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Improvement of cocoa powder properties through ultrasonic- and microwave-assisted alkalization

  • Dimas Rahadian Aji Muhammad EMAIL logo , Dion Pratama , Danar Praseptiangga , Setyaningrum Ariviani , Mary Faith Adan , Sastia Prama Putri and Eiichiro Fukusaki
Published/Copyright: December 11, 2024
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Open Agriculture
From the journal Open Agriculture Volume 9 Issue 1

Abstract

Improving the process efficiency is still a challenge in the alkalization process of cocoa powder. This research aims to study the effect of ultrasonic- and microwave-assisted alkalization on the quality attributes of cocoa powder. Three levels of process duration were used (5, 10, and 15 min), and then the physical and antioxidant properties of the cocoa powder were evaluated. The results show that ultrasonic- and microwave-assisted alkalization is more effective in improving cocoa powder’s darkness and red intensity than the conventional alkalization process. The cocoa powder produced using ultrasonic- and microwave-assisted alkalization significantly improved the pH to 7.59, solubility from 20 to 28% and wetting time to almost twice, depending on the type and duration of the process. However, both advanced methods caused a significant decrease in total phenols, flavonoids, and antioxidant activity by about 35, 22, and 38%, respectively, compared to the conventional method. This research provides further information on the potential use of ultrasonication and microwave techniques, particularly in cocoa powder processing that has not been explored previously.

Keywords: alkalization; cocoa powder; microwave; ultrasonic

1 Introduction

Cocoa is a vital economic agroforestry product in many countries, and it can be processed into many products, including cocoa powder, chocolate, and beverages [1]. The products of the cocoa agroindustry are highly competitive in the market, and thus, innovation of cocoa-derived products by the industry is needed mainly to attract consumers. Some attempts have been made previously by developing chocolate and cocoa drinks enriched with probiotics, various herbs and spices, and other functional ingredients [2–4]. However, up till now, innovation in cocoa powder products and production processes is still scarce.

Cocoa powder is one of the main products of the cocoa industry, which is widely used as an ingredient for baking and beverages. However, natural cocoa powder has some limitations for its application, particularly for beverage production purposes, including poor dispersibility and unappealing appearance. Hence, additional research must be carried out to ameliorate the characteristics of cocoa powder [5]. Alkalization is a strategy that can be carried out to improve cocoa powder properties. Basically, alkalization generally consists of mixing natural cocoa material with an alkali solution and treating this mixture with the combined effects of temperature and pressure. Thus, in this research the alkalization was conducted using a pressured pan in which the working principle is boiling with an increased pressure [6]. This method is usually done to improve cocoa powder dispersibility in water as well as for enhancing its flavor and color. Many research groups have attempted to design more effective alkalization methods and investigate its effects on the physicochemical and sensory properties of the alkalized cocoa. It is presumed that the process of alkalization can be improved by combining the conventional method with advanced techniques.

Ultrasound and microwave are successfully employed in many areas, including food production. Microwave, with its wavelength ranging from 106 to 109 nm, induces rapid chemical reactions due to the increase in temperature during its application. It has a frequency range of 0.3–300 GHz and is proven to be a process with high reproducibility [7]. Meanwhile, ultrasound is composed of mechanical sound waves with a frequency of >20 kHz, which can form cavitation bubbles that induces biochemical reactions [8]. Thus, microwave treatment and ultrasonication are techniques that can potentially be combined with alkalization process to alter the properties of cocoa powder. It is hypothesized that waves produced by microwave and ultrasonic devices can cause rapid chemical reactions and cavitation, respectively, in the cocoa powder, assisting the acceleration of alteration of cocoa powder characteristics.

To the best of our knowledge, there is no study involving microwave and ultrasound treatment in alkalization process. Recent research studies related to modification of cocoa powder for food and beverage making purposes only include the effect of cocoa powder production method on the flavor compounds [9], the impact of alkaline type and concentration on the quality of cocoa powder [10], and the influence of various types of cocoa powder and stabilizers on the quality attributes of cocoa beverages [5]. Therefore, it is important to investigate the feasibility of microwave- and ultrasound-assisted alkalization which can be applied in small-scale industry. As emphasized by Valverde-Garcia and colleagues [6], the effects of alkalization on the nutritional and functional properties of cocoa need to be deeply investigated since this process can substantially affect cocoa powder characteristics. Hence, this research aims to examine the effect of ultrasonic- and microwave-assisted alkalization on the physicochemical properties and antioxidant activities of cocoa powder.

2 Materials and methods

2.1 Samples and chemicals

Natural cocoa powder, also known as non-alkalized cocoa powder, was obtained from PT Cargill Cocoa and Chocolate Gresik (Indonesia). KOH, FeCl3, ascorbic acid, sodium carbonate, acetic acid, and Folin–Ciocalteu reagent were purchased from Merck KGaA (Darmstadt, Germany). Meanwhile tannic acid, quercetin, gallic acid, and trichloroacetic acid were purchased from Sigma-Aldrich (Stenheim, Germany). 2,2-Diphenyl-1-picrylhydrazyl (DPPH) for molecular biology was obtained from HiMedia Laboratories Pvt. Ltd (Nashik, India) AlCl3 and K3[Fe(CN)6] were purchased from PT Smart Lab Indonesia (Tangerang, Indonesia). All the chemicals and reagents are of analytical grade.

2.2 Sample preparation

An alkali solution made of 1% KOH (w/v) in distilled water was prepared. The selected alkali concentration followed the previous study of Li et al. [11], in which 1% is considered light alkaline. Light alkali produced alkalized cocoa powder with higher antioxidant properties than heavy alkaline. The alkali solution was mixed with natural cocoa powder at a ratio of 3:1 (v/w) by manually stirring for about 3 min to get a homogenous mixture. The mixture was then separated into two parts in which one part was treated by ultrasonication at 40 kHz and 120 W using ultrasonicator (Baku BK-2000, Baku Guangdong, China) and the other part was treated with the lowest power (900 W) of the microwave (Sammic HM1001, DKSH Group, Bangkok Thailand). Ultrasonication and microwave treatment were conducted for 5, 10, and 15 min. After the treatments, the samples were then boiled in a small-scale pressured pan (Maxim 20 cm/4 L Maspion Group, Sidoarjo, Indonesia) for 15 min. Afterward, the samples were poured in a 20 × 20 baking pan with a thickness of 0.5 mm. Then, the samples were dried in an oven (Memmert 75, No. F-0109.0088, Schwabach, Germany) at 80°C for 16 h to obtain the dry alkalized cocoa powder. The dried samples were milled using a miller (Retsch ZM 200 Ultra Centrifugal Mill, Retsch GmBH, Haan, Germany). A maximum peripheral rotor speed of 92.8 m/s was set during the milling until the fineness of the product was smaller than 10 mm. Natural cocoa powder (without alkalization) and conventionally alkalized cocoa powder (without ultrasonication and microwave treatment) were also prepared as controls. The sample preparation is shown schematically in Figure 1.

Figure 1 Schematic diagram of the experimental design.
Figure 1

Schematic diagram of the experimental design.

