Assessing dangke whey as a viable substitute for coconut water in bacterial cellulose production using Komagataeibacter xylinus

Abstract

Dangke whey is a by-product of the dangke processing process and has not been optimally utilized; therefore, it is often discarded. Coconut water, commonly used for bacterial cellulose or nata de coco production, has nutritional content similar to that of dangke whey, particularly in carbon and nitrogen sources, making whey a potential alternative with comparable fermentative properties. This study aimed to evaluate the potential of dangke whey as an alternative fermentation medium for bacterial cellulose production using Komagataeibacter xylinus. The study substituted coconut water with dangke whey in varying proportions: N1 (100:0), N2 (70:30), N3 (50:50), N4 (30:70), and N5 (0:100). The physicochemical characteristics (yield, thickness, and moisture content) and organoleptic attributes (texture, chewing residue, lightness, and overall preference) were evaluated. The substitution of coconut water with dangke whey significantly affected (P < 0.01) yield, thickness, lightness, moisture content, and all sensory attributes. The whey proportion was inversely related to yield, thickness, moisture content, and organoleptic scores for texture and chewing residue, but directly related to lightness and clarity perception of the colour. These findings suggest that dangke whey has significant potential as a sustainable, cost-effective alternative fermentation medium for bacterial cellulose production by K. xylinus.

Keywords:
Extracellular polysaccharide; Microbial fermentation media; Dairy by-product valorisation; Physicochemical; Yield; Sustainable fermentation media, Nata medium

Highlights

The whey proportion was inversely related to yield, thickness, moisture content, and organoleptic scores

The whey proportion is directly related to the perception of colour lightness and clarity

Dangke whey has significant potential as an alternative medium for bacterial cellulose production

1 Introduction

Cellulose can be synthesised by Komagataeibacter xylinus through fermentation. Its quality is highly dependent on the substrate's nutritional profile. Commonly, coconut water is utilised as a fermentation medium in the bacterial cellulose production, yielding the well-known product nata de coco (Aviradsya et al., 2022). Komagataeibacter xylinus requires essential nutrients, including carbon, hydrogen, nitrogen, and various minerals, for optimal growth. This bacterium can oxidise sugars, sugar alcohols, and ethanol to produce acetic acid as a primary metabolite and cellulose as an extracellular polysaccharide (He et al., 2022; Putri et al., 2021). While coconut water contains some essential nutrients, it often requires supplementation with macronutrients, particularly carbon and nitrogen, to enable bacteria to optimise cellulose production (Kadier et al., 2021; Quijano et al., 2024; Ramana et al., 2000). The availability of carbon and nitrogen significantly influences bacterial cell proliferation and metabolite biosynthesis (Sari et al., 2021).

The use of alternative substrates in fermentation is essential for sustainable food production. Dangke whey is a by-product of the traditional production of dangke, a type of soft cheese which is a culinary specialty of Enrekang Regency, South Sulawesi Province. This whey contains relatively high levels of lactose (approximately 5.08%), protein (0.63%), and fat (0.2%), while its pH reaches around 6.31 (Soeparno et al., 2012; Maruddin et al., 2019). Given its valuable nutritional components, dangke may serve as a suitable growth medium for K. xylinus in the production of bacterial cellulose, a fermented food product produced as a thick extracellular cellulose layer.

Several studies have examined the use of both coconut water and general cheese whey in bacterial cellulose production (Anam, 2019; Khusna et al., 2021). However, the specific use of dangke whey, which is compositionally distinct and locally sourced, has not been extensively studied, especially in comparison with coconut water. Addressing this gap represents a novelty in the current study. In this study, dangke whey is examined as an alternative medium to coconut water for the cultivation of K. xylinus, with a focus on its potential to support cellulose formation. The research examined both the characteristics of cellulose production and the organoleptic properties of the bacterial cellulose product. This study aimed to evaluate the potential of dangke whey as an alternative fermentation medium for bacterial cellulose production using K. xylinus.

