Abstract In the process of product development, formulation is one of the key stages in determining the quality of the final product. Therefore, this study focused on identifying the optimal mixing ratio between ST purple brown rice extract and soy milk to develop a yogurt product that meets both nutritional standards and sensory preferences aligned with consumer demand in the market. The ratio of ST purple brown rice was gradually increased in the mixture with soy milk, from 0 to 100%, and the soluble solids levels (°Brix) varied between 10 and 18. The findings identified the optimal formulation as soy milk containing 60% ST purple brown rice extract, adjusted to 16°Brix for sensory evaluation with the highest referable recognition for color, flavor, taste, texture and favorite. Along with the acceptable water-holding capacity (67.83%) and firmness (1.67 g-force), contributing to a stable texture; the color indication with L, a and b values were 40.84, -1.41 and 2.70, respectively; the chemical properties such as lactic acid, protein, total sugar and reducing sugar (per 100 g of dry matter) were 0.55, 8.64, 23.86 and 16.70 g, respectively. Moreover, bioactive components such as anthocyanins and phenolics (per 100 g of dry matter) were 0.07 g and 1.09 g TAE, respectively, indicating the potential antioxidant capacity of the product.

Keywords: Antioxidant potential, Non-dairy alternatives, Organoleptic, Physicochemical, Product development

Citation:  Giang, N.T.N. and Khai, T.V. 2026. Formulation ratios of ingredients towards a sustainable plant-based yogurt from ST purple brown rice. Natural and Life Sciences Communications. 25(2): e2026030.

Graphical Abstract:

INTRODUCTION

The global non-dairy alternatives market has been experiencing significant growth especially product derived from plants; its distribution has expanded for over a decade and continuously rising continued to rise. This development has been led by the rise in awareness of consumers’ health such as due to lactose intolerance, milk allergies, and the desire for lower-calorie, nutrient-rich options (Alcorta et al., 2021), green sustainability, and moral responsibility. The global market for plant-based yogurt made up to over $1.5 billion in 2019 and it has been estimated to climb up to nearly $3 billion by 2026 (Dhakal et al., 2023). Following this trend, the popularity of plant-forward dietary patterns has intensified the interest in plant-based yogurt as a wholesome and accessible substitute for conventional dairy products as it is predicted to accounted for about 20% of the overall market share for milk’s products (Montemurro et al., 2021). Vegan dairy choices vary from its sources, soybean, almond, coconut, rice, and oats are highly recommended (Pua et al., 2022). Yogurts in both traditional and plant-based possess its own nutritional value and health-promoting properties such as enhancing digestive tolerance and minimizing bloating from the action of bacterial α-galactosidase, which hydrolyzes oligosaccharides throughout the fermentation process (Vijaya et al., 2015; Harper et al., 2022). Unlike traditional yogurt made from cow’s milk, vegan yogurt is produced from various plants’ extracts, it is different from nutritional characteristic and also offer functional advantages (Grasso et al., 2020; Silva et al., 2020; Boukid et al., 2023). According to previous studies on plant-derived yogurts, they are outstanding for naturally free of cholesterol and bioactive compounds, which highlight their antioxidant, anti-inflammatory and anti-diabetic properties (Wang et al., 2025; Zhai et al., 2025).

A highly demand source to consider for making the vegan-based product is ST purple brown rice, it is valued by health-conscious consumers as a natural source of anthocyanins, especially for those who rely on rice as a dietary staple (Yamuangmorn and Prom-u-Thai, 2021). It is also rich in amino acid, dietary fiber, vitamin, essential minerals and other elements for humans’ health, which turn this naturally gluten-free crop into is a wholesome choice the future (Xiong et al., 2024).

The formulation of an optimal mixing ratio plays a vital role in the research and development of a new food product, particularly those combine of multiple ingredients. As its effects are not only on sensory quality and nutritional value but also on the product’s stability, shelf-life, and processing efficiency. In order to achieve the desired texture, flavor, and stability especially in colloidal food systems such as yogurt, the mixing ratios of ingredients must be optimized (BeMiller and Huber, 2017). In plant-based product development, the proportion of carbohydrate-, protein-, and antioxidant-rich ingredients is a key determinant of gel structure, water-holding capacity, and the ability to form a stable dispersion (Grasso et al., 2020). Furthermore, Deziderio et al. (2023) emphasized that in dairy alternative products, identifying appropriate ratios of core ingredients such as soybeans, grains, or fruits significantly impacts both nutritional composition and consumer sensory acceptance. Particularly, attributes like color, aroma, taste, and viscosity or texture are strongly influenced by mixing ratios underscoring their critical role in shaping products that meet both scientific standards and consumer preferences (Gallina et al., 2019). Therefore, this study focused on formulating and evaluating suitable mixing ratios for a plant-based yogurt developed from ST purple brown rice with the supplement of soy milk.