2.3 Analytical determination

2.3.1 Wettability

A method described by Muhammad et al. [5] was used as the reference for the wetting time which is also known as wettability. The wetting time was determined by rapidly pouring 4 g of the milled cocoa powder in a glass with 40 mL of water (80°C), and then the time duration by which the poured cocoa powder becomes totally wet and has disappeared from the surface of the water was observed.

2.3.2 Solubility

The solubility analysis was conducted by initially mixing cocoa powder and water (80°C) in a ratio of 1:4 (w/v) using a magnetic stirrer for 30 min, after which the solution was centrifuged at 492g (2,000 rpm) for 10 min (Kokusan H-107, Kokusan Corp., Saitama, Japan). The supernatant was then collected and dried in an oven dryer at 120°C until a stable weight was reached. Solubility was stated as the percentage of the weight of soluble matter per weight of the initial material [5].

2.3.3 Sedimentation index (SI)

SI analysis was performed to determine the stability of the cocoa powder suspension. SI was calculated using equation (1) after visual assessment to see the relatively clear area where V is the total sample volume and V S is the volume of the relatively clear area after 24 h [5]

(1) SI = ( V S / V ) × 100 .

2.3.4 pH and morphology

The pH of the cocoa powder was determined using a pH meter (Ohaus ST3100, Ohaus Co., NJ, USA) at 20°C, while the morphology analysis was conducted using a scanning electron microscope (SEM) (Quanta 250 FEG, FEI Company, OR, USA). A double-sided adhesive carbon tape was used to embed the sample and the stubs. An acceleration voltage of 10 kV at a pressure of 80 Pa was employed. Electron micrographs were obtained from secondary electrons collected by a large-field detector.

2.3.5 Color properties

The color coordinates of CIELAB. (L*, a*, b*) were determined using a spectrophotometer (ColorFlex EZ 45/0 LAV, Hunter Associates Laboratory Inc., VA, USA). Following the method as described by Muhammad et al. [5], the obtained L*, a*, b* values were further used to calculate the level of the Chroma (C*), the °Hue, and the redness intensity of the samples, as well as the color difference between the alkalized and natural cocoa powder (ΔE) using equations (2)–(5), respectively:

(2) C ⁎ = a ⁎ 2 + b ⁎ 2 ,

(3) ° Hue = arctan ( b ⁎ / a ⁎ ) ,

(4) Redness intensity = a ⁎ / b ⁎ ,

(5) Δ E = ( L 1 ⁎ − L 2 ⁎ ) 2 + ( a 1 ⁎ − a 2 ⁎ ) 2 + ( b 1 ⁎ − b 2 ⁎ ) 2 .

2.3.6 Extraction of antioxidant compound

Antioxidant compound extraction is substantial prior to the antioxidant properties determination. Extraction was carried out following the method of Muhammad et al. [12]. Briefly, the fat content of cocoa powder (10 g) was removed by washing with 50 mL of n-hexane thrice. Afterward, n-hexane was discarded, and the cocoa powder was air-dried for 24 h to obtain the defatted cocoa powder. The dried defatted cocoa powder (4 g) was mixed with 10 mL of extractive solvent composed of acetone, distilled water, and acetic acid (70:29.8:0.2) in an ultrasonic bath for 30 min to extract antioxidant compounds, mainly phenols and flavonoids. It was then centrifuged for 10 min at 1,107g (3,000 rpm) and the supernatant was collected. The procedure was repeated twice. The collected supernatant was filtered to remove the residual particles and obtain the cocoa powder extract. The extract was then used for further analyses following the methods of Muhammad et al. [13].

2.3.7 Total phenol content

In the total phenol analysis, a solution of the cocoa powder extract (200 µL), distilled water (1 mL), and Folin–Ciocalteu reagent (200 µL) were prepared. After which, 7% of Na2CO3 (2.5 mL) solution and distilled water (2.1 mL) were added. The mixture was placed at ambient temperature condition (±25°C) in the absence of light for 1.5 h. After the incubation, the absorbance was measured at 760 nm in an UV-vis spectrophotometer (Shimadzu BioSpec-1600, Shimadzu Corp., Kyoto, Japan). A standard curve of gallic acid was constructed to determine the total phenolic content expressed as milligram gallic acid equivalent per gram dry weight (mg GAE/g DW).

2.3.8 Total flavonoid content

In the total flavonoid content analysis, 0.1 M AlCl3 (4 mL) was mixed with 160 µL of extract, followed by incubation for 40 min at ambient temperature (±25°C) in a dark condition. The absorbance was measured at 415 nm and the total flavonoid content was expressed as milligrams of quercetin equivalent per gram of dry weight (mg QE/g DW).

2.3.9 Ferric reducing antioxidant power (FRAP)

FRAP assay was performed by incubation (50°C) of a mixture containing cocoa powder extract (1 mL), phosphate buffer (0.2 M, pH 7, 2.5 mL), and 1% of K3[Fe(CN)6] (2,5) for 0.5 h. After that, 10% trichloroacetic acid (2.5 mL) was added to the mixture and then centrifuged (1,107g, 10 min) to remove the large particles and get the supernatant. Distilled water and 0.1% FeCl3 were then added to the supernatant. The ratio of distilled water, FeCl3 solution, and the supernatant was at 5:1:5. The absorbance was measured at 700 nm. A standard curve of ascorbic acid was prepared (0–100 µg/mL). Thus, FRAP was expressed as milligrams of ascorbic acid equivalent per gram of the extract (mg AAE/g).

2.3.10 DPPH-radical scavenging activity

In the DPPH assay, the cocoa powder extract (100 µL) was mixed with 4 mL of DPPH solution (0.01 mM). After incubation in the dark for 0.5 h, the absorbance was determined at 517 nm, and then the DPPH radical scavenging activity (% inhibition) was calculated using equation (6). The DPPH radical scavenging activity was expressed in IC50 (the concentration required to scavenge 50% of the initial DPPH radicals):

(6) % inhibiton = ( Absorbance of the control ( Ac ) − Absorbance of the sample ( As ) ) × 100 Absorbance of the control  ( Ac ) . .

2.3.11 Experimental design and statistical analysis

The parameters that were considered to be affecting the characteristics of the alkalized cocoa powder were the technique and the duration. The experiment was performed by means of a completely randomized design, and the results represented the means of three replicates, except for SEM analysis. One-way ANOVA method followed by Duncan’s Multiple Range Test to test the differences among the samples. The differences were considered significant at 0.95 confidence level. The statistical analysis was executed by SPSS 23.0 Software (SPSS Inc., Chicago, IL, USA).

3 Results and discussion

3.1 Effect of ultrasonic- and microwave-assisted alkalization on physical properties of cocoa powder

Table 1 shows that alkalization using 1% KOH increased the pH of cocoa powder in which the pH of natural cocoa powder was 5.72 and the pH of alkalized cocoa powder (all treatments) was 7.48 or even higher. It was shown that ultrasonic- and microwave-assisted alkalization resulted in a very slight effect in the pH as compared to the conventional alkalization. Yet, statistical analyses showed a significant difference between alkalized cocoa powder obtained by conventional method and ultrasonic-/microwave-assisted alkalization method (p < 0.05). It is also shown that the increase in pH of the alkalized cocoa powder was linearly correlated with the duration of microwave and ultrasonic treatment. It is believed that those treatments caused more intense chemical reactions, resulting in a higher pH alteration.

