WO2023239318A2

WO2023239318A2 - An alternative method for the alkalization of cocoa and its products by cold plasma technique

Info

Publication number: WO2023239318A2
Application number: PCT/TR2022/051460
Authority: WO
Inventors: Ömer Said TOKER; Nevzat Konar; İbrahim PALABIYIK
Original assignee: Innobiota Arge Ve İnovasyon Li̇mi̇ted Şi̇rketi̇
Priority date: 2022-06-06
Filing date: 2022-12-08
Publication date: 2023-12-14
Also published as: WO2023239318A3; TR2022009310A2

Abstract

The invention is related to the production method of cocoa products with lower ash content and water-holding capacity as well as improved solubility, color and aroma properties by applying cold plasma technique in an environmentally friendly way without using alkaline solutions, where the cold plasma is applied in a continous and/or batch mode to cocoa nibs, cocoa mass, liquor and/or powders with different fat contents to increase the solubility of cocoa solids and modify the flavor, taste and color properties depending on the working gas type, treatment time and/or treatment distance, as well as to obtain cocoa products with higher antioxidant activity and lower ash content and water-holding capacity.

Description

AN ALTERNATIVE METHOD FOR THE ALKALIZATION OF COCOA AND ITS PRODUCTS BY COLD PLASMA TECHNIQUE

Technical Field:

The invention relates to the production method of cocoa nibs, cocoa liquor, and cocoa powder with low ash content and water holding capacity as well as improved solubility, color, and aroma properties by cold plasma technique without using alkaline chemicals.

The process subject to the invention is to increase the solubility of cocoa solids as a result of the application of different gases in plasma form to cocoa products (nib, mass, liquor, and/or powder) with different fat ratios and to modify color, taste, and flavor properties depending on the working gas type, processing time and/or electrode distance as well as obtaining cocoa products with lower ash content and water holding capacity and higher antioxidant activity compared to conventional methods.

Background:

In the state of the art of the invention, modification of color, taste, and flavor properties of cocoa nibs, mass (liquor), and/or powder with alkalization reactions are performed using the carbonate, bicarbonate, hydroxide, and oxide salts of chemicals such as potassium, sodium, ammonium, and magnesium. For this purpose, solutions prepared by the addition of water in the range of 10- 50% and alkaline chemicals in the range of 1-6% are mixed with cocoa nibs, cocoa liquor, cocoa mass, and/or cocoa powder, and the process is carried out in the pressurized reactors (1.00-12.0 atm pressure) or normal tanks with aeration (0.0-5.0 bar/min) and high temperatures (60-150^cC) for 5-180 minutes. However, the current processing method has disadvantages; • Obtaining cocoa products with high levels of ash,

• High temperatures, pressures, chemicals and long processing times,

• Energy-intensive process,

• Need for extra drying after processing,

• Difficulties in the control of color change in the final product,

• • A significant decrease in bioactive compounds, especially polyphenols, antioxidant activity, and bioaccessibility depending on the processing parameters,

• A decrease in the total fat content and the formation of soapy flavor as a result of hydrolyzation and saponification of fatty acids during processing,

• Problems in the final product applications of obtained cocoa products, especially in baked goods.

Cocoa, which has a very high commercial value today, is one of the most utilized raw materials in the snack and confectionery industry in order to provide flavor, color, taste, and technological properties (melting profile, brittleness, lightness, etc.) to the products. The composition and sensorial properties of cocoa beans are influenced by both botanical and geographical properties and processing. By processing the cocoa bean, cocoa derivatives with different properties and usage areas, such as cocoa mass, cocoa liquor, and cocoa powder are obtained. Characteristic properties like color, flavor, and taste of cocoa derivatives are influenced by fermentation, drying, roasting, and alkalization and can be modified by differentiating the processing parameters.

The cocoa tree (Theobroma cacao L.) belonging to the Sterculiaceae family, first appeared in Central and South America and is now widely cultivated in regions with tropical climates located 20° North an d South of the equator (Bertazzo et al., 2013). These regions can be grouped as East Africa, West Africa, Central America, South America, and Asia according to their geographic locations. Among these regions, Africa, which consists of Ghana, Ivory Coast, and Nigeria, is the region with the highest cocoa production. On a country basis, Ghana, Ivory Coast, Brazil, Ecuador, Malaysia, Cameroon, Indonesia, and Nigeria are the leading countries in cocoa production worldwide with their high production tonnages, and approximately 90% of the total production is carried out in these regions (Marty-Terrade & Marangoni, 2012; Jahurul et al., 2013).