MATERIALS AND METHODS

Materials

ST purple brown rice is from the purple ST variety (Soc Trang, Vietnam), which was purchased from Shrimp Rice Co. Ltd (Vietnam); soybeans were supplied by Tam Nong Co. Ltd (Vietnam).

Yoghurt was made using commercial starter culture consists of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus. Strain information was reported exactly as provided on the product label (without specific strains codes or additional proprietary details are disclosed), obtained from Happy Energy Co. Ltd (Vietnam).

Other analytical-grade chemicals were sourced from Sinopharm Chemical Reagent Co. Ltd.

Sample procedure

Soymilk preparation: soybeans were rinsed to remove impurities and soaked for 8 hours in order to remove the outer layer of soybean. After that, soybeans were blended (Blue Stone BLB-6035), the ratio of soybeans and water was 125 g: 600 mL (Ny et al., 2015), the mixture after blending was filtered and filtrate was collected.

ST purple brown rice paste: 100 g of ST purple brown rice were sorted and rinsed thoroughly. After draining the rice was cooked for 40 minutes in a cooker (TC-NK6D, China), water was added with a ratio of 1/4 (w/v). The cooked rice mixture was then blended into a puree and passed through a 0.5 mm sieve to collect the filtrate.

Experimental design

The experiment was conducted using a two-factor completely randomized design (CRD) with three replications. All treatments were arranged following a full factorial structure, in which all possible combinations of the predefined levels of the two factors were included. Specifically, a mixture of ST purple brown rice extract and soy milk with investigating ratios of 0/100, 20/100, 40/100, 60/100, 80/100, 100/0 (% w/v) were pasteurized at 85°C for 15 minutes. Its total soluble solids content was modified to 10, 12, 14, 16, 18 °Brix using sucrose and cooled to 43°C. Next, 1.5 (% w/v) of yogurt culture starter was added for the fermentation (Dung et al., 2015). The mixture was fermented at 43°C until pH level reached 4.6. Yogurt was stored in 24 hours at cold temperature (4-6 °C) before evaluating. Each yogurt sample after fermenting was collected for the further analysis and quality’s assessment.

Physical properties analysis

Color analysis: L, a, b values of yogurt were measured using a colorimeter (Konica Minolta CR400, Japan). Texture analysis: The firmness (g-force) of yogurt was recorded using an analyzer for food’s texture (CT3, Brookfield, USA). Samples were measured at a temperature of 6-8 °C using a TA-MP cutting blade, setting up with target value (3.0 mm); trigger load (2 g) and test speed (5 mm/s). Total dissolved solids (°Brix): The assessment was performed using a hand-held refractometer value from 0 to 32%.

Water holding capacity (WHC)

Phase separation was checked by centrifugation according to Zannini et al. (2018). Approximately, 10 g of yogurt sample was placed into a centrifuge tube and centrifuged at 4,000 rpm for 20 minutes at 4°C. After centrifugation, the supernatant was carefully decanted, and the tube containing the remaining gel was weighed. WHC was calculated using the following Eq. 1

Where: W is the weight of sample after centrifugation, W_o is initial weight of sample

Chemical properties analysis

Lactic acid determination

Lactic acid was identified by a yellowish-green iron (III) lactate complex in solution from reaction with FeCl₃ (Borshchevskaya et al., 2016). Briefly, 50 μL of sample was mixed with 2 mL of a 0.2% FeCl₃ solution. The absorbance of the complex was checked at 390 nm. The concentration of lactic acid was determined using a standard calibration curve, y = 31.1360x + 0.2709 (R² = 0.9999), where y denotes the absorbance and x denotes the concentration of solution in the tube.

