The IP intercom system is an intercom system connected by a network cable and POE Switch connects the whole system for stable intercom and monitoring.
The intercom system we developed was Linux intercom system, which can support intercom, monitoring and unlocking functions. They are based on Linux system, adopt TCP/IP networking architecture, and support multi-way unlocking and elevator linkage. Our equipment supports the connection of 9999pcs apartments at most, which can meet the needs of most projects. At the same time, they also support connection to the central management machine, which is convenient for the management of properties and communities.
There are functions of Video Door Phone:
1. Support face recognition, which can be unlocked by dynamic face information;
2. Support card opening, which can be unlocked by IC/ID/NFC cards;
3. Support monitor, which can be monitoring by Indoor Monitor;
4. Support video intercom, when someone coming and users can see who is coming;
5. Support intercom, indoor units can call and intercom with each other;
6. Support customization language, which can be made on the intercom system
7. Support elevator linkage on the indoor monitor
Our intercom systems have various designs to meet the needs of different customers. We have 4.3-inch and 10.1-inch screens with physical buttons, touch buttons and sensor buttons for customers to choose. Refer to the following pictures.
They all use color high-definition display, aluminum alloy shell and luminous solid buttons. They can be used in multi-apartment systems, can be used in apartments, buildings, hotels, etc.
Our factory is located in Zhuhai, China. We have been focusing on independent research and development of intercom systems for 11 years. We can provide you with professional products and services, as well as complete intercom solutions according to your requirements. If you want to know more, please contact us and we can send a catalogue for your reference.
FAQ
Q: What is your service ?
a. we can offer OEM&ODM services
b. All software free provide , and technical support after-service
c. Online installation guide services.
Q: Whats the MOQ?
To ensure the best logistic cost, we suggest 100pcs(one carton).However, we are open to take orders with small qty.Welcome to sample order, contact with us.
Q: What payment terms are available?
T/T, Paypal, Western Union, credit card.
Q: How long is your production lead time?
Sample Order-Within 1-5 working days.
Bulk Order - 15-20 days for neutral items, 7 days if the items we have stock
Q: What's Your Products Warranty?
We Offer 12 Months Warranty after shipment sent.
Linux Intercom System,Intercom System,Intercom System For Home,Gate Intercom Systems Zhuhai Mingke Electronics Technology Co., Ltd , https://www.mingke-tech.com
Food preservatives are food additives used to prevent deterioration of foods caused by microorganisms, improve food preservation performance, and extend the shelf life of foods. Since preservatives can extend the shelf life of foods, China's Food Sanitation Law stipulates that foods can be added with appropriate amounts of preservatives.
Preservatives <br> Commonly used food preservatives can be divided into chemical preservatives and natural preservatives. Chemical preservatives are further divided into inorganic preservatives and organic preservatives.
Organic chemical preservatives mainly include benzoic acid (sodium benzoate), sorbic acid (potassium sorbate), p-hydroxybenzoic acid ester, dehydroacetic acid, sodium diacetate, citric acid and lactic acid;
Inorganic chemical preservatives mainly include sulfurous acid (sodium sulfite), sulfur dioxide, nitrates and nitrites, free chlorine and hypochlorite, phosphate and the like.
Common preservatives in beverages <br> Benzoic acid, also known as benzoic acid, is slightly soluble in water, soluble in ethanol, and has obvious antibacterial activity against various microorganisms (yeast, mold, bacteria) under acidic conditions. weak. The maximum use in direct drinking beverages is 0.2 g/kg. Because benzoic acid has low solubility and is inconvenient to use, most of its actual production uses its sodium salt, and its antibacterial action of sodium salt acts after conversion to benzoic acid.
Sorbic acid, also known as citric acid, is slightly soluble in water and soluble in ethanol. It is stable to light and heat, and it is easy to be oxidized and colored for a long time. It has antibacterial action against mold, yeast and aerobic bacteria. Sorbic acid is an acidic preservative. The application range is below pH 5.5 and the toxicity is 1/4 of benzoic acid. Therefore, from the perspective of foreign development, there is a tendency to gradually replace benzoic acid and its sodium salt. Maximum usage: 0.6 g / kg.
Methods for the detection of food preservatives <br> Most of the preservatives currently in use are inherently toxic to humans, and an overdose can be hazardous to health. Therefore, each country has strict regulations on the amount and residual amount of preservatives. The accurate detection of preservatives is of great significance to food hygiene and safety.