Forastero, which is one of three cocoa varieties preferred worldwide, is widely cultivated in Brazil and West Africa. Contrary to its high productivity, this variety has disadvantages in terms of various quality parameters and aroma components and constitutes approximately 95% of the annual cocoa bean production (Diomande et al., 2015). Criollo, which is mainly cultivated in Venezuela, is less preferred than other varieties around the world due to its low productivity despite its high-quality features and rich aroma content. The third variety, Trinitario is a hybrid variety obtained by the hybridization of Forastero and Criollo and has advantages in terms of both quality and productivity. Cultivation of Trinitario is generally carried out in Venezuela, Cameroon, Ecuador, Sri Lanka, and Papua New Guinea (Jahurul et al., 2013). The cocoa bean contains approximately 85% cotyledon and 15% shell. The main constituent of cocoa bean is cocoa butter, which shows differences depending on the botanical origin (variety) as well as geographic origins (Nair, 2021 ).

Cocoa derivatives with high commercial value such as cocoa mass (liquor), cocoa nib, cocoa butter, and cocoa powder are obtained by subjecting the cocoa beans to a series of processes (fermentation, drying, roasting, alkalization, etc.). Nutritional and health-promoting components (carbohydrate, protein, fat, phenolic compounds, vitamin, mineral), as well as components that determine the technological properties (triglyceride amount, fatty acid composition, the solid fat content of fatty acids, etc.) of these cocoa derivatives, are affected both by the botanical and geographic properties of cocoa beans used and methods and processing parameters that are used to process the cocoa beans to different products (Nair, 2021 ).

The processes during the production of cocoa derivatives determine the formation of cocoa-specific taste, flavor, and odor as well as color properties. In addition to the factors depending on cocoa beans and cultivation conditions, fermentation, roasting, drying, and alkalization processes, where the chemical, enzymatic and physical transformations happened, have an effect on the formation of a specific color, flavor, and taste profiles of cocoa beans (Garcia, 2020). Among them, alkalization is a complex process that can be applied to different cocoa derivatives and includes physical and chemical changes that result in modifications in the color, taste, and flavor compounds of cocoa depending on the temperature, time, and pressure combinations as well as the type and concentration of alkaline used (Afoakwa, 2000).

In the alkalization process, the cocoa material is treated with alkaline solutions at different temperatures and time combinations, and this process induces various chemical reactions in which the polyphenols from the cocoa bean (catechin, epicatechin, anthocyanin, etc.) are involved, resulting in different tones of color and removal of acidic, astringent and bitter aroma originating from the natural cocoa bean. The obtained alkalized cocoa derivatives have a wide range of uses from milk and dairy products to bakery products, from cream fillings to acidic beverages.

The alkalization process (Dutching) developed by Dutch chemist Coenraad Van Houten in 1828 to increase the solubility of cocoa powder, is primarily effective on the polyphenol compounds found in the cocoa bean (Moser, 2015). Proteinpolyphenol complexes found in cocoa beans combine with the cell walls and produce water-insoluble structures. With the alkalization process, cell walls are hydrolyzed and ester bonds are ruptured, resulting in a cocoa powder with increased solubility. Dutching or alkalization process is used in cocoa bean processing technology in order to develop color tones from light brown to red and dark black in cocoa derivatives and to remove astringent, acidic, and bitter flavors originating from natural cocoa derivatives (Dyer, 2003).

Depending on the alkalization process applied, the pH of cocoa material changes, and its color, taste, and flavor properties are modified. In general, as the degree of alkalization increases, the color darkens and dark brown and black colors are obtained (Garcia, 2020).

Although the alkalization process can be applied to different forms of cocoa material (nib, liquor, cocoa powder) depending on the desired product property, each method has advantages and disadvantages. Cocoa nibs are obtained by mechanically crushing the fermented cocoa bean after cleaning and contain a high amount of cocoa butter (52-54%). Since the cocoa butter has not been separated yet, higher amounts of water can be added, so that maximum color and flavor development can be achieved. To avoid the effects of added water on the quality and rheological properties of cocoa butter, deodorization is required, which leads to an increase in production costs. Since cocoa liquor contains a high amount of cocoa butter that has been separated from cells, the adverse effects of added water on the cocoa butter are more severe. Therefore, less amount of water is added, and accordingly, moderate flavor and color development can be achieved. Moreover, there is also a risk of saponification reactions occurring in cocoa butter if the added water is not removed properly. In the alkalization of cocoa powder, the factor limiting the amount of water to be added is not cocoa butter. Unlike other cocoa derivatives, cocoa powder contains low amounts of cocoa butter (0-24%), and thus, the removal of added water with deodorization is not necessary. There is a high amount of starch and protein in the cocoa powder obtained by grinding the cocoa cake. In addition, the surface area of the tissues is increased by the grinding process. As a result of the addition of water and high-temperature applications, irreversible gelation reactions occur in starch in cocoa powder and denaturation in proteins. These reactions adversely affect both the texture and grinding performance of cocoa powder and cause difficulties in reaching the industrial particle size standard (>99.5% below 74 micrometers) (Dyer, 2003).