2 Materials and methods

2.1 Experimental design

A completely randomised design (CRD) was arranged with 5 treatments and 5 replications as follows:

• N1: 100% (v/v) coconut water and 0% (v/v) dangke whey

• N2: 70% (v/v) coconut water and 30% (v/v) dangke whey

• N3: 50% (v/v) coconut water and 50% (v/v) dangke whey

• N4: 30% (v/v) coconut water and 70% (v/v) dangke whey

• N5: 0% (v/v) coconut water and 100% (v/v) dangke whey

2.2 Formulation of the nata medium and fermentation process

The proportion of ingredients is presented in Table 1. The mixture of coconut water and dangke whey was prepared (see 2.1 above). Sugar cane (2.5%, w/v) and ZA (Ammonium Sulfate) (0.4%, w/v) were added to the mixture and homogenised. To adjust pH, vinegar was added until a pH of 4.3 was achieved. The media were then sterilised by autoclaving (Tomy -500 SX-500, High pressure steam sterilizer) at 105 °C for 5 min. Once cooled, each medium was inoculated with 3% (v/v) of starter culture K. xylinus and incubated for 21 days under static aerobic conditions (at a temperature of around 30 °C).

Table 1
Formulation of nata.

Ingredients	Amount (%)
Coconut water, whey dangke	According to the respective treatments
Komagataeibacter xylinus	1.5
ZA	0.4
Cane sugar	2.5
Vinegar	1

• Note: Modified from Hendrarti & Nasarani (2020).

2.3 Physicochemical analyses

2.3.1 Yield determination

Analysis of the nata results in this study was carried out after 21 days of fermentation. The nata yield was measured using the gravimetric method and expressed as a percentage of the weight of nata formed during fermentation by K. xylinus per volume of liquid medium used for growth, and is usually stated as a percentage (%)(b/v). The yield value (Herawati et al., 2020; Paudi et al., 2020; Wijaya et al., 2022) is calculated as follows (Equation 1):

$Yield\left(\%\right)=\frac{\text{Final weight}\left(\text{nata}\right)}{\text{Initial amount}\left(\text{growth medium}\right)}\times 100\%$ (1)

2.3.2 Thickness

The thickness of the sample was measured with a micrometer model MDC-25M (Mitutoyo, MFG, Japan) after washing the bacterial cellulose. Five different points on the sample were randomly selected to best represent the sample conditions (Fahrullah et al., 2020; Sabil et al., 2021).

2.3.3 Moisture content

A gravimetric method was used to assess the moisture content of the samples. Briefly, the sample (1 g) was dried in an oven at 102-105 °C for 24 h. The final weight was recorded after the sample reached a constant weight. Moisture content was calculated as follows (Equation 2):

$Moisturecontent\left(\%\right)=\frac{\text{Initial weight}-\text{final weight}}{\text{Initial weight}}\times 100\%$ (2)

2.3.4 Colour analysis (lightness)

Colour was expressed in L (lightness) and determined using a digital colour meter test (T 135), following a previous method (Maruddin et al., 2018, 2020). The L* colour value range is 0 (black) to 100 (white). The instrument is calibrated with a white standard (calibration values: L* = 94.76, a* = -0.795, and b* = 2.200).

2.4 Antioxidant activity

DPPH (0.008 g) was diluted in methanol (50 mL) and used as a blank. Sample (1 mL) was added to the DPPH solution (3.8 mL) and methanol (0.2 mL). The mixture was homogenised in a vortex and left for 60 min in a dark room. Absorbance of the samples and the blank solution was measured using an Ultraviolet-Visible (UV-Vis) spectrophotometer (Shimadzu UV-11800, Japan) at 515 nm. Antioxidant activity was determined using the following Equation 3 (Mangalisu et al., 2020):

$Antioxidantactivity=\frac{\text{Blank absorbance}-\text{Sample absorbance}}{\text{Blank absorbance}}\times 100\%$ (3)

2.5 Shear force

The shear force of the samples was measured using a CD-Shear Force Instrument, and the results were expressed in kg cm^-2, as in the previous method (Abustam & Ali, 2016). The calculation of the shear force (A) was performed as follows (Equation 4):

$A=\frac{\text{A}1}{\text{L}}\times 100\%$ (4)

where A1 refers to force (kg), and L refers to area of the tested sample (𝜋𝑟² = 3.14 x (0.635)² = 1.27 cm²).

2.6 Organoleptic test

An organoleptic test was conducted in a controlled room with 30 semi-trained panellists. The panellists were asked to characterise nata samples by giving a 1-6 scale rate for each attribute as follows: texture (1 = very soft, 6 = very firm), chewing residue (1 = no fibrous, 6 = highly fibrous), colour (1 = yellowish and transparent, 6 = very transparent), overall preference (1 = strongly dislike, 6 = strongly like).

