Potassium and / or ammonium salts of coffee melanoidins and their fractions for soil and plant improvement

Abstract

The present disclosure pertains to a composition for soil and plant improvement comprising potassium and / or ammonium salt of melanoidin extracted from roasted coffee, preferably from spent coffee grounds and methods for treating plants and / or soil with said compositions.

Description

[0001] POTASSIUM AND / OR AMMONIUM SALTS OF COFFEE MELANOIDINS AND THEIR FRACTIONS FOR SOIL AND PLANT IMPROVEMENT

[0002] Field

[0003] The present disclosure is directed to compositions for soil and plant improvement comprising potassium and / or ammonium salts of melanoidins extracted from roasted coffee , preferably spent coffee grounds and methods for treating plants and / or soil with said compositions

[0004] Background

[0005] Humic substances constitute a highly transformed fraction of natural organic matter with a heterogeneous structure . Water- soluble humic substances are generally referred to as humic acids and fulvic acids . Humic acids are random polycondensates with polyelectrolyte / polyampholite behaviour with a polyphenol or quinone-based aromatic core , in which functional side structures contain carboxylic, phenolic , and carbonyl groups , as well as sugar , peptide fragments . The sub entities are connected by various connectors , such as -0- , - CH2 - , =CH- , -NH- , -S-S- , and similar groups . The contained chemical functionality determines its properties in ion exchange , water absorption, its dispersion and cohesion energy, as well as interactions and complexation .

[0006] Agricultural usage of humic acid is a traditional , well developed application, and the weakly condensed precursor, compost , does not only contain P , N, and K and other essential elements as such, but promotes plant growth beyond that . Metabolites included in humic acid can serve as phytohormones , while the complexes of HA with salts , inorganic clusters and minerals bind water , retain nutrients in soils and thereby make up land quality . Addition of humic substances is now a part of modern agricultural practice as both application of irrigation and fertilizer can be lowered . The actual picture of the role of humic acid in soil fertility is multi-facetted and includes physico-chemical aspects as wettability and soil textural aspects as well as the increase of water and ion binding capacity . Generally, humic acid can exchange , adsorb and complex mineral elements , making it a good fertilizer synergist . For example , humic acid in soil is positively correlated with the mineralization rate of organic nitrogen . The addition of humic acid makes fertilizer decomposition slower and more plant effective . Moreover , it can improve the mobility of phosphorus in the soil and slows down the process of phosphorus remineralization .

[0007] However , the formation of humic substances under natural conditions requires many years and involves biotic and abiotic reactions . Therefore , several attempts have been made to prepare humic acid substances artificially . See Artificial Humic Acids : Sustainable Materials against Climate Change Yang F, Antonietti M, Adv . Sci . Lett . , 2020 .

[0008] Beside being ubiquitous in food stuffs , melanoidins have long been believed to be amongst the building blocks of humic substances . Like humic and fulvic acids melanoidins exert a partially anionic character in aqueous solution over a wide pH range . For instance US 2015 / 0351392 discloses the use of melanoidins for improving the properties of plants . The melanoidins used in this publication are synthetic melanoidins that have been prepared by treating a mixture of a commercially obtained protein hydrolysate and reducing sugar at a temperature of 150 ° C . The hydrolysate can be made from beef , casein, soy rice etcetera . These types of synthetically prepared melanoidins do not have the high amounts of phenol- based compounds nor the quinone-based compounds that are considered to attribute to the positive properties of humic acid as wettability and soil textural aspects as well as the increase of water and ion binding capacity . Thus in general the ability to exchange , adsorb and complex mineral elements .

[0009] We have found that melanoidin extracts from roasted coffee have a very high resemblance in the chemical structures and physico- chemical properties of humic acids . Especially potassium salts of melanoidin extracts from roasted coffee were found to have excellent properties that promote plant growth, the ability of the plant to withstand either or both abiotic and biotic stresses , and soil improvement .