Table 1

pH wetting time, solubility, and SI of alkalized cocoa powder

Treatment pH Wetting time (s) Solubility (%) SI
Control (natural cocoa powder) 5.72 ± 0.01a 80.87 ± 0.38c 20.52 ± 0.08a 50.67 ± 0.94d
Conventional alkalization 7.50 ± 0.04b 89.24 ±± 0.51e 24.29 ± 0.17b 49.06 ± 0.27cd
Ultrasonic-assisted alkalization
   5 min 7.60 ± 0.02c 22.31 ± 0.36b 24.79 ± 0.61bc 48.47 ± 0.39cd
   10 min 7.68 ± 0.02cd 92.23 ± 0.37f 25.56 ± 1.01d 45.65 ± 0.54ab
   15 min 7.59 ± 0.01cd 158.04 ± 0.84h 27.68 ± 1.02e 44.19 ± 0.09a
Microwave-assisted alkalization
   5 min 7.48 ± 0.01cd 6.81 ± 0.49a 25.43 ± 0.53cd 47.05 ± 0.28bc
   10 min 7.53 ± 0.01cd 86.73 ± 0.55d 26.00 ± 0.10d 44.61 ± 0.95ab
   15 min 7.49 ± 0.01d 141.97 ± 0.34g 28.81 ± 0.28f 43.92 ± 0.13a

Mean values with different lowercase notations within the same column differ significantly (p < 0.05).

Substantial improvement in the solubility of cocoa powder was also observed in the microwave- and ultrasound-assisted alkalization. As shown in Table 1, alkalized cocoa powder produced by ultrasonic- and microwave-assisted alkalization had better solubility than that produced by conventional alkalization as well as natural cocoa powder. As such, the solubility of natural cocoa powder and alkalized cocoa powder processed using conventional method were about 20.52 and 24.29%, respectively, while the alkalized cocoa powder processed by ultrasonic- and microwave-assisted methods were about 27.68 and 28.81%, respectively. The statistical analyses showed a significant difference between alkalized cocoa powder obtained by conventional method and ultrasonic-/microwave-assisted alkalization method (p < 0.05). Table 1 also shows that increasing the duration of alkalization notably increased the solubility, regardless of the type of the treatments (p < 0.05).

In any case, the improvement in solubility by alkalization is attributed to the chemical modification due to alkali treatment. As for microwave-assisted alkalization, the microwave increased the temperature, triggering rapid chemical reactions [7]. Meanwhile, mechanical sound waves formed cavitation bubbles for ultrasonic-assisted alkalization, inducing more intense biochemical reactions [8]. In both cases, therefore, at a similar duration of the process, the solubility of alkalized cocoa powder assisted by microwave or ultrasonic process is better than that of the powder obtained by a conventional process.

In addition to solubility, a significant improvement was shown in the wetting time parameters. As shown, the conventional alkalization resulted in wetting time of 89 s, while the ultrasonication (10 and 15 min) resulted in the wetting time of 92 and 158 s, respectively, and the microwave treatment (15 min) resulted in the wetting time of 141 s. It is interesting that the duration of assisted alkalization was directly proportional to the wetting time implying that ultrasonication and microwave treatment had significant effect on this parameter. Furthermore, it is also notable that the lower duration of ultrasonication and microwave treatment resulted in a lower wetting time as compared to conventional alkalization. Up until now, this phenomenon is still under investigated.

Table 1 shows that ultrasonic treatment resulted in a longer wetting time than microwave treatment at a similar duration (p < 0.05). As such, ultrasonic-assisted alkalization at 5, 10, and 15 resulted in the wetting time of 22.31, 92.23, and 158.04 s, respectively. In contrast, microwave-assisted alkalization at the duration of 5, 10, and 15 resulted in the wetting time of 6.81, 86.73, and 141.97 s, respectively. Wetting time indicates the interfacial dynamics of particle–water interactions and it is substantially affected by hydrophobic properties of the particle. It was also reported by Amer et al. [14] that the higher alkalization degree, such as longer alkalization duration in this case, causes more intensive base-catalyzed hydrolysis reactions increasing the chemical sorption sites for water molecules in cocoa particles.

Wetting time has a linear correlation with suspension stability [5], which is also presented in this study. Cocoa powder can be suspended in the drink for a longer period in the condition of longer wetting time. Suspension stability is an important parameter in the quality of cocoa drink indicating how fast the cocoa powder deposits as sediment. The suspension stability can be measured by SI. The results showed that ultrasonic- and microwave-assisted alkalization had lower SI (p < 0.05) (Table 1), meaning that the treatments resulted in more stable suspensions. Interestingly, longer duration of treatments led to lower SI. For instance, ultrasonic-assisted alkalization at 5, 10, and 15 resulted in the SI of 48.47, 45.65, and 44.19, respectively. Meanwhile, microwave-assisted alkalization at the duration of 5, 10, and 15 resulted in the SI of 47.05, 44.61, and 43.93, respectively. Muhammad et al. [5] stated that insoluble matter may also affect the sedimentation of particles. Therefore, it is rational if the SI aligns with solubility, as clearly shown in Table 1. It is also noted that at 10 and 15 min, the SI between cocoa powder obtained by ultrasonic and microwave treatments was not statistically different (p > 0.05).

SEM analysis was able to visualize the physical modification of cocoa powder after the ultrasonic- and microwave-assisted alkalization. As revealed in Figure 2, natural cocoa powder had a regular and oval form. However, alkalization generally causes disruption of the powder structure; in the case of ultrasonic- and microwave-assisted alkalization, the disruption may be more intense, and thus the alkalization effect may be more pronounced. As well known, the microwave provides an alternative heat source and can create the opportunity to induce rapid chemical reactions [7], while ultrasonic wave creates cavitation bubbles causing hotspots and extreme local condition. These hotspots expedite the biochemical reactions in its vicinity [8]. Simply put, ultrasonication provides more access for alkali solution to interact with cocoa powder surface.

Figure 2 Microstructural properties of natural cocoa powder (a) and cocoa powder with alkalization – control (b), ultrasonic-assisted alkalization (c), and microwave-assisted alkalization (d).
Figure 2

Microstructural properties of natural cocoa powder (a) and cocoa powder with alkalization – control (b), ultrasonic-assisted alkalization (c), and microwave-assisted alkalization (d).

The effects of ultrasonic- and microwave-assisted alkalization were also visibly shown in the color properties of cocoa powder. Generally, alkalization can darken the color of cocoa powder due to oxidation caused by the alkali. As shown, the lightness of the natural cocoa powder was 21.31 and that of alkalized cocoa powder was 14.19. In this study, the application of ultrasonic and microwave in the alkalization process led to a more pronounced effect of alkalization to the color properties of the cocoa powder (Table 2). Ultrasonic- and microwave-assisted alkalization caused darker powder, lower value of chroma and °Hue than conventional alkalization (p < 0.05). At the same time, it led to higher redness intensity (p < 0.05) and higher value of color difference between the alkalized and the natural cocoa powder (p < 0.05). The variation in color properties was also shown to be linearly correlated with the duration of the treatment. Nevertheless, at a similar duration, the color properties of the cocoa powder obtained by ultrasonic treatment were not significantly different with that obtained by microwave treatment. The appearance of the alkalized cocoa powder is presented in Figure 3.