Total sugar and reducing sugar content (g/100 g dry matter)

They were both measured using DNS method with some modifications. Mainly based on the oxidation of the C=O group by 3,5-Dinitrosalicylic acid forming orange red complex in an alkaline medium (Nielsen, 2017). Briefly, 1 mL of sample was put in a test tube and then added 2 mL of reagent DNS. The solution of standard glucose and samples were mixed well then divided into two for measuring reducing sugar (without hydrolysis) and total sugar content (with 3 hours hydrolysis in boiling water). Next, 7 mL distilled water was added into the solution before analysing the absorbance at 575 nm. The concentration of total sugar was based on a standard curve of glucose, y =23.885x + 0.126 (R²=0.9999), where y is the absorbance and x is the concentration of the solution in the tube.

Total protein content (g/100 g dry matter)

This attribute was determined exploited a modified Lowry method (Nielsen, 2017). Briefly, 0.1 mL of the solution (after 1 g of sample digested with 10 mL concentrated H₂SO₄) was mixed with 0.1 mL of 2 N NaOH and heated in boiling water for 10 minutes. After cooling, 1 mL of a reagent (forming from Na₂CO₃, CuSO₄.5H₂O and C₄H₄O₆KNa.4H₂O) and 0.1 mL of Folin–Ciocalteu reagent were added. The mixture was left at room temperature for 30 minutes and the absorbance was measured at 750 nm. Protein content was calculated based on a standard curve, y = 0.0041x + 0.0118 (R²=0.9999), where y represents the absorbance, and x denotes the concentration of the solution in the tube.

Bioactive compounds analysis

Anthocyanin determination (g/100 g dry matter)

This pigment, expressed as cyanidin-3-glucoside, was detected based on the principle of change color depending on pH. Samples were diluted in two buffer solutions: 0.025 M KCl buffer (pH 1.0) and 0.4 M CH₃COONa buffer (pH 4.5). Absorbance measurements are taken at wavelengths of 520 nm and 700 nm using a spectrophotometer (Gabriela et al., 2010). The anthocyanin content is calculated using Eq. 2.

Where: A = (A₅₂₀ nm - A₇₀₀ nm) at pH 1.0 - (A₅₂₀ nm - A₇₀₀ nm) at pH 4.5; F = dilution factor; V = volume of extract (L); l = path length of cuvette (1 cm); ε = 26,900 (molar absorptivity), m = initial weight of sample (g).

Phenolic compounds (g TAE per 100 g of dry matter)

They were detected through a blue phosphomolybdenum complex created
by the interaction between phenolic compounds and Folin-Ciocalteu reagent (Sumaiyah et al., 2015) as the following procedure. 150 µL of sample was mixed with 450 µL of Na₂CO₃ solution 5% (w/v) and 1.2 mL of distilled water in a test tube. Next, 100 µL of Folin-Ciocalteu solution was added and let it react in one and a half hours. The absorbance was carried out at 750 nm, phenolic content was obtained using a standard tannic acid curve (TAE), y = 0.0021x + 0.0064 (R² = 0.9999), where y represents the absorbance, while x denotes the solution concentration in the tube.

Organoleptic evaluation

Sensory perception of the product was assessed by color, flavor, taste and favorite preference criteria. This evaluation was carried out using Quantitative Descriptive Analysis method (QDA). Briefly, 40 participants for the panelists were trained carefully for each attribute before grading these sensory properties of each yogurt sample. There is a detail descriptive scale ranging from 1 to 5 (sensory values from poor to excellent levels), which was created based on the common standards for this type of product (Thuy et al., 2012). The preference level was assessed using the Hedonic scale.

Ethical Considerations

All panelists participated voluntarily and provided informed consent prior to the sensory evaluation. The study was conducted in accordance with ethical standards, and all procedures were reviewed and deemed appropriate for research purposes.

Data analysis

Statgraphics Centurion XVI software (U.S.A.) was utilized to analyze the statistic of this study, LSD test was used to identify differences between trial averages at a 5% confidence level (P = 0.05), and Microsoft Excel for computation and graph demonstration.

