Kaala Dhaan (Indian black rice) from heritage feasts to global exports: The genetics, phytochemical profiling, therapeutic applications, and modern commercial potential

Introduction

The ancient China has a history of utilizing Black rice (Oryza sativa L.) before dynastic times (Newman, 2004) [18] , often known by names like "emperor's rice" or "forbidden rice," it was valued/prized for its rarity and therefore served as a tribute food (Oikawa et al., 2015) [19] . Contrary to Chinese varieties of Black rice (which were limited to aristocrats and royalty), Indian races like Chak-Hao (in Manipur) and Karuppu Kavuni (in Tamil Nadu) were historically integrated into community feasts and religious offerings (Devi et al., 2024) [4] . In the current global market, Asia, specifically India, has appeared as a budding major market because of Indian black rice, also known as Chak-Hao, which has gained international recognition with its 2020 GI tag, thus ensuring economic returns with its easy availability on e-commerce platforms, and economic profits are reaching rural Indians because of this recognition, which has generated export interest in gourmet stores, making it a high-value functional food product (Devi et al., 2024) [4] . The current business statistics from 2024 to 2025 report an annual growth rate of 23% in the export of Black Rice from India, directly competing with the existing production belts in China and Vietnam. Although China leads in the race to supply more volume, Indian variants are branded as 'Artisanal and Heritage Grains,' sold with high prices in the EU and US markets because of their better Aroma Uniqueness. Limited to the North Eastern Himalayas and scattered regions in Southern India earlier, the cultivation of 'Black Rice' is now experiencing an expansion strategy of 'Pan-India,' as of 2024, through the 'One-District One-Product' scheme, where experimental plantation activities were started in non-traditional growing states such as Maharashtra and Uttar Pradesh (VolzaTradeData,2025) [32] .

Ethnobotany and Cultural Importance

The credit for survival of black rice in India must be given to tribal communities, who preserved the races by "Traditional Ecological Knowledge" (TEK). By them it was not merely grown for food, but also as a functional remedy (long before the term "nutraceutical" existed). Contrary to the present hight yielding "Green Revolution" varieties, these historical races were grown and for centuries in rainfed conditions and with minimal external fertilizer inputs, and thereby making them reservoirs of stress-tolerant genes (Borah et al., 2018) [1] . Two most prominent landraces of Indian Black Rice are: a) Manipur (Chak-Hao): The name translates to "Delicious Rice" (Chak = Rice; Ahaoba = Delicious) in the Meitei language. Traditionally in Manipur, sisters present black rice to their brothers as symbol of love and prosperity during Chak-Hao Amubi ritual of the Ningol Chakouba festival. The brewed product, called Chakhao-atingba (Loukrakpam et al., 2025) [14] is a a traditional beverage. Such socio-cultural importance was formally recognized with a Geographical Indication (GI) tag in 2020 by Government of India (GoI, 2020). b) Tamil Nadu (Karuppu Kavuni): Known as "Burma

Black" or the "Black Pearl," folklore suggests this variety was brought to Tamil Nadu from Burma by the Nattukottai Chettiars, a trading community who were once the primary financiers of Burma's rice industry (Rudner, 1994) [27] .

Botany and Origin

Black rice differs from the normal white rice due to the deposition of anthocyanin pigments within the pericarp, seed coat, and aleurone layers (Goufo and Trindade, 2014) [8] . Black rice differs genetically from the wild ancestor Oryza rufipogon, which generally has red grains. Recent genomic studies indicate that the black trait originated through a mutation in the Kala4 gene on chromosome 4, a basic helix-loop-helix transcription factor. This rearrangement in the Kala4 promoter originally took place in the subspecies tropical japonica and then introgressed into the indica varieties through natural crossbreeding cross breeding (Oikawa et al., 2015) [19] . This evolutionary distinctiveness categorizes Indian varieties such as Chak-Hao and Karuppu Kavuni as distinct landraces rather than mere hybrids.