[0010] Summary

[0011] The present disclosure provides a composition for soil and plant improvement comprising potassium and / or ammonium salt of melanoidin extracted from coffee , preferably from spent coffee grounds .

[0012] The melanoidins may be molecular weight (Mw ) fractions of melanoidin extracted from spent coffee grounds . The molecular weight (Mw) of the melanoidin fraction is preferably above 5 kDa, more preferably ranging from 10 KDa to 500 KDa , and most preferably between 50 to 200 KDa .

[0013] Preferably the melanoidin is obtained by alkaline extraction from spent coffee grounds , more preferably by extraction with potassium hydroxide . Optionally the extraction is assisted by ultrasonic treatment

[0014] Especially preferred are melanoidins with a phenolics content of at least 3 wt% , more preferably ranging from 3-30 wt , most preferable ranging from 5-20 wt% of the total melanoidin, calculated as tyrosol equivalents .

[0015] The melanoidin salt may be present in the composition in liquid or solid particulate form .

[0016] The melanoidin salt may be present in a concentration of between 10-5-5% w / v of the total composition . The melanoidin salt may also be present in the composition on a carrier in solid particulate form.

[0017] In one embodiment the composition additionally comprises potassium fatty acid salts . Said potassium fatty acid may be retrieved from of coffee oil .

[0018] In another embodiment the composition additionally comprises mannan oligosaccharide or its potassium and / or ammonium salt .

[0019] The composition according to the invention may additionally comprise other constituents that are conventionally used in plant and soil improvement compositions .

[0020] The composition according to the present disclosure may suitably be used for the treatment of plants and / or soil by providing a composition according to any one of the preceding claims to the plant and / or soil to be treated . Said treatment may be conducted by spraying , drenching , irrigation, fertigation, or any other way of application .

[0021] The composition was found to be especially suitable for the treatment of plants and / or soil infected by nematoid pests .

[0022] The composition according to the description may also suitably be used for the treatment of polluted water or soil .

[0023] Figure 1 : Table I : elemental composition of humic acid extracted from different sources .

[0024] Figure 2 : Table I I : elemental composition of potassium and / or ammonium salt of melanoidin extract from spent coffee grain according to the disclosure .

[0025] Detailed Description

[0026] The present disclosure provides a composition for soil and plant improvement comprising potassium and / or ammonium salt of melanoidin extracted from roasted coffee, preferably from spent coffee grounds. As explained above, it was found that melanoidins extracted from roasted coffee have a very high resemblance in the chemical structures and physio-chemical properties of humic acids. Owing to these similar amounts, nitrogen and carbon cycles will be incorporated and fixated readily into the soil. Furthermore, the presence of potassium ensures better aeration and breathability of the soil and proper nutrient uptake into the plant while ammonium helps with the pH balance of the soil, while contributing essential nitrogen for plant growth. The use of potassium salt of melanoidin is preferred.

[0027] The present disclosure provides a method and composition useful for improving plant properties. The method and composition are specifically useful in preventing and controlling plant diseases caused by fungal pathogens (e.g. foliar fungal pathogens) , for protecting plants from draught conditions and for promoting and improving plant growth. The composition comprises melanoidins, and can be applied by spray, drench, irrigation, fertigation, or any other way of application.

[0028] The terms "properties of a plant" or "plant properties" relate to growth, development, and / or robustness of a plant. Growth refers to an increase in size, development refers to the process of going through developmental stages (e.g. , germinating, budding, flowering, etc. ) , and robustness refers to ability of the plant to withstand either or both abiotic and biotic stresses. Abiotic stresses involve environmental conditions such as but not limited to temperature and drought. Biotic stresses involve pests ( e.g., insects, worms or parasitic plants, etc. ) and pathogens ( e.g., fungi, bacteria, viruses, etc. ) . The term "improving plant properties" relates to any characteristic of a plant that is advanced to a more desirable and / or valuable state, for example, improved growth and development, enhanced resistance to pathogens, better tolerance to abiotic stresses such as drought and temperature . Drought is one of the stresses that plants face while growing . Drought may be caused by limited availability of water or the inability of plants to absorb and transfer water to the canopy because of disturbed plant water relations and reduced water-use efficiency . It may also be caused by high temperatures or high vapor pressure deficit . Morphologically, plant reactions to drought conditions include reduced growth, for instance , as observed in plant height , leaf size and stem width .

