Gardenia Blue is a natural colorant that originated in Japan. In the 1990s, when I was a researcher in the division of food additives, National Institute of Health Sciences, the colorant was commonly used in Japan. Since the nature of this colorant is a polymer from genipin and amino acids, it is thought to be safe, as far as control of the residual content of genipin itself. Regulation of food additives; however, is complicated in the world. FDA and JECFA has allowed its use as a food additive in recent years. This report describes my memories of this colorant as a foreword to the special issue related to Gardenia Blue.

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The Japanese government, anticipating a shrinkage in the domestic market for agricultural, forestry, and fishery products, and food due to population decline, has set an export target of 5 trillion yen (including 2 trillion yen for processed foods) by 2030, aiming to find new opportunities through exports. To achieve this target, it has formulated the "Strategy for Expanding Exports of Agricultural, Forestry, and Fishery Products and Food." Regulations on food additives vary across countries, and processed foods containing additives not approved overseas cannot be exported, making food additives one of the obstacles to promoting exports.

To address this issue, one approach is to obtain approval for food additives from foreign countries, and the other is to use food additives already approved abroad. This article outlines both approaches. Regarding the first approach—obtaining approval—significant effort, time, and expenses are required, making the commitment of company management a critical factor. For the second approach—using approved additives—it is essential to accurately understand the regulations on food additives in various countries.

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Gardenia blue is a natural blue colorant that has been used in Japan for many years. In 2008, the UK Food Standards Agency (FSA) requested voluntary restrictions on synthetic colorants. Anticipating increased demand for natural colorants, the Japanese color industry sought overseas approval. In 2014, the Abenomics export strategy explicitly included support for international approval of food additives, leading to the establishment of the Gardenia Blue Interest Group (GBIG) by San-Ei Gen F.F.I., Riken Vitamin, and Glico Nutrition. In July 2025, the US FDA approved "Gardenia (genipin) blue." Applications to EFSA and JECFA are also underway. Gardenia jasminoides is a plant native to Japan and China. Its fruit has long been used in traditional Chinese medicine and food coloring. Main components: geniposide (a source of blue and red colorants) and crocin (a yellow colorant). In Japan, the three primary colors of yellow, red, and blue are produced from gardenia and widely used in processed foods. This article will explain the manufacturing process and explain characteristics, such as its relative stability to heat and light, and its resistance to pH changes, although it may aggregate in acidic ranges. Gardenia blue is used in beverages, sweets, ice cream, candy, and more. It can also be used in combination with yellow or red pigments to produce green and purple colors. This article will explain the safety of gardenia blue pigment and its future prospects.

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A major initiative of the Japanese government is to promote the export of Japanese agricultural, forestry and fishery products and foods produced in Japan. Japanese processed foods, including those containing food additives, are highly regarded overseas and are considered to have significant export potential. However, it is known that the types and definitions of food additives that can be used in foods vary from country to country. Since food additives approved for use in Japan may not be permitted in importing countries, it is important to thoroughly understand the regulations governing food additives in other countries when considering the export of Japanese processed foods containing food additives. Therefore, to deepen understanding of food additives abroad, this paper focuses on Europe and the United States as representative foreign countries and on the Codex Alimentarius Commission as an international body, and outlines the physicochemical properties, specifications, and analytical methods of chemical substances that are permitted as food additives. Furthermore, curcumin is introduced as an example of a food colorant permitted for use in Japan and overseas, and jagua blue is introduced as a food colorant currently approved for use in food.

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The increasing preference for natural food colorants has highlighted Gardenia Blue Pigment, derived from the fruits of Gardenia jasminoides Ellis and Gardenia augusta Merrill, due to its intense color and stability compared to other natural blue pigments. This pigment is synthesized by hydrolyzing geniposide to produce genipin, which then reacts with protein hydrolysates. Despite its utility, the molecular structure of the pigment remained unknown for decades, primarily because it is a high-molecular-weight compound. This complexity made it difficult to separate and analyze, leading to a lack of clear NMR signals. Early research conducted in the 1980s proposed structures for low-molecular-weight intermediates in a model experiment with genipin and glycine, confirming that an extensive conjugated system was necessary for the blue color. However, these proposed structures did not represent the final high-molecular-weight pigment. Subsequent studies confirmed the pigment's broad molecular weight distribution but failed to obtain NMR signals from the final product. A significant breakthrough occurred in 2016, which allowed researchers to isolate intermediates with an expanded conjugated system. Using UPLC-TOFMS analysis, sharp peaks were identified, leading researchers to propose a monomer and a mechanism for the high-molecular-weight pigment. The crucial advancement was the use of solid-state NMR, which enabled the detection of signals directly from the high-molecular-weight pigment. This obstacle hindered previous research efforts. Combined with pyrolysis gas chromatography-mass spectrometry, which identified a characteristic 5H-2-pyrindine structure, the proposed molecular structure was confirmed. Quantum chemistry calculations on the pigment's molecular model supported the structural findings, indicating that the planar tetramer structure contributes to the characteristic blue absorption peak around 600 nm. This successful confirmation of the chemical structure in the model experiments opens the door to further research, particularly concerning the chemical structure of commercial gardenia blue pigments with protein hydrolysates.