2.7 Statistical analysis

Analysis of variance (ANOVA) was performed to assess the effects of treatments on the parameters using SPSS 26.0. The Duncan test was carried out to verify significant differences between means (p < 0.05).

3 Results and discussion

3.1 Yield of bacterial cellulose

As shown in Table 2, the highest yield of 51.69% was obtained with the 100% coconut water treatment. In contrast, the lowest yield was observed in the treatment using 100% dangke whey, reaching only 17.67%. Statistically, the treatments given have a significant effect on yield (p < 0.01). Moreover, based on the Duncan test, the yields of samples containing dangke whey at 30% and 50% are not different. The average physicochemical characteristics of bacterial cellulose are shown in Table 2.

Table 2
Test results of samples.

Formulations	Yield (%)	Thickness (mm)	Moisture content (%)	Lightness L*	Antioxidant activity (%)	Shear force (kg/cm2)
100 : 0	51.69 ± 1.96d	8.58 ± 1.33c	98.04 ± 0.54d	38.60 ± 0.30a	31.77 ± 0.54a	0.861 ± 0.0035c
70: 30	42.94 ± 0.63c	6.38 ± 0.27b	97.52 ± 0.07c	42.51 ± 0.89b	38.69 ± 0.82b	0.858 ± 0.0000c
50: 50	41.62 ± 0.40c	6.23 ± 0.34b	97.34 ± 0.15c	42.59 ± 0.98b	46.75 ± 0.91d	0.837 ± 0.0117b
30: 70	23.44 ± 1.98b	5.75 ± 0.22b	96.76 ± 0.10b	45.19 ± 0.50c	51.19 ± 0.31e	0.611 ± 0.0046a
0: 100	17.67 ± 0.09a	3.03 ± 0.52a	96.09 ± 0.03a	63.55±1.28d	41.25 ± 0.054c	0.603 ± 0.0046a
Average	35.48 ± 1.02	5.99 ± 0.54	97.15 ± 0.19	46.49±0.70	41.93 ± 0.61	0.754 ± 0.0049

• Note: Different superscripts in the same column show very significant differences (P < 0.01).

Table 2 suggests that K. xylinus remains capable of converting a whey-enriched medium into product, albeit with lower productivity. The sucrose content in coconut water serves as a primary nutrient source for the bacteria, and its chemical composition is altered when dangke whey is introduced, significantly influencing bacterial growth in the medium.

Komagataeibacter xylinus requires several carbohydrate nutrients as carbon sources for growth in coconut water, particularly glucose, fructose, and sucrose. Meanwhile, in dangke whey, the necessary carbohydrate nutrients that the microorganism can use include glucose and galactose. In contrast, lactose, as the most abundant carbon source in dangke whey, cannot be directly utilized in the metabolic process. This limitation contributes to the decline in the bacterial cellulose yield when dangke whey was used as a growth medium for K. xylinus. Additionally, previous research has demonstrated the ability of Acetobacter to thrive on various media with different carbon sources, including glucose, xylose, sucrose, galactose, mannose, and fructose (Mohammed & AlZubaidy, 2020); D-glucose, D-galactose, and D-mannose; as well as L-arabinose, sucrose, and D-xylose (Mamlouk & Gullo, 2013); and glucose and fructose (Potočnik et al., 2023).

The significant role of sugars during the fermentation of nata has been reported in numerous studies. Sucrose is an important carbon source in the fermentation process (Juwita et al., 2022). Similarly, Putri et al. (2021) explained that sugar influences the fermentation process in the bacterial cellulose production, where a portion of the sugar is synthesised into cellulose and acids. Yanti et al. (2017) noted that the sugar content of the fermentation medium significantly affects bacterial cellulose yield, as higher sugar levels result in greater extracellular cellulose synthesis. He et al. (2022) and Siti et al. (2014) argued that disaccharides such as sucrose serve as carbohydrate sources for K. xylinus, therefore providing energy and nutrients essential for bacterial growth.

In this study, increasing the proportion of whey in the medium demonstrated the suitability of the fermentation medium for K. xylinus. The differences in composition between coconut water and dangke whey as fermentation media were likely the primary cause of the observed decrease in yield. Previous research by Budiyanto & Usmiati (2022) found that the yield of nata produced using cheese whey as the substrate ranges from 34.97% to 52.84% when supplemented with 10% sucrose and glucose after pre-fermentation of whey for 2-5 days. Meanwhile, Hakiki et al. (2019) enriched the medium with taro, resulting in yields ranging from 12.74% to 30.98% depending on the inoculum level of K. xylinus (10% to 25%).