[0029] Optionally specific molecular weight (Mw ) fractions of melanoidin are chosen . The molecular weight (Mw) of the melanoidin fraction is preferably above 5 kDa, more preferably ranging from 10 kDa to 500 kDa, and most preferably between 50 to 200 kDa . It is found that the lower molecular weight compounds extracted from spent coffee grounds , such as caffeine is toxic to certain plants and may negate the positive effect of the higher molecular weight fractions . In some applications , the presence of lower molecular weight fractions may not be an issue .

[0030] A further advantage of using spent coffee grounds is that this material which has been considered waste material in the past is now upcycled to a useful material which poses no threat to human' s safety and the environment . Furthermore , it also reduces the need of synthetically obtained fertilizers and / or pesticides , which are considered detrimental to the environment .

[0031] The method for extracting melanoidins from spent coffee grounds is known from for instance WO 2012 / 130349 and WO 2022 / 268898 which have been incorporated by reference herein for this purpose .

[0032] Preferably the melanoidin is obtained by alkaline extraction from spent coffee grounds , more preferably by extraction with potassium hydroxide and / or ammonium hydroxide . It was found that alkaline extraction ensures high yields of melanoidin without destroying the various useful compounds present in roasted coffee . Optionally the extraction process is assisted by ultrasonic treatment . Generally the extraction can be performed at a temperature between 100 and 140 ° C and a pressure of 1 to 8 bar .

[0033] It was found that ultrasonic treatment assisted in the extraction by creating increased melanoidin yield with higher phenolic and quinone content . Without wishing to be bound to any theory it is thought the ultrasonic mechanism for the fragmentation of coffee and melanoidins particles partition occurs under ultrasound in two ways , pitting of the defatted coffee grounds surface to produce fines and crack formations , which are further widened and deepened upon prolonged ultrasound exposure , releasing the melanoidins . In combination, those effects lead to the breaking of condensed structures and driving the reagent into the melanoidin particles ' core . We have also reason to believe that this treatment induces the formation of phenolic structures comprising both carboxyl and phenolic groups such as ketones , quinones or similar groups .

[0034] The ultrasonic treatment may be conducted at increased temperature of between 20-100 ° C .

[0035] A lot of humic acids positive properties are attributed to the presence of phenolics and the nitrogen containing species . These compounds are thought to provide the Reduction / Oxidation capacity and the metal complexation capacity of humic acid . The potassium and / or ammonium salt of the melanoidins according to the disclosure was found to have high concentrations of phenolic compounds . Especially the melanoidin salts were found to have a phenolics content of at least 3 wt . % , more preferably ranging from 3-30 wt . % , most preferably ranging from 5-20 wt . % of the total melanoidin, calculated as tyrosol equivalents .

[0036] Owing to this high amount of phenolic compounds the composition according to the disclosure is found to readily form complexes with heavy metals and radionuclides . This reduces their mobility, bioavailability and environmental toxicity . The composition is also suitable for treating water or soil polluted with heavy metals .

[0037] The melanoidin salt according to the disclosure was also found to have a relatively high amount of quinone , which is also attributed to the redox capacities of humic acid and the ability to form metal complexes . The melanoidin salt was found to have a quinone content of more than 3 wt% , even more than 5 wt% , or even more than 10 wt% .

[0038] The composition according to the disclosure may be used as a liquid or solids composition . The melanoidin salt present therein may also be in liquid or solid particulate form depending on the application . Particlutation may be conducted by for instance by spray drying, ball milling or any other conventional particulation method . The resulting particle size may be adj usted to the desired final surface area from nano size ( i . e below 1000 nm) to as much as 500 micrometer particles . The method for particulation of the melanoidin is known from for instance WO 2012 / 130349 and WO 2022 / 268898 which have been incorporated by reference herein for this purpose .

