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Recycling coffee and tea wastes to increase plant available Fe in alkaline soils

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Abstract

Coffee beans and tea leaves contain large amounts of potentially metal-chelating substances which could remain in the wastes after extraction by hot water. The following two experiments have been carried out: a) an incubation experiment with the objective of verify whether coffee grounds and green tea wastes could be used as an Fe chelating agent to increase Fe availability to plants in the soil; b) a pot experiment to verify the effect of those composts on the Fe content of the edible part of vegetables. Japanese leaf radish (Raphanus raphanus sp), whose the leaves are the edible part, was chosen as test plant. Calcareous subsoil (shell fossil soil) with original pH 9.3 and a B horizon of Andisol (Typic melanudand) with pH adjusted to 7.7 were used. For the incubation experiment, the treatments included of the direct addition of Fe at rates of 0 (control), 10, 20 and 40 μg g−1 dry soil as ferrous sulfate (FS); coffee waste compost (CWC) and tea waste compost (TWC). Both composts contained approximately 40 g Fe kg−1 dry mass. Thus, the total amounts of CWC and TWC added were of 0, 0.25, 0.5 and 1.0 mg g−1 soil. Considering a soil density of 1 g cm−3 and 10 cm of plow layer, the total amounts of compost applied were of 0, 0.25, 0.5 and 1.0 ton ha−1. Soil samples were collected after 30 and 60 days of incubation and then analyzed for plant available Fe. For the pot experiment, the doses of 0 (control) and 1 mg g−1 soil of CWC or TWC were used to grow radish. Plants were harvested after 60 days. For samples incubated for 30 days, the CWC and TWC treatments led to the largest increase in the ammonium bicarbonate diethylene triamine pentaacetic acid (AB-DTPA) extractable Fe levels of both soils (P

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... The consequences of adding SCG to the soil-plant system have been assessed previously taking into account different soil types, doses, application forms (composted vs. fresh SCG) and experimental designs (end-point vs. time-series). In the case of soil types, artificial (Cruz et al. 2012(Cruz et al. , 2014a(Cruz et al. , 2015, tropical-acidic (Kasongo et al. 2013;Yamane et al. 2014), Andosols (Morikawa and Saigusa 2008;Kim et al. 2014) and Australian sandy soil (Hardgrove and Livesley 2016) have been studied. However, they are different from Mediterranean cultivation soils. ...
... Statistically pH is closely linked to soil type (according to the principal components matrix stated in Table 3) since the pH of the Vega soil pots was significantly higher (p < 0.001, Table 4) than that of the Red soil pots. In the literature on SCG (Morikawa and Saigusa 2008;Cruz et al. 2015) pH increased in line with cultivation time. In the present study, this increase can be attributed to the buffering capacity of the soils, which is higher in the Vega soil due to the abundance of carbonates (Brady and Weil 2002). ...
... The decrease in EC 25 could be attributed to the plants' absorption activity, since the pots used in the experiment do not lose ions by leaching. Another explanation for the decline in salinity could be that the transformation of organic residues produced an increased cation exchange capacity (greater retention of ions) (Morikawa and Saigusa 2008). ...
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The use of spent coffee grounds (SCG) as organic amendment is a triple solution: a reuse of this bio-residue (6 millions of tons per year), an increase in soil organic carbon (SCG contain 82% of carbohydrates and 13% of proteins) and a decrease in CO2 emissions into the atmosphere. Thus, we investigate the effect of SCG on soil and plants in an in vitro assay. The variables considered were SCG dose (2.5 and 10%), two agricultural soils (Calcisol and Luvisol), and four cultivation times (15, 30, 45 and 60 days). The chemical and physicochemical soil properties, SEM images and growth parameters were analyzed. The highest dose of SCG increased organic carbon, total N and available K and P by 286%, 188%, 45%, and 9%, respectively, while decreasing lettuce growth by 233% compared to control. The SEM study revealed that SCG particles are incorporated into soil aggregates and microorganisms grow over them, which is also corroborated by a 10-times increase of soil respiration rate. The behavior of both soils differs for some SCG effects. In conclusion, SCG have a great potential to increase soil fertility and further investigations are needed in order to improve the use of SCG as amendment.
... The consequences of adding SCG to the soil-plant system have been assessed previously taking into account different soil types, doses, application forms (composted vs. fresh SCG) and experimental designs (end-point vs. time-series). In the case of soil types, artificial (Cruz et al. 2012(Cruz et al. , 2014a(Cruz et al. , 2015, tropical-acidic (Kasongo et al. 2013;Yamane et al. 2014), Andosols (Morikawa and Saigusa 2008;Kim et al. 2014) and Australian sandy soil (Hardgrove and Livesley 2016) have been studied. However, they are different from Mediterranean cultivation soils. ...
... Statistically pH is closely linked to soil type (according to the principal components matrix stated in Table 3) since the pH of the Vega soil pots was significantly higher (p < 0.001, Table 4) than that of the Red soil pots. In the literature on SCG (Morikawa and Saigusa 2008;Cruz et al. 2015) pH increased in line with cultivation time. In the present study, this increase can be attributed to the buffering capacity of the soils, which is higher in the Vega soil due to the abundance of carbonates (Brady and Weil 2002). ...
... The decrease in EC 25 could be attributed to the plants' absorption activity, since the pots used in the experiment do not lose ions by leaching. Another explanation for the decline in salinity could be that the transformation of organic residues produced an increased cation exchange capacity (greater retention of ions) (Morikawa and Saigusa 2008). ...
... The use of agricultural waste products is a logical answer to the problem outlined above. Their volume is constantly increasing with growing population (Sönmez et al., 2017) and their organic matter content offers the possibility of containing potentially metal-chelating substances (Morikawa and Saigusa, 2008). Sönmez et al. (2017) applied greenhouse wastes, used coco peat and spent mushroom compost at different ratios for greenhouse-grown lettuce. ...
... Large amounts of coffee and tea wastes are produced by companies manufacturing coffee and tea beverages. These wastes should be reused on a sustainable way (Morikawa and Saigusa, 2008). It was found that coffee waste application to an Arenosol in the Democratic Republic of Congo promoted nutrient retention of this sandy soil besides of several other favourable physico-chemical changes (Kasongo et al., 2011). ...
... Coffee and tea are very rich in phenolic compounds which can act as metal chelating agents (Brown et al., 1998). Morikawa and Saigusa (2008) composted coffee grounds and tea leaf wastes together with ferroussulphate. Application of the resulting compost increased plant-available iron concentration in neutral and alkaline soils, and significantly enhanced iron content of Japanese leaf radish. ...
... Deviations of element amounts in lettuce among literature data are very common, since metal bioavailability as well as plant-uptake is strictly related to its form of entering the soil, the chemical and physical properties of the soil around the plant roots and the crop type (Alloway, 1995;Morikawa & Saigusa, 2008). According to Kabata-Pendias (2004), plants reveal a great adaptation to the variable composition of growth media, developing uptake/exclusion mechanisms for a given nutrient, either under deficiency or excessive conditions in soil. ...
