L-Cystine(L-Cystine) is a kind oforganic compound, the molecular formula is CsixHtwelveNtwoOfourStwo, molecular weight 240.3, white hexagonal plate crystal or white crystal powder, soluble in dilute acid and alkali solutions, extremely insoluble in water, insoluble inethanol。stayproteinIt is mainly contained in hair, fingers, claws, etcKeratinMedium.
Pharmaceutically used for productionantidoteandexpectorantOf raw materials,food industryUsed as dairy additive andbreadQuick completionacceleratorIt can produce various special flavors when heated with the sugar in food, and prevent the oxidation of oil. It is widely used in food processing;In the cosmetics industry, productionCold perm essenceRaw materials.[1-3]
② Extract from hair, especiallyHorsehairThe medium content can reach 8%.The hair is hydrolyzed in acid at 110 ℃, or keratin is hydrolyzed,Remove impuritiesAfter that, neutralize with alkali to pH=4.8, crystallize to obtain crude products, and then heat them to dissolve inhydrochloric acidAdd activated carbon to decolorize, filter, neutralize the filtrate with ammonia, recrystallize, wash until it is free ofChloride ionandIron ionuntil.
It is mainly extracted from hair in industry,yield Up to 7.5-8%.Some of them only reach 5% in actual production.[5]
Specifically: set the concentration to 10mol/L720kg of hydrochloric acid is added into the hydrolysis tank, heated to 70 ～ 80 ℃, quickly put 400kg of human hair or pig into the tank, continue to heat to 100 ℃, and within 1 ～ 1.5h, heat up 110 ～ 117 ℃, hydrolyze for 6.5 ～ 7h (from 100 ℃), cool down, filter.Add 30%~40% industrial solution into the filtrate under stirringsodium hydroxideSolution, when the ph value reaches 3.0,LyeSlow down to add until the ph value is 4.8,Stand still36h, take precipitation, centrifuge and dry it to getCystineCrude product (I),mother liquorWithglutamate、ArginineandleucineEtc.Weigh 150kg of crude cystine (I), add about 90kg of 10mol/L hydrochloric acid and 360kg of water, heat to 65~70 ℃, stir and dissolve for 0.5h, and then addActivated carbon12kg, temperature rise to 80~90 ℃, heat preservation for 0.5h, plate and framePressure filtration。Heat the filtrate to 80~85 ℃, add 30% sodium hydroxide while stirring, and stop at ph 4.8.Let it stand still to make crystallization precipitate,siphonThe supernatant is separated from the bottom sediment and then centrifuged and dried to obtain crude cystine (II).WeighingCystine100kg of crude product (II), add 500L of 1mol/L hydrochloric acid, heat to 70 ℃, and then add 3-5 kg of activated carbon.Then heat up to 85 ℃, mix for 0.5h, and press filter with plate and frame.Add about 1.5 times of filtrate volume into the filtratedistilled water, heated to 75~80 ℃, 12% under mixingammoniaNeutralization to ph3.5-4.0, whenCystine crystal Precipitation.Centrifuge and dry crystallization, wash with distilled water until noChloride ion，vacuum drying And then the finished cystine can be obtained.The yield of human hair can reach 8%,Pig hairThe yield can reach 5%.[4]
Risk terms:R36 Irritating to eyes.R37stimulaterespiratory system。R38 Irritating to skin.R36/37/38 Irritating to eyes, respiratory system and skin.
Safety terminology:S22 Do not breathe dust.S25 Avoid eye contact.S26 In case of contact with eyes, please immediately flush with plenty of water and seek medical advice.S36 Wear appropriate protective clothing.S24/25 Avoid contact with skin and eyes.
