydrates was connected with the estimation of changes in extract content, colour of the roasted materials, pH and the sensoric evaluation of the brew. The changes in the content of the respective carbohydrates in the basic stages of the whole process of production of coffee substitute extract were also investigated.In the case of roasted rye and barley the high quality of the brew was connected with the highest content of dextrin and reducing sugars. In the case of roasted chicory the highest fructose content (～13%) and the relation between inulin and fructose may be recognised as parameters for ‘optimum’ quality.As a result of the specific technology of the enzymatic treatment of the extract, a very characteristic carbohydrate composition in the final product, with a high content of dextrins (above 30%) and of reducing sugars, could be observed.     

Discrimination between defective and non-defective Brazilian coffee beans by their volatile profile

The coffee roasted in Brazil is considered to be of low quality, due to the presence of defective coffee beans that depreciate the beverage quality. In view of the fact that coffee flavour is directly related to the volatile compounds produced during roasting, the objective of the present study was to perform a comparative evaluation of the volatile fraction of defective (black, immature, sour) and healthy coffee beans, in order to find possible chemical markers for detection of defective coffee beans in roasted coffee. Volatiles extraction and concentration was performed by solid phase micro-extraction (SPME) of the roasted coffee headspace, using a triple phase (divinylbenzene/carboxen/polydimethylsiloxane) fiber. Analysis of the volatile profiles was performed by GC–MS. The results obtained showed that the proposed methodology was adequate for extraction, concentration and analysis of the coffees volatile profile. Several substances were identified as possible markers for differentiating black, sour and immature beans from healthy coffee beans. Statistical analysis of the data by principal components (PCA) demonstrated that the volatile profile enables the differentiation of healthy and defective coffees. The data were separated into two major groups, one represented by immature and black beans and the other by healthy and sour coffee beans. Such results indicated that black and sour beans can be associated to fermentation of immature and of healthy beans, respectively.     

Proximate composition and fatty acids profile of green and roasted defective coffee beans

Defective coffee beans are responsible for the depreciation of the quality of roasted coffee consumed in Brazil. The extraction of the oil of defective beans for applications in the food and pharmaceutical sectors is being considered as an alternative use for those beans. The objective of this work was to determine the composition of the fatty acid fraction of the pressed oil and the proximate composition of crude defective beans in order to provide subsidiary information for proposals of alternative uses for these beans. The amounts of oil extracted from the defective beans were smaller than the amounts extracted from healthy mature beans. The fatty acid composition of oils from defective beans was not significantly different than that from healthy mature coffee beans.     

D-最优混料设计优化肉苁蓉速溶咖啡加工工艺

目的 结合工厂实际优化肉苁蓉速溶咖啡配方加工工艺。方法 运用模糊综合评价法结合D-最优混料设计对肉苁蓉速溶咖啡配方进行优化, 考察总粉量、加糖量、总浸粉的占比及肉苁蓉和咖啡浓缩液的质量比对感官评分的影响。建立组成成分与肉苁蓉速溶咖啡感官评价之间的回归模型, 通过JMP软件优化得到最佳的加工工艺条件。结果 肉苁蓉速溶咖啡的最佳工艺配方: 总粉量20%、加糖量25%、总浸粉55%、肉咖比1:2、2种混合浓缩液与麦芽糊精之比1:0.6; 最佳的冲调比例: 粉水比1:8。在此条件下的感官评分为96.80分, 与预测感官评分的偏差为0.23%, 不存在显著性差异(P>0.05)。结论 本研究建立的方法及模型真实有效, 可为实际生产提供参考依据。     

Recent developments in the manufacture of instant coffee and coffee substitutes

This paper describes modern production methods resulting from the developments that have been taking place recently in the field of instant coffee and coffee substitutes. Such developments involve new processing techniques to achieve higher extraction yields and improve extract concentration, and more efficient spray drying. A tabulated comparison of operating conditions when spray drying chicory, pure coffee and chicory/coffee mixtures is given.     

