How to make purple-skinned eggplant without discoloration?
Experimental materials:
Purple-skinned eggplant cut into segments and hobnail pieces.
Old vinegar, salt, water, vegetable oil, mixed seasoning sauce.
Different cooking methods:
Popping: large areas of brown color, a small amount of purple.
Steaming: large areas of tan, small amounts of purple.
Microwaving: large area purple, few discolorations.
Note:Eggplants have not been otherwise treated.
Steaming - different pre-treatments:
No treatment, soaking in water, soaking in 2.5% salt water, soaking in 5% vinegar water, soaking in salt + vinegar mix - soaking time is 10 minutes.
No treatment - tan color.
Water immersion-large areas of tan, retaining purple color locally.
5% vinegar water immersion-large area purple, localized browning.
Mixed salt + vinegar soak-large area purple, small amount brown.
Frying - different pre-treatments:
No treatment, 5g salting, frying at 160°C for 1min.
200g of eggplant per portion.
Frying at 160°C for 1min - purple color almost unchanged.
Color of fried:
No treatment-brown color, few purple.
Salted-mostly purple, less brown.
Fried-mostly purple, a little tan.
Steamed eggplant discoloration fact sheet.
Every time you order eggplant for eating out, you are always amazed at its well-preserved purple color when you serve it, and you wonder more than that: why is it that the purple-skinned eggplants in restaurants retain their bright purple color after cooking? But when you make it at home, it always changes color! What to do to retain the fragile purple color of the eggplant skin.
Purple-skinned eggplants were pre-treated in different ways, and a few common ways were chosen for cooking (simplified); after the eggplants were cooked all the way through, the color change of the skin was compared to summarize the practices for eggplants that don't change color.
Experimental results
Different cooking methods
Purple color retention area: stir-frying < steaming < microwave heating.
Steaming - different pre-treatment
Purple retention area: no treatment Frying - different pre-treatments Purple retention area: no treatment Summary: In terms of cooking methods, microwaving retains more purple, while stir-frying loses almost all of it. Before steaming, soaking in brine or vinegar is good for retaining the purple color, but the salt and vinegar mixture will change the eggplant skins from purple to reddish-purple. Before frying, both salting and deep-frying treatments were favorable for retaining the purple color, but deep-frying was more effective. Experiment principle: What is the purple color in eggplant Anthocyanin. Anthocyanins are one of the main color-presenting substances in plant fruits and petals. Purple-skinned eggplant contains anthocyanins mainly delphinium pigment and petunia pigment, accounting for about 90% and 5% respectively. Eggplant fruit skin, the higher the anthocyanin content, the darker the color of the skin. Why the purple will change Anthocyanin is very active, temperature, pH, light, oxygen, metal ions, etc. will affect its stability; especially heat-sensitive, thermal processing will lead to the degradation of anthocyanin, so that its content is reduced. Heating temperature below 60 ℃ when the impact is not obvious, more than 80 ℃, anthocyanin content is significantly reduced. In addition, the purple skin eggplant anthocyanins in the pH4-10 between the more stable. How to keep more purple 1, choose dark purple eggplant The darker the color of the eggplant skin, the higher the anthocyanin content. When cooking, degradation of anthocyanins caused by heating is unavoidable; at this time, eggplants with high anthocyanin content are prone to retain more purple color. 2, soaking with salt or acid Anthocyanins are oxidized and degraded under the action of enzymes, and salt and acid can reduce the activity of enzymes. High concentration of salt water soaking or direct rubbing salt pickling can reduce the oxidation of anthocyanins in the cooking process. Anthocyanins are stabilized in acidic conditions, so vinegar can help maintain the purple color, but acid can also give it a purplish hue. 3, microwave heating or frying, shorten the cooking time High-temperature short-time heating on anthocyanins have less impact. Compared with water steaming, stir-frying, microwave and deep-frying higher temperature, shorter time, less impact on anthocyanins. Cooking eggplant in microwave or deep-frying and then seasoning it also retains a large purple color. But eggplant deep-frying requires a wide range of oil, the remaining oil is difficult to deal with; and the eggplant itself has a strong oil-absorbing capacity, after the oil taste greasy; want to refreshing and not greasy taste, or microwave heating is recommended.