Alkali salts used in the alkalization are also changed depending on the desired properties of the final product. When the potassium, sodium, and ammonium salts are used alone, red, brown, and dark colors are obtained, respectively. The most common potassium, sodium, and ammonium salt is K2CO3 (potassium carbonate), NaOH (sodium hydroxide), and HN4HCO3 (ammonium bicarbonate), respectively (Moser, 2015). However, alkali salts are generally used in combination rather than alone in alkalization, with the most common combination being the use of KOH (potassium hydroxide) and NaOH salts together. The alkaline concentration is usually determined depending on the desired properties of the final product and the type of alkali salt to be used and it also varies according to the cocoa derivative to be used. Preferred ratios in industrial applications are between 1-6%, and their effects on the color are followed by measurements of L* a* and b* values determined colorimetrically by the CIE-Lab technique (Rodriguez et al., 2009).

It is possible to decrease the time required to obtain cocoa products with the same L* a* and b* values by using pressure in the alkalization process. The amount of pressure needed should be assessed together with the type and concentration of alkaline used, temperature, and time. Ellis (1990) treated the cocoa powder with K2CO3 (3.20%) for 45 minutes at 77G in an unpressurized tank and obtained a bright light red color. Kopp et al. (2010), on the other hand, preferred the application of gradual temperature (124 3 for 10 min, 85 0 for 60 min) and 1 ,5-2 atm pressure in the alkalization process with K2CO3 salt (3.20%) to achieve the same color tones.

The color development in the alkalization process is an oxidation reaction that occurs in the basic medium. Air feeding to the medium means the addition of oxygen, which accelerates the reactions. As the concentration of O2 in the medium is increased, an increase in the a* and a*/b* values of the cocoa derivative is observed. Generally, 10% to 50% of water is added to the alkaline solution. The reason for this addition is to ensure that the alkaline agents are homogeneously dispersed in the solution and oxidized to reach the color precursors that will provide the color transformation. However, the addition of water to cocoa material creates extra process needs such as drying and deodorization (Garcia, 2020).

Time-temperature combinations vary depending on the color tones and aroma substances desired to be obtained in the alkalization process. In general, the time required decreases as the temperature is increased to achieve the same L* a* and b* values while keeping other parameters constant. At temperatures of 60-10010 and 100-15010, dark brown and black col or tones are obtained, respectively. When the temperature is kept constant, shorter alkalization (5-60 min) yields light red, while longer alkalization (60-180 min) yields darker colors (Garcia, 2020). In general, as the temperature rises, the L* value decreases and the color tone becomes darker (Dyer, 2015).

In addition to the Maillard and caramelization processes that occur due to the application of heat in the alkalization process, the main compounds responsible for color, taste and aroma developments are polyphenols, and the desired color tones, aroma and taste indicators are formed by the participation of these compounds in different chemical reactions (Li et al., 2014). Changes in polyphenols that are responsible for color development; a. Decreased amount of total polyphenol and flavanol: (i) Formation of “Melanoids” by polyphenol oxidation due to the polyphenol oxidase enzyme activity, (ii) The formation of “o-quinone” compounds as a result of interactions of polyphenol and flavanol compounds with amino acids, peptides, and proteins and their participation in Maillard reactions, (iii) Glycolysation of sugars with proteins, b. Chemical modification of polyphenol compounds (especially flavanols): (i) Epimerization of polyphenols (e.g., colorless (+) Catechin -> reddish brown (-) Catechin), (ii) Isomerization of polyphenols (e.g., colorless (-)Epicatechin -> reddish brown (-) Catechin), (iii) Polymerization of polyphenols (e.g., colorless (+) Catechin -> red 5,6-Xanthenocatechin), c. Decreased amount of monomeric anthocyanin and increased amount of darkcolored anthocyanin polymers: (i) Participation of anthocyanins in Maillard reactions, (ii) Glycosylation of anthocyanins with sugars and proteins.