基于响应面法优化咖啡乳酒发酵工艺

为寻求咖啡乳酒的最佳发酵工艺,以开菲尔菌与酿酒酵母（Saccharomyces cerevisiae）为发酵剂,咖啡、牛奶、白砂糖为原料进行咖啡乳酒的酿制。在单因素试验的基础上,选取白砂糖添加量、咖啡添加量、酿酒酵母接种量及发酵时间4个因素,以感官评分为响应值,通过响应面法对咖啡乳酒的发酵工艺进行优化。结果表明,咖啡乳酒最优的发酵工艺条件为：白砂糖添加量10.5%、咖啡添加量1.3%、酿酒酵母接种量0.4%、发酵时间3.5 d;在此最优条件下,咖啡乳酒的色泽褐黄透明,咖啡香、奶香与酒香和谐,酒体丰满圆润,感官评分为88.9分。     

The mineral profile affects the coagulation pattern and cheese-making efficiency of bovine milk

Natural variations in milk minerals, their relationships, and their associations with the coagulation process and cheese-making traits present an opportunity for the differentiation of milk destined for high-quality natural products, such as traditional specialties or Protected Designation of Origin (PDO) cheeses. The aim of this study was to quantify the effects of the native contents of Ca, P, Na, K, and Mg on 18 traits describing traditional milk coagulation properties (MCP), curd firming over time (CF_t) equation parameters, cheese yield (CY) measures, and nutrient recoveries in the curd (REC) using models that either included or omitted the simultaneous effects of milk fat and casein contents. The results showed that, by including milk fat and casein and the minerals in the statistical model, we were able to determine the specific effects of each mineral on coagulation and cheese-making efficiency. In general, about two-thirds of the apparent effects of the minerals on MCP and the CF_t equation parameters are actually mediated by their association with milk composition, especially casein content, whereas only one-third of the effects are direct and independent of milk composition. In the case of cheese-making traits, the effects of the minerals were mediated only negligibly by their association with milk composition. High Ca content had a positive effect on the coagulation pattern and cheese-making traits, favoring water retention in the curd in particular. Phosphorus positively affected the cheese-making traits in that it was associated with an increase in CY in terms of curd solids, and in all the nutrient recovery traits. However, a very high P content in milk was associated with lower fat recovery in the curd. The variation in the Na content in milk only mildly affected coagulation, whereas with regard to cheese-making, protein recovery was negatively associated with high concentrations of this mineral. Potassium seemed not to be actively involved in coagulation and the cheese-making process. Magnesium content tended to slow coagulation and reduce CY measures. Further studies on the relationships of minerals with casein and protein fractions could deepen our knowledge of the role of all minerals in coagulation and the cheese-making process.     

Numerical modeling of heat and mass transfer during coffee roasting process

In this work a numerical model, based on a 3D geometry, able to describe the heat and moisture transfer inside a coffee bean during the roasting process, was developed. The model makes reference to a rotating cylinder roaster in natural convection conditions.For the multiphysics model development heat and mass transfer equations inside the coffee bean were numerically solved using a finite element technique. Two domain geometries were tested. One simplified, based on a simple semi-ellipsis, and one made acquiring the shape of an Arabica coffee bean using a 3D scanner. To validate the numerical model, green coffee bean was singularly roasted using a rotating drum roasters prototype. The calculated moisture concentration and time-temperature curves were then compared with the observed data.The calculated temperature values, in the centre of the bean, appear to be in good agreement with those measured inserting thermocouples into the coffee bean (RMSE 5.97 °C). Similarly the calculated volume averaged moisture was in good agreement with the experimental data (RMSE 264.251 mol/m³) over the entire time span. This model can be useful to optimise the roasting process control.     

Improvement of coffee beverage quality by using selected yeasts strains during the fermentation in dry process

Coffee is an important commercial product to Brazil with its consumption distributed globally. The aim of this work was to evaluate the potential of yeast strains as starter cultures for dry fermentation of washed and non-washed coffee beans. Four yeast strains (Saccharomyces cerevisiae UFLA YCN727, S. cerevisiae UFLA YCN724, Candida parapsilosis UFLA YCN448 and Pichia guilliermondii UFLA YCN731) were inoculated separately in washed and non washed coffee cherries and in the control was not added any of the starter cultures. The fruits inoculated were spread on trays and placed on a terrace until the coffee beans reached 11% of moisture. Samples were collected for evaluation of the persistence of the inoculum by PCR-DGGE, and for chemical composition by HPLC and GC-FID. Sensory analysis was performed using the Temporal Dominance of Sensations (TDS) methodology. In all tests the yeasts persisted until the end of fermentation. There was no propionic and butyric acid production in concentrations that could compromise the final quality of the beverage. Forty-eight volatile compounds were identified, some were similar for green and roasted coffee. The most abundant class of compounds was alcohols (11–27%) followed by furan in roasted grains (~ 27%), and aldehydes (~ 13%) in green grains. The coffee inoculated with yeast showed sensations of flavors higher than the control coffee indicating increased sensory quality. The treatment with C. parapsilosis UFLA YCN448 showed dominance rate higher (near 1) for the sensation of caramel. In non-washed coffee those sensations were not pleasant in relation to the washed coffee, except when P. guilliermondii UFLA YCN731 was inoculated, suggesting that washing the fruit before the fermentation process positively influenced the final product quality. A coffee with special aroma of caramel, herbs and fruits could be produced using the starter cultures C. parapsilosis UFLA YCN448 and S. cerevisiae UFLA YCN727 in coffee processed by the dry method.     

