Pretreatment processes assisted subcritical water hydrolysis for valorisation of spent coffee grounds

This study investigated the effect of sequential extraction techniques and pretreatment methods in enhancing the recovery of high-value products from spent coffee ground. Supercritical carbon dioxide (SC-CO₂) deoiling was performed to recover non-polar lipids, and subcritical water (SCW) hydrolysis of deoiled spent coffee ground (SCG) was conducted involving pretreatment with ultrasound (US-SCG), and sample particle size reduction (PS-SCG). SCW temperature, solid/liquid mixing ratio, constant pressure and residence time were studied for their effect on extracting reducing sugars (RS), total phenolic content (TPC), total flavonoid content (TFC), 5-HMF, and furfural. Temperature increase enhanced hydrolysis efficiency and promoted RS dehydration into 5-HMF and furfural. At 180 °C and 40 mg/600 mL, TPC, TFC and RS values increased significantly with ultrasound pretreatment correlating with improved antioxidant activities by DPPH and ABTS assays. Highest amount of 5-HMF and furfural was obtained at 210°C (highest temperature studied) with 44.71 and 2.36 mg/100 g. Chlorogenic acid recovery was the highest in the non-deoiled SCG (15.07 mg/100 g), with no significant difference observed in PS-SCG, suggesting an increase due to its reduced particle size. The results of this study provide comprehensive knowledge on the combined effects of integrated engineering systems to boost the valorisation of SCGs into high-value products.     

Determination of caffeic and chlorogenic acids and their derivatives in different sunflower seeds

Five different genotypes (Tesoro, Marko, Clip, Vyp‐70 and Nanta) of sunflower seeds were studied and the phenolic compositions of their kernel and hull were characterised by HPLC and MS techniques. The main phenolic compounds present in both the kernel and hull are chlorogenic acid, caffeic acid and two caffeoylquinic derivatives. Both derivatives were characterised by partial alkaline hydrolysis and LC/MS. The four phenolic compounds present in the kernel ranged from 94.6% (genotype Clip) to 99.3% (genotype Marko) of the total phenolic compounds of the whole seed. Therefore the dehulling of the seed scarcely improves its nutritional value. © 2000 Society of Chemical Industry     

Separation and characterisation of chlorogenic acid‐rich conserves from green coffee beans and their radical scavenging potential

Methanolic extract (Me₁) obtained from low‐grade green coffee beans (LCB), which is one of the major by‐products in the coffee industry, was enriched with phenolics by different methods viz., partitioning in solvents, chromatographic separation using dowex & diaion HP20 resins and precipitation by lead acetate. Separated fractions and Me₁ were analysed for total polyphenol, chlorogenic acid, caffeine and radical scavenging activity (RSA). Chlorogenic acid isomers of Me₁ and the isolated fractions were analysed by HPLC. Me₁ found to contain total polyphenol (16.60 ± 0.4%), chlorogenic acids (CGAs) (29.60 ± 0.9%), caffeine (7.52 ± 0.2%) and exhibited RSA (92.50%) at 100 ppm concentration. Precipitation method resulted significantly (P ≤ 0.05) higher phenolics (46.33 ± 0.5%) as well as CGAs (43.50 ± 0.7%). HPLC analysis indicated that the composition of 5‐Caffeoylquinic acid (5‐CQA) was more in all the isolated fractions.     

出芽短梗霉固态发酵啤酒糟制备阿魏酰低聚糖和膳食纤维工艺研究

以啤酒糟为试验材料,研究固态发酵制备阿魏酰低聚糖和膳食纤维的最佳发酵工艺条件。以阿魏酰低聚糖和可溶性膳食纤 维含量为评价指标,选择木聚糖、尿素、磷酸二氢钾为影响因素,通过正交试验确定最佳固态培养基配方。在接种量、发酵时间和发酵 温度3个单因素试验的基础上,利用响应面法优化出芽短梗霉发酵啤酒糟的发酵工艺条件。结果表明,固态发酵的最佳培养基配方为 木聚糖6%、尿素4%和磷酸二氢钾1%;最佳固态发酵条件为接种量12%、发酵时间4 d和发酵温度29 ℃。在此优化条件下,阿魏酰低聚 糖含量和可溶性膳食纤维含量都达到最高,分别为37.67μmol/L和23.76%。     

The influence of brewing method on bioactive compounds residues in spent coffee grounds of different roasting degree and geographical origin

The content of bioactive compounds in spent coffee grounds (SGC) was studied. SGC were obtained from Coffea arabica beans of different roasting degrees (light and dark) and different geographical origins (Nicaragua, Columbia and Mexico) processed using four brewing methods (mocha, filtered, drip and infusion). The highest caffeine and chlorogenic acid contents were determined in filtered spent coffee extracts. All extracts of light roasted spent coffee grounds showed lower browning index levels in comparison to that from dark roasted spent coffee grounds. Generally, the highest content of total polyphenolic compounds and highest antioxidant capacity were determined in extracts prepared in drip. In conclusion, the results obtained in this study indicate that the spent coffee grounds produced of domestic levels, especially those obtained from filter coffeemaker, could be considered as a good source of natural antioxidants.     