Table 2

Color properties of alkalized cocoa powder

Sample and treatment Lightness Chroma °Hue Redness intensity ∆E
Control (natural cocoa powder) 21.31 ± 0.09d 14.35 ± 0.06e 43.95 ± 0.20c 1.04 ± 0.01a —
Conventional alkalization 14.19 ± 0.06c 10.14 ± 0.04d 39.54 ± 0.25b 1.21 ± 0.01d 8.33 ± 0.09a
Ultrasonic-assisted alkalization
   5 min 14.08 ± 1.03c 9.83 ± 0.73cd 39.44 ± 0.52b 1.22 ± 0.02d 8.52 ± 1.05ab
   10 min 13.51 ± 0.34ab 9.65 ± 0.30bc 38.35 ± 0.45a 1.26 ± 0.02c 8.51 ± 0.38cd
   15 min 13.09 ± 0.02a 9.59 ± 0.36bc 38.04 ± 1.14a 1.28 ± 0.05c 9.58 ± 0.03de
Microwave-assisted alkalization
   5 min 13.76 ± 0.05bc 9.81 ± 0.03cd 38.37 ± 0.31a 1.26 ± 0.01c 8.87 ± 0.03b
   10 min 13.42 ± 0.19ab 9.34 ± 0.17ab 38.22 ± 1.31a 1.27 ± 0.01b 9.41 ± 0.25de
   15 min 13.04 ± 0.03a 9.13 ± 0.22a 37.93 ± 1.04a 1.28 ± 0.05a 9.85 ± 0.09e

Mean values with different lowercase notations within the same column differ significantly (p < 0.05).

Figure 3 Appearance of alkalized cocoa powder.
Figure 3

Appearance of alkalized cocoa powder.

3.2 Effect of ultrasonic- and microwave-assisted alkalization on antioxidant properties of cocoa powder

These results evidently show the potential use of ultrasonic and microwave treatment in alkalization process. However, the treatments also have drawbacks such that it reduced the phenolic content and antioxidant activity of the cocoa powder (Table 3). In general, the total phenols, total flavonoids, and antioxidant activity of alkalized cocoa powder were lower than that of natural cocoa powder (p < 0.05). The additional treatment of ultrasonic and microwave resulted in more noticeable reduction which may be due to a more intense chemical reaction during the alkalization process. As such, the total phenols and flavonoids of cocoa powder produced by conventional alkalization were about 20.90 mg GAE/g and 0.89 mg QE/g, respectively, while those of cocoa powders produced by advanced treatments were less than 20 mg GAE/g and 0.89 mg QE/g, respectively. Longer duration of treatments also caused lower phenol and flavonoid content. Similar phenomenon was also found in the FRAP activity as one of the antioxidant activity parameters of cocoa powder. It is understandable since FRAP activity had a positive correlation with phenolic content according to previous reports [13]. This result is also confirmed by the result of IC50 DPPH radical scavenging activity. As shown, the higher degree of alkalization caused the higher IC50 value meaning that more concentration of cocoa powder extract is required to inhibit 50% of radical reaction. This indicates that the antioxidant activity of the samples is lower. A similar phenomenon was found in the study of Sioriki et al. [15] explaining the decrease of active compounds after alkalization. Several studies reported a similar reduction in active compounds after alkalization [16–18].

Table 3

Antioxidant properties of alkalized cocoa powder

Treatment Total phenolic content (mg GAE/g) Total flavonoid content (mg QE/g) DPPH IC50 (ppm) FRAP (mg AAE/g)
Control (natural cocoa powder) 35.23 ± 0.04g 2.85 ± 0.02d 35.07 ± 0.45a 28.03 ± 0.27d
Conventional alkalization 20.90 ± 0.01f 0.89 ± 0.01c 57.95 ± 0.65b 21.40 ± 0.03c
Ultrasonic-assisted alkalization
   5 min 19.20 ± 0.45e 0.88 ± 0.01c 81.62 ± 0.02c 15.15 ± 0.50b
   10 min 15.36 ± 0.09c 0.81 ± 0.01b 82.48 ± 0.50cd 14.21 ± 0.94ab
   15 min 14.99 ± 0.73c 0.78 ± 0.01b 84.76 ± 0.10cd 13.47 ± 0.76a
Microwave-assisted alkalization
   5 min 17.74 ± 0.01d 0.72 ± 0.03a 82.15 ± 0.82cd 14.76 ± 0.59ab
   10 min 14.32 ± 0.01b 0.70 ± 0.09a 82.72 ± 0.04cd 13.70 ± 0.78ab
   15 min 13.63 ± 0.56a 0.68 ± 0.03a 85.75 ± 0.76d 13.25 ± 0.08a

Mean values with different lowercase notations within the same column differ significantly (p < 0.05).

Phenolic content and antioxidant activity have gained high interest nowadays because they are closely associated with beneficial health effects [19,20]. This study shows that the alkalization coupled with microwave or ultrasonic may negatively impact these parameters. However, the primary purpose of alkalization is to improve the pH, color, solubility, and stability of cocoa powder. In these aspects, microwave or ultrasonic treatment demonstrates a significant contribution to improving the process of obtaining cocoa powder with a more intense color and better solubility and suspension stability. Further study related to the sensory profile of cocoa powder is recommended to investigate the other possible positive impacts of microwave- and ultrasonic-assisted processes.

Despite its limitations, this study provides the first attempt to involve microwave and ultrasonic processes and strengthen the new paradigm in combining the advanced method with conventional alkalization. The methods proposed in this study can be alternatives in addition to a recent method combining alkalization with extrusion and cold plasma technique [21,22]. As all the novel proposed alkalization methods still have limitations, particularly regarding the bioactive content, finding a new alkalization method for retaining the phenolic content and antioxidant activity of the cocoa powder is encouraged to be explored in the future. To better understand the bioactive compounds’ stability during alkalization, analysis using metabolomic approaches is highly recommended [23].

4 Conclusion

To sum up, ultrasonication and microwave treatment were potentially used in the alkalization process to improve the physical properties of cocoa powder to some extent. Ultrasonication and microwave treatment modify the color properties of cocoa powder to be more appealing by increasing the darkness and red intensity. The color difference of cocoa powders produced by the treatments was higher than that of the cocoa powder produced by conventional alkalization. Cocoa powders produced by using ultrasonic- and microwave-assisted alkalization are suitable for beverage making purposes as the technique is proven to improve the pH, solubility, and wetting time, and at the same time decrease the SI of cocoa powder. However, the methods also cause significant decrease in total phenols, flavonoids, and antioxidant activity. Based on the evaluation of each parameter, ultrasonic-assisted alkalization seems more promising in changing the physical properties of cocoa powder with a better retainment of antioxidant properties. However, the solubility of the alkalized cocoa powder obtained by ultrasonic treatment was lower than that obtained by microwave treatment. Thus, the results obtained in this study are still considered not satisfying. Further research by combining other advanced methods with alkalization process may be required. Despite the limitation of each method, this research provides new insights for the application of ultrasonic and microwave treatment to assist alkalization process. Metabolomic approach may be significant to understand the behavior of bioactive compounds during ultrasonic- and microwave-assisted alkalization.

