A Novel Biodegradable Technology for Wool Fabric Restoration and Cotton Color Retention Based on Shikimic Acid and L-Arginine

Abstract

The textile and garment care industries significantly impact ecological conditions and resources worldwide. Possible ways of minimizing the harmful influence on the environment include giving a preference to natural textiles; reducing the consumption rate by extending the lifespan of clothes, e.g., preserving colors and fibers; and using biodegradable garment care products. Wool is a natural fabric that must be washed with special laundry care products to preserve its initial appearance. Currently, there are no approaches that focus not only on preserving but also restoring wool fibers. To investigate the efficacy of biodegradable technology, consisting of natural-derived shikimic acid and L-arginine, in the restoration of wool fabric, SEM was applied. To analyze the obtained data, a novel three-point scale was suggested. In comparison with untreated samples, the composition promoted a smoothing of the scale structure of wool fibers of up to 34.87%. The system has shown efficacy in both the low pH (fabric softener) and high pH (laundry gel) systems. To further investigate biodegradable technology, the color retention of dark-colored cotton fabric was tested. It was shown that the composition promotes 96.15% color preservation after 10 laundry cycles when used in the fabric softener. Biodegradable technology is a promising solution for the maintenance of wool fabrics and color preservation solutions.

1. Introduction

Garment care is an industry that is constantly developing and looking for new solutions, dictated by current trends in the fashion industry as well as by sustainability challenges. The latter is driven by the textile and garment industries’ impact on the environment—the washing, drying, and ironing of textiles accounts for 39% of greenhouse gas emissions worldwide [1]. Components of household products, such as surfactants, adjuvants, and additives, are discharged into the environment, causing a disbalance in aquatic systems, thus negatively impacting the environment [2]. The other factor that highly contributes to pollution is the release of micro- and nanosized plastic fragments from the washing of synthetic clothes into the water, causing marine contamination [3,4,5]. In this regard, it is crucial to formulate products, particularly laundry powders, gels, and fabric softeners, which will both maintain high cleaning and softening efficacy and will not cause any negative effects on the environment.

Another possible way of reducing the negative impact on the environment is giving a preference to natural textiles, e.g., cotton, silk, and wool. The latter can minimize the release of micro- and nanosized plastic into the environment [6]. However, the release of microfibers of natural origin and regenerated cellulose fibers into aquatic systems and the atmosphere may also be harmful to living organisms, something that has recently been gaining more and more attention [7,8]. In this regard, it is crucial to decrease the consumption of clothes, which can be achieved by extending their lifespan, e.g., by preserving the color and structure of their fibers.

One natural and biodegradable textile is wool. Fabrics, made of wool, are highly valued thanks to their properties—they provide better thermal insulation and have greater breathability than other textiles and are durable, long-lasting, hypoallergenic, and readily recyclable [9,10]. Even though the COVID-19 pandemic significantly influenced the production of wool, it has been returning to pre-pandemic levels, reaching 15,600 tons in 2022. The latter pinpoints wool’s high demand throughout the world and indicates the need to develop sustainable and effective solutions for maintaining its initial appearance [3,4,5,9,10,11].

Fabrics made from wool differ from other bio-based textiles and require special care, including washing under lower temperatures and using enzyme-free and neutral pH laundry products [12,13]. Failing that, the textile would lose its initial performance, including color and elastic and sensorial properties, which is usually the cause of neglecting clothing and significantly shortening its lifespan. Current approaches, made for restoring the damaged wool, lack the performance and evidence base to fulfill this aim.

Unlike the garment care market, there are many solutions within the cosmetics segment for the restoration of a similar structure to wool fibers—hair. Despite minor differences between the structure of human hair and wool fibers, the surfaces of human hair and wool fibers are alike—when undamaged, they are covered with an epicuticle, whose outmost surface is mostly composed of a monolayer of 18-methyleicosanoic acid (18-MEA) [14,15,16,17,18]. The cleavage of these linkages in hair, either by bleaching with lotion at an alkaline pH or weathering, such as by repeatedly shampooing, produces cysteic acid and releases negatively charged sulfonate groups onto the surface of the cuticle [19]. Wool fibers can be treated using similar agents under alkaline conditions, such as cetyltrimethylammonium bromide (CTAB), to remove the lipid layer from the surface and increase the efficacy of dyeing with reactive dyes [20].