... Interestingly, an inverse pattern is observed in the post-harvest soil samples (Table 1), where an underlying increment of such minerals is observed. This increase may be the result of the actual SCG mineral composition, particularly due to its richness in K or a retention of minerals by the coffee matrix through the presence of potentially metal-chelating substances (Morikawa & Saigusa, 2008), making them less available for the plant. Still, all quantified mineral amounts correspond to their total content, thus such cannot be directly explored as available for plant nutrition, justifying the reduction in the plant mineral status despite the increased amounts in the soil. ...
Article
Spent coffee grounds (SCG) are usually disposed as common garbage, without specific reuse strategies implemented so far. Due to its recognised richness in bioactive compounds, the effect of SCG on lettuce's macro- and micro-elements was assessed to define its effectiveness for agro industrial reuse. A greenhouse pot experiment was conducted with different amounts of fresh and composted spent coffee, and potassium, magnesium, phosphorous, calcium, sodium, iron, manganese, zinc and copper were analysed. A progressive decrease on all lettuce mineral elements was verified with the increase of fresh spent coffee, except for potassium. In opposition, an increment of lettuce's essential macro-elements was verified when low amounts of composted spent coffee were applied (5%, v/v), increasing potassium content by 40%, manganese by 30%, magnesium by 20%, and sodium by 10%, of nutritional relevance This practical approach offers an alternative reuse for this by-product, extendable to other crops, providing value-added vegetable products.
... The biodiesel obtained by this procedure was approximately 51% saturated methyl esters and was stable for more than one month at ambient temperature. Another application exploiting the ability of SCG to bind metal ions is the use of Fe-treated SCG to increase Fe availability to plants in neutral to alkaline soils (Morikawa and Saigusa, 2008). According to these authors, the Fe-containing material can be prepared easily by adding appropriate amounts of a soluble ferric compound to SCG and composting the material. ...
... Coffee ground is one of the wastes has been studied to recycle by composting and vermicomposting (Adi and Noor, 2009). Morikawa and Saigusa, (2008) also showed that application of coffee ground compost increased available Fe for plants. The use of SCG as a potential source of bioactive compounds particularly polyphenols (Esquivel and Jiménez, 2012). ...
Article
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Coffee industries are responsible for the generation of large amount of wastes which are toxic and serious environmental problems. Currently, there is great political and social pressure to reduce the pollution arising from industries. Different management options have been applying to overcome the problems. The wastes can be used for alleviating the scarcity of animal feeds, a suitable substrate for mushroom cultivation, raw material for bioprocess like biogas, enzyme, hormones, dyes and compost. They also have importance for microbial growth, protein extraction, caffeine extraction, biofuels and others. Coffee hulls have high concentration of crude fiber which is mainly used as fillers in animal feeds. Coffee husks are rich in carbohydrates, proteins, fibers and minerals. Coffee husks used for production of gibberellin acid (GA3) which is a plant hormone widely used in the agro-industry in solid state fermentation and as filter for metal ion absorption or dye absorption. Coffee husk biochar and P fertilizer significantly improved soil chemical properties, P accumulation, N2 fixation and seed yield of soybean. Similarly coffee husk compost increases the yield and yield component of lettuce, cabbage, rice and coffee. Combined and sole application of the bioslurry of coffee waste with chemical fertilizer positively increased the yield, yield component of the wheat and organic carbon of soil. Briquette produced from coffee husk molasses shows better combustibility than coffee husk clay. Coffee mucilage is very rich in pectin content and could be used as a substrate for pectinases and cellulase induction. Wet coffee processing waste is important to produce bio-ethanol which provides the alternative energy source. SCG are richer in sugars than coffee silver skin; among these mannose and galactose are the most abundant. It is also used for producing a biofuel product which was approximately 51% saturated methyl esters and stable for more than one month at ambient temperature. Application of coffee ground compost increased available Fe for plants. SCG contain large amounts of Chlorogenic acid and its derivatives which are powerful in-vitro antioxidants and are believed to provide many health benefits.
... At the same time, spent ground coffee (SCG) has been receiving growing attention in the quest for possible applications of this waste. In particular, some studies have highlighted the possibility of using SCG to remove heavy metal ions [7][8][9] from contaminated waters, increase Fe 2+ availability to plants in neutral to alkaline soils [10]. Based on total phenolic content, SCG may also be an exploitable resource for natural antioxidant production [10]. ...
... In particular, some studies have highlighted the possibility of using SCG to remove heavy metal ions [7][8][9] from contaminated waters, increase Fe 2+ availability to plants in neutral to alkaline soils [10]. Based on total phenolic content, SCG may also be an exploitable resource for natural antioxidant production [10]. ...
Article
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Recovery of phenolic content from waste is one of the main concerns for any possible applications. This study was done to investigate and explore the functional properties of cocoa waste (CW) from espresso cocoa production. The total phenolic content (TPC), total flavonoid content (TFC), 2,2-diphenyl-1-picrylhydrazyl scavenging assay (DPPH), metal (Fe²⁺) chelating activity was determined. Parameters include water holding capacity (WHC), oil holding capacity (OHC), swelling capacity (SWC), proximate compositions, total dietary fiber (TDF), insoluble dietary fiber (IDF) and soluble dietary fiber (SDF) were also determined. As a reference spent coffee ground (SCG) was also studied under all parameters. Two solvents, ethanol and water were used to extract the bioactive compounds from CW. The ethanol-CW extract was found to contain significantly the highest (p < 0.05) TPC and TFC with 52.3 mg GAE/ml sample and 84.36 mg Quercetin/ml sample respectively. This was correlated to its high (p < 0.05) antioxidant activities in DPPH (IC50 3.58 ± 0.07 mg/ml) and metal chelating activity (IC50 2.32 ± 0.09 µg/ml). Positive correlations ranging from r² = 0.82 to 0.98 were established between the phytochemicals and antioxidant activities of all extracts. All samples displayed significantly (p < 0.05) high WHC and SWC, in relevance to their high (p < 0.05) TDF which were over 60% of 100 g dry matter. CW exhibited significantly high (p < 0.05) IDF/SDF ratio, in contrast to SCG with also high protein content of 13%. This study indicates that CW has a potential as a source of natural antioxidant and phytochemical in functional food development and intermediate food ingredient.
... Dry phenolic extracts obtained under optimum process conditions exhibited high antioxidant activity, suggesting their potential use in a variety of food and non-food applications. Furthermore, the solid residue remaining after polyphenol extraction could be used for heating purposes, due to its high calorific value [14], as a low-cost adsorbent [37] or in agronomic applications [38]. This would allow full exploitation and valorization of SCG. ...