Acknowledgements

The authors thank PT Cargill Cocoa and Chocolate Gresik (Indonesia) for giving the opportunity for the second author (D.P.) to do internship and giving free sample of natural cocoa powder.

  1. Funding information: This research was financially supported by Universitas Sebelas Maret through Hibah Kolaborasi Internasional 2023 (Grant no. 228/UN27.22/PT.01.03/2023).

  2. Author contributions: All authors have accepted responsibility for the entire content of this manuscript and consented to its submission to the journal, reviewed all the results and approved the final version of the manuscript. D.R.A.M.: conceptualization, funding acquisition, supervision, writing – review and editing; D.P. (2nd author): data curation, formal analysis, investigation; D.P. (3rd author): validation, writing – review; S.A.: writing – review & editing; M.F.A.: writing – review and editing; S.P.P.: supervision; E.F.: supervision.

  3. Conflict of interest: The second author (D.P.) did internship at PT Cargill Cocoa and Chocolate Gresik (Indonesia). The company gave free sample of natural cocoa powder, but was not involved in the experimentation, data interpretation, writing, or publication of this study at Universitas Sebelas Maret. The other authors declare that they have no conflicts of interest to disclose. None of the authors received payment for consultation or expert testimony and do not own stock or stock options from PT Cargill Cocoa and Chocolate Gresik (Indonesia).

  4. Data availability statement: The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

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Received: 2024-02-19
Revised: 2024-10-10
Accepted: 2024-11-12
Published Online: 2024-12-11

© 2024 the author(s), published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

Articles in the same Issue

  1. Regular Articles
  2. Supplementation of P-solubilizing purple nonsulfur bacteria, Rhodopseudomonas palustris improved soil fertility, P nutrient, growth, and yield of Cucumis melo L.
  3. Yield gap variation in rice cultivation in Indonesia
  4. Effects of co-inoculation of indole-3-acetic acid- and ammonia-producing bacteria on plant growth and nutrition, soil elements, and the relationships of soil microbiomes with soil physicochemical parameters
  5. Impact of mulching and planting time on spring-wheat (Triticum aestivum) growth: A combined field experiment and empirical modeling approach
  6. Morphological diversity, correlation studies, and multiple-traits selection for yield and yield components of local cowpea varieties
  7. Participatory on-farm evaluation of new orange-fleshed sweetpotato varieties in Southern Ethiopia
  8. Yield performance and stability analysis of three cultivars of Gayo Arabica coffee across six different environments
  9. Biology of Spodoptera frugiperda (Lepidoptera: Noctuidae) on different types of plants feeds: Potency as a pest on various agricultural plants
  10. Antidiabetic activity of methanolic extract of Hibiscus sabdariffa Linn. fruit in alloxan-induced Swiss albino diabetic mice
  11. Bioinformatics investigation of the effect of volatile and non-volatile compounds of rhizobacteria in inhibiting late embryogenesis abundant protein that induces drought tolerance
  12. Nicotinamide as a biostimulant improves soybean growth and yield
  13. Farmer’s willingness to accept the sustainable zoning-based organic farming development plan: A lesson from Sleman District, Indonesia
  14. Uncovering hidden determinants of millennial farmers’ intentions in running conservation agriculture: An application of the Norm Activation Model
  15. Mediating role of leadership and group capital between human capital component and sustainability of horticultural agribusiness institutions in Indonesia
  16. Biochar technology to increase cassava crop productivity: A study of sustainable agriculture on degraded land
  17. Effect of struvite on the growth of green beans on Mars and Moon regolith simulants
  18. UrbanAgriKG: A knowledge graph on urban agriculture and its embeddings
  19. Provision of loans and credit by cocoa buyers under non-price competition: Cocoa beans market in Ghana
  20. Effectiveness of micro-dosing of lime on selected chemical properties of soil in Banja District, North West, Ethiopia
  21. Effect of weather, nitrogen fertilizer, and biostimulators on the root size and yield components of Hordeum vulgare
  22. Effects of selected biostimulants on qualitative and quantitative parameters of nine cultivars of the genus Capsicum spp.
  23. Growth, yield, and secondary metabolite responses of three shallot cultivars at different watering intervals
  24. Design of drainage channel for effective use of land on fully mechanized sugarcane plantations: A case study at Bone Sugarcane Plantation
  25. Technical feasibility and economic benefit of combined shallot seedlings techniques in Indonesia
  26. Control of Meloidogyne javanica in banana by endophytic bacteria
  27. Comparison of important quality components of red-flesh kiwifruit (Actinidia chinensis) in different locations
  28. Efficiency of rice farming in flood-prone areas of East Java, Indonesia
  29. Comparative analysis of alpine agritourism in Trentino, Tyrol, and South Tyrol: Regional variations and prospects
  30. Detection of Fusarium spp. infection in potato (Solanum tuberosum L.) during postharvest storage through visible–near-infrared and shortwave–near-infrared reflectance spectroscopy
  31. Forage yield, seed, and forage qualitative traits evaluation by determining the optimal forage harvesting stage in dual-purpose cultivation in safflower varieties (Carthamus tinctorius L.)
  32. The influence of tourism on the development of urban space: Comparison in Hanoi, Danang, and Ho Chi Minh City
  33. Optimum intra-row spacing and clove size for the economical production of garlic (Allium sativum L.) in Northwestern Highlands of Ethiopia
  34. The role of organic rice farm income on farmer household welfare: Evidence from Yogyakarta, Indonesia
  35. Exploring innovative food in a developing country: Edible insects as a sustainable option
  36. Genotype by environment interaction and performance stability of common bean (Phaseolus vulgaris L.) cultivars grown in Dawuro zone, Southwestern Ethiopia
  37. Factors influencing green, environmentally-friendly consumer behaviour
  38. Factors affecting coffee farmers’ access to financial institutions: The case of Bandung Regency, Indonesia
  39. Morphological and yield trait-based evaluation and selection of chili (Capsicum annuum L.) genotypes suitable for both summer and winter seasons
  40. Sustainability analysis and decision-making strategy for swamp buffalo (Bubalus bubalis carabauesis) conservation in Jambi Province, Indonesia
  41. Understanding factors affecting rice purchasing decisions in Indonesia: Does rice brand matter?
  42. An implementation of an extended theory of planned behavior to investigate consumer behavior on hygiene sanitation-certified livestock food products
  43. Information technology adoption in Indonesia’s small-scale dairy farms
  44. Draft genome of a biological control agent against Bipolaris sorokiniana, the causal phytopathogen of spot blotch in wheat (Triticum turgidum L. subsp. durum): Bacillus inaquosorum TSO22
  45. Assessment of the recurrent mutagenesis efficacy of sesame crosses followed by isolation and evaluation of promising genetic resources for use in future breeding programs
  46. Fostering cocoa industry resilience: A collaborative approach to managing farm gate price fluctuations in West Sulawesi, Indonesia
  47. Field investigation of component failures for selected farm machinery used in small rice farming operations
  48. Near-infrared technology in agriculture: Rapid, simultaneous, and non-destructive determination of inner quality parameters on intact coffee beans
  49. The synergistic application of sucrose and various LED light exposures to enhance the in vitro growth of Stevia rebaudiana (Bertoni)
  50. Weather index-based agricultural insurance for flower farmers: Willingness to pay, sales, and profitability perspectives
  51. Meta-analysis of dietary Bacillus spp. on serum biochemical and antioxidant status and egg quality of laying hens
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  54. Empowering farmers: Unveiling the economic impacts of contract farming on red chilli farmers’ income in Magelang District, Indonesia
  55. Evaluating salt tolerance in fodder crops: A field experiment in the dry land
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  57. Cropping systems and production assessment in southern Myanmar: Informing strategic interventions
  58. The effect of biostimulants and red mud on the growth and yield of shallots in post-unlicensed gold mining soil
  59. Effects of dietary Adansonia digitata L. (baobab) seed meal on growth performance and carcass characteristics of broiler chickens: A systematic review and meta-analysis
  60. Analysis and structural characterization of the vid-pisco market
  61. Pseudomonas fluorescens SP007s enhances defense responses against the soybean bacterial pustule caused by Xanthomonas axonopodis pv. glycines
  62. A brief investigation on the prospective of co-composted biochar as a fertilizer for Zucchini plants cultivated in arid sandy soil
  63. Supply chain efficiency of red chilies in the production center of Sleman Indonesia based on performance measurement system
  64. Investment development path for developed economies: Is agriculture different?
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  72. Yield stability of biofertilizer treatments to soybean in the rainy season based on the GGE biplot
  73. Evaluating agricultural yield and economic implications of varied irrigation depths on maize yield in semi-arid environments, at Birfarm, Upper Blue Nile, Ethiopia
  74. Chemometrics for mapping the spatial nitrate distribution on the leaf lamina of fenugreek grown under varying nitrogenous fertilizer doses
  75. Pomegranate peel ethanolic extract: A promising natural antioxidant, antimicrobial agent, and novel approach to mitigate rancidity in used edible oils
  76. Transformative learning and engagement with organic farming: Lessons learned from Indonesia
  77. Tourism in rural areas as a broader concept: Some insights from the Portuguese reality
  78. Assessment enhancing drought tolerance in henna (Lawsonia inermis L.) ecotypes through sodium nitroprusside foliar application
  79. Edible insects: A survey about perceptions regarding possible beneficial health effects and safety concerns among adult citizens from Portugal and Romania
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  88. Optimizing inorganic blended fertilizer application for the maximum grain yield and profitability of bread wheat and food barley in Dawuro Zone, Southwest Ethiopia
  89. The acceptance of social media as a channel of communication and livestock information for sheep farmers
  90. Adaptation of rice farmers to aging in Thailand
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  116. Yield assessment of new streak-resistant topcross maize hybrids in Benin
  117. Improvement of cocoa powder properties through ultrasonic- and microwave-assisted alkalization
  118. Potential of ecoenzymes made from nutmeg (Myristica fragrans) leaf and pulp waste as bioinsecticides for Periplaneta americana
  119. Analysis of farm performance to realize the sustainability of organic cabbage vegetable farming in Getasan Semarang, Indonesia
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https://doi.org/10.1515/opag-2022-0400
Keywords for this article
alkalization; cocoa powder; microwave; ultrasonic
Creative Commons
BY 4.0