The similarities between the structure of human hair and wool fibers open the possibility of considering solutions from the hair care market for wool fiber restoration. However, such solutions are usually too expensive to incorporate them into garment care products. Thus, they must be renovated not only to be suitable for wool textiles but also to meet the economic expectations of consumers.

Previously, Oshimura et al. demonstrated that a system composed of the basic amino acid arginine and the salt of pyrrolidone carboxylic acid (PCA) promoted significantly better color retention of human hair than deionized water and silicone. Arginine serves as an “anchor”, as it carries a guanidium group with high affinity for the hair’s surface. The salt of PCA is quite hygroscopic and can retain not only water but also water-soluble molecules on the surface of hair, including dyes [21,22]. These factors contribute to the high efficacy of color retention of hair using arginine and PCA composition.

In accordance with the above, it was hypothesized that the bio-based composition, which consists of L-arginine and small-molecule shikimic acid (SA), can promote wool fabric restoration. The ratio chosen for further analysis was 1:1, which is a standard ratio in primary studies. SA is a naturally derived molecule from the plant Illicium verum. It was not previously studied for the preparation of household products. L-arginine is a basic amino acid, which is produced using a biotechnological method—fermentation with such bacterial strains as C. glutamicum (C. acetoacidophilum), Brevibacterium flavum, and E. coli [23]. To understand how the complex composed of SA and L-arginine influences wool fabric, scanning electron microscopy (SEM) was applied to investigate the surface of wool fibers.

The composition was also tested on dark-colored cotton fabric for color retention efficacy—a common problem in garment care. Current approaches for minimizing color fading are mostly focused on the inhibition of dye transfer—the transfer of dyes from one piece of clothing to another, usually to the lighter one, which can result in the staining of the lighter clothes and a patchy appearance of colored ones rather than the preservation of color [24]. In the washing machine, dye transfer occurs mainly during the washing part of the laundry cycle (LC) and is dependent on surfactant concentration, temperature, and the cycle time [24,25].

The results that were obtained in the current study are further given and discussed.

2. Materials and Methods

2.1. Preparation of Laundry Gel and Fabric Softener Samples

Formulations containing a novel wool fiber restoration technology, which is composed of SA (Shaanxi Huike Botanical Development Co., Ltd., Xi’an, China) and L-arginine (Daesang Corporation, Seoul, Republic of Korea), were used as shown in

Table 1. Formulation of the laundry gel.

Compounds	Concentration, wt.%
Purified water	up to 100
Tetrasodium glutamate diacetate, 40% solution	1.60
Trisodium citrate dihydrate	0.80
Sodium laureth sulfate, 70% solution	7.50
Decyl glucoside, 15–50% solution	3.50
Lauryl glucoside, 15–50% solution	3.50
Fatty alcohol ethoxylate, 7 mol	3.20
Glycerin	3.00
Beta cyclodextrin	0.10
Cocamidopropyl betaine, 40–45% solution	1.50
1,2-benzisothiazol-3(2H)-one, potassium hydroxide, 2.5–5% solution	0.10
N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine, 2.5–5% solution
Potassium hydroxide, 1–2.5% solution
2-Pyridinethiol-1-oxide sodium salt, 0.5–1% solution
Sodium carboxymethyl inulin	0.5
Sodium chloride	2.8
Citric acid monohydrate	0.25
Potassium cocoate	2.00
Protease (Subtilisin), 1–2.5% solution	0.30
Cellulase, 0.1–1% solution
Lipase, 0.1–1% solution
Alpha-amylase, 0.1–1% solution Mannanase, 0.1–1% solution Pectinase, 0.1–1% solution
Shikimic acid	0.001–0.25
L-arginine	0.001–0.25

and

Table 2. Formulation of the fabric softener.