... Certaines études ont mis en évidence les propriétés adsorbantes du marc de café vis-à-vis des colorants [5], tels que le bleu de méthylène dans une solution aqueuse [6], ainsi que les métaux lourds [7], tels que les ions de plomb dans l'eau potable [8]. D'autres travaux ont confirmé la possibilité d'utiliser le marc de café comme agent chélateur pour augmenter la disponibilité du fer dans le sol pour les plantes [9]. Par ailleurs, d'autres études ont démontré qu'il est possible d'extraire jusqu'à 15 % de l'huile de marc de café en utilisant des solvants organiques [10]. ...
... In addition, activ ity of effect ive microorganisms in the co mpost such as nitrogen fixing bacteria and phosphate soluble bacteria also play important roles to increase in uptake mineral nutrients in the leaves of the coffee. Morikawa and Saigusa also showed that application of coffee ground compost increased available Fe for p lants[22]. It was clear that content of mineral nutrients in the leaves were improved significantly in formu las which substituted partially with the co mpost. The content of N%, P% and K% in the formula 1 and formula 2 increased higher by 4.2%, 14% and 10% than control. ...
Article
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Co ffee husk supplemented with cow manure, and fertilizers (phosphorus and urea) were studied. The results showed that 5.0% thermophosphate fertilizer, 1.0% urea fertilizer and 1.2m in height of heap were suitable conditions for composting coffee husk. The quality of the co mpost was better than original coffee husk and some bio-organic fertilizers on the agriculture market. The co mpost was used for coffee plant on the field with amount of 2.0-3.0 kg.plant-1 .year-1 during 3 years and reduced using fro m 20% to 30% chemical fertilizers. The results showed that fertility of soil, mineral nutrients in the coffee leaf and the growth of the coffee were improved in co mparison with plots that no using the compost. This report demonstrates a method of using agricultural waste-coffee husk to produce compost and contributes to inhibit environmental pollution in rural and develop eco-sustainable agriculture.
... Coffee (Coffea arabica L.) and tea (Camellia sinensis (L.) Kuntze) are familiar beverages and considered as a medicine since the ancient times to polyphenolic contents and having high amount of metal chelating substances that may remain in the wastes when extracted with hot water (Morikawa & Saigusa, 2008). In some studies reported that tea has been associated in reducing risk of heart disease and cancers, anti-allergic action and antimicrobial properties (Paola et al., 2005). ...
Article
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The pot experiment was carried out to evaluate the effect of tea compost on plant growth under salinity. Plants were grown in clay pots filled with sandy loam soil and irrigated by saline water (0, 50 and 100mM NaCl) with and without tea compost amendments. Soil evapotranspiration (ET), vegetative and reproductive growth and biochemical parameters were studied in this experiment. ET rate was increased with increasing salinity, whereas, it decreased with application of tea compost under all salinity. Vegetative (shoot height, number of leaves, fresh and dry biomass) and reproductive (number of seeds per plant) growth significantly decline under increasing salinity levels. Tea compost treatment helped in improving all these parameters. Total photosynthetic pigments (chlorophyll a, b, carotenoids and total chlorophyll content) showed reduction under raising salinity levels, while betterment was recorded with application of tea compost. Organic solutes (soluble sugars, proteins, free amino acids and phenolic content) increased with increasing salinity (50-100mM NaCl). Increased soluble sugars were found with tea compost treatment under non-saline control and decreased in salinity. Soluble proteins, amino acids and phenolic content increased with application of tea compost under both control and salinity. It is concluded that tea compost treatment is found to cope with salinity stress and improve plant growth and biochemical parameters by diluting the hazardous effects of salinity.
... The phenols of SCG may be toxic to soil microorganisms and plants, but at the same time these toxins provide a natural pesticide and herbicide (Cruz et al., 2012). Composted coffee grounds have been shown to positively increase the growth of certain horticultural plants in specific soils (Morikawa and Saigusa, 2008), but the evidence for non-composted SCG is less clear. Soil amendment with SCG can simultaneously increase plant biomass whilst decreasing plant foliar N content, although the impacts vary among plant species (Cruz et al., 2012;Yamane et al., 2014). ...
... Nevertheless, the organic nitrogen contents of plants were decreased (Cruz et al., 2012). Treating a calcareous subsoil (pH= 9.3) with different rates of composted SCG, containing 40 mg Fe kg -1 dry weight, improved soil Fe phytoavailability compared with the soil treated with only ferrous sulfate (Morikawa and Saigusa, 2008). This might due to its content of organic compounds such as fatty acids, amino acids, polyphenols, and polysaccharides (Campos-Vega et al., 2015). ...
... Coffee waste compost (CWC) and green tea waste compost (TWC) were efficient and cheap sources of Fe chelating agents that increase Fe availability to Japanese leaf radish plants (Raphanus raphanus) in Fe depleted soils (Morikawa and Saigusa, 2008). The CWC and TWC treated soils always had higher levels of available Fe, and radish plants grown in the control displayed chlorosis due ...
Article
This review summarizes the literature related to agricultural wastes published during 2008. This review is divided into the following sections: waste characterization, waste management and pollution minimization, waste treatment, and waste recycle and reuse.
... However, looking at the behavior of most element concentrations analyzed, we have found that these trends were not linear (saw-tooth pattern) except for Mn (Fig. 2a) where a progressive lineal increase of this element by SCG addition was observed. The general increase in the concentrations of elements by SCG and other coffee wastes addition has been related to the chelating effect of some of its components such as melanoidins, polyphenols and carbohydrates (Morikawa & Saigusa, 2008). In this sense, Rufián-Henares and de la Cueva (2009) determined the chelating capacity of melanoidins extracted from coffee against Fe and observed how these compounds decreased free Fe while increasing chelated Fe. ...
... Another application exploiting the ability of SCG to bind metal ions is the use of Fe-treated SCG to increase Fe availability to plants in neutral to alkaline soils (Morikawa and Saigusa, 2008). According to the authors, the Fe-containing material can be prepared easily by adding appropriate amounts of a soluble ferric compound to SCG and composting the resulting material. ...
Article
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Spent coffee grounds collected from coffee bars (SCG-1) or recovered from coffee capsules (SCG-2) were investigated as a potential source of phenolic compounds and energy. Preliminary characterization of these materials provided a total phenolic content of 17.75 mg GAE/g for SCG-1 and 21.56 mg GAE/g for SCG-2. A solvent-extraction procedure using aqueous ethanol as the solvent and operating under mild temperature conditions was developed and tested. A two-level factorial design was used to study the effects of temperature (T = 30-50 °C), extraction time (E = 60-120 min), liquid-to-solid ratio (R = 20-40 mL/g) and ethanol concentration in the aqueous mixture (C = 30-70 vol%) on the recovery of phenolic compounds. Under the best conditions, over 90% of the phenolic compounds contained in the starting waste materials were recovered. T, R and C were the most influential factors and all of them had a positive effect on the extraction efficiency. The calorific values of the two coffee wastes were 23.72 MJ/kg (SCG-1) and 24.07 MJ/kg (SCG-2). They were only marginally affected by the extraction procedure, which supports the possibility of integrating the recovery of phenolic compounds with the use of the resulting solid residue to produce pellets or other agglomerates for heating purposes. A case study application aimed at evaluating the potential valorization of the spent coffee produced in the Province of Rome is also presented. Copyright © 2012 Published by Elsevier Ltd. All rights reserved.