RESULTS

Effects of ST purple brown rice: Soy milk ratios and soluble dissolved solids levels on the texture, water holding capacity and lactic acid content of the product

The texture of yogurt is characterized by its firmness value and the capacity of holding water, the evaluations revealed that yogurt’s firmness reduced when volumed up the proportion of added ST purple brown rice extract. At the control sample (without the addition of ST purple brown rice extract), the sample’s firmness was 3.02 g-force, but at the highest addition ratio, the value declined to 1.33 g-force. Along with the effect of soluble dissolved solid levels (°Brix), the firmness went up to the peak then reduced with the increasing in °Brix value. The peak was achieved at 16°Brix (2.19 g-force) then gradually lowered to 2.10 g-force at 18°Brix (Figure 1a). Water holding capacity (WHC) aligned with the firmness’s results (Figure 1b), the highest value was recorded at 88.37% with the control sample (without the addition of ST purple brown rice extract). Along with the °Brix level, WHC’s yogurt reached its peak level at 75.26% when the soluble dissolved solid level was at 16°Brix.

Lactic acid reflected the fermenting efficiency, in this study, the mixing ratio and the level of total soluble solids had a direct impact on the substrate concentration during fermentation. The results indicated that lactic acid content increased to a maximum value then decreased gradually with the rise of ST purple brown rice ratio and °Brix value. According to values, lactic acid content went up from 0.56 to 0.62 g/100 g dry matter when the ratio was from 0% to 60%, respectively. However, the value declined back to 0.56 g/100 g dry matter at the highest percentage of ST purple brown rice extract. Similarly, lactic acid content was 0.52 and 0.63 g/100 g dry matter at 10 and 16°Brix, respectively, but the value remained at 0.56 g/100 g dry matter when the mixture was at the highest °Brix level (Figure 1c).

Figure 1. Firmness, water holding capacity and lactic acid content at different mixture ratios and soluble dissolved solid levels.

Effects of ST purple brown rice: Soy milk ratios and soluble dissolved solids levels on the chemical properties of the product

According to the statistical analysis, the total sugar and reducing sugar content of the product tended to increase with the rising proportion of purple brown rice to soy milk (% w/v), reaching an optimal value before decreasing with further increases in the soluble solids level after mixing. Specifically, the highest total sugar content was obtained at the highest addition of ST purple brown rice extract, with a value of 25.86 g/100 g dry matter, whereas the maximum total sugar content (24.97 g/100 g dry matter) was achieved at 14°Brix. However, there were no statistically significant differences in total sugar content that were found between the treatments 80/20 and 100/0 (% w/v); 12, 14, and 16°Brix (Figure 2b). The similarity was found at a ST purple brown rice/soy milk ratio of 80/20 (% w/v) and a soluble solids content of 14°Brix after mixing, the reducing sugar content in the yogurt reached the peak for each factor at 16.78 and 14.90 g/100 g dry matter, respectively (Figure 2a).

On the contrary, the protein content decreased with increasing soluble solids level after mixing then increased to an optimal value before slightly declining with the highest proportion of ST purple brown rice addition. The highest protein contents (9.54 and 10.62 g/100 g dry matter), were observed at a ratio of 80/20 (% w/v) and 10°Brix (Figure 2c). However, the differences in protein content among the 60/40, 80/20, and 100/0 (% w/v) samples were not statistically significant.

Figure 2. The content of reducing sugar (a), total sugar (b) and protein (c) at different mixture ratios and soluble dissolved solid levels.

Effects of ST purple brown rice: Soy milk ratios and soluble dissolved solids levels on anthocyanin and phenolic contents of the product

The results indicated that the total phenolic and anthocyanin contents increased with the increasing proportion of ST purple brown rice to soy milk (Figure 3). The highest levels of phenolic compounds and anthocyanins were recorded at 1.40 g TAE and 0.21 g/100 g dry matter, respectively, when the ST purple brown rice/soy milk ratio was 100/0 (% w/v). Moreover, phenolic content decreased as the soluble solids concentration increased, reaching its peak at 10°Brix (1.27 g TAE/100 g dry matter). In contrast, anthocyanin content increased to an optimal level and then went down gradually with the further rising in soluble solids level. At 16°Brix, anthocyanin content in the yogurt reached a maximum of 0.09 g/100 g dry matter, which was not significantly different from the value at 18°Brix.

Figure 3. The content of phenolic (a) and anthocyanin (b) at different mixture ratios and soluble dissolved solid levels.

Effects of ST purple brown rice: Soy milk ratios and soluble dissolved solids levels on the color indicators of the product

As a result, the product becomes darker and less visually appealing, negatively affecting its overall sensory quality. This phenomenon can be explained by the presence of anthocyanins compound in black-purple rice, primarily cyanidin-3-glucoside, which has strong light absorption properties, leading to a decrease in lightness (L) and an increase in the values of a (greenness to redness) and b (blueness to yellowness) (Table 1).

