Crocin (gardenia yellow), commonly known as the yellow gardenia, belongs to the carotenoid series. It is the yellow pigment in gardenia, whose composition is crocin-a kind of carotenoid pigment, the same to the crocin in saffron crocus. The molecular formula is C44H64O24, and relative molecular mass is 976.97. Gardenia yellow can be used for fruit juice, drinks, mixed wine, colorfulcakes, popsicles, ice cream, jelly, puffed food, bread, candies and canned chestnuts.

English name: Gardenia Yellow

Alias: Crocin

Molecular formula: C44H64O24

Molecular weight: 976.9656  

CAS: 94238-00-3 

The main composition of gardenia yellow pigment is carotenoid crocin and crocetin, and it also contains iridoid glycoside-geniposide, flavone, and chlorogenic acid. Crocin and crocetin are rare water-soluble carotenoid, with a number of conjugated double bonds which give gardenia yellow pigment on one hand and instability of gardenia pigment on the other hand [2]. Gardenia yellow pigment has seven kinds of crocetin derivatives, whose chroma and lightness show little difference. However, with the increase of glucosyl connected to crocetin, the derivative hue shall reduce, and the tinct shall change from red to yellow.

It’s of orange yellow crystalline powder with slight odor, soluble in water, and in water it shall immediately dissolve into transparent yellow liquid; soluble in ethanol and propylene glycol, insoluble in oil, and pH value has little effect on tonality. Its tonality in acid (pH 4~6) and alkaline (pH 8~11) is more stable than beta carotene, especially in the alkaline, yellow is much more distinct, and wavelength around 440nm gives maximum absorbance. Salt tolerance, reducibility resistance, and microbial resistance are good, in neutral or alkaline conditions, gardenia yellow shows good heat and light resistance; while at low pH value, heat and light resistance is poor with easy brown stain. It has good dyeing effect on protein and starch, that is, hydrophilic food, but in aqueous solution it is not stable enough. It fades much more significantly in acidic than in alkaline solution. For metal ions (such as aluminum, calcium, lead, copper, tin, etc.) it’s quite stable, and iron ions tend to darken gardenia yellow [1]  

Food industry

Gardenia yellow pigment can restrain 80% of the oxidation of linoleic acid , thus it can be used as an antioxidant in food processing; it shows good heat resistance, and the pigment remains at over 85% under the condition of 80 ℃ for 120 minutes.  In visible light (40lun -700nln), it’s stable against light irradiation, but unstable in the light with wavelength 250nm-390nm. Therefore, gardenia yellow pigment can be used as a colorant and antioxidant in the food industry. 

Gardenia yellow pigment shows strong dyeing power against proteins and starches, and can be widely used in cakes, candies, beverages, flour, biscuits, jelly, ice cream and other food.

Silk fabrics

Research shows that natural gardenia yellow has strong dyeing power against silk fabrics. Direct dyeing and mordant dyeing are applied under various conditions, and an optimal dyeing process is obtained through orthogonal test. The results show that silk fabrics can be directly dyed with gardenia yellow, and dye dosage has the greatest influence on dyeing results, the improving performance of dyes is relatively good. Post-mordant dyeing is suitable for gardenia yellow mordant, compared with direct dyeing; fabric color with post-mordant dyeing shows little change. Except that the light fastness is no more than 3, the fastness of almost all other items is more than 4. 

Pharmaceutical industry

In addition to the composition of pigments for coloring, gardenia yellow pigment also contains a certain amount of expensive crocetin, which has the effect of promoting blood circulation, dispelling fatigue, relieving pain, depressurization, and other medical value, thus can be applied to the pharmaceutical industry.

Safety

Mouse per os LD50 is 22000mg/kg. Accumulative toxicity and mutagenicity test shows weak accumulation, and no mutagenic effect. Subchronic toxicity test by adding 2% gardenia yellow pigment to fodder shows the results without any exception, so the pigment is safe. According to Hygienic Standard for Food Additives GB2760-2011: gardenia yellow can be used for fruit juice (flavored) drinks, mixed wine, colorful cakes, popsicles, ice cream, jelly, puffed food, bread, candies and canned chestnuts with maximum dosage of 0.3/kg. In actual use, 0.2/kg for soda water and sparkling wine, 0.19/kg for Zhuyeqing liquor. Prepare gardenia yellow pigment solution by adding the pigment into water at the ratio of 1:7. Good dyeing effect on egg rolls can be obtained by adding the solution into flour at the ration of 25:1 when knead dough. For dyeing cake crust, the maximum dosage of gardenia yellow is 0.3/kg; for candies, 0.05%~0.2%; for pastry, 0.01%~0.1%. Gardenia yellow pigment has good effect on beverages, which can produce bright color, and it does not change even under high temperature boiling. The amount should be 0.02%~0.1%. It should not be used in acidic beverages in case of fading. Moreover, it can be used for the preparation of health products.