3.2 Nata thickness

Variations in thickness reflect the quantity of cellulose, commonly referred to as bacterial cellulose, produced during the process. In this study, the thickness of bacterial cellulose ranged from 3.03 mm to 8.58 mm. As shown in Table 2, it could be noted that increasing the proportion of dangke whey in the growth medium reduced thickness. Using analysis of variance, it was shown that substituting coconut water with dangke whey had a significant effect on thickness (p < 0.01), and the Duncan test revealed that the sample without any replacement (100% coconut water) produced a thicker layer. The thickness of samples in treatments with 30% to 70% dangke whey was comparable, but it markedly decreased when 100% dangke whey was used. This indicates that coconut water is a more suitable medium for the growth of K. xylinus.

The results indicate that using dangke whey at concentrations between 30% and 70% in the formulation affects the production threshold with respect to bacterial cellulose thickness. The thickness is closely linked to K. xylinus's growth capacity for cellulose formation. This growth is primarily influenced by the presence of carbon sources such as sucrose, glucose, fructose, and galactose found in coconut water or dangke whey. In this context, the carbon sources in the nutrient media, as noted by Siti Nurhayati (2006) and Mardin & Lasalewo (2021), play a crucial role in the growth of K. xylinus, which is reflected in the thickness of the nata.

3.3 Moisture content

Moisture content is a crucial parameter, as it affects the quality of nata. As presented in Table 2, it ranged from 98.04% to 96.09% and differed between treatments (p < 0.01). A higher proportion of dangke whey in the formulation can reduce the water content of nata, while a higher proportion of coconut water can increase cellulose production. This increase in cellulose is closely linked to the enhanced growth of K. xylinus, which produces cellulose. However, using more coconut water can also make the organoleptic texture of nata harder (Table 3).

Table 3
Organoleptic profiles of the samples.

Formulations	Colour	Texture	Chewing residue	Preference
100:0	2.99 ± 0.73a	4.67 ± 0.86b	3.56 ± 0.86b	3.96 ± 0.16a
70:30	3.14 ± 1.03a	4.36 ± 0.75b	3.08 ± 0.81a	4.03 ± 0.67a
50:50	3.72 ± 0.67b	3.78 ± 0.56a	2.95 ± 0.74a	4.10 ± 0.40ab
30: 70	3.74 ± 0.56bc	3.40 ± 0.50a	2.86 ± 0.60a	4.32 ± 0.47bc
0:100	4.16 ± 0.64c	3.38 ± 0.66a	2.68 ± 0.90a	4.50 ± 0.53c
Average	3.53 ± 0.74	3.92 ± 0.67	3.03 ± 0.79	4.19 ± 0.45

• Note: Different superscripts in the same column show very significant differences (p < 0.01).

Rahmah et al. (2023) noted that when K. xylinus grows in a suitable medium, it produces extracellular cellulose, which can be further oxidised, converting acetic acid into carbon dioxide and water. Additionally, fermentation time can influence water entrapment within the bacterial cellulose layers, thereby increasing moisture content. Putri et al. (2021) also reported that moisture content may be related to the amount of cellulose formed. Thin bacterial cellulose generally has a denser structure and lower water content, and vice versa. Fidyasari & Ula (2021) stated that the water content in bacterial cellulose is closely related to the amount of fibre (cellulose) produced. Thick, heavy bacterial cellulose indicates a high fiber content, which significantly affects its moisture content. According to Putri et al. (2021), the standard moisture content of the bacterial cellulose produced from various raw materials should not be less than 85%. Overall, the findings of this research and those from various studies demonstrate a key similarity in the production of bacterial cellulose by K. xylinus: the high water content (generally >85%) as an indicator of good bacterial cellulose quality. This is influenced by factors such as fermentation time, carbon source, and fiber thickness. Specifically, the studies by Rahmah et al. (2023) and Budiyanto & Usmiati (2022) could share similarities with this research in highlighting the role of fermentation media derived from natural by-products (coconut water versus whey) to achieve optimal water content, with both reporting values above 85%, supporting the application of bacterial cellulose as a biocomposite material or functional food. For comparison, the water content of bacterial cellulose in this study is around 96.09% to 98.04% with a fermentation period of 21 days. In the study by Rahmah et al. (2023), BC water content reached 95.3% after extended fermentation (28 days) in coconut water media supplemented with turmeric, demonstrating advantages in oxidative stability and antioxidant potential. Meanwhile, Budiyanto & Usmiati (2022) reported a cellulose water content of about 86.67% to 91%, requiring only 2-5 days in whey media supplemented with 10% sucrose/glucose, offering the advantages of time efficiency and a more economical use of dairy industry waste.