Table 1. L, a, b values of product’s color at different mixture ratios and soluble dissolved solid levels.

Note: *Mean values of three replications; different superscript letters within the same column indicate significant differences; **significant at the 1% level (P < 0.01); ns: not statistically significant at the 5% level (P > 0.05).

Effects of ST purple brown rice: Soy milk ratios and soluble dissolved solids levels on the sensory perception of the product

The analysis results showed that the ST purple brown rice/soy milk ratio and soluble solids concentration significantly influenced the sensory attributes of the product (Table 2). In terms of color, the sample with a 60/40 ST purple brown rice-to-soy milk ratio received the highest sensory scores (3.10) although the differences were not statistically significant compared to the other samples. This is likely due to the characteristic purple hue from the rice, which, when combined with the color of soy milk, created a more appealing bright purple tone. Regarding to flavor, the 60/40 ratio sample was scored 3.16, which was not significantly different from samples with the ratio at 20/80 and 0/100 (3.23 and 3.18, respectively). This ratio was rated highly by the panelists because of its balanced and distinctive aroma from both ST purple brown rice and soy milk, outperforming other formulations. Additionally, the taste of the same samples (with a ratio of 60/40 and 16°Brix) were both superior at 3.13 compared to the other samples. For texture evaluation, the sample with a 60/40 ST purple brown rice-to-soy milk ratio and 16°Brix also received significantly higher scores (3.17 and 3.63, respectively) with statistically significant differences (P < 0.05).

In terms of overall acceptability, the 60/40 rice-to-soy milk ratio at 16°Brix was the most preferred formulation (7.06), with a statistically significant difference compared to all remaining samples. Samples with lower ratios of ST purple brown rice extract exhibited a pale, slightly opaque purple color from the rice and soy milk mixture, along with weak aroma and flavor profiles lacking the characteristic blend of rice and soy. These samples also had a relatively smooth but inconsistent texture. In contrast, at higher ST purple brown rice ratios (80/20; 100/0), the products displayed a deeper purple color characteristic of the rice, but the flavor lacked a distinctive aroma, and the texture showed signs of phase separation and an uneven, coarse surface, resulting in lower overall acceptability.

Table 2. Sensory evaluation at different mixture ratios and soluble dissolved solid levels.

Note: *Mean values of three replications; different superscript letters within the same column indicate significant differences; **significant at the 1% level (P < 0.01).

DISCUSSION

The effects of ratio ST purple brown rice and soy milk on the texture water holding capacity and lactic acid content can be explained due to the interaction among proteins, lipids, and stabilizers, which can vary significantly depending on the raw materials that plays a crucial role in determining the structure of yogurt (Grasso et al., 2020). When soy milk is used as a base, it tends to form a firmer gel due to its higher protein content (Deepak and Jayadeep, 2022). Yogurt made from soy milk typically exhibits high values in firmness, cohesiveness, adhesiveness, and viscosity. Additionally, starch present in the ST purple brown rice solution acts as an effective stabilizer, thereby enhancing the water-holding capacity of the yogurt (Cui et al., 2014). Moreover, phenolic compounds have a strong affinity for proteins and can affect the protein gel network by forming soluble complexes and weakening the gel structure (Rashwan et al., 2023). Furthermore, according to Kaur et al. (2017) and Dinh et al. (2023), approximately 30% of lactose is converted into lactic acid during yogurt fermentation. Lactic acid bacteria (LAB) are capable of utilizing the carbon sources present in black-purple rice to support growth and lactic acid production. In addition to contributing to flavor, sugars serve as essential carbon substrates for LAB fermentation. Therefore, the amount of lactic acid produced depends on the sugar content available in the fermentation medium. However, excessively high initial sugar concentrations can lead to a reduction in acid production, as the high osmotic pressure disrupts the physiological balance and metabolic activity of LAB cells (Giang and Tan, 2023; Giang et al., 2024; Hoang et al., 2024).