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Various toxicological studies of Gardenia Blue (GB) used as a colorant were performed to obtain approval for use in the US and EU, by which the safety evaluation of GB by JECFA has also been requested. In this paper, in addition to the data in these current studies, various studies used in the JECFA evaluation were summarized and the conclusion made by USFDA or JECFA was introduced. GB was poorly absorbed upon oral exposure and excreted unchanged through the feces. In genotoxic studies, GB showed negative outcomes. In various toxicological studies, including short-term toxicity, long-term toxicity and carcinogenicity, and reproductive and developmental toxicity studies, GB showed no toxicological effects at the highest doses examined. Therefore, the NOAEL was selected using the highest dose in the rat carcinogenicity study and the ADI was determined to be 0-7 mg/kg bw per day. Additionally, geniposide and genipin, impurities identified in the GB manufacturing process, were also evaluated. The ADIs for both of these chemicals were determined to be 50 mg/kg bw per day. Overall, GB as well as the residual impurities do not present evidence of safety concerns at the expected dietary exposure.

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This report provides a comprehensive estimation of the daily intake of gardenia blue, a natural food coloring, in Japan. The study was conducted to support the application to JECFA by providing accurate exposure data based on Japanese consumption patterns and regulatory framework. In Japan, multiple studies have been conducted on food additive intake using production statistics surveys and market basket methods. However, these were insufficient for the international regulatory application. This study aimed to bridge this gap by more accurately estimating the daily intake of gardenia blue through intake estimation based on NHNS and production and import volume-based estimated daily intake (EDI) using Mintel database analysis. The study successfully established scientifically valid estimates of gardenia blue intake in Japan, supporting its safety and regulatory approval. It also highlighted the need to introduce a standardized EDI calculation system in Japan, similar to those used in the US and EU.

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Gardenia Blue has been submitted to the US FDA, EU EFSA for permission of use, and included in the FAO/WHO Joint Expert Committee on Food Additives (JECFA) priority list. The US FDA approved Gardenia Blue in July 2025, and an additional application will be submitted to expand the current permitted uses.

As a key component of the risk assessment, the Estimated Daily Intake (EDI) was calculated. The EDI evaluation used consumption data from the US, EU, UK, and Brazil, along with the CIFOCOss (Chronic Individual Food Consumption Database – Summary Statistics) developed by FAO/WHO and the commercial market database to adjust maximum use levels and estimate intake for model foods.

For the JECFA evaluation, the EDIs for Gardenia Blue were calculated based on food consumption data from multiple countries and model diets. The EDI on a Gardenia Blue Polymer basis was estimated by assuming a maximum content level of 40%.

Genotoxicity studies demonstrated that Gardenia Blue has no mutagenic or genotoxic potential. In chronic toxicity studies, the NOAEL was determined to be 2,175.3 mg/kg body weight/day. Based on the maximum EDI, a margin of exposure (MOE) greater than 100 was derived, indicating an adequate safety margin.

In the JECFA evaluation, the NOAEL for Gardenia Blue Polymer was determined to be 700 mg/kg body weight/day, and the Acceptable Daily Intake (ADI) was established at 0–7 mg/kg body weight/day. The safety of Gardenia Blue was confirmed based on the ADI and EDI assessments.

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The U.S. regulatory landscape for blue color additives reflects growing consumer demand for naturally derived colors. Several exempt from certification blue colors, including most recently Gardenia (genipin) blue, have been approved for use in food by the U.S. Food and Drug Administration (FDA) to try to meet this demand. However, all color additives in the US are subject to strict pre-market regulatory review, regardless of source. It is expected that stakeholders will collaborate to ensure that color additives used in the U.S. continue to be of the highest safety and quality, in an effort to satisfy consumer demand, regardless of source.

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About 250 species of Gardenia are native to the world, and several species are considered medicinal worldwide. It has diuretic, sedative, antifebrile, and anti-inflammatory effects, and is used in Kampo medicine such as Inchinkoto, Ourenngedokuto and Saikoseihaito. The main components of Gardenia are iridoid glycosides and the yellow pigment crocin. There are two types of dyes obtained from Gardenias fruit, the yellow dyes based on crocins and blue dyes based on iridoid glycosides, which are widely used as food dyes in the world.

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In the culinary arts, visual appeal is just as crucial as how it tastes. There has been a growing trend across various cuisines, not limited to French cuisine, to avoid artificial food dyes and instead embrace dishes with the original colors of natural ingredients. Against this backdrop, a natural blue pigment extracted from gardenia fruit has garnered increasing attention. Its crystal-clear and stunning blue possesses a unique beauty that is difficult to achieve with other natural food color, capable of adding a refreshing and impressive splash of color to sauces, gelée, drinks and desserts. Furthermore, when mixed with a yellow pigment from the same gardenia plant, it enables the creation of a diverse spectrum of colors, including green. This enables a wider range of culinary expressions and presentations, further enhancing the visual delight of dishes. This blue pigment is also highly valued for its practicality; it is relatively stable against heat and light, which means minimal discoloration after cooking. As an ingredient that brings a new expression to dishes while preserving the integrity of natural color, gardenia blue is expected to garner even greater attention and find broader application in the future.

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