At present, the detection of food preservatives mainly includes high performance liquid chromatography, gas chromatography, ultraviolet spectrophotometry, thin layer chromatography, titration and the like. Among them, gas chromatography, high performance liquid chromatography, and ultraviolet spectrophotometry have high accuracy and fast analysis, and are the most commonly used detection methods.
Commonly used detection methods
1. High Performance Liquid Chromatography <br> Principle:
Prepare a standard solution of sodium benzoate, potassium sorbate and acesulfame, and draw a standard curve at 230 nm. The sample is directly degassed by ultrasonic degassing and membrane filtration, and chromatographed according to the above conditions to obtain various components. The regression equation and the correlation coefficient.
Evaluation:
High performance liquid chromatography has the advantages of fast analysis speed, high separation efficiency and accurate measurement results, and is the most commonly used method for detecting sodium benzoate in food. The preferred method now is to extract the sample with diethyl ether, then dry the extracted sample in a water bath, then dilute to volume with methanol, filter the membrane and perform HPLC detection. This test uses ultrasonic extraction method, which has simple sample pretreatment, which makes the operation simple, fast and accurate, and worthy of promotion.
However, this method is limited to certain foods, and when used in a variety of foods, it often appears to prevent peak interference.
2. Ultraviolet spectrophotometry <br> Principle:
Simultaneous determination of sodium benzoate and potassium sorbate in beverages by multivariate linear regression UV spectrophotometry using ultraviolet absorption spectra of sodium benzoate and potassium sorbate. The sample does not require pretreatment.
Evaluation:
The sample does not require pretreatment, is simple to operate, and can measure multiple components simultaneously. Good addition and high accuracy.
3. Gas Chromatography <br> Principle:
The sample was accurately weighed and acidified with hydrochloric acid, and sorbic acid, benzoic acid and p-hydroxybenzoic acid ester were extracted and concentrated with diethyl ether, and separated by a gas chromatograph having a hydrogen flame ionization detector, and compared with the standard.
Evaluation:
It is relatively simple and sensitive, but the equipment input cost is high, there are illegal operations, and there are hidden dangers of flammability and explosion.
4. Infrared spectroscopy <br> Principle:
The infrared spectrum of potassium bromide-milk powder (taking milk powder as an example) was subtracted from the infrared spectrum of potassium bromide-benzoate at the optimum quantitative accuracy and speed to obtain a characteristic analysis peak (1555 cm), which was determined at the wave number. The absorbance of a standard solid solution with a gradient of equal concentration, and the absorbance value as the ordinate, and the corresponding concentration as the abscissa, draw a working curve, and the absorbance of the sample to be tested is substituted into the regression equation to calculate the sodium benzoate content.
The sample pretreatment is a method in which the sample is ground with a potassium bromide in a mortar, dried, and pressed.
Evaluation:
The method is simple and accurate, and can measure a variety of samples at the same time, and is suitable for industrial production, food testing and the like.
At present, the methods that can be put into production and testing are mainly the high performance liquid chromatography, gas chromatography and ultraviolet spectrophotometry described above, while infrared spectroscopy is rarely reported at home and abroad, and the fluorescence spectroscopy is still in the experimental stage. Mature and widely used. High-performance liquid chromatography is the most widely used method for a certain period of time due to its low cost and convenience.
The detection of preservatives in foods is related to food safety issues and cannot be wrong. What problems have you encountered in the preservative testing process of food, and have any good experience and summary, welcome to leave a message, we share with each other and make progress together.
The National Standard Material Resource Platform is mainly engaged in chemical reagents (high-end reagents, general-purpose reagents, analytical reagents), standard products, reference materials, experimental chromatographic consumables, instrumentation devices and other nearly 200,000 kinds of goods. Another biobw.com agent introduces well-known suppliers at home and abroad, from quality inspection, commodity storage management, professional preservation, logistics and transportation, after-sales service, etc., all links are controlled by professionals. Through online operation and self-delivery logistics, the 3%-5% of the cost saved will be returned to the customer to ensure the high quality and low price of the product. Imported brands include American ACC, US USP, German DR, German weitge, Canadian TRC, Canadian CDN, BEPURE and other well-known brands, with short delivery time and low price. Click on the online customer service to inquire about the purchase. 
Method for detecting food preservatives
Method for detecting food preservatives <br> As a kind of food additive, preservatives have always been the focus of food testing industry. There are many kinds of preservatives, and there are various detection methods. What are the advantages and disadvantages of each test method? Let's talk about it together!