The nutrients present in the initial fermentation medium not only serve as resources for biomass accumulation and energy generation to support biosynthetic activities but also act as metabolic, transcriptional, and developmental signals (Giang and Tan, 2023). In addition to their role in flavor enhancement, sugars also serve as essential substrates for lactic acid bacteria (LAB) to carry out fermentation and produce lactic acid (Hoang et al., 2024). The main raw materials for yogurt fermentation in this study are purple brown rice and soybeans. LAB are capable of producing enzymes that hydrolyze starch into sugars, which are then utilized during fermentation (Barbosa et al., 2020). However, an excessively high sugar concentration can increase osmotic pressure, disrupting microbial physiological balance and metabolic processes (Giang and Tan, 2023; Giang et al., 2024; Hoang et al., 2024). Moreover, as lactic acid accumulates during fermentation, the pH of the yogurt decreases, which can affect the viability and activity of LAB. Low pH levels can alter the charge properties of the bacterial cell wall and modulate nutrient permeability and fermentation pathways (Giang et al., 2024). On the other hand, soybeans serve as the primary protein source in the formulation, as their protein content is higher than that of rice. Therefore, increasing the ST purple brown rice to soy milk ratio results in a decrease in protein content in the final yogurt product.

Soybeans possess a natural source of phenolic compounds, which enhance the antioxidant activity of its products (Qin et al., 2022), so it was chosen to combine with rice in order to create an optimum substrate for the fermentation and with the aim to enhance product’s functional features. Along with soybean, ST purple brown rice is rich of soluble anthocyanins, which further increase antioxidant capacity and health benefits (Van Ngo et al., 2024; Van Ngo and Luangsakul, 2025). According to Morata et al. (2019), bioactive compounds such as phenolics and anthocyanins are primarily derived from raw materials or generated during fermentation through microbial activity. The incorporation of ST purple brown rice significantly increased the phenolic and anthocyanin contents in the yogurt approximately 1.04 - 1.75 times and 1.34 - 1.70 times higher, respectively, compared to the control sample (100% of soy milk) (Figure 3). These findings are consistent with previous studies aiming to enhance the bioactive compound content of yogurt by supplementing it with plant extracts (Galin and Milena, 2019; Gurkan et al., 2019; Sahingil and Hayaloglu, 2022; Celik et al., 2023).

The color of the product has been similarly reported in several studies involving the addition of anthocyanin-rich ingredients to plant-based yogurts (Zheng et al., 2022; Machado et al., 2023). Notably, the soluble solids content (°Brix) had an insignificant impact on the perceived color of the product: there were no statistically significant differences in lightness (L) and a value (P > 0.05), and although the b value showed a statistically significant difference, it did not lead to a substantial change in the overall color perception. These findings highlight the key role of lightness (L) in determining the visual appeal of the product. This supports the assertion that a and b values are secondary parameters influencing hue, whereas lightness (L) is the primary visual factor that governs the perception of brightness or dullness, ultimately determining the attractiveness of the overall color (Głuchowski et al., 2024).

CONCLUSION

At the mixing ratio of 60/40 (% v/v) between ST purple brown rice extract and soya milk with the total soluble dissolved solids content was adjusted to 16°Brix, which was were considered as the potential parameters for the ingredient blending process. Align with the conditions, a plant-based yogurt with the most favorable physicochemical and sensory properties was created. All the attributes’ evaluation meets the conventional quality criteria for commercially available yogurt. Beyond the basic nutritional requirements, anthocyanins and phenolics were also retained at a small amount, indicating product’s beneficial feature for health. These findings contribute to the development of nutritious non-dairy alternatives.

ACKNOWLEDGEMENTS

The authors thank the Experimental-practical Area, An Giang University, for providing instruments.

AUTHOR CONTRIBUTIONS

Nguyen Thi Ngoc Giang: Conceptualization (Lead), Methodology (Lead), DataCuration (Lead), Validation (Equal), Formal Analysis (Equal), Investigation (Lead), Resources (Lead), Writing – Original Draft (Lead), Writing – Review & Editing (Equal), Visulaization (Lead), Supervision (Equal), Project Administration (Equal); Tran Van Khai: Conceptualization (Supporting), Methodology (Supporting), Data Curation (Supporting), Formal Analysis (Equal), Investigation (Supporting), Resources (Supporting), Validation (Equal), Visualization (Supporting), Writing –Review & Editing (Equal), Supervision (Equal), Project Administration (Equal).

CONFLICT OF INTEREST

The authors declare that they hold no competing interests.

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