Background technology
Chinese yam is edible good vegetables, is again medicinal herbs most in use.Chinese yam is the piece root of Dioscoreaceae plant Chinese yam, the effect of have the tonifying spleen nourishing the stomach, invigorating the lung and the kidney, can be used for treating insufficiency of the spleenly rush down for a long time, chronic enteritis, the deficiency syndrome of the lung cough breathe heavily, disease such as chronic gastritis and diabetes.Chinese yam is as health food, in China's history in existing more than 2000 year at least, is on record excellent tonic product.Studies show that Chinese yam also contains indispensable inorganic salts of human body and trace elements such as iodine, calcium, iron, phosphorus except that containing compositions such as protein, carbohydrate, vitamin, fat, choline, amylase.The modern science analysis result shows that the maximum characteristics of Chinese yam are to contain a large amount of glutinous albumen.Glutinous albumen is a kind of mixture of proteinpolysaccharide, and human body is had special health-care effect: 1) can prevent the sedimentation of fat on cardiovascular, have the maintenance blood vessel elasticity, the effect that stops atherosclerotic to take place too early; 2) can reduce subcutaneous fat piles up; 3) can prevent the atrophy of connective tissue, can be used for preventing the generation of collagen diseases such as rheumatoid arthritis, chorionitis.Have multiple medicinal, health-care efficacy based on Chinese yam, its deep processed product has the wide development prospect in industries such as health foods.
But, in the deep-processing process of Chinese yam, there are serious problems, exactly because the product discoloration problem that enzymatic browning causes, if handle bad, not only influence the exterior quality of product, nutritional labeling and local flavor also can change a lot simultaneously, and product quality is descended, and have influence on the sale and the economic benefit of enterprises of product.The reason that enzymatic browning produces mainly is to be subjected to mechanical damage or to be in poor environment when Chinese yam, as endure cold, when being heated, especially in process, the oxidation and present brown under the effect of polyphenol oxidase (PPO) of the contained polyphenols of Chinese yam.This shows that three necessary conditions that the enzymatic browning reaction takes place are: polyphenols, PPO and oxygen.The most important factor of decision enzymatic browning rate is active PPO and the concentration of phenolic compound, available oxygen content, pH value and temperature etc. in the tissue.
At present, China is just greatly developing fruits and vegetables deep processing industry, and therefore how solving the brown stain problem that occurs in the deep-processing process has caused people's extensive concern.Studies show that, inhibition to enzymatic browning can be started with from following three aspects: (1) reduces aldehydes matter content: by cultivating the new varieties of anti-brown stain, improve cultivation management technology, reduce gather, the mechanical damage in the storing, process, reduction is induced phenylalanine lyases activity, thereby the phenols substrate that control can be oxidized forms, and delays the brown stain of fresh-cut product; (2) activity of control PPO: utilize the PPO activity brown stain to be controlled by the characteristic of materials such as heat, organic acid, aldehydes matter, sulphur, chelating agent and quinone coupling agent inhibition; (3) reduce oxygen concentration: because brown stain is to take place under aerobic conditions, therefore can utilize bleed, methods such as tunicle, controlled atmosphere reduce the oxygen concentration in the environment, thereby the generation of control brown stain.
At present, the method of the inhibition enzymatic browning of having reported mainly comprises physical method (as heating blanching, expeling oxygen, controlled atmospheric packing etc.), chemical method (as acid treatment, sulphite processing, ascorbic acid processing etc.), and latest developments enzyme process that gets up and the method for utilizing genetic engineering to cultivate improved seeds.But above-mentioned physics, chemical method, there is some other negative effect in meeting that all can be more or less to quality, the local flavor of fruits and vegetables itself.When for example heat treatment makes the PPO sex change, also can cause the fruits and vegetables quality softening, local flavor reduces, and easily by infected by microbes; And for example the sulphite processing can make residual a certain amount of sulfide in the fruits and vegetables, does not possess generally acknowledged security.Therefore, people just are being devoted to develop the method for new inhibition fruits and vegetables oxidizing brown stain, not only need to possess and suppress effect preferably, can reduce the influence to the quality of fruits and vegetables own simultaneously again to greatest extent.
Summary of the invention
The purpose of this invention is to provide a kind of safe, effective, little to the quality influence of the Chinese yam own simultaneously method that prevents Chinese yam oxidizing brown stain in process.
For achieving the above object, the present invention takes following design: a kind of method that prevents Chinese yam oxidizing brown stain in process, be with Chinese yam in process with final concentration be the proteolytic enzyme liquid of 0.1-10mg/L at 20-70 ℃, soak under the pH2-10, oxidizing brown stain is inhibited.
In the above-mentioned method that prevents Chinese yam oxidizing brown stain in process, the selection of described proteolytic enzyme is widely, as being selected from commercially available any one or the multiple protease that polyphenol oxidase (PPO) is had hydrolysis, be preferably in ficin, papain and the bromelain one or more.
Temperature during described immersion treatment is preferably 35-65 ℃, and the pH value is preferably 5-8.