[0039] It was found that the melanoidin salt is highly effective and may be present in a concentration of between 10-5-5 i / r% of the total composition . When simply trying to improve the soil or plants growth lower concentrations can be used ( 10-5- 0 . 001 v / w% ) When, however , treating pests higher concentrations may be warranted ( about 0 . 01 to 5 v / w % ) .

[0040] When it is desired to treat plants and / or soil with a particulate composition, the melanoidin salt may also be present in the composition on a carrier . This carrier preferably is inert and releases the melanoidin salt controlled over time . These types of carriers are known in the art and need no further elucidation here . In one embodiment the composition additionally comprises potassium fatty acid salts . Said potassium fatty acid may be retrieved from of coffee oil . Potassium and / or ammonium salts of fatty acids may help to improve the wettability and penetration ability of the composition in plants but also in insects , worms or parasitic plants and pathogens ( fungi , bacteria, viruses etcetera ) . It was found that the composition according to the description including also fatty acids of coffee oil was extremely useful as a nematocide .

[0041] Such a nematocidal composition preferably comprises between 5 -15 wt% of potassium fatty acid salt of coffee oil and 5-15 wt% of potassium melanoidin salt .

[0042] In one embodiment the composition additionally comprises Mannan Oligosaccharides (MOS ) . Said MOS or its potassium and / or ammonium salts thereof may be retrieved from of spent coffee grounds . MOS has been reported to have beneficial anti-fungal , anti-nematode and antibacterial effects and as such may be added to the compositions according to the disclosure .

[0043] The composition according to the invention may additionally comprise other constituents that are conventionally used in plant and soil improvement compositions . For example surfactants , solvents , additional minerals , but also conventional fertilizers , anti-pest , anti-fungal and anti-microbial agents may be added to the composition . However , it is preferred to use a composition that is totally or virtually free of synthetically obtained compounds .

[0044] The composition according to the present disclosure may suitably be used for the treatment of plants and / or soil by providing a composition according to any one of the preceding claims to the plant and / or soil to be treated .

[0045] It should be noted that compositions of the disclosure may be adapted for application by spray, drench, irrigation, or fertigation . Thus both solutions , suspensions , but also particulate formulations may be used

[0046] According to the invention, the melanoidins can be applied to the plant at any stage of its life cycle , including seed, germination, vegetative growth, flowering, and fruiting .

[0047] The melanoidins according to the invention may also be sprayed onto vegetation or applied by land or aerial irrigation systems . It is also possible to apply the melanoidins according to the invention onto a cover sheet that is used to cover the soil between the crops to avoid weed, fungal and bacterial growth . The melanoidins may also be incorporated into said cover sheets . Examples of the cover sheets are mulch plastic , antiseptic film, and irrigation film.

[0048] The melanoidins may be used in mixtures with fertilizers ( for example nitrogen- , potassium- or phosphorus- containing fertilizers ) , which can be in the form of solution or solid . The mixtures contain between 0 . 0001 and 0 . 01 % by weight of the melanoidins , more specifically, 0 . 001 % of the final fertilizer .

[0049] EXAMPLES AND FIGURES

[0050] The present disclosure is further elucidated by figures 1 and 2 . In figure 1 a table is depicted giving the elemental composition of humic acid extracted from different sources .

[0051] In figure 2 a Table is given with the elemental composition of potassium and / or ammonium salt of melanoidin extract from spent coffee grain according to the disclosure .

[0052] Comparison of the compositions shows that the potassium and / or ammonium salt of the melanoidin extracts according to the present disclosure is very similar to the elemental composition of humic acid .

[0053] EXAMPLE 1

[0054] A melanoidin product has been prepared by a process comprising an alkaline extraction step with KOH and a precipitation of the resulting potassium melanoidin .

