Biologically Active Components and Skincare Benefits of Rice Fermentation Products: A Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper deals with the relationship between the rice active components in fermentation products with skincare benefits. It cannot be published in its current state. A major revision needs to be made.

1.     In the introduction of your research, please add a paragraph based on the latest trend data on why and why not focus on rice in 2025.

2.     Fermentation requires a carbon source. Rice generally has three parts: the husk, the bran, and the endosperm part. So, the authors should state which parts are used to make the RFP. If whole parts are used to make RFP, some discussion should be made to distinguish the contribution from three parts. Some figures are needed before section 2.1

3.     The words absorption and penetration should be used with caution. The active/inactive action of cosmetic ingredients onto the skin is often due to the transdermal transport system, not the ingredients. Therefore, section 2.2.2 should be rewritten.

4.     In section 3., general composition % should be mentioned before 3.1

5.     Table 1 should be re-arranged; Based on rice variety or skincare benefits. The table is too mixed, so not clearly summarized.

Author Response

This paper deals with the relationship between the rice active components in fermentation products with skincare benefits. It cannot be published in its current state. A major revision needs to be made.

[Response] Thank you for the Reviewer’s valuable feedback. We appreciate your insights regarding the manuscript. We understand that significant revisions are required, and we are committed to making the necessary improvements. We will carefully address the issues raised and revise the manuscript accordingly to enhance its clarity and depth. We hope that the revised version will meet the standards for publication.

 

Comment 1: In the introduction of your research, please add a paragraph based on the latest trend data on why and why not focus on rice in 2025.

[Response] Thank you for the Reviewer’s insightful comment. We appreciate your suggestion to include a discussion on the latest trends regarding the focus on rice in 2025. In response, we have added a new paragraph in the Introduction that addresses the current and emerging trends in rice-based research, particularly with regard to the year 2025. This new paragraph emphasizes the growing interest in rice as a sustainable, bioactive resource, driven by its rich composition of bioactive compounds and its potential applications in skincare. It provides readers with an updated perspective on why rice is gaining traction as a key ingredient for future research and development in the cosmetic industry.

The newly added paragraph and figure are as follows:

Rice, a rich source of amino acids, peptides, organic acids, polyphenols, vitamins, and polysaccharides, has garnered growing attention for its diverse skincare benefits [3]. Research has demonstrated its potential to enhance skin hydration, improve skin barrier function, mitigate oxidative stress, promote skin whitening, and address signs of aging [2]. Recent trends indicate a significant rise in scientific interest regarding the skincare applications of rice, demonstrated by the increasing number of related publications in the Google Scholar database (Figure 1). This expanding research underscores the potential of rice as a promising natural ingredient for future exploration, driving innovation in the development of advanced and effective skincare formulations.

 

Comment 2: Fermentation requires a carbon source. Rice generally has three parts: the husk, the bran, and the endosperm part. So, the authors should state which parts are used to make the RFP. If whole parts are used to make RFP, some discussion should be made to distinguish the contribution from three parts. Some figures are needed before section 2.1.

[Response] Thank you for the Reviewer’s valuable suggestion. We agree that it is important to specify which parts of the rice are used in the production of RFP and to discuss the contributions of each part. In the revised manuscript, we have added a more detailed description in Section 2.1 and included relevant figures (Figure 2) to clarify the parts of rice involved in fermentation.

The added section is as follows:

Rice generally consists of four main parts: the husk (~20%), the germ (~2%), the endo-sperm (~70%), and the bran (~8%) (Figure 2). The husk, primarily composed of cellulose, serves as the outer protective layer and is removed during processing. For fermentation purposes, the germ and bran of rice are commonly utilized due to their higher nutrient content (e.g., proteins, vitamins, amino acids, and polyphenols) and their capacity to support microbial growth. The endosperm, primarily composed of starch, is less frequently utilized in fermentation; however, it can function as a secondary carbon source, as microorganisms are capable of hydrolyzing the starch into fermentable sugars.

 

Comment 3: The words absorption and penetration should be used with caution. The active/inactive action of cosmetic ingredients onto the skin is often due to the transdermal transport system, not the ingredients. Therefore, section 2.2.2 should be rewritten.

[Response] Thank you for the Reviewer’s valuable comment. We appreciate the reviewer’s insightful comment regarding the terminology used in the manuscript. We agree that the terms "absorption and penetration" are not appropriate in this context. The more suitable terms are "biocompatibility and bioavailability," as the fermentation process enhances the biochemical and physiological activity of active ingredients in rice by breaking down high-molecular-weight compounds into smaller, low-molecular-weight substances. This transformation significantly improves their biocompatibility and bioavailability, enabling these compounds to be more effectively utilized by the skin, which better aligns with the intended meaning we wish to convey.