Articles in the same Issue

  1. Regular Articles
  2. Supplementation of P-solubilizing purple nonsulfur bacteria, Rhodopseudomonas palustris improved soil fertility, P nutrient, growth, and yield of Cucumis melo L.
  3. Yield gap variation in rice cultivation in Indonesia
  4. Effects of co-inoculation of indole-3-acetic acid- and ammonia-producing bacteria on plant growth and nutrition, soil elements, and the relationships of soil microbiomes with soil physicochemical parameters
  5. Impact of mulching and planting time on spring-wheat (Triticum aestivum) growth: A combined field experiment and empirical modeling approach
  6. Morphological diversity, correlation studies, and multiple-traits selection for yield and yield components of local cowpea varieties
  7. Participatory on-farm evaluation of new orange-fleshed sweetpotato varieties in Southern Ethiopia
  8. Yield performance and stability analysis of three cultivars of Gayo Arabica coffee across six different environments
  9. Biology of Spodoptera frugiperda (Lepidoptera: Noctuidae) on different types of plants feeds: Potency as a pest on various agricultural plants
  10. Antidiabetic activity of methanolic extract of Hibiscus sabdariffa Linn. fruit in alloxan-induced Swiss albino diabetic mice
  11. Bioinformatics investigation of the effect of volatile and non-volatile compounds of rhizobacteria in inhibiting late embryogenesis abundant protein that induces drought tolerance
  12. Nicotinamide as a biostimulant improves soybean growth and yield
  13. Farmer’s willingness to accept the sustainable zoning-based organic farming development plan: A lesson from Sleman District, Indonesia
  14. Uncovering hidden determinants of millennial farmers’ intentions in running conservation agriculture: An application of the Norm Activation Model
  15. Mediating role of leadership and group capital between human capital component and sustainability of horticultural agribusiness institutions in Indonesia
  16. Biochar technology to increase cassava crop productivity: A study of sustainable agriculture on degraded land
  17. Effect of struvite on the growth of green beans on Mars and Moon regolith simulants
  18. UrbanAgriKG: A knowledge graph on urban agriculture and its embeddings
  19. Provision of loans and credit by cocoa buyers under non-price competition: Cocoa beans market in Ghana
  20. Effectiveness of micro-dosing of lime on selected chemical properties of soil in Banja District, North West, Ethiopia
  21. Effect of weather, nitrogen fertilizer, and biostimulators on the root size and yield components of Hordeum vulgare
  22. Effects of selected biostimulants on qualitative and quantitative parameters of nine cultivars of the genus Capsicum spp.
  23. Growth, yield, and secondary metabolite responses of three shallot cultivars at different watering intervals
  24. Design of drainage channel for effective use of land on fully mechanized sugarcane plantations: A case study at Bone Sugarcane Plantation
  25. Technical feasibility and economic benefit of combined shallot seedlings techniques in Indonesia
  26. Control of Meloidogyne javanica in banana by endophytic bacteria
  27. Comparison of important quality components of red-flesh kiwifruit (Actinidia chinensis) in different locations
  28. Efficiency of rice farming in flood-prone areas of East Java, Indonesia
  29. Comparative analysis of alpine agritourism in Trentino, Tyrol, and South Tyrol: Regional variations and prospects
  30. Detection of Fusarium spp. infection in potato (Solanum tuberosum L.) during postharvest storage through visible–near-infrared and shortwave–near-infrared reflectance spectroscopy
  31. Forage yield, seed, and forage qualitative traits evaluation by determining the optimal forage harvesting stage in dual-purpose cultivation in safflower varieties (Carthamus tinctorius L.)
  32. The influence of tourism on the development of urban space: Comparison in Hanoi, Danang, and Ho Chi Minh City
  33. Optimum intra-row spacing and clove size for the economical production of garlic (Allium sativum L.) in Northwestern Highlands of Ethiopia
  34. The role of organic rice farm income on farmer household welfare: Evidence from Yogyakarta, Indonesia
  35. Exploring innovative food in a developing country: Edible insects as a sustainable option
  36. Genotype by environment interaction and performance stability of common bean (Phaseolus vulgaris L.) cultivars grown in Dawuro zone, Southwestern Ethiopia
  37. Factors influencing green, environmentally-friendly consumer behaviour
  38. Factors affecting coffee farmers’ access to financial institutions: The case of Bandung Regency, Indonesia
  39. Morphological and yield trait-based evaluation and selection of chili (Capsicum annuum L.) genotypes suitable for both summer and winter seasons
  40. Sustainability analysis and decision-making strategy for swamp buffalo (Bubalus bubalis carabauesis) conservation in Jambi Province, Indonesia
  41. Understanding factors affecting rice purchasing decisions in Indonesia: Does rice brand matter?
  42. An implementation of an extended theory of planned behavior to investigate consumer behavior on hygiene sanitation-certified livestock food products
  43. Information technology adoption in Indonesia’s small-scale dairy farms
  44. Draft genome of a biological control agent against Bipolaris sorokiniana, the causal phytopathogen of spot blotch in wheat (Triticum turgidum L. subsp. durum): Bacillus inaquosorum TSO22
  45. Assessment of the recurrent mutagenesis efficacy of sesame crosses followed by isolation and evaluation of promising genetic resources for use in future breeding programs
  46. Fostering cocoa industry resilience: A collaborative approach to managing farm gate price fluctuations in West Sulawesi, Indonesia
  47. Field investigation of component failures for selected farm machinery used in small rice farming operations
  48. Near-infrared technology in agriculture: Rapid, simultaneous, and non-destructive determination of inner quality parameters on intact coffee beans
  49. The synergistic application of sucrose and various LED light exposures to enhance the in vitro growth of Stevia rebaudiana (Bertoni)
  50. Weather index-based agricultural insurance for flower farmers: Willingness to pay, sales, and profitability perspectives
  51. Meta-analysis of dietary Bacillus spp. on serum biochemical and antioxidant status and egg quality of laying hens