Beta-cyclodextrin complexes with chlorogenic and caffeic acids from coffee brew: Spectroscopic,thermodynamic and molecular modelling study

Coffee brew is rich in chlorogenic and cinnamic acids, potent antioxidants. Its interaction with beta-cyclodextrin leads to formation of inclusion complexes which affect the physicochemical properties of the guest molecule. We investigated spectral changes in coffee-originated phenols, chlorogenic (CHA) and caffeic (CA) acids, due to complexation with beta-cyclodextrin (betaCD) in aqueous solutions and studied thermodynamic properties of the complexes formed. The spectroscopic data (absorption and fluorescence) were used for deducing the position of both phenols inside the beta-cyclodextrin cavity, as well as to calculate the binding constants of the complexes. The obtained data indicate the formation of a 1:1 complex between betaCD and CHA or CA. The temperature-dependence of the latter allowed the calculation of thermodynamic parameters (ΔH, ΔS and ΔG) of the complexation. The negative values of all the thermodynamic parameters indicated that the formation of these inclusion complexes was an enthalpy-driven process in which a crucial role is played by weak van der Waals forces and hydrogen bonds. Molecular modelling confirmed experimental observations that, in aqueous phase, betaCD–CHA and –CA complexes are stable and energetically favourable, and additionally provided information regarding conformation and interaction between atoms forming the complexes. The experimental data were used to characterise the molecular mechanism of the complexation.     

Overview on the mechanisms of coffee germination and fermentation and their significance for coffee and coffee beverage quality

Quality of coffee is a complex trait and is influenced by physical and sensory parameters. A complex succession of transformations during the processing of seeds to roasted coffee will inevitably influence the in-cup attributes of coffee. Germination and fermentation of the beans are two bioprocesses that take place during post-harvest treatment, and may lead to significant modifications of coffee attributes. The aim of this review is to address the current knowledge of dynamics of these two processes and their significance for bean modifications and coffee quality. The first part of this review gives an overview of coffee germination and its influence on coffee chemistry and quality. The germination process initiates while these non-orthodox seeds are still inside the cherry. This process is asynchronous and the evolution of germination depends on how the beans are processed. A range of metabolic reactions takes place during germination and can influence the carbohydrate, protein, and lipid composition of the beans. The second part of this review focuses on the microbiota associated with the beans during post-harvesting, exploring its effects on coffee quality and safety. The microbiota associated with the coffee cherries and beans comprise several bacterial, yeast, and fungal species and affects the processing from cherries to coffee beans. Indigenous bacteria and yeasts play a role in the degradation of pulp/mucilage, and their metabolism can affect the sensory attributes of coffee. On the other hand, the fungal population occurring during post-harvest and storage negatively affects coffee quality, especially regarding spoilage, off-tastes, and mycotoxin production.     

Effect of shading on yield, sugar content, phenolic acids and antioxidant property of coffee beans (Coffea Arabica L. cv. Catimor) harvested from north-eastern Thailand

BACKGROUND: Environmental conditions, including shading, generally influence the physical and chemical qualities of coffee beans. The present study assessed the changes in some phenolic compounds, antioxidant activity and agronomic characters of coffee beans (Coffea arabica L. cv. Catimor) as affected by different shading conditions including full sun, three artificial shading conditions using a saran covering (50% shade, 60% shade, and 70% shade) and lychee shade. RESULTS: Bean weight and bean size increased significantly (P < 0.05) when the shade level was progressively increased. The coffee beans grown under lychee shade exhibited superior bean yield, 1000‐bean weight, total phenolic content and antioxidant activity compared to all other beans. Chlorogenic acid was the most predominant phenolic acid in all samples studied, being the highest in the beans grown under lychee shade, followed by 60% shade, 70% shade, 50% shade and full sun, respectively. In contrast, bean grown under full sun had the highest amount of vanillic acid and caffeic acid. CONCLUSIONS: Antioxidant activity was highly positively associated with chlorogenic acid content. The content of total sugar (fructose, glucose and sucrose) was found highest in coffee beans grown in 60% shade, with fructose the predominant sugar. Under climatic conditions similar to this experiment, it is advisable that growers provide shade to the coffee crop to reduce heat from direct sunlight and promote yield as well as obtain good quality coffee beans. Copyright © 2012 Society of Chemical Industry     