Nutritional Profile and Phytochemistry a) Macronutrient Composition

Indian black rice is being increasingly grouped with "functional foods." Proximate analysis shows that Indian black rice such as Chak-Hao and Kalavati has 8.5% to 9.0% protein content compared to 6.8% in white rice (Roy et al., 2021) [26] . The protein part includes all nine essential amino acids with higher amounts of Lysine and Tryptophan than usually found in grains (Jha et al., 2017; Javed et al., 2025) [12,11] . Moreover, it has lipids rich in lipophilic antioxidants such as gamma-oryzanol and tocopherols (Min et al., 2011; Ito & Lacerda, 2019) [16,10] . As mentioned by Miftahurrahmi et al., 2025 [15] even if the fatty acid composition of black rice is primarily dominated by linoleic acid (same is case with white and red varieties) its functional lipid fraction is highly enriched.

b) Micronutrient Density

One of the strongest reasons for black rice being promoted as a food is its efficacy in fighting the problem of "Hidden Hunger." Variability in black rice was found to be high, along with higher mineral concentration. The iron content in black rice was found to be 3.5 mg/100g, while that of zinc was around 3.3 mg/100g (Kumari, 2020) [13] . Ramanathan et al. (2014) [22] directly compared the iron and calcium content in Kavuni black rice with improved white rice, finding that iron levels in black rice are 20-30% higher than in modern white rice, along with 33-45% higher calcium.

It must be noted that iron & zinc in black rice could be unaffected by the amount of anthocyanin accumulation (Gogoi et al., 2024) [7] .

c) Phytochemistry: The Anthocyanin Advantage

The dark purple-black pericarp is determined by the Kala4 gene. Cyanidin-3-glucoside (C3G) is the most abundant anthocyanin, followed by peonidin-3glucoside, accounting for over 80% of total anthocyanin content (Thapa et al., 2024; Zhang et al., 2010) [30,37] . HPLC analysis confirms the presence of both compounds (Sahewalla et al., 2023) [28] . The total antioxidant capacity is notable, with phenolic content ranging from 37.101 to 493.611 mg GAE/100 g (Gallic Acid Equivalent per 100 grams). in studied genotypes. d) Glycemic Index (GI) and GABA Black rice, in particular the Kavuni variety, is characterized by possessing a low Glycemic Index (GI) food with a value of 53.10, attributed to its low simple starch (60%) and high resistant starch (38%) content. It also contained higher fibre content (4.7g/100g) (Parthiban, 2025) [20] . Moreover, upon germination, black rice exhibits a noticeable increase in Gammaaminobutyric acid (GABA), a neurotransmitter aiding in stress reduction and hypertension management (Yamuangmorn et al., 2024) [36] .

Agronomy, Genetics, and Breeding a) Genetics and Plant Breeding

In the past, the constraints like low yield (<2.0 tonnes/ha) and lodging due to tall plant height were major bottlenecks. This changed for the better in 2024-2025, being a historic moment. The ICAR-Research Complex for NEH Region released RC Manichakhao-1, the first High-Yielding Variety (HYV) of black rice. This semi-dwarf crop has lodging resistance with an estimated yield potential of 4.5-5.0 tonnes/ha (PIB, GoI, 2024 pib.gov.in) [21] . In addition, Nameirakpam et al. (2024) [17] incorporated the blast resistance gene 'Pi54' with the high-yielding gene 'OsSPL14' using markerassisted backcrossing in the Chak-Hao genome, resulting in line ChM 68 which retained high anthocyanin content (240.31 mg/100g).

b) Agronomy and Remote Sensing

Precision farming is increasingly being integrated into current agronomy practices. Rao et al. (2022) [23] employed Sentinel-2 satellite data along with the Modified Anthocyanin Reflectance Index (mARI) to differentiate black rice crops from green paddy fields.

In efficient agricultural methods, Dambale et al., (2025) [3] found that the application of vermicompost from the pseudo-stem of banana plants improved rice tillers and weight within the context of the System of Rice Intensification (SRI) method, providing an efficient alternative to the use of potash chemicals.

Clinical Biology and Therapeutic Mechanisms

Recent in vivo clinical trials provide evidence for health claims: a) Malnutrition: In the groundbreaking study conducted by Sharma & Priyadarshini (2024) [29] at the Sambalpur University, 'Nutri-Nest,' an iron-rich supplementary food prepared from Kalavati Rice (black rice race in Orrisa), reached conclusive weight gain and improvement from malnutrition when tested on mice pre-clin b) Diabetes: Eviana et al. (2023) [5] [33] on 60 coronary heart disease (CHD) patients, results suggested that supplementation with Black Rice Pigment Fraction (BRF) noticeably improved plasma Total Antioxidant Capacity (TAC) and reduced critical inflammatory biomarkers (sVCAM-1 and hs-CRP). Thereby concluded that anthocyanins could play an active role in stabilizing atherosclerotic plaques and reducing vascular inflammation in patients. e) Improvement in immunity and defence: Fan et al. in 2017 [6] , demonstrated the immunomodulatory effects of black rice anthocyanins in WEHI-3 leukemia murine models. The extracts promoted in-vivo multiplication of T-cells (CD3) and macrophages (Mac-3) and augmented phagocytosis. Their work showed the potential of black rice in improving enhance immune surveillance in cases of immunocompromised subjects.