Some compounds found in cocoa beans or formed by the fermentation process are responsible for the acidic, bitter, and astringent flavors defined as natural cocoa taste. With various chemical reactions occurring in the alkalization process, the amounts of the compounds that make up the natural cocoa flavor decrease decreases and chemical transformations take place (Aprotosoaie et al., 2016). Many compounds, both volatile and non-volatile, are responsible for the formation of cocoa aroma, and the most specific cocoa flavor compound is pyrazinesDifferent pyrazine derivatives can be found in cocoa beans, and these pyrazine compounds vary depending on the ambient pH. The pyrazine responsible for the characteristic cocoa aroma is trimethylpyrazine, and as the environment becomes basic, the amount of tetramethylpyrazine decreases, while trimethylpyrazine increases. (TMP/TrMP) is monitored as an alkalization aroma indicator (Li et al., 2012).

The alkalization process includes the application of temperature and pressure, alkaline and water is added and the components in the environment are exposed to oxidation. Due to all these factors, various changes occur in the nutritive and regulatory substances in the cocoa bean depending on the alkalization process (Garcia, 2020).

In the alkalization process, carbohydrates in the cocoa matrix undergo Maillard reactions, while the total carbohydrate amount remains the same, and the amount of reducing sugar decreases. In addition, hydrolysis of triacylglycerol (TAG) and saponification reactions occur in the fat phase. Consequently, in addition to a decrease in the total amount of fat, a soapy flavor and taste occur if high levels of alkaline are used. Depending on the addition of alkaline salts in mineral substances, the concentration of sodium and potassium ions increases. Related to proteins, Maillard reactions, deamination and polyphenol interactions occur, and amino acid amounts decrease. Moreover, degradation of protein structures due to oxidative degradation with deamination reactions is observed. The change in ash content is the most important disadvantage of current method. Because ash content increases in parallel to the increase in alkaline concentration. Polyphenols are the main bioactive components present in the cocoa composition. A decrease in the amount of polyphenols and thus in the antioxidant activity with the alkalization process occur.

Changes take place in the cocoa aroma and taste compounds depending on the alkalization process. Before the alkalization process, components such as citric acid, lactic acid, oxalic acid, and succinic acid, which are responsible for the acidic taste and flavor in the cocoa composition, undergo neutralization, and their volatile fractions decrease from a concentration of approximately 60% to 30%. Caffeine, theobromine, diketopiperazine, catechin and flavan-3-ols, which are responsible for the bitter taste and flavor in cocoa composition, participate in epimerization, isomerization, glycosylation reactions and the bitter taste decreases. Compounds such as polyphenolic acids, anthocyanins, and proanthocyanidins, on the other hand, are responsible for astringent taste. With the participation of these components in the glycosylation reactions, the acrid and bitter tastes decrease.

As a result, there is a need to develop alternative methods to overcome the various disadvantages of conventional cocoa alkalization. With this invention, an alternative and environmentally friendly method using the cold plasma technique for the production of cocoa nib, cocoa mass, and cocoa powder with improved solubility, color, and aroma properties without the use of chemicals (alkaline components) and without increasing the ash content in the final product has been developed. The main advantages for the processing of the cocoa products with the developed cold plasma system are as follows;

(i). Unlike the conventional alkalization, the addition of water and thus the extra drying is not required in the cold plasma system,

(ii). Decreasing the risk of oxidation of cocoa butter,

(iii). Increasing the digestibility of cocoa-originated proteins and other peptides,

(iv). Increasing the concentrations of compounds that can behave as aroma pre-cursors in the chocolate process,

(v). Low energy costs,

(vi). Short processing times,

(vii). Simple control of final product color properties,

(viii). Obtaining cocoa products with low ash content,

(ix). Low temperature applications,

(x). Reducing the decrease in the total fat content compared to conventional alkalization,

(xi). Reducing the decrease in the total polyphenol content compared to conventional alkalization, (xii). Reducing the decrease in the antioxidant activity compared to conventional alkalization,

(xiii). Reducing the decrease in the bioaccessibility levels of bioactive compounds in cocoa products compared to conventional alkalization,

(xiv). Opportunity to develop “Bake-Stable” products by reducing the increase in the water-holding capacity caused by increased ash content of cocoa products compared to conventional alkalization,

(xv). Obtaining cocoa products with high solubility.