... The reason behind this could be attributed to that the hot water extraction process dissolves the various chemical compounds found in the tea residues and increases its concentration in the extract and thus increases its readiness to be absorb by the roots of the plant. This result was in agreement with previous findings from Morikawa and Saigusa (2008) where they found that tea leaves retained a good proportion of nutrients even after extraction with hot water. They found that the addition of tea residues to radish increase its leaves content of iron and improved its growth and this was in line with the results of the current study as the results shows noticeable development in the vegetative and productive characteristics of the chili pepper was obtained from the addition of home tea residues to the plant, especially when it was added in the form of extract. ...
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An experiment was conducted in the greenhouse belong to the Department of Biology-college of Education for Pure Sciences-University of Diyala to study the impacts of home tea residues as (dry tea residues and tea residues extract), Aspergillus niger fungus and their synergistic effect on the growth and yield of chili pepper (Capsicum annuam). Results showed significant increments in the plant height, fresh and dry weights of shoot and fruits, number of leaves and number of fruits per plant as a result of watering the plants with tea residues extract. On the other hand, the results also showed that the bio fertilization with Aspergillus niger fungus caused significant increments in all the studied characteristics of the pepper plant exception the total chlorophyll content of leaves and the number of flowers per plant, the results indicate to noticeable increments in these two characteristics, but they were not significant. As for the synergistic effect between home tea residues (dry tea residues and tea residues extract) and Aspergillus niger fungus, the results showed significant increments in the plant height, fresh and dry weights of shoot and fruits and the combination consist of (home tea residues extract + Aspergillus niger fungus) recorded the highest averages of (44.573 cm) for the plant height, (30.16 g) for shoot fresh weight, (6.153 g) for shoot dry weights and (18.236 g) for fresh weight of fruits , while the control treatment recorded the lowest averages of (30.017 cm, 20.866 g, 2.38 g, 10.596 g) for the mentioned characteristics respectively.
... These results are similar to those reported by Cruz et al. (2014) for composted SCG and could be related to the reduction in the carbon structure of SCG, decreasing its metal-binding capacity. In this sense, vermicomposting probably caused the decomposition of some of natural organic components of SCG such as polyphenols (Table 2) and the generation of heat-processing related compounds like coffee melanoidins (Rufian-Henares et al., 2006), which have been reported as chelating agents that facilitate elements uptake, and therefore the availability by plant (Morikawa and Saigusa, 2008). Consequently, vermicomposting would impair Zn, Cu and Fe availability to lettuce. ...
Article
Spent coffee grounds (SCG) are a bioresidue generated in large amounts worldwide, which could be employed as either fresh or transformed organic soil amendment, by means of different treatments in order to improve its agronomic qualities. An in vitro experiment was conducted in order to evaluate the effect of using different bioamendments derived from spent coffee grounds (SCG) on biomass and Zn, Cu and Fe content of lettuces. Application of 7.5% (w/w) fresh SCG, vermicompost, compost, biochars (at 270 and 400 °C; pyrolysis), SCG washed with ethanol and water, and hydrolysed SCG was carried out in an agricultural soil (Cambic Calcisol). In order to compare with conventional agriculture, the addition of NPK fertilizer was also assessed. Only vermicompost and biochar at 400 °C overcome the growth limitation of SCG. However, these treatments diminished Zn, Cu and Fe concentrations in lettuce probably due to the destruction (microbial degradation/thermal treatment) of natural chelating components (polyphenols). Increase in mineral content was observed in those treatments that did not completely eliminate polyphenols. NPK fertilizer gave rise to lettuces with higher biomass but lower micronutrients content. The results lead us to the possible solution for the use of SCG as organic amendment by vermicomposting and biocharization in order to eliminate toxicity.
... Even so, it should be remembered that not all SCG nitrogen is "free", and composting should be considered to increase its availability. 30 Total Fat and Fatty Acids Contents. Roasted coffee is composed by 11−20% lipids, with higher amounts in Arabica (14−20%) than Robusta coffee (11−16%). ...
Article
Espresso spent coffee grounds were chemically characterized to predict their potential, as a source of bioactive compounds, by comparison with the ones from the soluble coffee industry. Sampling included a total of 50 samples from 14 trademarks, collected in several coffee shops and prepared with distinct coffee machines. A high compositional variability was verified, particularly with regard to such water-soluble components as caffeine, total chlorogenic acids (CGA), and minerals, supported by strong positive correlations with total soluble solids retained. This is a direct consequence of the reduced extraction efficiency during espresso coffee preparation, leaving a significant pool of bioactivity retained in the extracted grounds. Besides the lipid (12.5%) and nitrogen (2.3%) contents, similar to those of industrial coffee residues, the CGA content (478.9 mg/100 g), for its antioxidant capacity, and its caffeine content (452.6 mg/100 g), due to its extensive use in the food and pharmaceutical industries, justify the selective assembly of this residue for subsequent use.
... 11 The use of landlls should be limited to the most possible to avoid environmental impact sources, like ineffective land use, CO 2 production, the release of caffeine, tannin, and polyphenols, and other chemicals in the environment. [12][13][14] Today, it is common to use SCGs as a natural amendment for farming purposes, 15 though it does not allow valorizing SCGs best. Various alternatives have been presented over the years and included the use of SCGs as a direct solid fuel or for the production of biodiesel, biogas, bioethanol, and various extraction products for cosmetics and medicine. ...