3.4 Lightness

Lightness (L*) values of the nata ranged from 38.60 to 63.55 (as seen in Table 2) and differ significantly (P < 0.01). They indicate that the rise of dangke whey proportion in the fermentation medium results in a brighter appearance. Treatments containing 30% to 50% whey showed no significant differences in L* value, but were significantly brighter than the 100% coconut water sample. Furthermore, when dangke whey was added at more than 50%, the nata brightness increased. Overall, the results reveal that the nata's lightness varies significantly with the proportions of dangke whey and coconut water, and the sucrose content likely influences this. It dictates the Maillard reaction during processing and fermentation. According to Hustiany (2016), a chemical reaction occurs between amino acids and reducing sugars when heated together, producing melanoidin compounds.

Another possible factor affecting brightness is the difference in nata thickness. The thickest nata was observed in treatments using 100% coconut water, highlighting the significant role of coconut water as a more compatible medium for the growth of K. xylinus. This favourable growth environment supports enhanced metabolism, leading to greater cellulose production as the primary metabolite. As the amount of cellulose increases, the brightness of the nata decreases. The results of this experiment are consistent with those of Putriana & Aminah (2013), who reported that nata colour is influenced by thickness; however, thicker nata tends to exhibit lower brightness.

3.5 Antioxidant activity

As presented in Table 2, the antioxidant activity of the nata ranged from 31.77% to 51.19% (p < 0.01). According to Anam (2019), nata de coco analysed using Gas Chromatography-Mass Spectrometry (GC-MS) contained 9-octadecanoid acid and p-cresol, both of which possess antioxidant activity. In this study, increasing the proportion of dangke whey up to 70% enhanced antioxidant activity, reaching 51.19%. The higher the antioxidant activity of bacterial cellulose is, the greater its ability to counteract free radicals will be. Coconut water and whey, both used as growth media for K. xylinus, are rich in bioactive compounds that contribute to the final antioxidant activity of bacterial cellulose. Coconut water is rich in electrolytes (K, Mg) and phenolic compounds such as catechin, epicatechin, and ferulic acid, as well as vitamin C, which acts as an electron donor for scavenging reactive oxygen species (Shi et al., 2025). Meanwhile, whey contains soluble proteins (β-lactoglobulin, α-lactalbumin). When these proteins are hydrolyzed, they yield bioactive peptides with strong antioxidant activity via metal chelation and lipid peroxidation inhibition. In addition, whey is rich in branched-chain amino acids and minerals (Ca, Zn) that support antioxidant enzymes such as superoxide dismutase (Machado et al., 2025). Other antioxidant compounds in bacterial cellulose in this study may also be derived from bioactive compounds produced during fermentation. Khusna et al. (2020) also reported that various multifunctional bioactive compounds were produced during whey fermentation, including organic acids (e.g., lactic acid), bioactive peptides, and proteins. They can act as antioxidants, antimicrobials, and enhance the immune system. Additionally, the sucrose content in the medium is suspected to contribute to Maillard reactions during both processing and fermentation. Hustiany (2016) stated that the Maillard reaction occurs between amino acids and reducing sugars and, when heated, produces melanoidin compounds that also exhibit antioxidant properties.

3.6 Breaking strength

The breaking strength values of the nata ranged from 0.603 to 0.861 kg cm^-2 (Table 1) and differed significantly (p < 0.01). The breaking strength was strongly related to crude fibre content and positively correlated with thickness. A higher crude fibre content was associated with a higher breaking strength. Budiyanto & Usmiati (2022) reported that the fibre content of "nata de whey" made with 10% of sucrose and glucose ranged from 0.27% to 0.64% and 0.44% to 0.92%, respectively. Khusna et al. (2021) successfully produced coconut water-based nata with crude fibre reaching 0.44% and 0.62% for 11 and 14 days of fermentation, respectively. In addition, in the same period, nata made with whey as a medium contained 0.31% and 0.47% crude fibre, respectively.