  52. Biochemical characterization of trypsin from Indonesian skipjack tuna (Katsuwonus pelamis) viscera
  53. Determination of C-factor for conventional cultivation and soil conservation technique used in hop gardens
  54. Empowering farmers: Unveiling the economic impacts of contract farming on red chilli farmers’ income in Magelang District, Indonesia
  55. Evaluating salt tolerance in fodder crops: A field experiment in the dry land
  56. Labor productivity of lowland rice (Oryza sativa L.) farmers in Central Java Province, Indonesia
  57. Cropping systems and production assessment in southern Myanmar: Informing strategic interventions
  58. The effect of biostimulants and red mud on the growth and yield of shallots in post-unlicensed gold mining soil
  59. Effects of dietary Adansonia digitata L. (baobab) seed meal on growth performance and carcass characteristics of broiler chickens: A systematic review and meta-analysis
  60. Analysis and structural characterization of the vid-pisco market
  61. Pseudomonas fluorescens SP007s enhances defense responses against the soybean bacterial pustule caused by Xanthomonas axonopodis pv. glycines
  62. A brief investigation on the prospective of co-composted biochar as a fertilizer for Zucchini plants cultivated in arid sandy soil
  63. Supply chain efficiency of red chilies in the production center of Sleman Indonesia based on performance measurement system
  64. Investment development path for developed economies: Is agriculture different?
  65. Power relations among actors in laying hen business in Indonesia: A MACTOR analysis
  66. High-throughput digital imaging and detection of morpho-physiological traits in tomato plants under drought
  67. Converting compression ignition engine to dual-fuel (diesel + CNG) engine and experimentally investigating its performance and emissions
  68. Structuration, risk management, and institutional dynamics in resolving palm oil conflicts
  69. Spacing strategies for enhancing drought resilience and yield in maize agriculture
  70. Composition and quality of winter annual agrestal and ruderal herbages of two different land-use types
  71. Investigating Spodoptera spp. diversity, percentage of attack, and control strategies in the West Java, Indonesia, corn cultivation
  72. Yield stability of biofertilizer treatments to soybean in the rainy season based on the GGE biplot
  73. Evaluating agricultural yield and economic implications of varied irrigation depths on maize yield in semi-arid environments, at Birfarm, Upper Blue Nile, Ethiopia
  74. Chemometrics for mapping the spatial nitrate distribution on the leaf lamina of fenugreek grown under varying nitrogenous fertilizer doses
  75. Pomegranate peel ethanolic extract: A promising natural antioxidant, antimicrobial agent, and novel approach to mitigate rancidity in used edible oils
  76. Transformative learning and engagement with organic farming: Lessons learned from Indonesia
  77. Tourism in rural areas as a broader concept: Some insights from the Portuguese reality
  78. Assessment enhancing drought tolerance in henna (Lawsonia inermis L.) ecotypes through sodium nitroprusside foliar application
  79. Edible insects: A survey about perceptions regarding possible beneficial health effects and safety concerns among adult citizens from Portugal and Romania
  80. Phenological stages analysis in peach trees using electronic nose
  81. Harvest date and salicylic acid impact on peanut (Arachis hypogaea L.) properties under different humidity conditions
  82. Hibiscus sabdariffa L. petal biomass: A green source of nanoparticles of multifarious potential
  83. Use of different vegetation indices for the evaluation of the kinetics of the cherry tomato (Solanum lycopersicum var. cerasiforme) growth based on multispectral images by UAV
  84. First evidence of microplastic pollution in mangrove sediments and its ingestion by coral reef fish: Case study in Biawak Island, Indonesia
  85. Physical and textural properties and sensory acceptability of wheat bread partially incorporated with unripe non-commercial banana cultivars
  86. Cereibacter sphaeroides ST16 and ST26 were used to solubilize insoluble P forms to improve P uptake, growth, and yield of rice in acidic and extreme saline soil
  87. Avocado peel by-product in cattle diets and supplementation with oregano oil and effects on production, carcass, and meat quality
  88. Optimizing inorganic blended fertilizer application for the maximum grain yield and profitability of bread wheat and food barley in Dawuro Zone, Southwest Ethiopia
  89. The acceptance of social media as a channel of communication and livestock information for sheep farmers
  90. Adaptation of rice farmers to aging in Thailand
  91. Combined use of improved maize hybrids and nitrogen application increases grain yield of maize, under natural Striga hermonthica infestation
  92. From aquatic to terrestrial: An examination of plant diversity and ecological shifts
  93. Statistical modelling of a tractor tractive performance during ploughing operation on a tropical Alfisol
  94. Participation in artisanal diamond mining and food security: A case study of Kasai Oriental in DR Congo
  95. Assessment and multi-scenario simulation of ecosystem service values in Southwest China’s mountainous and hilly region
  96. Analysis of agricultural emissions and economic growth in Europe in search of ecological balance
  97. Bacillus thuringiensis strains with high insecticidal activity against insect larvae of the orders Coleoptera and Lepidoptera
  98. Technical efficiency of sugarcane farming in East Java, Indonesia: A bootstrap data envelopment analysis
  99. Comparison between mycobiota diversity and fungi and mycotoxin contamination of maize and wheat
  100. Evaluation of cultivation technology package and corn variety based on agronomy characters and leaf green indices
  101. Exploring the association between the consumption of beverages, fast foods, sweets, fats, and oils and the risk of gastric and pancreatic cancers: Findings from case–control study
  102. Phytochemical composition and insecticidal activity of Acokanthera oblongifolia (Hochst.) Benth & Hook.f. ex B.D.Jacks. extract on life span and biological aspects of Spodoptera littoralis (Biosd.)
  103. Land use management solutions in response to climate change: Case study in the central coastal areas of Vietnam
  104. Evaluation of coffee pulp as a feed ingredient for ruminants: A meta-analysis