Compounds	Concentration, wt.%
Purified water	up to 100
Triethanolamine ammonium methyl sulfate di-alkyl ester	13.50
Glycerin	3.00
3-acetyl-6-methyl-2H-pyran-2,4(3H)-Dione	0.02–0.03
Benzoic acid	0.04
Benzyl alcohol	0.24–0.25
Calcium lactate	0.05
Shikimic acid	0.00-0.25
L-arginine	0.00-0.25
Fragrance and essential oils	0.40

. The concentrations of SA and L-arginine varied from 0% (control) to 0.25% and were either equal to 0.25%, 0.01%, or 0.001%, which is further discussed in the Results section. For the disruption of wool fabric, additional protease (subtilisin, 5.00–7.50% solution) was used at a concentration of 0.25 wt.% in the laundry gel. The pH of the laundry gel lies in the range of 8–9, and the pH of the fabric softener is 2.5–3.5.

The additional formula of the laundry detergent, which was used in the color retention experiment, is disclosed in

Table 3. Formulation of the laundry gel for dark-colored clothing.

Compounds	Concentration, wt.%
Purified water	Up to 100
Sodium laureth sulfate, 70% solution	7.50
Decyl glucoside, 51–55% solution	3.50
Fatty alcohol ethoxylate, 7 mol	3.20
Glycerin	3.00
Methyl glycine diacetic acid trisodium salt, 40% solution	1.60
Sodium hydroxide, 0.3–1% solution	1.60
Beta cyclodextrin	0.10
Cocamidopropyl betaine, 40–45% solution	1.50
Trisodium citrate dihydrate	0.8
1,2-benzisothiazol-3(2H)-one, potassium hydroxide, 2.5–5% solution	0.10
N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine, 2.5–5% solution
Potassium hydroxide, 1–2.5% solution
2-Pyridinethiol-1-oxide sodium salt, 0.5–1% solution
Sodium carboxymethyl inulin	0.5
Sodium chloride	2.8
Citric acid monohydrate	0.25
Potassium cocoate	2.00
Protease (Subtilisin), 1–2.5% solution	0.30
Lipase, 0.1–1% solution
Alpha-amylase, 0.1–1% solution Mannanase, 0.1–1% solution Pectinase, 0.1–1% solution Cellulase, 0.1–1% solution
Cellulase, 1.1–3.5% solution	0.28

.

2.2. Wool Fabric Washing Procedure

To investigate the effect of washing wool fabric with the prepared laundry gels and softeners on wool fiber restoration, red-colored wool fabric was used (Figure 1). The fabric was cut into 2 cm × 2 cm pieces for the convenience of further SEM investigation. The samples were stitched with cotton threads to maintain their integrity and for labeling. A total of 8 wool samples, cut from the same wool textile piece, were used.

The samples were washed in a Miele W1 PowerWash & TwinDos & Steam washing machine (Miele & Cie. KG, Gütersloh, Germany) with a maximum laundry load of 9 kg, which is widely used in garment care and household manufacturers’ laboratories. The samples were washed for 20 or 39 min (express 20 or wool wash regimes with a total water volume equal to 35 and 30 L, respectively; approximately 10 L of water is required for the washing part of the LC). Each LC was carried out with ballast—bleached cotton fabric with a total weight of 1 kg. The total weight of the samples from Figure 1 was equal to 1 g. Thus, the total load was approximately equal to 1 kg. The temperature in both regimes was 30 °C. In total, 39 min LC was applied when washing with the laundry gel, containing additional protease, and for samples 1–4. A shorter LC (20 min) was applied to samples 5–8. For each LC, 50 mL of laundry gel and 30 mL of fabric softener were used, except for the cycle with the laundry gel containing additional protease, where no fabric softener was used. To evaluate the influence of formulations containing SA and L-arginine, 5 LCs were applied to each sample. Water hardness was equal to 8.96–11.76 dH.