Cold plasma also referred to as non-thermal plasma (near the ambient temperature of 30 °C-60 °C), can be generated whether in both vacuum and atmospheric pressure conditions by applying energy to a neutral gas or a mixture of gases, which causes the ionization and the formation of active components, including radicals, charged particles, and UV radiations (Tappi et al., 2016; Pandey & Chauhan, 2019). At atmospheric conditions, these chemically active species are generated due to collisions between electrons and heavier particles, in which the free charge carriers are accelerated by the application of an electric or electromagnetic field, causing the gas to break down (via elastic and inelastic collisions). Although elastic collisions are characterized by kinetic and internal energy conservation, with a re-distribution of kinetic energy and a very low energy transfer, inelastic collisions involve considerable amounts of energy transfer in a collision between electrons with amounts varying from less than 0.1 eV (for rotational excitation of molecules) to 10 eV and more (for ionization) (Surowsky et al., 2015). However, inelastic collisions do not raise the temperature of the heavy particles, and the accumulation of heat is avoided by providing short nano-second bursts of excitation energy, thus a much lower plasma temperature is achieved (Tendero et al., 2006; Sanguansri et al., 2010).

When the electrons are accelerated in an electric field through the gaseous medium, multiple collisions take place among the electrons and the atoms and molecules present in the gas. Then the species will be produced by primary and secondary processes including electronic impact processes (vibration, ionization, attachment, excitation, and dissociation), ion-ion neutralization, ionmolecule reactions, Penning ionization, quenching, three-body neutral recombination, and neutral chemistry as well as photoemission, photoabsorption, and photo-ionization (Misra, Pankaj, Segat, & Ishikawa, 2016). Collisions between electrons and oxygen and nitrogen molecules lead to the formation of primary reactive oxygen species (O«, 02*-, 1O2, OH, H2O2, O3, *H ve OOH) and reactive nitrogen species (*NO, «NO3, N2O5, NO-, NO2-, NO3-, N₂O- ve ONOOH/ONOO-).

The type and concentration of reactive species generated depend on different gas types and mixtures, the configuration of a plasma reactor, and relative humidity, as well as operating conditions such as power input, the extent of the treatment, gas pressure, and application method. These reactive species can be transferred to the sample direct or indirect, as well as by means of plasma- activated solutions (PAS), such as water. In the direct exposure method, the food is exposed to the plasma discharge itself, and interactions between food and reactive species can be maximized, but it is difficult to achieve homogenous treatment on complex surfaces due to pores. Indirect exposure includes the transfer of produced plasma via the flow of the feed gas onto the surface, so the treatment surface can be separated from plasma-generating electrodes. However, it is important to note that, since the higher chemical activity means a shorter lifetime for reactive species, only relatively long-lived species can reach and interact with the target. Although lower activity is achieved compared to direct exposure, reactive species can be transferred more uniformly and detrimental effects are avoided (Niemira & Gutsol, 2011 ; Sarangapani et al., 2018). Recently, plasma-activated water is also used in food processing applications, due to its biological activity, accessibility, and suitability (Herianto et al., 2021 ; Xiang et al., 2020).

The factors related to a power supply such as voltage and frequnecy, as well as exposure time, are significantly influencing the effectiveness of CP treatment. Generally, an increase in power input produces electrons with higher density and thus leads to an increase in the concentration of reactive species and plasma activity (Lerouge et al., 2001 ). Furthermore, it has been observed that there is a close relation between voltage and ozone production by Morgan (2009), who reported that no ozone generation occurred below 2 kV due to inadequate energy for the gas breakdown. Moreover, the author has found an increase in the dissociation of oxygen molecules to singlet oxygen atoms at higher voltages and thus, in ozone concentration. However, the effects of process parameters on the modification of food macromolecules are productspecific. For example, the efficacy of CP treatment on functional properties such as cooking properties and degree of gelatinization of brown rice was reported to enhance at 50 W compared to 40 W treatment (Thirumdas et al., 2016). Similarly, a linear relationship between the degradation rate of P-chitosan and frequency and reaction time has been determined. It has been found that the crystal structure of chitosan was disrupted during plasma treatment. In a different study, Miao et al. (2020) found that 40 kV voltage has led to the most remarkable enhancements in functional properties of Alaska pollock myofibrillar protein compared to higher or lower voltages. According to Misra et al. (2015), functional and rheological properties of wheat flour were significantly influenced by the applied voltage and treatment time, and a minimum of 60 kV and 5 min was required to achieve dramatic changes.