The revised version of section 2.2.2 is as follows:

2.2.2. Enhanced biocompatibility and bioavailability

Fermentation increases the biochemical and physiological activity of active ingredients in rice by breaking down high-molecular-weight compounds into smaller, low-molecular-weight substances. This transformation significantly improves their biocompatibility and bioavailability, enabling these compounds to be more effectively utilized by the skin [33]. The fermentation process also facilitates the utilization of active ingredients that might otherwise be too large to efficiently penetrate the skin barrier. For example, the protease generated during fermentation hydrolyzes large proteins into smaller amino acids and peptides, which are more readily absorbed by the skin [34]. Furthermore, a review by Janarny et al. demonstrated that rice fermentation modifies the structural properties of polysaccharides by converting larger molecules into smaller, more absorbable forms, thereby boosting their absorption and efficacy [29].

 

Comment 4: In section 3., general composition % should be mentioned before 3.1

[Response] Thank you for the Reviewer’s helpful suggestion. Indeed, a general composition for each component should be provided in Section 3. We have now included the general composition of the key bioactive compounds found in rice fermentation products (RFP) and their typical composition ranges. Consequently, we have revised Figure 1 into Table 1 (as shown below). However, this is an approximate value, as the exact composition percentages of bioactive compounds in RFPs can vary due to several factors, including the rice variety, fermentation process, microbial strains, extraction methods, and the specific conditions under which fermentation occurs.

Table 1. Key bioactive compounds present in rice fermentation products (RFP).

Key Bioactive Compounds	General Composition	Typical Compounds
Amino acids	10~30%	Glutamic acid, lysine, glycine, serine
Peptides	5~15%	Glutathione, rice peptides
Organic acids	5~15%	Lactic acid, citric acid, malic acid
Polyphenols	1~5%	Ferulic acid, γ-oryzanol, phytic acid
Polysaccharides	15~30%	Mannan, hyaluronic acid, β-glucans
Vitamins and minerals	1~5%	Vitamin B, Vitamin E, Mg, P, Se, Zn

 

Comment 5: Table 1 should be re-arranged; Based on rice variety or skincare benefits. The table is too mixed, so not clearly summarized.

[Response] Thank you for the Reviewer’s valuable comment. We agree that the organization of Table 1 could be improved to enhance clarity. Given that skincare benefits are closely associated with rice variety and its bioactive components, it is preferable to present these relationships in a single table. However, the information regarding the fermentation strain is not directly relevant to this table, and the active ingredients can be more clearly categorized to enhance clarity and simplicity. Therefore, we have revised Table to improve its organization and enhance the clarity of the summary.

Reviewer 2 Report

Comments and Suggestions for Authors

This is outstanding manuscript and I enjoyed reading this valuable review. Data is nicely presented, figures are of high quality, tables nicely present data and references are appropriate. I believe this manuscript adds to the body of literature in the field of cosmetic science and it will be of interest to a broad audience. I only have few suggestions for the authors: 

1. I would add some insights to the abstract of previous studies to make it more interesting to readers

2. Line 52 - e

3. Use full term for figure 1 title 

4. If table 1 is only presenting in vitro studies or animal studies explain in the title, if not add another table for clinical trials

5. Subsection 4.4. - you say clinical trials but cite only reference 97

6. 4.7. - extensively documented but again only one clinical trial 

7. Line 408 - i would say there is a general lack of clinical trials with rice products 

Author Response

This is outstanding manuscript and I enjoyed reading this valuable review. Data is nicely presented, figures are of high quality, tables nicely present data and references are appropriate. I believe this manuscript adds to the body of literature in the field of cosmetic science and it will be of interest to a broad audience. I only have few suggestions for the authors.

[Response] Thank you very much for the Reviewer’s positive feedback and kind words. We are delighted to hear that you found the manuscript valuable and that the data, figures, tables, and references were well presented. Your comments are greatly appreciated, and we are pleased that the manuscript contributes to the field of cosmetic science. We will carefully consider your suggestions and look forward to addressing them to further improve the manuscript.

 

Comment 1: I would add some insights to the abstract of previous studies to make it more interesting to readers.

[Response] Thank you for the Reviewer’s valuable suggestion. We agree that adding insights from previous studies will enhance the manuscript and make it more interesting for readers. In the revised manuscript, we have revised the abstract and introduction section to include key findings from prior research, highlighting their relevance to the current study to make it more interesting to readers.

 

Comment 2: Line 52 – e.

[Response] Thank you for the Reviewer’s helpful comment. We appreciate your observation regarding the extra "e" in Line 52 “We first discuss the e fermentation process and advantages of RFP”. In the revised manuscript, we have removed the unnecessary "e" from the relevant section.

 

Comment 3: Use full term for figure 1 title.

[Response] Thank you for the Reviewer’s comment. We have revised the title to include the full term: “Key bioactive compounds present in rice fermentation products (RFP).” 

 

Comment 4: If table 1 is only presenting in vitro studies or animal studies explain in the title, if not add another table for clinical trials.

[Response] Thank you for the Reviewer’s comment. This table presents only in vitro studies and animal studies, and we have clarified this in the title. The title has been revised from “Representative RFP and their multifaceted skincare benefits” to “Representative RFPs and their multifaceted skincare benefits at the in vitro and animal levels.”