2.3. SEM Studies

To obtain µm scale images of the wool fibers, an FEI Teneo (2015) scanning electron microscope (Thermo Fisher Scientific, Waltham, MA, USA) was used. A low voltage of 1 kV and an EDS detector were used to optimally visualize the fabric surface structure. Approximately 30 SEM images of the scale structure of wool were taken from the different parts of each wool sample at all SEM stages.

2.4. Fiber Damage Degree Scale

To analyze the obtained data, a novel three-point fiber damage scale was developed. The scale structure of wool was suggested as the test object. In this scale, 1 stands for the most striated (damaged) scale structure, and 3 for the smoothest (undamaged) scale structure. Examples of each degree are illustrated in Figure 2. For the statistical analysis of the obtained data, GraphPad Prism 8.4.0 (GraphPad Software Inc., San Diego, CA, USA) for macOS was used.

2.5. Color Retention of Cotton Fabric

As an additional test, the color retention of blue-colored cotton fabric was investigated. The fabric was cut into 50 mm × 100 mm pieces and then washed with the laundry gel without shikimic acid and L-arginine (Table 1; the concentrations of shikimic acid and L-arginine are 0%; 50 mL) and fabric softener containing SA and L-arginine in concentrations of 0.001% each (30 mL). For each laundry product sample, 3 pieces of blue-colored cotton fabric were used. Of the 3 samples, 2 were washed with the tested laundry system, and 1 was washed only with water without laundry detergent (negative control). The LC was 20–30 min long, with a temperature of 40 °C, and water hardness equal to 14.98 dH. The color retention was measured by photometric evaluation of the reflection coefficient of the fabric’s surface on a glossmeter and compared with the control sample treated with water. To precisely evaluate the coefficient, the samples were dried and ironed after each cycle. This procedure was repeated 10 times; the measurements were taken after the 1st, 5th, and 10th LC. The composition of SA and L-arginine within fabric softener together with the laundry gel was compared with 4 laundry gels from renowned brands that are available on the market, and with the laundry gel for dark-colored textiles previously developed by authors (Table 3). These laundry gels were developed for black-colored textiles and claim to retain color.

3. Results

3.1. Evaluation of System Efficacy with a 0.25% Concentration of SA and L-Arginine

To record the initial state of the damage of the wool fibers, SEM was used. The mean value of damage to the scale structure of wool was 2.44 ± 0.63 conventional units (c.u.). Next, the fibers were damaged by washing them with laundry gel (Table 1) with a final concentration of protease (subtilisin, 1–2.5% solution) reaching 0.33% and without the SA and L-arginine composition. The treatment of wool with protease causes the hydrolytic attack of peptide bonds within proteins, which are present on the surface of wool and in the cortex. Patrial diffusion of the enzyme into the deeper layers of the fibers may result in loss of strength of the fabric [26]. However, after analyzing the images after the protease treatment, no significant changes were observed within the scale structure of wool (2.23 ± 0.63 c.u., p > 0.05), which may be linked to the insufficient concentration of protease in the final formulation. Nevertheless, due to the possible increase in the fibers’ smoothness after the SA and L-arginine treatment, the samples were used further in the study.

To evaluate the effect of the biotechnology, consisting of SA and L-arginine, the wool fabric was treated with laundry gels and fabric softeners (Table 1 and Table 2) in the following pattern (samples 1–4,

Table 4. Concentrations of SA and L-arginine in the studied formulations of laundry gel and fabric softener.

Sample	Laundry Gel		Fabric Softener
	SA, wt.%	L-Arginine, wt.%	SA, wt.%	L-Arginine, wt.%
1	0	0	0	0
2	0.25	0.25	0	0
3	0	0	0.25	0.25
4	0.25	0.25	0.25	0.25
5	0	0	0.01	0.01
6	0.01	0.01	0.01	0.01
7	0	0	0.001	0.001
8	0.001	0.001	0.001	0.001

):

The data obtained from the analysis of SEM images are summarized in

Table 5. The influence of washing the wool fabric with the laundry gels and softeners comprising the biodegradable technology.