Another important factor for the effectiveness of cold plasma treatment is relative humidity. Dorai and Kushner (2003), investigated the relationship between water and reactive plasma species on the polypropylene surface and reported that increasing the relative humidity led to an increase in the production of peroxy and acid groups, while a decrease in the production of alcohol and carbonyl groups. Dobrynin et al. (2009) studied three different moisture conditions including dry treatment, moist treatment, and wet treatment, and found the most remarkable inactivation effects in the moist treatment Dobrynin et al. (2011) showed that there is an optimum relative humidity value for the maximum inactivation effects and excess water leads to dilution of the effects. Briefly, relative humidty in the discharge absorbs energy because of the molecular structure of water, resulting in a reduction in the electron energy and density, quenching of the excited states and thus decreasing the plasma activity. Furthermore, water vapor can decrease the surface resistance of dielectric barriers due to the coating effect, causing a reduction of microdischarges and discharge homogeneity, which finally leads to a reduction in the yield of reactive species (Butscher et al., 2019). However, in the case of tapioca starch modification via dieletric barrier discharge configuration argon plasma at atmospheric pressure, a higher degree of cross-linking was observed under low relative humidity levels (11 %) compared to higher relative humidity levels (68% and 78%) (Deeyai et al., 2013). In addition, the relative humidity of the surrounding atmosphere of treatment media could significantly change the moisture content of products, as reported by Jahromi et al. (2020).

Any gas can be utilized in the generation of cold plasma. However, the effects and reactive species will be depended on the type of gas, which determines the efficiency of ionization, the intensity and wavelength of UV emission, and the formation of reactive species (Pankaj et al., 2018; Feizollahi et al., 2021). Conventionally, noble gases such as argon and helium are employed to create cold plasma due to high thermal conductivity, rich UV emission spectrum and a lower operating discharge voltage at atmospheric pressure. However, since the reactive species generated from these gases have short lifetimes (<10^-6 s) and employment of these gases is expensive, air stands out as a cheaper option and thus becomes more popular in recent studies (Misra & Jo, 2017). Furthermore, the flow rate of the gas or gases used in plasma generation is also an important factor. The gas flow rate determines the transmit velocity of the reactive species toward the sample surface (Nishime et al., 2017). Indeed, two contrast effects are achievable depending on the flow rate. On the one hand, the transportation of the reactive species is accelerated as the flow rate increases, thereby increasing the efficiency of the treatment. On the other hand, when the flow rate increases, the residence time will become too short and there will be too many active species present to be used effectively, hence the plasma activity will decrease (Lerouge et al., 2001 ). It It should also be noted that some short-living species may not reach the sample depending on the flow rate. Nowadays, the food industry looks forward to finding eco-friendly, fast and costefficient non-thermal technologies for the modification of food macromolecules. Cold plasma technology has a promising potential to improve the properties of food macromolecules in different ways. Studies demonstrated that active plasma species can change the allergenicity of proteins, improve the technofunctional properties of macromolecules, and convert liquid oils to semi- solid/solid fats. There are a series of underlying mechanisms responsible for these modifications. For proteins, the most important changes include unfolding and denaturation of secondary and tertiary structures, exposing the embedded hydrophobic residues, oxidation of side-chains of amino acids, cleavage of peptide bonds, formation of disulfide bonds, aggregation, and formation of cross-linkages. Similarly, the main effects of cold plasma on polysaccharides are related to the oxidation, formation of cross-links, depolymerization, changes in the hydrophilicity, introduction of functional groups and increase in surface energy. These interactions are among the main reasons for the use of cold plasma as an alternative method to the alkalization of cocoa products.

Short Description of the Invention:

The invention is a method for the modification of color, taste, and flavor of cocoa nib, mass, and powder and to improve the solubility of cocoa solids by using the cold plasma technique as an alternative to conventional alkalization without using alkaline chemicals. The advantages achieved as a result of the use of the products obtained with this invention and its advantages compared to its current counterparts are given below;

• Eliminating the need for extra drying,

• Decreasing the risk of oxidation of cocoa butter,

• Increasing the digestibility of cocoa-originated proteins and other peptides,

• Increasing the concentration of compounds that could behave as aroma precursors in chocolate process,

• Low energy costs, • Short process times,

• Improving the controllability of final product color properties,

• Obtaining cocoa products with low ash content,

• Low temperature applications,

• Reducing the decrease in the total fat content compared to conventional alkalization,

• Reducing the decrease in the total polyphenol concentration compared to conventional alkalization,

• Reducing the decrease in the antioxidant activity of cocoa products compared to conventional alkalization,

• Reducing the decrease in the bioaccessibility of bioactive compounds in cocoa products compared to conventional alkalization,

• Obtaining cocoa products with high solubility,

• Opportunity to develop “Bake-Stable” products by reducing the increase in the water-holding capacity of cocoa products compared to conventional alkalization.