Value Addition and Processing Technology

Processing plays a key role in preserving the bioactivity of such products. According to Javed et al. (2025) [11] , High-Temperature/Pressure Processing (HTP) at 115°C for 20 mins proved effective with increased heat-stable flavonoids and quercetin derivatives by 22%, whereas milling decreased anthocyanins by 74%, whereas in its application for the production of puff snacks, it preserved 70-80% of anthocyanins Fermentation represents another area for value addition. In fact, the optimized procedures for Chak-Hao wine were assessed in a review undertaken by Loukrakpam et al.

(2025) [14] , which indicated that the fermentation process helps retain compounds like anthocyanins that act as a functional food competitor in the form of red wine in the foreign market due to its rich sensory attributes.

Global Economy and Market Dynamics

In 2024, the black rice market across the globe is calculated to be USD 9.38 billion, whereas at the end of the year, the figure is expected to reach USD 10.13 billion, with a CAGR of 8.5% (Research And Markets, 2025) [24][25] . Some major drivers are plant-based proteins and the natural colorant industry. This is a premium crop for Indian farmers.

Comparing the Minimum Support Price for regular paddy rice at ₹23/kg, their organic black rice is sold for ₹80-120/kg in the domestic market (Introspective Market Research, 2025) [9] . Export markets are Europe, the USA, and New Zealand; but these strictly necessitate Organic Certification for the products when being exported. The most notable achievement was signing a MoU in 2025 for exporting Chak-Hao to Japan. [35,2] . c) Supply Chain: The 2023-2024 ethnic conflict in Manipur resulted in approx. 60% drop in exports, pointing to the danger of geographical centralization (The New Indian Express, 2024) [31] . d) Adulteration: There is an increased adulteration of white rice with artificially colored rice. More stringent FSSAI regulations are required to cope with this menace, along with consumer awareness through domestic tests (simple water tests). [34] 2 Cardiovascu lar Plaque Stabilization Supplementation with Black Rice Pigment Fraction (BRF) improved plasma antioxidant capacity and reduced inflammatory markers (sVCAM-1, hs-CRP) in CHD patients.

Major

Wang et al. (2007) [33] 3 Diabetes Insulin Regulation Bioactive compounds from black rice bran restored insulin levels in Type 2 diabetic rats to near-normal levels, comparable to Metformin. Eviana et al. (2023) [5] 4 Immunity Immunomodulation Extracts significantly enhanced in vivo proliferation of T-cells and macrophages, improving immune surveillance in leukemia models. Fan et al. (2017) [6] 5 Nutrition Malnutrition Recovery

Nutri-Nest' supplementary food resulted in conclusive weight gain and recovery from malnutrition in murine models.

Sharma & Priyadarshini (2024) [29] 6 Agronomy First HYV Release Release of RC Manichakhao-1, a semi-dwarf, lodging-resistant variety with a yield potential of 4.5-5.0 t/ha (vs. traditional <2.0 t/ha).

PIB. GoI, 2024 pib.gov.in, [21] 7 Breeding Marker-Assisted Selection Developed line ChM 68 by incorporating blast resistance (Pi54) and highyield (OsSPL14) genes while retaining high anthocyanin (240 mg/100g).

Nameirakpam et al.

(2024) [17] 8 Processing Nutrient Retention High-Temperature/Pressure (HTP) processing (115 °C) increased heatstable flavonoids by 22%, whereas traditional milling destroyed 74% of anthocyanins.

Javed et al. (2025) [11] 9 Value Addition Fermentation Optimized fermentation (wine) retains anthocyanins and offers sensory attributes competitive with premium red wines.

Loukrakpam et al.

(2025) [14] 9. Conclusion and Future Prospects Indian Black Rice, Kaala Dhaan, occupies the space where traditional agricultural practices meet the nutraceutical food system. The product's history, which ranges from the royal cuisines of Manipur to the health food shelves in the West, establishes its robustness. For future success, its cultivation needs to be decentralized to non-traditional states to deal with potential supply chain issues, technological advancements for low-cost processing methods should be pursued for small farmers, and then from animal-based studies to human clinical studies should be pursued to establish its health properties. The black rice crop is not just an agricultural product; it is an opportunity for the biofortification of nutritional deficiencies with the global demand for organics.

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