Sample Number	Mean Value of Scale Structure of Wool Damage	Decrease in the Scale Structure of Wool Damage Compared to the Control *, %
Before treatment	2.44 ± 0.63	-
After treatment with protease	2.23 ± 0.63	-
1	1.93 ± 0.62	13.65
2	1.46 ± 0.69	34.87
3	2.20 ± 0.63	1.49
4	1.80 ± 0.63	19.40
5	1.71 ± 0.56	29.67
6	1.80 ± 0.63	26.15
7	1.53 ± 0.77	13.65
8	1.68 ± 0.67	30.90

*—the control is the value of the scale structure of wool damage obtained from washing the wool fabric with protease-containing laundry gel for samples 1–4 and the value of the scale structure of wool damage of the untreated wool fabric for samples 5–8.

(samples 1–4).

As seen from Table 5, the highest score of the smoothing of the surface of wool fibers was obtained by washing the fabric with the laundry gel containing SA and L-arginine in the concentration of 0.25% and the fabric softener that did not contain the composition. A statistically significant difference was obtained only between the control (after treatment with protease) and sample #2. Nevertheless, all formulations had a positive effect on the scale structure of wool.

3.2. Evaluation of System Efficacy with a 0.001% and 0.01% Concentration of SA and L-Arginine

To test the efficacy of laundry gels and fabric softeners, which contain smaller concentrations of SA and L-arginine (0.001%, 0.01%) and are more commercially feasible, the same method was applied. In accordance with the absence of a statistically significant difference between the samples of wool fabric before and after protease treatment, protease treatment was not applied, and the data were compared with the initial state of the scale structure of wool. The concentrations of SA and L-arginine in the formulation are disclosed in Table 4 (samples 5–8). The wool samples were then subjected to SEM, and the data obtained from the analysis are summarized in Table 5 (samples 5–8). A statistically significant difference was found between untreated wool and all the test samples (5–8) values. Given that the biodegradable technology showed efficacy at higher concentrations (0.25%) as well as at lower concentrations (0.01% and 0.001%), it can be stated that SA and L-arginine can be used in laundry gel and fabric softener formulations even in smaller concentrations for the maintenance and regeneration of wool fabric clothing.

3.3. Evaluation of the Color Retention of Cotton Fabric

To further investigate the biodegradable technology consisting of SA and L-arginine, blue-colored cotton fabric was used. As a dark-colored fabric, it has a higher tendency to fade than lighter-colored fabrics. To compare our technology with other products designed specifically for dark-colored textiles that are available on the market, four laundry detergents were used. In order to avoid potential professional and financial conflicts, these products are not disclosed and are further referred to as “Product 1”, “Product 2”, “Product 3”, and “Product 4”. In addition to the four laundry gels that are available on the market, the laundry gel further referred to as “Laundry System 5” was used (Table 3). This laundry gel was developed specifically for darker-colored textiles, but it does not contain any specific technology that is responsible for it. The formula of the latter laundry detergent contains a soft washing system and a higher concentration of cellulase, which eliminates the pills on the surface of cotton, making it smoother. The results with “Product 1–4” and “Laundry System 5” were obtained prior to the current study and were not published before. It is crucial to note that the length of the LC differed in the prior study and was 30 min long, compared with the 20 min cycle in the current study. Nevertheless, to highlight the practical use of biodegradable technology and to review the efficacy of the products available on the market, all the data are presented together.

The laundry system, which is used in the current experiment, is composed of the laundry gel (Table 1) that does not contain the technology, and the fabric softener (Table 2) with a minimal concentration of SA and L-arginine—0.001% each. To collect the extended data, four fabric softeners, which vary only by aromatic composition, were used. The laundry systems, comprising the laundry gel and one of the four fabric softeners, are further referred to as “Laundry System 1”, “Laundry System 2”, “Laundry System 3”, and “Laundry System 4”. The color fading (CF) was measured on a glossmeter by photometric evaluation of the reflection coefficient of the fabric’s surface after the 1st, 5th, and 10th LC and compared with the control sample treated with water (

Table 6. The influence of the biodegradable technology on color fading in blue-colored cotton fabric compared with products available on the market.