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Turning waste products into useable resources is a necessity for the sustainable future of our planet. Such is the case with popular beverage coffee that produces solid waste in the form of spent coffee grounds (SCG). There is an opportunity to use SCG material as a cheap, sustainable, and biodegradable polymer filler that is received as waste from espresso machines. There have been relatively many studies that prove the concept of various agricultural and forestry waste, which can be integrated into modern green materials. Building upon this concept, we have selected a promising polyester poly(butylene succinate) (PBS) as a matrix owing to its bio-based and biodegradable nature. High loadings of SCG from 20 to 60 wt% were tested for optimal composition performance. Tensile, dynamic mechanical, thermal, and structural properties of the composites were examined, while their biodegradation in composting conditions was also analyzed. SCG filler showed different performance from various cellulose fiber-based composites, and properties significantly varied depending on loading. Compared to neat PBS, biodegradation occurred twice as fast for composite materials with high SGC loadings. This journal is
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A wide range of organic amendments (OA) is currently available to Australian farmers. These products have numerous agronomic applications, including the supply of plant nutrients, control of pests and diseases, and in management of soil health. Several of these products are also used in contaminated and degraded land remediation. The most commonly identifiable groups of OA in Australia are composts, compost teas, vermicasts, humic substances, meat, blood and bone meal, fish hydrolysates, seaweed extracts, bio-inoculants, biodynamic products, and biochars. Many of these OA contain nutrients within organic molecular structures; these nutrients are usually not immediately available to plants and must first be mineralised. Mineralisation often occurs as OA are consumed by microbes, thereby stimulating soil microbial activity. The application of OA such as bio-inoculants, humic substances, and seaweed extracts can potentially stimulate crop growth and development through the actions of plant growth-promoting hormones, including cytokinins, auxins, and gibberellins. Yet despite these apparent benefits, the widespread adoption of OA in Australia has been limited, due in part to the high application rates required to produce agronomic benefits, a lack of consistency in the composition of some products, a poor public perception of their utility, and a lack of unbiased scientific research into the agricultural potential of these products.
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Fenton’s chemistry has long been useful in industry because of the power of hydrogen peroxide (HP), in the presence of ferrous iron (Fe2+), to produce a highly reactive free radical species capable of oxidizing aqueous materials. However, its application has been limited due to the rapid oxidation of ferrous iron. The rapid oxidation of ferrous iron limits the production of free radicals necessary for a powerful reaction. We developed two ‘green’ iron catalysts using used tea leaves (tea dregs) or coffee grounds as raw material. The new ‘green’ iron catalysts contained iron in a reductive stable status for a Fenton catalyst. The study showed that the developed ‘green’ iron catalysts can be used as iron fertilizer and for the Fenton’s reaction on the degradation of methylene blue (MB), and in the disinfection of Escherichia coli. The tea and coffee polyphenols were estimated to be responsible for the reductive stable state of the iron in the developed catalysts, due to their reducing power and chelating iron ability. The developed new ‘green’ iron catalysts are expected to diffuse in wide fields such as food, medicine, public health, agriculture, the environment, etc.
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The agricultural sector plays a major role in improving economic growth in terms of raising people’s income and reducing poverty in the developing countries, along with fulfilling food and nutritional needs for a growing world population. About 1 billion people are facing severe problems in accessing nutritionally adequate and safe food worldwide. By 2050, the world population is projected to be 9 billion and food production needs to be raised by 70% between 2005/07 and 2050 to feed such a huge population (FAO, 2009). Globally, more than 870 million people are hungry and the majority of them are small-scale farmers living in rural areas and often managing marginal lands (Godfray et al., 2010; FAO, 2012). At present, agricultural production is facing increasing challenges such as water shortage, climate change and volatility, raising the risk of production shortfalls. The future vision of the world would be to adopt new methods to increase sustainability of agricultural production. Most of agricultural food production was dependent on chemical inputs such as fertilizers and pesticides before the 1990s, and these synthetic compounds have played a key role in increasing food production. Since the 1990s, food demand has increased sharply for which farmers need increasing use of these chemicals. As a result, a major risk is created to the environment and human health (Gottlieb and Joshi, 2010). In order to reduce damage to the environment and health, some major classes of pesticides were banned, thus creating a market for biopesticides and microbial inoculants.
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Response surface methodology (RSM) was employed to optimize subcritical water extraction (SWE) of spent coffee grounds (SCG) with emphasis on the yield of total phenolics and radical scavenging capacities on 2,2-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid) (ABTS +) and 1,1-diphenyl-2-picrylhydrazyl (DPPH+). The analysis involved three variables: temperature (160-180°C), time (35-55min) and solid-to-liquid ratio (14.1-26.3g/L). The optimal conditions for total phenolic compounds (86.23mg GAE/g), antioxidant activity in terms of ABTS+ (81.38 mmol TE/100g) and DPPH+ (42.13 mmol TE/100g) scavenging activities were predicted to be in ranges of 160-180°C/37.9-55.0min/14.1g/L. The verified TPC (88.34mg GAE/g), antioxidant activity on ABTS+ (88.65 mmol TE/100g) and DPPH+ (38.28 mmol TE/100g) based on superimposing contour plots (179°C, 36min, and 14.1g/L) were in good agreement with the predicted data obtained under optimal conditions. 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid and 5-O-caffeoylquinic acid were found to be the major contributor to the antioxidant activities of SCG extract.
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Respected and known worldwide in the field for his research in plant nutrition, Dr. Horst Marschner authored two editions of Mineral Nutrition of Higher Plants. His research greatly advanced the understanding of rhizosphere processes and trace element uptake by plants and he published extensively in a variety of plant nutrition areas. While doing agricultural research in West Africa in 1996, Dr. Marschner contracted malaria and passed away, and until now this legacy title went unrevised. Despite the passage of time, it remains the definitive reference on plant mineral nutrition. Great progress has been made in the understanding of various aspects of plant nutrition and in recent years the view on the mode of action of mineral nutrients in plant metabolism and yield formation has shifted. Nutrients are not only viewed as constituents of plant compounds (constructing material), enzymes and electron transport chains but also as signals regulating plant metabolism via complex signal transduction networks. In these networks, phytohormones also play an important role. Principles of the mode of action of phytohormones and examples of the interaction of hormones and mineral nutrients on source and sink strength and yield formation are discussed in this edition. Phytohormones have a role as chemical messengers (internal signals) to coordinate development and responses to environmental stimuli at the whole plant level. These and many other molecular developments are covered in the long-awaited new edition. Esteemed plant nutrition expert and Horst Marschner's daughter, Dr. Petra Marschner, together with a team of key co-authors who worked with Horst Marschner on his research, now present a thoroughly updated and revised third edition of Marschner's Mineral Nutrition of Higher Plants, maintaining its value for plant nutritionists worldwide. A long-awaited revision of the standard reference on plant mineral nutrition Features full coverage and new discussions of the latest molecular advances Contains additional focus on agro-ecosystems as well as nutrition and quality.
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Recently, we developed two new Fenton catalysts using iron (Fe) and spent tea leaves or coffee grounds as raw material. In this study, Fe-to-tea or Fe-to-coffee polyphenol complexes were successfully tested as heterogeneous photo-Fenton catalysts. The photodegradation efficiency of methylene blue solutions with Fe-to-polyphenol complexes was higher than that of homogeneous iron salts in the photo-Fenton process. Furthermore, the tested Fe-to-polyphenol complexes could be reused by simply adding H2O2 to the solutions. After three sequential additions of H2O2, the conventional catalysts FeCl2·4H2O and FeCl3 removed only 16.6% and 53.6% of the dye, while the catalysts made using spent coffee grounds and tea leaves removed 94.4% and 96.0% of the dye, respectively. These results showed that the complexes formed between Fe and chlorogenic acid, caffeic acid, gallic acid and catechin, which are the main polyphenols in tea and coffee, can be used to improve the photo-Fenton process.