The soak time of described proteolytic enzyme can be grasped flexibly according to the characteristic of concrete used proteolytic enzyme, preferably is no more than 1h, is preferably 5-20min.
Above-mentioned processing method all is suitable in any processing technology of Chinese yam, as peel, cut off, pulverize and/or squeeze the juice etc.
The invention provides a kind of method that prevents Chinese yam oxidizing brown stain in process.This method has utilized proteolytic enzyme that PPO is had hydrolysis properties, by Chinese yam is handled with proteolytic enzyme, makes the active reduction of PPO of Chinese yam to reach the purpose that suppresses brown stain.This method has following advantage:
1. safe: selected protease is natural origin, can directly extract from food, can not work the mischief to health:
2. little to the influence of the quality of product own: use enzymatic treatment, the inhibition enzymatic browning, the treatment conditions gentleness can keep the quality of Chinese yam product preferably:
3. effect is good: experiment shows, method of the present invention can suppress the activity of PPO effectively, maximum inhibition is up to 38%, thereby has slowed down the oxidizing brown stain process of Chinese yam in process effectively, has solved degradation problem under the product variable color that causes because of brown stain, the mouthfeel.
The present invention will play a significant role in the dark product processing of Chinese yam, have a extensive future.
Below in conjunction with specific embodiment the present invention is described in further detail.
The specific embodiment
Method therefor is conventional method if no special instructions among the following embodiment.
Embodiment 1, detection the inventive method are to the inhibition situation of Chinese yam PPO activity and the effect detection in actual process
One, detect the inhibition situation of the inventive method to Chinese yam PPO activity,
Detect the inhibition situation of the inventive method to Chinese yam PPO activity with following method, concrete grammar may further comprise the steps:
1) fresh Chinese yam is cleaned up, the peeling section obtains the Chinese yam tissue;
2) smash the Chinese yam tissue to pieces homogenate with high-speed tissue mashing machine, add freezing acetone in the ratio of 1: 2 (W/V), PPO extracts with Chinese yam, obtains the PPO crude enzyme liquid;
3) get 0.5mL PPO crude enzyme liquid, add 0.1mL papain (2mg/mL, glad available from Beijing) through biotech company of section, at 40 ℃, hydrolysis 5min under the condition of pH6.0 uses substrate mixed liquor (1.4mL pH6.0 phosphate buffer+1mL 0.04mol/L catechol) to measure the residual activity of Chinese yam PPO then under 40 ℃, pH6.0 condition; Simultaneously, in the substrate mixed liquor of forming by 1.9mL pH6.0 phosphate buffer and 1mL 0.04mol/L catechol, add 0.1mL PPO crude enzyme liquid, measure in contrast without the activity of the Chinese yam PPO of papain hydrolysis.
Testing result shows, handles with method of the present invention, can suppress the activity of Chinese yam PPO35%.
Two, the effect detection in actual process
Fresh Chinese yam is cleaned up, after the peeling, the Chinese yam tissue is handled with the method for step 1, the papain of promptly using 2mg/mL soaks hydrolysis 5min at 40 ℃ under the condition of pH6.0.Through comparing with the Chinese yam tissue of handling without the inventive method (contrast), with the Chinese yam tissue after the inventive method processing, color and luster is pure white, and the Chinese yam tissue of contrast is taupe, and oxidizing brown stain takes place.After testing, the quality of the Chinese yam of handling with the inventive method does not change, and is safe to eat, proves with method of the present invention to prevent the oxidizing brown stain of Chinese yam in process effectively.
Embodiment 2, detection the inventive method are to the inhibition situation of Chinese yam PPO activity and the effect detection in actual process
One, detect the inhibition situation of the inventive method to Chinese yam PPO activity,
Detect the inhibition situation of the inventive method to Chinese yam PPO activity with following method, concrete grammar may further comprise the steps:
1) fresh Chinese yam is cleaned up, peeling obtains the Chinese yam tissue;
2) smash the Chinese yam tissue to pieces homogenate with high-speed tissue mashing machine, add freezing acetone in the ratio of 1: 2 (W/V), PPO extracts with Chinese yam, obtains the PPO crude enzyme liquid;
3) get 0.1mL PPO crude enzyme liquid, add 0.5mL ficin (0.8mg/mL, glad available from Beijing) through biotech company of section, at 50 ℃, hydrolysis 20min under the condition of pH4.0 uses substrate mixed liquor (1.4mLpH6.0 phosphate buffer+1mL 0.04mol/L catechol) to measure the residual activity of Chinese yam PPO then under 40 ℃, pH6.0 condition; Simultaneously, in the substrate mixed liquor of forming by 1.9mL pH6.0 phosphate buffer and 1mL 0.04mol/L catechol, add 0.1mL PPO crude enzyme liquid, measure in contrast without the activity of the Chinese yam PPO of ficin enzyme hydrolysis.
Testing result shows, handles with method of the present invention, can suppress the activity of Chinese yam PPO23%.