3.7 Colour profiles

The results of the organoleptic test are presented in Table 3. Overall, the highest clarity score was achieved by the sample using 0% coconut water and 100% dangke whey, with a score of 4.16; in contrast, the lowest was achieved by the sample using 100% coconut water and 0% dangke whey, with a score of 2.99. This result indicates that dangke whey markedly affects the appearance of the nata (p < 0.01), as seen in Figure 1.

Figure 1
Physical appearance of the nata made from different proportions of fermentation medium. Research treatment with comparison treatment of coconut water: dangke whey as follows: (a) 100:0, (b) 70:30, (c) 50:50, (d) 30:70, and (e) 0:100.

The changes in clarity caused by varying proportions of coconut water and whey dangke possibly result from sucrose in the medium. It can facilitate the Maillard reaction during processing and fermentation. This result is consistent with the study by Hustiany (2016), which shows that the Maillard reaction occurs between reducing sugars and amino acids when heated. The reaction plays an important role in the development of flavour and colour in various foods. Moreover, the products of the Maillard reaction depend on several factors, including the types of reducing sugars and amino acids, their ratio, temperature, pH, moisture content, and water activity.

In addition, the amount of cellulose formed may contribute to differences in nata colour, particularly in yellowish colour and clarity. The proportion of coconut water at 70% to 100% showed higher cellulose content, as indicated by greater thickness, because this range provides an ideal environment for K. xylinus, enabling the bacteria to adapt and grow more efficiently. As a result, metabolism is more active, leading to increased cellulose production. In fact, higher cellulose content is associated with reduced clarity or brightness. This result aligns with findings of Putriana & Aminah (2013), who reported that thicker nata appears more turbid, while thinner nata tends to be clearer and brighter.

3.8 Bacterial cellulose texture

As seen in Table 3, the highest liking score for texture was observed in the sample using 100% coconut water and 0% dangke whey, with a score of 4.67 (indicating a chewy texture). On the contrary, the lowest score was recorded in the sample from medium made with 0% coconut water and 100% dangke whey, with a value of 3.38 (indicating a softer, less chewy texture). These findings clearly highlight the significant impact of dangke whey on nata texture, where lower levels of whey in the medium result in a firmer product. Overall, analysis of variance showed that the proportions of coconut water and dangke whey had a significant effect on panellists' liking scores for texture (p < 0.01). It can be seen that coconut water at 70% to 100% consistently produced chewy products, whereas those made with 50% to 100% whey were less chewy. This suggests that substituting more than 30% of coconut water with dangke whey reduces the chewiness of nata.

The chewy texture of nata results from a higher cellulose yield. The growth of K. xylinus is dependent on the availability of essential nutrients and environmental conditions. Therefore, when cellulose production increases, it represents ideal conditions for their growth. The high chewiness of nata corresponds to its greater cellulose content, and this condition is observed in samples harvested from media containing 70% to 100% coconut water, which exhibit the most favourable characteristics. This result confirms that coconut water is a superior medium for the growth of K. xylinus. In addition, one key factor is the quantity of glucose molecules formed during the breakdown of sugars in the fermentation medium. Sucrose is hydrolysed into two glucose molecules, while lactose is broken down into glucose and galactose. The greater availability of glucose may better support the growth of K. xylinus than whey-substituted media. Siti Nurhayati (2006) reported that K. xylinus can synthesize nata from glucose, maltose, or glycerol. Furthermore, two studies by Xia et al. (2022) and Gallego et al. (2022) noted that the chemical and physical structure of nata was greatly influenced by the nutritional composition of the medium, which significantly affects its texture.

3.9 Chewing residue

In this study, chewing residue refers to the amount of the “fibrous” fraction remaining in the mouth after chewing the samples. Panellists estimated this attribute, and the higher score corresponds to the higher cellulose content. Our experiment revealed the significant differences in the response due to the treatments (p < 0.01). As shown in Table 3, the chewing residue score decreases as more dangke whey is added to the medium formulation.