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Climate change is considered one of the major contributing factors to soil salinization, leading to land degradation. Several alternative organic waste materials are proposed for agricultural sustainability. Strawberry (Fragaria ananassa cv. Tioga) is one of the most consumed crop plants on a global scale due to its numerous economic and industrial benefits. Therefore, the purpose of this study was to understand how varying concentrations of diluted salt water (0%, 10%, 40%, 80%, 100%) affected the growth and physiology of Fragaria ananassa cv. Tioga. Our results indicated that shoot fresh weight (SFW), shoot dry weight (SDW), root fresh weight (RFW), root dry weight (RDW), leaf area, fruits weight, fruits per plants, relative water content (RWC), chlorophyll a and b significantly decreased in salt-stressed strawberry plants as compared to control plants. Moreover, salinity stress increased the malondialdehyde (MDA), hydrogen peroxide (H2O2), sodium (Na) content, SOD and APX activity. However, the application of dry waster of tea leaves (DWT) and dry waste of rose petals (DWR) led to improvements in chlorophyll content, RWC and potassium (K) content, antioxidant enzymes activity, and fruit yield of strawberry plants. In comparison to DWT, the best outcome was observed in plants treated with DWR, suggesting a new and eco-friendly strategy to increase crop yields under salt stress in commercial production. In conclusion, DWT and DWR treatments helps in the improvement of strawberries grown under salt stress conditions and increases their tolerance to salt stress.
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Three composts made of industrial wastes were prepared by mixing olive oil mill waste water (OMW), olive pomace, coffee grounds, and phosphogypsum (0, 10, and 30%). Potato plants (Solanum tuberosum) cultivated in a greenhouse were used to screen compost tea suppressive ability. All compost tea treatments inhibited Fusarium solani growth and improved plant growth and response to F. solani infection. The antagonistic effects of the different treatments were associated with a marked increase of the antioxidant enzymes and PR (pathogenesis related) protein expression and a decrease of disease severity. These results also showed that plant growth and disease suppression were improved by application of phosphogypsum-supplemented compost teas (A10 and A30). This enhancement can be attributed to the influence of phosphogypsum on nutrient elements and microbial diversity in the resulting compost teas.
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An Fe-polyphenol catalyst was recently developed using anhydrous iron (III) chloride and coffee grounds as raw materials. The present study aims to test the application of this Fe-polyphenol catalyst with two hydrogen peroxide (H2O2) sources in soil as a new method for controlling the soil-borne disease caused by Ralstonia solanacearum and to test the hypothesis that hydroxyl radicals are involved in the catalytic process. Tomato cv. Momotaro was used as the test species. The results showed that powdered CaO2 (16% W/W) is a more effective H2O2 source for controlling bacterial wilt disease than liquid H2O2 (35% W/W) when applied with an Fe-polyphenol catalyst. An electron paramagnetic resonance spin trapping method using a 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) assay and Fe-caffeic acid and Fe-chlorogenic acid complexes as models showed that these organometallic complexes react with the H2O2 released by CaO2, producing hydroxyl radicals in a manner that is consistent with the proposed catalytic process. The application of Fe-polyphenol with powdered CaO2 to soil could be a new environmentally friendly method for controlling soil-borne diseases.
Article
The ever-growing environmental concerns over the unrestricted fossil sources exploitation for non-biodegradable materials production has stimulated research on alternative renewable resources. The pectin films (HDM) were incorporated in different concentrations of spent coffee grounds (SCG) (5–20% w/w HDM) aiming at developing biodegradable films and the use of an underutilized resource. The films were obtained by continuous casting. The chemical composition, morphology, thermal stability, barrier and mechanical properties (traction and puncture), and functional groups were investigated. Overall, SCG showed sound dispersibility and good interaction with the polymer matrix. The addition of SCG resulted in important pectin-based film properties changes, allowing an increase in color and thermal stability. SCG incorporation significantly improved the water vapor permeability rate improving or at least preserving the physicochemical properties.
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Food by‐products happen at various stages of production and processing at home and on commercial scales. In the recent years, because of the fast‐growing food companies and production, food processing by‐products have gained a lot of interest and attracted many technical and health professionals as well as policy makers internally and internationally. Also, concerns are increasing about food by‐products due to their ecological and environmental impact on the planet. This is particularly of concern when large companies emit. Large quantities of food by‐products are thrown into environment in which they can be exploited technically, medicinally, and pharmaceutically. This is due to their chemical component and biologically active compounds of the by‐products. Therefore, this systematic review focuses on the food by‐product biological compounds present in different parts of the food products, particularly in some common foods such as fruits, vegetables, cereals, dairy products, meat, eggs, nuts, coffee, and tea. Moreover, the review also explains the kind of biologically active compounds and their quantity not just in edible foods, but also in part and types of the by‐product which then can be reused and recycled into different processes in order to extract and get benefit from.
Article
Spent coffee grounds (SCG), an ever-increasing food waste whose annual generation is 15 million tons, have the potential to fulfil many different purposes after being recycled. However, though SCG have been used as soil organic amendment, their utilization is limited by their phytotoxic nature. Although SCG favour the assimilation of nutrients by plants, whether or not they could be used as an agronomical bio-fortifying agent has not been investigated yet. Therefore, we carried out an in vitro investigation to analyse the influence of SCG and coffee melanoidins functionalised with Fe and Zn (biochelates) on the agronomic biofortification of lettuce (Lactuca sativa var. longifolia), one of the most consumed edible plants worldwide. Commercial chelates (EDDHA-Fe and EDTA-Zn) and non-functionalised SCG and melanoidins were used as controls. Total Fe and Zn content in lettuces and available Fe and Zn in soil were measured. Functionalized SCG and melanoidins were able to significantly increase both Fe and Zn levels in lettuces. While Fe levels increased around 28–30%, Zn showed a much larger improvement with levels up to 177–416% higher. According to our results, both SCG and coffee melanoidins could be used as agronomical bio-fortifying agents. Additionally, bio-fortified lettuce would provide up to a 16.3% of the Fe recommended daily intake and up to a 6.6% of that of Zn, reflecting positively in human health.