Two, the effect detection in actual process
Fresh Chinese yam is cleaned up, and handle with the method for step 1 the Chinese yam tissue peeling back, and the ficin of promptly using 0.8mg/mL soaks hydrolysis 20min at 50 ℃ under the condition of pH4.0.Through comparing with the Chinese yam tissue of handling without the inventive method (contrast), with the Chinese yam tissue after the inventive method processing, color and luster is pure white, and the Chinese yam tissue of contrast is taupe, and oxidizing brown stain takes place.After testing, the quality of the Chinese yam of handling with the inventive method does not change, and is safe to eat, proves with method of the present invention to prevent the oxidizing brown stain of Chinese yam in process effectively.
Embodiment 3, detection the inventive method are to the inhibition situation of Chinese yam PPO activity and the effect detection in actual process
One, detect the inhibition situation of the inventive method to Chinese yam PPO activity,
Detect the inhibition situation of the inventive method to Chinese yam PPO activity with following method, concrete grammar may further comprise the steps:
1) fresh Chinese yam is cleaned up, peeling obtains the Chinese yam tissue;
2) smash the Chinese yam tissue tissue to pieces homogenate with high-speed tissue mashing machine, add freezing acetone in the ratio of 1: 2 (W/V), PPO extracts with Chinese yam, obtains the PPO crude enzyme liquid;
3) get 0.1mL PPO crude enzyme liquid, add 0.5mL bromelain (0.1mg/mL, glad available from Beijing) through biotech company of section, at 65 ℃, hydrolysis 10min under the condition of pH7.0 uses substrate mixed liquor (1.4mL pH6.0 phosphate buffer+1mL 0.04mol/L catechol) to measure the residual activity of Chinese yam PPO then under 40 ℃, pH6.0 condition; Simultaneously, in the substrate mixed liquor of forming by 1.9mL pH6.0 phosphate buffer and 1mL 0.04mol/L catechol, add 0.1mL PPO crude enzyme liquid, measure in contrast without the activity of the Chinese yam PPO of bromelain hydrolyzate.
Testing result shows, handles with method of the present invention, can suppress the activity of Chinese yam PPO26%.
Two, the effect detection in actual process
Fresh Chinese yam is cleaned up, and handle with the method for step 1 the Chinese yam tissue peeling back, and the bromelain of promptly using 0.1mg/mL soaks hydrolysis 10min at 65 ℃ under the condition of pH7.0.Through comparing with the Chinese yam tissue of handling without the inventive method (contrast), with the Chinese yam tissue after the inventive method processing, color and luster is pure white, and the Chinese yam tissue of contrast is taupe, and oxidizing brown stain takes place.After testing, the quality of the Chinese yam of handling with the inventive method does not change, and is safe to eat, proves with method of the present invention to prevent the oxidizing brown stain of Chinese yam in process effectively.
Embodiment 4, detection the inventive method are to the inhibition situation of Chinese yam PPO activity and the effect detection in actual process
One, detect the inhibition situation of the inventive method to Chinese yam PPO activity,
Detect the inhibition situation of the inventive method to Chinese yam PPO activity with following method, concrete grammar may further comprise the steps:
1) fresh Chinese yam is cleaned up, peeling obtains the Chinese yam tissue;
2) smash the Chinese yam tissue tissue to pieces homogenate with high-speed tissue mashing machine, add freezing acetone in the ratio of 1: 2 (W/V), PPO extracts with Chinese yam, obtains the PPO crude enzyme liquid;
3) get 0.1mL PPO crude enzyme liquid, add 0.4mL bromelain (5mg/mL) and 0.1mL ficin (10mg/mL), at 45 ℃, hydrolysis 15min under the condition of pH8.0 uses substrate mixed liquor (1.4mL pH6.5 phosphate buffer+1mL 0.1mol/L catechol) to measure the residual activity of Chinese yam PPO then under 40 ℃, pH6.5 condition; Simultaneously, in the substrate mixed liquor of forming by 1.5mL pH6.5 phosphate buffer and 1mL 0.1mol/L catechol, add 0.5mL PPO crude enzyme liquid, measure in contrast without the activity of the Chinese yam PPO of papain hydrolysis.
Testing result shows, handles with method of the present invention, can suppress the activity of Chinese yam PPO38%.
Two, the effect detection in actual process
Fresh Chinese yam is cleaned up, and handle with the method for step 1 the Chinese yam tissue peeling back, promptly uses 5mg/mL bromelain and 10mg/mL ficin (mixed proportion 4: 1) at 45 ℃, soaks hydrolysis 15min under the condition of pH8.0.Through comparing with the Chinese yam tissue of handling without the inventive method (contrast), with the Chinese yam tissue after the inventive method processing, color and luster is pure white, and the Chinese yam tissue of contrast is taupe, and oxidizing brown stain takes place.After testing, the quality of the Chinese yam of handling with the inventive method does not change, and is safe to eat, proves with method of the present invention to prevent the oxidizing brown stain of Chinese yam in process effectively.