[0055] The extraction step was performed in a stainless steel reactor with an internal volume of 1 . 2 liter . The reactor was equipped with a mechanical stirrer inside the reactor volume , an external electrical heating and a serpentine cooling coil inside the reactor . The reactor was preheated to 80 ° C by the electrical heating . An amount of 100 g of spent coffee grounds powder was put into the reactor .

[0056] The extraction agent was prepared by dissolving 42 g of potassium hydroxide ( KOH ) in 1 liter of distilled water . The extraction agent was preheated to a temperature of 80 ° C and fed into the reactor immediately after the coffee grounds powder . The reactor was heated for 15 min until a temperature of 120 ° C was reached . The pressure inside the reactor rose to 3 bars ( abs ) . That temperature was maintained for another 30 min . The liquid contents of the reactor was rapidly cooled down to 40 ° C and the resulting melanoidin-containing mixture was filtered . The melanoidin-containing liquid was subjected to a precipitation step by evaporation. The phenolics content was measured with the Folin-Ciocalteau assay as described in J. Agric. Food. Chem.

[0057] 2010. 58 (14) , pp 8139-8144. It was measured to be 4 wt . % of the total melanoidin, calculated as tyrosol equivalents .

[0058] EXAMPLE 2

[0059] Compositions comprising potassium salt of melanoidin and potassium fatty acid salt of coffee oil ( 1:1) (in concentrations of 10 ppm, 1 ppm and 0.1 ppm of melanoidin salt, referred to as composition 1,2, and 3, respectively) were tested on root-knot nematode. The results after 24 hours and 48 hours after exposure are compiled below.

[0060] These results show that compositions comprising 10 ppm potassium melanoidin and 10 ppm potassium fatty acid of coffee oil are highly effective in the treatment of rootknot nematode.

Claims

CLAIMS1 . Composition for soil and plant improvement comprising potassium and / or ammonium salt of melanoidin extracted from roasted coffee , preferably from spent coffee grounds .2 . Composition according to claim 1 wherein the melanoidin is a molecular weight (Mw ) fraction of melanoidin extracted from spent coffee grounds are above 5 kDa , preferably ranging from 10 kDa to 500 kDa , and more preferably between 50 to 200 kDa .3 . Composition according to any one of the preceding claims wherein the melanoidin is extracted from spent coffee grounds .4 . Composition according to any one of the preceding claims wherein the melanoidin is obtained by alkaline extraction from spent coffee grounds , preferably by extraction with potassium hydroxide .5 . Composition according to any one of the preceding claims wherein the melanoidin is obtained by ultrasonic assisted alkaline extraction .6 . Composition according to any one of the preceding claims wherein the potassium and / or ammonium salt of the melanoidin has a phenolics content of at least 3 wt% , preferably ranging from 3-30 wt% , most preferably ranging from 5 -20 wt% of the total melanoidin, calculated as tyrosol equivalents .7 . Composition according to any one of the preceding claims wherein the melanoidin is present in liquid or solid particulate form .8 . Composition according to any one of the preceding claims wherein the melanoidin is present in a concentration of between 10-5-5% w / v .9 . Composition according to any one of the preceding claims wherein the melanoidin is present on a carrier in solid particulate form.10 . Composition according to any of the preceding claims wherein the composition additionally comprises potassium fatty acid salts .11 . Composition according to any of the preceding claims wherein the composition additionally comprises potassium fatty acid salts of coffee oil .12 . Composition according to any of the preceding claims wherein the composition additionally comprises mannan oligosaccharide or its potassium salt .13 . Composition according to any of the preceding claims wherein the composition additionally comprises other constituents conventionally used in plant and soil improvement compositions .14 . Method for the treatment of plants and / or soil by providing a composition according to any one of the preceding claims to the plant and / or soil to be treated .15 . Method according to claim 12 wherein the treatment is conducted by spraying, adding as solid particulate etc .16 . Method according to claim 12 or 13 wherein plants and / or soil infected by nematoid pests are treated .17 . Method for treating polluted soil or water wherein the composition according to any of the preceding claims is contacted with the polluted water or soil .

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