Why the garlic turn green?
1, Through a large number of experiments, Scientists found that the content of propylene cysteine sulfoxide (PECSO) have increased significantly in all the garlic which turn green. How to prove the relationship between PECSO and garlic greening? When scientists added the PECSO (which extracted from the onion) into garlic paste (which donot turn green), the garlic paste turned green very quickly. Therefore, PECSO is the key point to turning green.
2, PECSO, itself, has no color. Why does this colorless substance cause garlic to turn green? After more in-depth research, scientists found that this is the result of a very complex set of enzymatic reactions. PECSO is catalyzed by allinase to form a pigment intermediate; the pigment intermediate reacts with pyruvate, amino acid and allicin in garlic to form yellow pigment and blue pigment. When these two are mixed together, that is what we see–green color.
3. How PECSO produce in garlic? Why does this content of substance increase after shredding, acid treatment or refrigeration? We will have to mention another enzyme, which is called γ-glutamyl transpeptidase.
Garlic itself is made up of cells. Usually peptides and this enzyme cannot meet, but if they are chopped, the enzyme and the substrate will be combined, and the reaction speed will be much faster for surely. Acid treatment can increase the permeability of cell membranes and can also release enzymes from the cells. It can catalyze the hydrolysis of a certain polypeptide in garlic into PECSO. When the content of this enzyme increased significantly, PECSO can be produced in large quantities.
4. What are the conditions for a significant increasing the percentage of γ-glutamyl transpeptidase? that will be done. According to scientists’ experiments, under the temperature of 0-4°C, the enzyme have the highest activity.
In China, the harvest time of the garlic is every May. After harvested, the garlic will enters the dormant period. Generally, the dormant period is about 60-90 days, which is around three months after the harvest. At this time, the activity of γ-glutamyl transpeptidase is very low. At the end of August, we have to move the garlics into the cold house for storage, the temperature is between -2 and 2°C, the dormancy of garlic will be broken, and γ-glutamyl transpeptidase will be activated one by one, thus opening the first lock of the green change reaction.
Is it safe to eat the greening garlic?
There is no need to panic when garlic turns green. This is a normal phenomenon. This green pigment is not harmful, but has a good effect on the human body because it has a strong antioxidant capacity. But, if you find the garlic lose the right taste, please throw it away quickly.
How to prevent the garlic turning green?
1, Maintain the integrity of garlic, reduce chopped and acid treatment.
2, To blanched the garlic with hot water, to lower the activity of γ-glutamyl transpeptidase
3, To avoid stock the garlic at the temperature of 0-4°C. Directly freeze the garlic under -18°C.
Linyi Organic Foodstuffs Co., Ltd, is one leading factory to produce the frozen vegetables and frozen fruits in China. We can produce the frozen garlic all year round. However, if you want to order some frozen garlic without turning green after de-freezeing, please place the order before the middle of August. With 20 years of experience, We can freeze the garlic under -35°C with very quickly, to keep the garlic at dormant, to avoid the garlic greening.
Please check our production flow chart:
Raw garlic materials→cut the garlic head root→separate and peel the skin→choosing by hand→wash with clean water→blanched by hot water→cooling by clean water→draining water→Individual quick freeze→choosing by hand→metal detector→weight and pack with carton→stock with pallets
Linyi Organic Foodstuffs Co., Ltd is a professional manufacturer and supplier of Frozen vegetables and frozen fruits products in China. Our factory has rich experience production for frozen vegetables and fruits. We have self-owned and contracted farm to plant raw materials to guarantee quality from the source. Well-experienced worker and QA team, advanced traceability system will make sure our product reached European high-quality standard.