The Name of the Laundry System	CF after 1st LC, % *	CF after 5th LC, % *	CF after 10th LC, % *
Laundry System 1	2.5	3.8	6.4
Laundry System 2	1.9	3.8	5.8
Laundry System 3	1.3	1.3	2.6
Laundry System 4	0	0	2.6
Product 1	6.8	12.2	14.9
Product 2	8.1	12.2	13.5
Product 3	6.8	10.8	12.2
Product 4	6.8	9.5	12.2

* CF—color fading, LC—laundry cycle; %—a degree of color fading, compared to the sample, which was treated with water.

). The reflection coefficients of cotton fabric washed only with water after 1st, 5th, and 10th LC were the same. The results are summarized in Figure 3.

From the data obtained, it is clear that the laundry composition composed of the laundry gel (Table 1) and the fabric softener with concentrations of SA and L-arginine of 0.001% each was the most efficient in preventing color loss. To investigate the influence of the technology when used only in laundry gel, further studies are needed.

4. Discussion

Wool fabric is a biodegradable material that enjoys widespread use due to its excellent functional properties [11]. It requires special care to maintain its initial composition and appearance. Nowadays, there are plenty of solutions on the market that claim to be developed specifically for delicate fabric care, but they do not provide an extended scientific evidence base for fulfilling this aim. The current study was conducted to test biodegradable technology consisting of plant-derived SA and the basic amino acid L-arginine and its effect on the regeneration of wool fabric as well as the color retention of darker-colored cotton fabric.

The novel composition was incorporated in two systems: laundry gel and fabric softener and tested at concentrations ranging from 0.001% to 0.25%. Laundry gel and fabric softener represent two different systems used in garment care that have a different pH, which makes it harder to develop general-purpose technology for both. The pH of the laundry gel formulated in the current study was 8–9 while the pH of the fabric softener was 2.5–3.5. Oshimura et al. used a composition of arginine together with PCA, or salt of PCA, for color retention of hair. The team showed that this composition promotes color retention of previously bleached and dyed hair when used in hair shampoo (pH = 5.8) and highlighted that arginine has the highest affinity to the hair surface at pH > 4 (isoelectric point of hair) [21]. As a part of the system, arginine serves as an “anchor” that interacts with the surface of hair and interconnects PCA and hair together. The salts of PCA are highly hydroscopic and bind not only water but also dissolved hydrophilic molecules such as dyes [21].

The isoelectric point of wool is close to the isoelectric point of hair and lies between four and five [26,27]. In this regard, the highest uptake of arginine must also be observed at pH > 4. It was hypothesized that a system composed of L-arginine and another small molecule, SA, can provide similar properties as the system proposed by Oshimura et al. [21]. Following this aim, wool was washed with laundry gels and fabric softeners containing the biodegradable technology with concentrations ranging from 0.001% to 0.25% and then subjected to SEM.

To the best of our knowledge, there are no available scales for analyzing the degree of wool recovery/damage on a microscopic level. Lee et al. proposed a 12-point scale for human hair [28]. Nevertheless, the latter scale cannot be applied to wool fibers due to the differences between the cuticle morphology of human hair and wool. Unlike the regular arrangement of scales in human hair, wool has a less regular cuticle structure and appears less smooth from the outside [15]. In accordance with the latter, the novel 3-point scale was proposed, where 1 stands for the most damaged wool fibers and 3 for the least damaged. The scale structure of wool was chosen as an object for analyzing the degree of wool recovery using the obtained SEM images.

The scale structure of wool is striated by nature [29]. Nevertheless, it was shown that silicone softeners can decrease the striation of the scale structure of wool fibers by coating the surface with a thin film layer. Such fabric has decreased friction, increased softness value, tear strength, and dimensional stability, and improved wrinkle recovery [30]. Although these parameters were not tested in the current study, it was shown that the scale structure of wool becomes smoother when the laundry gel and fabric softener containing the SA and L-arginine are used. The best effect was reached by using samples 2 and 8 in descending order, which stand for the following systems: 2—laundry gel with 0.25% of SA and L-arginine and fabric softener, which does not contain the technology; 8—laundry gel and fabric softener with 0.001% of SA and 0.001% of L-arginine. Such correlation indicates that the best effect is reached when using the system only in the laundry gel or using it together in the laundry gel and the fabric softener in small concentrations, equal to 0.001%.