Descriptions of Figures Explaining the Invention:

Figure 1: Treatment time-dependent changes in the color properties of cocoa powders obtained by cold plasma treatment

Figure 2A: Treatment time-dependent changes in the solubility of cocoa powders

Figure 2B: Treatment time-dependent changes in the water-holding capacity of cocoa powders

Figure 2C: Treatment time-dependent changes in the total flavonoid content of cocoa powders

Description of the Invention: The present invention includes a method in which the gas and/or gas mixtures ionized by any of the cold plasma system configurations (dielectric barrier discharge, jet, arc, etc.) can be directly or indirectly applied to any of the cocoa nibs, cocoa mass (liquor), and cocoa powder whether in continuous or batch mode in order to modify the color, taste, and flavor properties of cocoa products depending on the process variables such as power levels used in ionization, treatment time, pressure conditions, gas type, gas flow rate, and distance. For this purpose, cocoa nibs, cocoa mass, or cocoa powder with different botanical and geographical origins are subjected to direct cold plasma whether mixed with water for the modification of the relative humidity (RH) levels or without applying hydration. Additionally, noble gases such as argon, helium, etc., or reactive gases such as air and mixtures of these gases at different concentrations are fed to the plasma jet at any flow rate and ionized by applying 0.1-100 kW power and applied to the products directly or indirectly using any type of cold plasma configuration (dielectric barrier discharge, jet, arc, etc.) by adjusting the distance between electrodes and cocoa products in the range of 0.1-200.0. The process can be performed under atmospheric pressure or vacuum conditions in a continuous or batch mode and the cocoa products are exposed to cold plasma for 1.0-100.0 minutes. At the end of the period, cocoa products can be adjusted to the desired pH with any alkaline and subjected to a process such as alkalization if desired.

Example 1

Argon gas is fed to the plasma jet with a flow rate of 100 mL/min and ionized with 70 kW power in the dielectric barrier discharge cold plasma system and the cold plasma is applied under atmospheric pressure to the cocoa mass (8. GO- 12.0 g/100 g moisture, 48.0-52.0 g/100 g fat) stirring at 10 rpm. The distance between electrodes is fixed at 8 mm. Following the 30 min treatment, the stirring speed is raised to 25 rpm and continued for 2 more minutes and the process is completed.

Example 2 The process in Example 1 is performed with dry air using 95 kW power for ionization, fixing the distance between electrodes at 5 mm and treating the product for 18 minutes.

Example 3

Dry air is fed to the plasma jet at a flow rate of 100 mL/min and ionized by 100 kW power in the dielectric barrier discharge cold plasma system and the cold plasma is applied to the product, which is spread at a 2 mm thickness on a conveyor made of stainless steel moving continuously with a speed of 0.5 m/min between two electrodes with an electrode gap of 5 mm. The process is performed on a 15 m long conveyor band.

Example 4

The process in Example 3 is performed with helium and 80 kW of ionization power.

Example 5

The processes in Examples 1 , 2, 3 and 4 are performed with jet plasma system.

The type of gas to be used in the cold plasma technique mentioned in this invention can be inert gases such as argon, and helium or reactive gases such as air or their mixtures in any ratio. The flow rates and pressures of gases can be adjusted according to the desired properties of the final product and if necessary, the gases can be recovered in a closed system and reused.

Depending on the plasma source to be used and the desired modification, the cold plasma techniques mentioned in this invention can be applied to the cocoa products at a distance of 0.1-200 mm, for the desired time, in the power range of 0.1-100 kW, in the voltage range of 0.1-100 kV and in the frequency range of 50-100000 Hz.

The cold plasma technique mentioned in this invention can be applied in batch or continuous mode in planar or axial configurations. Moreover, it is possible to apply the cold plasma technique while providing the mixing of the cocoa products homogeneously. The technique can be applied to cocoa products alone or in a combination with novel processing technologies such as ultrasonication, ohmic heating, pulsed electric fields, UV radiation, high pressure, and high voltage electrical discharges to cocoa products.