  105. Interannual variations of normalized difference vegetation index and potential evapotranspiration and their relationship in the Baghdad area
  106. Harnessing synthetic microbial communities with nitrogen-fixing activity to promote rice growth
  107. Agronomic and economic benefits of rice–sweetpotato rotation in lowland rice cropping systems in Uganda
  108. Response of potato tuber as an effect of the N-fertilizer and paclobutrazol application in medium altitude
  109. Bridging the gap: The role of geographic proximity in enhancing seed sustainability in Bandung District
  110. Evaluation of Abrams curve in agricultural sector using the NARDL approach
  111. Challenges and opportunities for young farmers in the implementation of the Rural Development Program 2014–2020 of the Republic of Croatia
  112. Yield stability of ten common bean (Phaseolus vulgaris L.) genotypes at different sowing dates in Lubumbashi, South-East of DR Congo
  113. Effects of encapsulation and combining probiotics with different nitrate forms on methane emission and in vitro rumen fermentation characteristics
  114. Phytochemical analysis of Bienertia sinuspersici extract and its antioxidant and antimicrobial activities
  115. Evaluation of relative drought tolerance of grapevines by leaf fluorescence parameters
  116. Yield assessment of new streak-resistant topcross maize hybrids in Benin
  117. Improvement of cocoa powder properties through ultrasonic- and microwave-assisted alkalization
  118. Potential of ecoenzymes made from nutmeg (Myristica fragrans) leaf and pulp waste as bioinsecticides for Periplaneta americana
  119. Analysis of farm performance to realize the sustainability of organic cabbage vegetable farming in Getasan Semarang, Indonesia
  120. Revealing the influences of organic amendment-derived dissolved organic matter on growth and nutrient accumulation in lettuce seedlings (Lactuca sativa L.)
  121. Identification of viruses infecting sweetpotato (Ipomoea batatas Lam.) in Benin
  122. Assessing the soil physical and chemical properties of long-term pomelo orchard based on tree growth
  123. Investigating access and use of digital tools for agriculture among rural farmers: A case study of Nkomazi Municipality, South Africa
  124. Does sex influence the impact of dietary vitD3 and UVB light on performance parameters and welfare indicators of broilers?
  125. Design of intelligent sprayer control for an autonomous farming drone using a multiclass support vector machine
  126. Deciphering salt-responsive NB-ARC genes in rice transcriptomic data: A bioinformatics approach with gene expression validation
  127. Review Articles
  128. Impact of nematode infestation in livestock production and the role of natural feed additives – A review
  129. Role of dietary fats in reproductive, health, and nutritional benefits in farm animals: A review
  130. Climate change and adaptive strategies on viticulture (Vitis spp.)
  131. The false tiger of almond, Monosteira unicostata (Hemiptera: Tingidae): Biology, ecology, and control methods
  132. A systematic review on potential analogy of phytobiomass and soil carbon evaluation methods: Ethiopia insights
  133. A review of storage temperature and relative humidity effects on shelf life and quality of mango (Mangifera indica L.) fruit and implications for nutrition insecurity in Ethiopia
  134. Green extraction of nutmeg (Myristica fragrans) phytochemicals: Prospective strategies and roadblocks
  135. Potential influence of nitrogen fertilizer rates on yield and yield components of carrot (Dacus carota L.) in Ethiopia: Systematic review
  136. Corn silk: A promising source of antimicrobial compounds for health and wellness
  137. State and contours of research on roselle (Hibiscus sabdariffa L.) in Africa
  138. The potential of phosphorus-solubilizing purple nonsulfur bacteria in agriculture: Present and future perspectives
  139. Minor millets: Processing techniques and their nutritional and health benefits
  140. Meta-analysis of reproductive performance of improved dairy cattle under Ethiopian environmental conditions
  141. Review on enhancing the efficiency of fertilizer utilization: Strategies for optimal nutrient management
  142. The nutritional, phytochemical composition, and utilisation of different parts of maize: A comparative analysis
  143. Motivations for farmers’ participation in agri-environmental scheme in the EU, literature review
  144. Evolution of climate-smart agriculture research: A science mapping exploration and network analysis
  145. Short Communications
  146. Music enrichment improves the behavior and leukocyte profile of dairy cattle
  147. Effect of pruning height and organic fertilization on the morphological and productive characteristics of Moringa oleifera Lam. in the Peruvian dry tropics
  148. Corrigendum
  149. Corrigendum to “Bioinformatics investigation of the effect of volatile and non-volatile compounds of rhizobacteria in inhibiting late embryogenesis abundant protein that induces drought tolerance”
  150. Corrigendum to “Composition and quality of winter annual agrestal and ruderal herbages of two different land-use types”
  151. Special issue: Smart Agriculture System for Sustainable Development: Methods and Practices
  152. Construction of a sustainable model to predict the moisture content of porang powder (Amorphophallus oncophyllus) based on pointed-scan visible near-infrared spectroscopy
  153. FruitVision: A deep learning based automatic fruit grading system
  154. Energy harvesting and ANFIS modeling of a PVDF/GO-ZNO piezoelectric nanogenerator on a UAV
  155. Effects of stress hormones on digestibility and performance in cattle: A review
  156. Special Issue of The 4th International Conference on Food Science and Engineering (ICFSE) 2022 - Part II
  157. Assessment of omega-3 and omega-6 fatty acid profiles and ratio of omega-6/omega-3 of white eggs produced by laying hens fed diets enriched with omega-3 rich vegetable oil
  158. Special Issue on FCEM - International Web Conference on Food Choice & Eating Motivation - Part II
  159. Special Issue on FCEM – International Web Conference on Food Choice & Eating Motivation: Message from the editor
  160. Fruit and vegetable consumption: Study involving Portuguese and French consumers
  161. Knowledge about consumption of milk: Study involving consumers from two European Countries – France and Portugal
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