桂圆酵素的发酵工艺优化及其酚类化合物生物转化分析

以桂圆水提液为原料,总酚含量为评价指标,采用单因素及正交试验优化桂圆酵素的发酵工艺,并用高效液相色谱（HPLC）分析桂圆酵素中酚类化合物的生物转化。结果表明,最优桂圆酵素发酵工艺为菌株组合酿酒酵母＋醋酸杆菌＋植物乳酸杆菌1∶1∶1、接种量10%、发酵温度30 ℃、发酵时间36 h。在此优化工艺条件下,桂圆酵素的总酚含量达（46.05±0.76） μg/mL,是桂圆水提液总酚含量（9.12±0.26） μg/mL的5.05倍。HPLC分析表明,桂圆水提液中10多种酚类化合物,除了绿原酸及其它4种酚类化合物外,其余酚类化合物经发酵后均被完全转化。桂圆酵素中至少含有20余种酚类化合物,至少有16种为新生成,其中1种可以确定为柚皮苷,含量达3.32 μg/mL。     

Electrochemical behavior of chlorogenic acid at a boron-doped diamond electrode and estimation of the antioxidant capacity in the coffee samples based on its oxidation peak

Abstract: In this study, an electroanalytical methodology for the determination of chlorogenic acid (CGA) was achieved at a boron‐doped diamond electrode under adsorptive transfer stripping voltammetric conditions. The values obtained for CGA were used to estimate the antioxidant properties of the coffee sample based on CGA oxidation. By using square‐wave stripping mode, the compound yielded a well‐defined voltammetric response at +0.49 V with respect to Ag/AgCl in Britton–Robinson buffer at pH 3.0 (after 120 s accumulations at a fixed potential of 0.40 V). At the optimum experimental conditions, linear calibration curve is obtained within the concentration range of 0.25 to 4.0 μg mL^?1 with the limit of detection 0.049 μg mL^?1. The developed protocol was successfully applied for the analysis of antioxidant capacity in the coffee products such as Turkish coffee and instant coffee.     

Use of coffee by‐products for the cultivation of Pleurotus citrinopileatus and Pleurotus salmoneo‐stramineus and its impact on biological properties of extracts thereof

Incorporating spent coffee grounds (SCGs), a by‐product from coffee brewing, in growth substrate of beneficial edible mushrooms is an approach that has to be further studied due to its potential positive outcomes: environmental impact mitigation, production costs reduction and beneficial impact on consumer health. Hence, cultivation of Pleurotus citrinopileatus and Pleurotus salmoneo‐stramineus was tested using SCG which enabled maximum production yield of P. citrinopileatus which was of 25.1% (w/w). Variable antidiabetic potential was observed between aqueous and enzymatic extracts (3.8%–29% inhibition) regardless species and substrates, whereas aqueous extract of P. citrinopileatus grown in substrate without SCG stood out presenting the highest antioxidant activity and inhibition activity of angiotensin I‐converting enzyme (IC₅₀ = 123 μg mL^?1). Ethanolic and aqueous extracts of both Pleurotus species grown in the presence or absence of SGC proved to be an interesting prebiotic source for growth of Bifidobacterium animalis Bo in comparison with fructooligosaccharides (FOS).     

固态发酵食醋中还原糖、总糖含量测定

采用直接滴定法、3,5-二硝基水杨酸法2种方法测定固态发酵食醋、加饭酒中还原糖、总糖含量,探讨样品颜色对还原糖、总糖测定的影响,同时为消除色素对糖含量测定的影响,用活性炭对其脱色.结果表明:直接滴定法因样品颜色的影响,不易判断滴定终点,使平均回收率仅为78.050％;活性炭脱色后平均回收率仅为76.414％,3,5-二硝基水杨酸法是比较准确的测定固态发酵食醋中糖含量的方法,平均回收率为100.933％.     