In the invention, the cold plasma technique can be applied to cocoa products directly, indirectly, and in-package or by immersing cocoa products in a solution such as water activated by cold plasma using different gases at various times. It is possible to apply the cold plasma technique to cocoa products at different temperature ranges using air or water cooling.

In the invention, chemicals (alkaline solutions) can be included prior to, during, or after the cold plasma process to provide different modifications in the pH, taste, flavor, solubility, and color properties of cocoa products. The cold plasma technique can be applied to cocoa powders with different moisture contents or cocoa suspensions prepared at different rates.

Claims

1. It is an alternative method of alkalization for cocoa and its products, and its feature is; Application of cold plasma produced by partial ionization of different gases, and/or gas mixtures to cocoa nibs, cocoa mass (liquor) and/or cocoa powders directly or indirectly to modify the color, taste, and aroma depending on the process parameters such as power, frequency, treatment time, pressure conditions, gas type, gas flow rate, and distance in a continuous or batch mode.

2. According to Claim 1 , it is an alternative method of alkalization for cocoa and its products, and its feature is; The cold plasma can be produced and applied to the cocoa products by using any of the cold plasma configurations such as dielectric barrier discharge, jet, arc, etc.

3. According to Claim 1 , it is an alternative method of alkalization for cocoa and its products, and its feature is; The cold plasma is generated by accelerating any type of working gases or gas mixtures in a reactive atmosphere (such as air atmosphere) or in a closed system with a modified atmosphere (such as argon inert atmosphere) using any type of cold plasma configurations (dielectric barrier discharge, jet, arc, corona, etc.) having different types of electrode and barrier materials with different thickness by using any type of the power supplies (microwave, radiofrequency, AC, DC, etc.) and transferred to the cocoa products under atmospheric or vacuum conditions.

4. According to Claim 1 , it is an alternative method of alkalization for cocoa and its products, and its feature is; The cold plasma is applied in planar, radial, or axial configurations in batch or continuous mode.

5. According to Claim 1 , it is an alternative method of alkalization for cocoa and its products, and its feature is; The cold plasma is generated using inert gases such as argon and helium or reactive gases such as dry air, or a mixture of these gases in any ratio.

6. According to Claim 5, it is an alternative method of alkalization for cocoa and its products, and its feature is; The gases or gas mixtures are fed at any flow rate and pressure according to the desired process temperature and to the properties of the final product, and the gases can be recycled in a closed system and reused for plasma production.

7. According to Claim 1 , it is an alternative method of alkalization for cocoa and its products, and its feature is; The cold plasma is applied to cocoa products for a desired period of time from a distance of 0.1-200 mm depending on the cold plasma configuration and desired properties of the final product.

8. According to Claim 1 , it is an alternative method of alkalization for cocoa ad its products, and its feature is; The cold plasma is generated by applying an electric voltage of 0.1-300 kV and frequency of 50-100000 Hz for a desired period of time.

9. According to Claim 1 , it is an alternative method of alkalization for cocoa and its products, and its feature is; The cold plasma is applied to cocoa products while mixing them homogenously using any type of mixer.

10. According to Claim 1 , it is an alternative method of alkalization for cocoa and its products, and its feature is; The cold plasma is applied to cocoa products alone or in combination with novel processing technologies such as ultrasonication, ohmic heating, pulsed electric fields, UV radiation, high pressure, high voltage electrical discharges.

11. According to Claim 1 , it is an alternative method of alkalization for cocoa and its products, and its feature is; The cold plasma is applied to cocoa products in combination with heating and/or microwave. According to Claim 1 , it is an alternative method of alkalization for cocoa and its products, and its feature is; The cocoa products are treated with chemical substances (alkalines) prior to, during, or after cold plasma in order to provide different modifications in the pH, taste, flavor, solubility and color properties of cocoa products. According to Claim 1 , it is an alternative method of alkalization for cocoa and its products, and its feature is; The cold plasma is applied to cocoa powders with different moisture contents or cocoa suspensions prepared at different ratios. According to Claim 1 , it is an alternative method of alkalization for cocoa and its products, and its feature is; The cold plasma is applied to cocoa products directly, indirectly, in-package, or immersing them in a solution such as water activated by cold plasma for a period of time. According to Claim 2, it is an alternative method of alkalization for cocoa and its products, and its feature is; The cold plasma is applied to cocoa products at different temperatures depending on the desired properties of the final product. According to Claim 2, it is an alternative method of alkalization for cocoa and its products, and its feature is; The cold plasma is applied with air or water cooling.