An upsurge in cellulose in the medium containing 100% coconut water is understandable, as it is the most suitable resource for K. xylinus. Anam (2019) and Kristiandi et al. (2022) reported that coconut water contains various nutrients beneficial for the growth of K. xylinus, such as carbohydrates, proteins, fats, minerals (such as potassium, sodium, magnesium, calcium, and phosphorus), vitamins, and growth hormones, which are favourable for bacterial growth. Although K. xylinus can grow on a medium containing whey dangke, its adaptation rate and growth are slower, resulting in less cellulose formation. This determines the amount of chewing residue in nata. As explained by Asri & Wisanti (2017), effective cellulose synthesis is closely linked to optimal growth conditions. Komagataeibacter xylinus can convert carbohydrates into cellulose, and the quality of nata depends on the type of substrate provided for bacterial growth. Siti Nurhayati (2006) highlighted that the type and concentration of sugars in the medium considerably affect the thickness and properties of nata. Additionally, Murtius et al. (2021) suggested that nutrient sufficiency in the medium would accelerate the biotransformation of sugars into cellulose by K. xylinus.

3.10 Panellist's preference

Preference testing is a type of sensory evaluation in which panellists are asked to express their personal degree of liking or disliking of a product. The results of the organoleptic preference test for nata (Table 3) showed that the highest preference score was given to the nata produced using 100% dangke whey as the fermentation medium, with a score of 4.50. In contrast, the lowest score was 3.96, observed for bacterial cellulose produced with 100% coconut water. In this work, the treatments significantly affected the preference score (p < 0.01). Overall, it can be seen that substituting coconut water with no more than 50% dangke whey did not significantly alter preference compared to that made with 100% coconut water. However, adding more whey dangke (70% to 100%) consistently yielded the highest preference scores.

The preference scores are closely associated with texture and chewing residue, both of which are influenced by cellulose abundance, as discussed previously. Typically, cellulose content is proportional to chewiness and to the insoluble fibrous residue remaining after chewing. In this study, even though the higher proportion of whey dangke yielded a thinner nata layer, it was clearer and more transparent. Other research by Putranto & Taofik (2017) and Hendrarti & Nasarani (2020) highlighted that the most preferred nata characteristics included a thin layer, compact fibre structure, low water content, and a chewy texture. These properties conform to the SNI standard for nata (SNI 01-4317-1996). Tamimi et al. (2015) reported that higher texture-preference scores were associated with adequate cellulose formation, which depends on nutrient availability. The type and concentration of sugars are believed to be key factors influencing K. xylinus activity in cellulose production.

Thus, the use of 50% to 100% whey dangke in nata bacterial cellulose processing results in a product that consumers find acceptable and enjoyable. In this study, consumers described the bacterial cellulose as being relatively thin. The thinness of the nata is related to its texture, which is less fibrous. It does not leave any residue when chewed, ensuring that the swallowing process is not hindered. This finding highlights the unique characteristics of the nata produced, and it emphasizes the advantage of using whey dangke to achieve a smoother texture.

4 Conclusion

Dangke whey shows potential as a fermentation medium for bacterial cellulose production using K. xylinus. With the increasing use of whey dangke as a substitute for coconut water, bacterial cellulose quality changed markedly, there has been a decrease in yield produced, a more transparent appearance, a softer texture, less residual chewiness, and a higher overall preference among panellists. Further research is needed on the use of 100% whey dangke in the production of bacterial cellulose enriched with various levels of sucrose and ZA (ammonium sulphate).

Acknowledgements

The authors would like to thank the Rector and the Institute for Research and Community Service (LPPM), Hasanuddin University, for funding this research project through a scheme of Penelitian Fundamental Kolaboratif with contract number 00309/UN4.22/PT.01.03/2024.

Data Availability Statement

All data generated or analyzed in this study are included in this published article.

• Cite as:
  Maruddin, F., Rahasia, I. P., Rahmatullah, K., Hajrawati, H., Sabil, S., Taufik, M., & Taggo, S. (2026). Assessing dangke whey as a viable substitute for coconut water in bacterial cellulose production using Komagataeibacter xylinus. Brazilian Journal of Food Technology, 29, e2025080. https://doi.org/10.1590/1981-6723.0802025
• Funding:
  Institute for Research and Community Service (LPPM) Hasanuddin University through a scheme of Penelitian Fundamental Kolaboratif (00309/UN4.22/PT.01.03/2024).

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Edited by

• Associate Editor:
  Airton Vialta.

Publication Dates

• Publication in this collection
  17 July 2026
• Date of issue
  2026

History

• Received
  28 July 2025
• Accepted
  25 Feb 2026