肉品加工中的烘烤

就肉品加工中烘烤机理与方法、烘烤过程肉的变化以及烘烤在几种典型的肉制品加工中的应用作了论述.     

Structure expansion of green coffee beans using instantaneous controlled pressure drop process

Since 1988, when the first experiments with the Instantaneous Controlled Pressure Drop (DIC) process were performed, a lot of investigations have been carried out concerning the structure expansion, processing kinetics (drying, extraction and sterilization) and the improvement of the functional and organoleptic properties of fresh and dried foods. In this study, two DIC technologies were used to expand the structure of green coffee beans. Two varieties of commercial Arabica coffee beans of different agricultural and geographical origins (Brazilian and Ethiopian) were inspected. The effect of initial moisture content (7–40% dry basis), type of heating in the DIC process (steam and microwaves), processing parameters like pressure (0.4–0.7 MPa) and heating time (20–200 s) on bean expansion were investigated. The expansion was evaluated as the ratio of the tapped density of raw beans to that of the treated material. The hydration capacity of the beans was also studied. The Response Surface Methodology was employed to optimize the processing parameters. After the steam DIC treatment, the maximum expansion ratio of the Brazilian beans (e = 1.74) was higher than that of the Ethiopian beans (e = 1.59). For Brazilian beans, the steam DIC treatment resulted in a higher value of expansion ratio than the MW DIC treatment (e = 1.39). Concerning hydration capacity, the steam DIC treatment gave values of 78.6% and 48.2% d.b. for the Ethiopian and Brazilian beans, respectively. It means almost two-fold increase in the hydration capacity using DIC treatment. The steam DIC treatment increased and accelerated in twice the weight loss of beans during roasting.

Industrial relevance

Preliminary experiments have shown that the structure expansion of green coffee beans significantly reduced the roasting time, amended the bean suitability to grinding and improved the kinetics and yield of caffeine and active compounds extraction. The industrial DIC processes can be distinguished by high quality of final products, energy saving and positive environmental impact. Due to the fragile structure of coffee beans, a batch process should be applied. Industrial plant can be designed as a tower plant with several compartments separated by guillotine valves where the material falls down by gravity force or a carrousel or a linear plant with filling, DIC treatment and discharging operations. The ABCAR DIC Process Company (La Rochelle, France) develops plants with a capacity of 50 kg/h to 8 ton/h of dry coffee beans. Despite the promising experimental results concerning microwave DIC technology, the industrial applications are so far limited to the steam DIC treatment due to technical reasons.     

Molecular weight of guar gum affects short-chain fatty acid profile in model intestinal fermentation

Dietary fiber exerts many beneficial physiological effects; however, not all types of dietary fiber display the same effects. Partially hydrolyzed guar gum (PHGG), a lower molecular weight form of guar gum, is more easily incorporated into food, but may have less pronounced physiological effects than the native form. The aim of this study was to identify differences in intestinal fermentability based on the molecular weight of guar gum. Guar gum of four molecular masses (15, 20, 400, and 1,100 kDa) was fermented using a batch in vitro fermentation system. Human fecal inoculum was the source of microbes. The 400-kDa fraction produced the greatest concentrations of total short-chain fatty acid (SCFA) at 8 h and the highest amounts of butyrate at 24 h. At 24 h, the 400-kDa fraction produced more total SCFA and propionate than the 15 kDa, but was not different than 20 kDa or 1,100 kDa fractions. The molecular weight of guar gum was positively correlated with acetate production and negatively correlated with propionate production. This study concludes that 400-kDa guar gum may be optimal for intestinal fermentability. In conclusion, the molecular weight of guar gum affects in vitro fermentability and should be considered when adding to a food or beverage.