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Coffee grounds and tea leaf wastes exhibit strong affinity for metals such as Fe and Zn. The objective of this experiment was to evaluate the effect of top-dressing application of Fe- and Zn-enriched coffee grounds and tea leaf wastes at the panicle initiation stage on the mineral content of rice grains and the yield of paddy rice. The Fe and Zn contents of brown rice grains increased significantly on application of both coffee and tea waste materials. The concentration of Mn was increased by top-dressing application of coffee waste material only. For Cu, no significant (P < 0.05) differences were found between the control and ferrous sulfate/zinc sulfate treatment. The application of coffee and tea waste materials led to a significant (P < 0.05) increase in the number of grains per panicle, which was reflected in increases in the total number of grains per hill and in grain yield. The top-dressing application of these materials is an excellent method to recycle coffee grounds and tea wastes from coffee shops. Use of these novel materials would not only reduce the waste going to landfill but would also benefit the mineral nutrition of rice consumers at low cost by increasing Fe and Zn levels of rice grains as well as grain yield.
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The objective of this paper is to discuss the use of coffee grounds in the Brazilian soluble coffee industry. This residue is used as a fuel in the boilers of the same industry; so, data about their utilization are presented and analysed, discussing the actual technology and the advantages of improving the drying of the biomass with the exhaust combustion gases. After that, an experimental study is reported on the characteristics of this material, which are important for the combustion process, including the transport, storage and drying, the mean diameter of the particles, talus angle, apparent and real density, sphericity, surface area, terminal velocity, spontaneous ignition temperature and heat of combustion.
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The flavonoids constitute a large group of polyphenolic phytochemicals with antioxidant properties in vitro. The interactions of four structurally related flavonoids (quercetin, kaempferol, rutin and luteolin) with Cu2+ ions were investigated in terms of the extent to which they undergo complex formation through chelation or modification through oxidation, as well as in their structural dependence. The ortho 3',4'-dihydroxy substitution in the B ring is shown to be important for Cu2+-chelate formation, thereby influencing the antioxidant activity. The presence of a 3-hydroxy group in the flavonoid structure enhances the oxidation of quercetin and kaempferol, whereas luteolin and rutin, each lacking the 3-hydroxy group, do not oxidize as readily in the presence of Cu2+ ions. The results also demonstrate that the reactivities of the flavonoids in protecting low-density lipoprotein (LDL) against Cu2+ ion-induced oxidation are dependent on their structural properties in terms of the response of the particular flavonoid to Cu2+ ions, whether chelation or oxidation, their partitioning abilities between the aqueous compartment and the lipophilic environment within the LDL particle, and their hydrogen-donating antioxidant properties.
This experiment was conducted to determine the optimum level of green tea by-product (GTB) in diets without antibiotics and to evaluate its effect on broiler performances. A total of 140 Ross broilers were kept in battery cages for a period of 6 weeks. Dietary treatments used in this experiment were antibiotic free group (basal diet as a control), antibiotic added group (basal+0.05% chlortetracycline), GTB 0.5% (basal+GTB 0.5%), GTB 1% (basal+GTB 1%) and GTB 2% (basal+GTB 2%). Antibiotic added group showed significantly higher body weight gain than other treatments (p0.05). The addition of green tea by-product to diets tended to decrease blood LDL cholesterol content compared to control group although there were no significant differences among treatments (p>0.05). Addition of green tea by-product increased docosahexaenoic acid (DHA) in blood plasma and tended to decrease cholesterol content in chicken meat, but a significant difference was not observed (p>0.05). The values of TBA in chicken meat decreased in groups fed diets with green tea-by product and antibiotics compared to control group (p
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The 0.1 M Na-pyrophosphate solution extracted some of the Fe-, Al-organic matter products in Podzol B and some Acid Brown Wooded B horizons, but it dissolved a low proportion of the free Fe in the B horizon of some Gleysolic soils. It did not dissolve the inorganic amorphous or crystalline Fe and Al substances tested. The oxalate solution extracted Fe and Al from some amorphous inorganic substances as well as from horizons of accumulation or Fe-, Al-organic matter complexes, but it did not dissolve crystalline Fe oxides. The pyrophosphate-dithionite solution removed some Fe from crystalline oxides as well as from amorphous organic and inorganic forms.Although the pyrophosphate solution appeared to be the most specific for the sesquioxide-organic complex accumulation products in some soils, high speed centrifugation was necessary to obtain extracts free of suspended material. The oxalate procedure was simpler and it appeared to be equally useful for differentiating the classes of soils tested. The pyrophos...
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Forty-two calcareous soils representing most of the soil groups of Saudi Arabia were used for assessing the ability of some soil extractants to predict the response of Sorghum (Sorghum bicolor L. Moench BTX378) to iron fertilizer added as Fe-EDDHA chelate (ferric ethylenediamine di-o-hydroxyphenyl acetate). Iron (Fe) was extracted from untreated and treated soils by utilizing five different extractants, namely, NH4HCO3-DTPA(AB-DTPA), DTPA, EDTA, 1.0 M NH4OAC, and 1.0 M NH4OAC containing 0.02% hydroquinone (H.Q). Amount of extractable Fe followed the order: NH4OAC + 0.02% H.Q >NH4OAC>EDTA > DTPA > AB-DTPA. Iron extracted by EDTA, DTPA, and AB-DTPA was significantly correlated with amorphous-Fe, poorly crystalline-Fe, pH, organic matter, and clay. However, NH4OAC+0.02% H.Q and/or NH4OAC solutions gave significant correlations with free iron oxides, total-Fe, and total CaCO3. The dry matter yield, Fe concentration and Fe-uptake of sorghum were affected by soil application of Fe at rates of 10 and/or 20 mg Fe kg−1, added in a chelated form. The lower and higher levels of Fe application increased the mean dry matter of yield by 34% and 60%, respectively. Iron uptake by sorghum consistently was related to the Fe extracted by AB-DTPA, DTPA and EDTA solutions. However, the highest correlation was attained in the case of AB-DTPA. Assessment of Fe critical levels in soils, detected by AB-DTPA through separating plots, the graphical method, the Cate and Nelson 3-classical, and the Chi-square method gave quite similar results. The Fe critical level as estimated by using AB-DTPA was 3.4 to 4.8 mg kg−1.
Article
A new soil test was developed for simultaneous extraction of NO3, P, K, Zn, Fe, Cu and Mn from alkaline soils. The new extraction solution is 1 M in ammonium bicarbonate (NH4HCO3), 0.005 M in Diethylene Triamine Pentaacetic Acid (DTPA) and has a pH of 7.6. The new extracting solution should be stored under mineral oil. Ten grams of soil are weighed out into 125 ml Erlenmeyer flasks. Two 2.5 ml scoops of Fisher G carbon black (to remove color for colorimetric determination of nitrates) are added to each soil, followed by 20 ml extracting solution. The soil mixture is then shaken on an Eberbach reciprocal shaker for 15 minutes at 180 cycles per minute. The extract is then filtered through a Whatman 42 filter paper or its equivalent for NO3, P, K, Zn, Fe, Cu and Mn determinations. The results obtained with the new procedure are highly correlated with results obtained with Olsen's P test, ammonium acetate K test, and Lindsay and Norvell's DTPA‐Zn, Fe, Cu and Mn test. Regression equations between the levels of nutrients extracted by the new procedure and those extracted by the procedures mentioned above were developed. These equations were used to calculate index values for nutrients extracted by the new extraction procedure based on values used at the Colorado State University Soil Testing Laboratory for the standard extraction procedures. The new procedure extracted about the same amounts of K and Fe as ammonium acetate and DTPA, respectively, from soils having low to marginal levels of these elements. However, it extracted about half as much P as NaHCO3 and about 0.5 PPM more Zn, 0.8 PPM more Mn, and 0.3 PPM more Cu from soils having low to marginal levels of these elements.