 

Comment 5: Subsection 4.4. - you say clinical trials but cite only reference 97.

[Response] Thank you for the Reviewer’s valuable comment. We appreciate the reviewer bringing this to our attention. We have revised Subsection 4.4 to include additional relevant references, such as Refs [15, 90, 98], which report a significant reduction in hyperpigmentation or a whitening effect following the use of RFP in clinical studies. Additionally, we have included an example from Ref [98] after Ref [97]. The revised Subsection 4.4 is as follows:

4.4. Whitening

Melanogenesis is a complex process involved in the synthesis of melanin pigments, which is the primary cause of skin pigmentation [94]. Sangkaew and collaborators demonstrated that fermented unpolished black rice significantly reduced cellular melanin content and markedly decreased intracellular tyrosinase activity in B16F10 melanoma cells [95]. Furthermore, the fermentation product notably decreased the mRNA and pro-tein expression levels of tyrosinase-related protein 1 and 2, as well as microphthalmia-associated transcription factor (MITF). Chung et al. found that co-fermentation of rice bran with Lactobacillus rhamnosus and Saccharomyces cerevisiae significantly inhibited α-melanocyte stimulating hormone (MSH)-induced melanin synthesis and notably reduced MITF expression [96]. Several clinical trials have also reported a significant reduction in hyperpigmentation or a whitening effect following the use of RFP [15, 90, 97, 98]. For example, Jufri et al. evaluated the efficacy of a lotion containing 10% fermented black rice bran extract in 34 female subjects [97]. After 14 days of use, the lotion significantly reduced both the melanin and erythema on the forearm, indicating its effectiveness in reducing skin melanin production. In another study, Manosroi et al. formulated a cream containing fermented rice bran-encapsulated niosomes, and skin pigmentation changes were evaluated using a mexameter. The results showed that, after 28 days of treatment, skin melanin levels were reduced by a factor of 33.2 compared to the untreated group [98].

 

Comment 6: 4.7. - extensively documented but again only one clinical trial.

[Response] Thank you for the Reviewer’s useful comment. As the reviewer pointed out, the phrase 'extensively documented' was not entirely accurate, given that the current body of work predominantly focuses on in vitro and animal studies. We have revised this expression accordingly. Additionally, we have added two more references as examples to strengthen this section, ensuring it encompasses in vitro, animal, and clinical studies. The revised Section 4.7 is as follows:

4.7. Anti-aging

Aging skin is characterized by wrinkles, loss of elasticity, and reduced collagen production [106]. Due to their rich content of bioactive compounds that promote collagen synthesis and inhibit collagen degradation, RFP has demonstrated anti-aging effects in numerous in vitro and animal studies, as well as in several clinical studies. For instance, JournLee et al. evaluated the anti-aging effects of rice koji fermented with Aspergillus oryzae and Aspergillus cristatus in HDFs [107]. They found that the fermented products significantly increased the RNA expression levels of collagen, elastin, and MMP-1. A study by Young-Kwon Seo et al. demonstrated that fermented rice bran extract could enhance type I collagen synthesis, reduce MMP-1 expression, and suppress IL-1α production in a photoaged human fibroblast model [108]. Moreover, Li et al. found that rice fermented with Lactobacillus plantarum protected mice from UVA-induced aging [93]. Histological analysis revealed improvements in skin photoaging, including reduced wrinkles, enhanced collagen organization, and a smoother epidermis compared to untreated mice. In a randomized controlled trial, Zhou et al. reported that, after 8 weeks of using a face cream containing yeast/rice fermentation filtrate, subjects exhibited a significant reduction in the area and length of wrinkles around the eyes, as well as improvements in skin firmness and smoothness [91].

 

Comment 7: Line 408: I would say there is a general lack of clinical trials with rice products.

[Response] Thank you for the Reviewer’s valuable suggestion. Upon careful consideration, we agree that emphasizing the general lack of clinical trials involving rice fermentation products (RFP) is more pertinent to the "Challenges and Limitations of RFP" section. We have revised the paragraph to address the scarcity of clinical trials in this area, which aligns more closely with the focus of the discussion (Discussion section, paragraph 4).

The revised paragraph is as follows:

Thirdly, existing research on RFP is predominantly limited to in vitro studies and a few animal models, with a notable lack of clinical trials involving human subjects. While cell-based and animal studies offer valuable insights into the biological activities and potential benefits of RFP, they may not fully reflect the complexities of human skin responses. The absence of well-designed clinical trials significantly hinders the comprehensive understanding of RFP’s efficacy, safety, and long-term benefits in practical ap-plications. To bridge this gap, future research must prioritize human clinical studies to validate the promising findings from preclinical models, assess the practical applicability of RFP in skincare, and explore potential variability in skin reactions across different populations. Specifically, large-scale, multi-center clinical trials involving diverse age groups, skin types, and geographic regions are essential to ensure the reliability and generalizability of findings.