混菌固态发酵米糠产谷维素的工艺及抗氧化活性评估

目的:提高米糠谷维素的得率。方法:以米糠为研究对象,经单因素试验筛选出酿酒酵母和枯草芽孢杆菌作为固态发酵菌种,以谷维素含量为指标,通过单因素试验结合Box-Behnken响应面法优化混菌固态发酵工艺,采用DPPH自由基和ABTS自由基清除试验对发酵提取物抗氧化活性进行评价,并通过扫描电镜(SEM)分析混菌固态发酵法富集谷维素的原理。结果:在酿酒酵母和枯草芽孢杆菌混菌处理下,米糠谷维素最优发酵工艺为发酵时间44 h,发酵温度34℃,接种量10%,含水量40%,在此条件下谷维素含量为(7.816±0.038) mg/g,是未发酵米糠谷维素含量的1.9倍。混菌固态发酵法制备的提取物具有较强的DPPH自由基和ABTS自由基清除活性,其IC₅₀值分别为(0.220±0.007),(0.409±0.014) mg/mL,与未发酵米糠相比,其IC₅₀值分别降低了28.6%和39.7%。SEM分析结果显示,混菌固态发酵后米糠组织表面油脂更少,结构疏松多孔,更加有利于米糠中谷维素的释放。结论:米糠经混菌固态发酵后,谷维素含量和抗氧化活性均得到显著提高。     

Development of normal and branched chain volatile fatty acids during the fermentation process in the manufacture of fish sauce

The formation of volatile fatty acids (VFAs) in fish sauce was investigated. When fish were allowed to spoil prior to salting, very high concentrations of VFAs were produced. The increase was probably caused by microbial action. Addition of salt to spoiled fish seemed to inhibit microbial action, thus suppressing the formation of VFAs. The contents of short and long straight chain VFAs in aerobically fermented sauces were significantly higher than in anaerobically fermented sauces, suggesting that straight chain VFAs developed from fish fats. Certain branched VFAs were derived from the degradation of specific amino acids, such as isobutyric acid from valine and isovaleric acid from leucine. Alanine and isoleucine did not have a clear influence on the production of VFAs. © 2001 Society of Chemical Industry     

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     

木贼醇提物不同萃取部位总酚酸、黄酮含量测定及抗氧化活性研究

目的:对木贼的乙醇提取物不同萃取部位进行总酚酸、黄酮含量测定及抗氧化活性比较,以探知木贼抗氧化活性物质基础。方法:木贼经70%乙醇超声提取浓缩后,采用有机溶剂萃取法依次得到石油醚、乙酸乙酯、正丁醇、水相4个部位萃取物;利用紫外-分光光度法比较各萃取部位总黄酮、酚酸含量差异;以抗坏血酸为阳性对照,比较不同萃取部位还原能力、羟自由基(·OH)、1,1-二苯基-2-三硝基苯肼(DPPH·)、2,2'-联氮-双(3-乙基苯并噻唑-6-磺酸)二铵盐(ABTS⁺·)清除率的差异,评价各部位抗氧化能力强弱。结果:木贼各萃取物总黄酮含量在5.70~61.55 mg/g 范围内,总酚酸含量在4.07~19.10 mg/g 范围内,乙酸乙酯萃取物总黄酮与酚酸含量明显高于其他萃取物,其还原能力、羟自由基、DPPH·、ABTS⁺·清除率也明显高于正丁醇、石油醚和水相萃取物,乙酸乙酯萃取物对羟自由基、ABTS⁺·、DPPH·清除能力IC₅₀值分别为:(0.321±0.0026)、(0.213±0.0010)和(0.169±0.0014) mg/mL。结论:经各相溶剂萃取后木贼有效成分得到初步分离,乙酸乙酯相萃取部位总黄酮和酚酸相对含量及抗氧化活性明显强于总提物和其他萃取部位,且其抗氧化能力呈量效关系。实验发现木贼中黄酮和酚酸类成分与其抗氧化能力密切相关。     

咖啡中功能性成分分离检测技术及安全性评价

咖啡以其独特的风味口感以及生理活性成为世界范围内最重要的食品类商品之一。咖啡的生理活性主要来自于咖啡中的咖啡因、绿原酸以及类黑精等功能性成分,这些成分具有醒脑提神、抗忧郁、抗氧化、抗菌以及预防癌症等方面的生物活性。因此,咖啡中功能性成分的分离提取、分析检测以及其安全性评价已经成为目前研究的热点。本文对咖啡中功能性成分咖啡因、绿原酸和类黑精的分离检测技术及其安全性评价研究进展进行综述,为咖啡中功能性成分的分离分析以及科学使用提供前沿的科学参考。