These results indicate that the system can be used both in low pH systems, like fabric softener, and higher pH systems, like laundry gel. The composition of SA and L-arginine promotes the smoothing of the scale structure of wool fibers and, thus, can be used for the regeneration of wool fibers when used in a fabric softener and laundry gel for “a silicon-like finish”.

Although it was not directly tested in the current study, previous research by Oshimura et al. provides evidence that L-arginine binds to the surface of wool fibers and serves as an “anchor” for the binding of SA [21]. Further studies can be conducted to further investigate the mechanism by which the arginine binds to the surface of wool fabric and, together with SA, promotes the smoothing of the scale structure of wool fibers. Such parameters as friction, tear strength, dimensional stability, and wrinkle recovery also lie outside of the scope of the current study and can be tested to further investigate the mechanism of SA and L-arginine-induced wool fabric recovery.

The system was also tested for color retention properties using blue-colored cotton fabric. To the surprise of the authors, besides smoothing the scale structure of wool fibers, the systems also showed great efficacy in retaining the color of cotton fabric, maintaining 96.15% of the color after 10 LC, compared with washing the cotton fabric with water alone for 10 LC. Such efficacy was greater not only when comparing with the laundry gels available on the market but also with the laundry gel for dark-colored textiles, which was previously developed by the team members of the laboratory. This laundry gel has a delicate washing system and additional cellulase for the elimination of the pills on the surface of cotton fabric. It creates a visually smoother and more well-conditioned appearance of clothing. It is important to note that the latter laundry gel was more efficient in retaining the color of the blue-colored cotton fabric after 10 LC than the other market solutions. Using “Laundry Systems 1–4” sufficiently increased the color retention of the cotton fabric even when compared to Laundry System 5. Such an effect can be linked to differences between the experimental designs of the current study and the prior study. Laundry Systems 1–4 are composed of laundry gel without shikimic acid and L-arginine (Table 1, concentration of shikimic acid and L-arginine are 0%) and fabric softener with SA and L-arginine concentrations of 0.001% each, while Laundry System 5 and Products 1–4 are only composed of laundry gels. Also, the fabric in the current study was washed for 20 min, while in the prior study, each LC was 30 min long. Nevertheless, the obtained results indicate that the additional usage of the fabric softener, which contains the biodegradable technology, can sufficiently increase the lifespan of darker-colored cotton fabric by maintaining its color, even when using a more “harsh” laundry detergent formula. Further studies are needed to indicate whether the composition can promote a similar effect when used only in laundry detergent.

The safety of using the system composed of SA and L-arginine in the composition of laundry gel and fabric softener must also be discussed. The incorporation of these ingredients into liquid laundry formulations restricts their inhalation, as they are not volatile. L-arginine is a basic amino acid that is produced using biotechnological methods for commercial purposes [23]. However, it is also a conditionally essential amino acid, which is present in all individuals and is used for a variety of purposes in the body [31]. There are no reported cases of topical allergy to L-arginine; conversely, there is evidence that the inhalation of a solution containing L-arginine can benefit patients with cystic fibrosis [32].

SA is a natural molecule that is derived from the plant Illicium verum (star anise). While star anise oil and its main component, anethole, can sensitize skin, there are no reported cases of topical allergic reactions to SA [33,34]. In addition to the latter, it was reported that the ethanol extract of Illicium verum inhibits atopic-like skin lesions by suppressing the expression of cytokines, chemokines, and adhesion molecules in mice [35].

Nevertheless, the powder raw materials used in production must be handled with caution. To ensure safety and a lack of allergic reactions, where the system is incorporated, it is highly recommended to perform dermatological tests.

5. Patents

The results of this research are part of the patent application “Biodegradable complex of shikimic acid and arginine for microregeneration and smoothening fibers of delicate fabric” related to EP2178408.