Article
Available iron (Fe) determination in calcareous soils by using commonly accepted method (DTPA+CaCl2+TEA) is not descriptive in estimating Fe concentration in plants. Therefore, this study was conducted to select appropriate methods for the evaluation of available Fe status in peaches grown in alkaline soils. Leaves and soil samples were collected from a peach orchard with trees showing various chlorosis levels. Twelve extraction methods were applied to the soils to determine the available Fe content of the soils. Total and active Fe concentrations in leaves were assayed, and a relationship was investigated among chlorosis levels, total and active Fe in the leaves, and Fe assayed by the various methods to select the most representative method. The methods of 0.05 M EDTA (pH 7.0), 1 M NH4HCO3+0.005 M DTPA (pH 7.6), 0.05 M HCl+0.012 M H2SO4 and active Fe were well correlated to visual chlorosis ratings, total and active Fe in the leaves and factors affecting Fe availability in the soils compared with other methods. Therefore, these four methods should be used for determination of available Fe status in peaches grown in different soils.
Article
In this study, the capacity of seven phenolic acids and hydroxytyrosol for complex formation with iron was quantified. A metal-chelation mechanism was described by means of spectrophotometry and calculating the binding constants of the complexes. The influence of phosphate buffer, Hepes buffer, Tris buffer and water on this mechanism was investigated. UV–Vis absorption spectroscopy showed that the absorption of phenolic acids changes upon the addition of Fe2+, which resulted in several shifts of their spectra. These batochromic shifts were analyzed and evaluated by calculating binding constants. Furthermore, in the presence of different concentrations of EDTA (0–1 mM), a reduction of the constants was observed. However, not all of the phenolic compounds assessed here showed complex formation, those not bearing catechol or galloyl moiety like vanillic acid, syringic acid and ferulic acid, did not show any complex formation in our study. The ability of the phenolic compounds which chelate iron have been ranked in line with the binding constants in ascending order rendering the protocatechuic acid (1.43 M−1) the weakest chelator, followed by hydroxytyrosol (2.66 M−1), gallic acid (4.78 M−1), caffeic acid (8.12 M−1) and chlorogenic acid (20.13 M−1) as the strongest chelator.
Article
Tea is grown in about 30 countries but is consumed worldwide, although at greatly varying levels. It is the most widely consumed beverage aside from water with a per capita worldwide consumption of approximately 0.12 liter per year. Tea is manufactured in three basic forms. Green tea is prepared in such a way as to preclude the oxidation of green leaf polyphenols. During black tea production oxidation is promoted so that most of these substances are oxidized. Oolong tea is a partially oxidized product. Of the approximately 2.5 million metric tons of dried tea manufactured, only 20% is green tea and less than 2% is oolong tea. Green tea is consumed primarily in China, Japan, and a few countries in North Africa and the Middle East. Fresh tea leaf is unusually rich in the flavanol group of polyphenols known as catechins which may constitute up to 30% of the dry leaf weight. Other polyphenols include flavanols and their glycosides, and depsides such as chlorogenic acid, coumarylquinic acid, and one unique to tea, theogallin (3-galloylquinic acid). Caffeine is present at an average level of 3% along with very small amounts of the other common methylxanthines, theobromine and theophylline. The amino acid theanine (5-N-ethylglutamine) is also unique to tea. Tea accumulates aluminum and manganese. In addition to the normal complement of plant cell enzymes, tea leaf contains an active polyphenol oxidase which catalyzes the aerobic oxidation of the catechins when the leaf cell structure is disrupted during black tea manufacture. The various quinones produced by the enzymatic oxidations undergo condensation reactions which result in a series of compounds, including bisflavanols, theaflavins, epitheaflavic acids, and thearubigens, which impart the characteristic taste and color properties of black tea. Most of these compounds readily form complexes with caffeine. There is no tannic acid in tea. Thearubigens constitute the largest mass of the extractable matter in black tea but their composition is not well known. Proanthocyanidins make up part of the complex. Tea peroxidase may be involved in their generation. The catechin quinones also initiate the formation of many of the hundreds of volatile compounds found in the black tea aroma fraction. Green tea composition is very similar to that of the fresh leaf except for a few enzymatically catalyzed changes which occur extremely rapidly following plucking. New volatile substances are produced during the drying stage. Oolong tea is intermediate in composition between green and black teas.
Article
The adsorption of the divalent cations of Cu, Zn, Cd and Pb by tea leaves and coffee grounds from aqueous solutions is described. Both adsorbents exhibited strong affinity for these ions which could be described by a simple single-site equilibrium model. For coffee, the order of increasing adsorption equilibrium constant K was Cu < Pb < Zn < Cd, while for tea the opposite order was observed indicating that the adsorption sites on each adsorbent have a different chemical nature. Adsorption decreased at low pH < 4 through competition with H+ for adsorption sites, and for all metals except Cu, at high pH > 10, probably because of anion formation in the case of Zn2+ and also increased leaching of metal-binding soluble materials. The effect of metal ion concentration on the adsorptive equilibria indicated a threshold concentration above which overall adsorption became limited by saturation of the adsorption sites. Competition between two metal ions for the same sites was not observed with Cu(II) and Pb(II), however Zn(II) reacted competitively with Cd(II) binding sites on both tea and coffee. If fresh coffee or tea adsorbents were used, the fraction of metal ion taken up by the adsorbent was diminished by the competitive effects of soluble metal-binding ligands released by the tea or coffee. Experiments with coffee showed that roasting temperature controls the formation of metal ion adsorption sites for this adsorbent.
Official methods of analysis of the Association of Official Analytical Chemists, 13th edn. Association of Official Analytical Chemists
  • G W Howitz
  • GW Howitz
Howitz GW (1980) Official methods of analysis of the Association of Official Analytical Chemists, 13th edn. Association of Official Analytical Chemists, Washington, DC, p 1018
Manual on soil sampling and methods of analysis. Soil Research Institute
  • J A Mckeague
McKeague JA (1976) Manual on soil sampling and methods of analysis. Soil Research Institute, Agriculture Canada, Ottawa, p 163
Assessment of five extractants for their ability to predict iron uptake and response of sorghum growth in calcareous soils
  • Al-Mustafa Wa Abdallah
  • A E Falatah
  • WA Al-Mustafa