Ring color Alkali content Conclusion judgment yellow No alkali Qualified milk yellow-green Alkaline 0.03% Abnormal milk Light green Alkaline 0.05% Abnormal milk green Alkaline ≥0.1% Severe abnormal milk Milk color Nitrite amount Conclusion judgment white No nitrite Qualified milk Pink Nitric acid salt containing 0.2mg/kg Abnormal milk Pink water With nitrite nitrate 0.3mg/kg Abnormal milk Pink Nitric acid salt with ≥0.4mg/kg Severe abnormal milk Milk color Nitrite or nitrate content Conclusion judgment milky No nitrite or nitrate Qualified milk Pink Contains nitrite or nitrate 0.2mg/kg Abnormal milk Pink water With nitrite or nitrate 0.3mg/kg Abnormal milk Pink With nitrite or nitrate 0.4mg/kg Severe abnormal milk red With nitrite or nitrate ≥ 0.5mg/kg Severe abnormal milk Natural Chrysanthemum Extract,Chrysanthemum Extract,Chamomilla Recutita Flower Extract,Pure Chrysanthemum Extract NANJING ZELANG MEDICAL TECHONOLOGY CO., LTD , https://www.hawfitness.com
(1. Baoji Huimin Dairy Group Co., Ltd., Baoji 721305, Shaanxi, China; 2. Xi'an Dongfang Dairy Product Factory, Xi'an 710065, Shaanxi, China; 3. Shanghai Heshaoyu Chemical Co., Ltd., Shanghai 210000, China)
Abstract: This article mainly introduces several technical methods for detecting adulteration of fresh milk, including alkaline substances, nitrite, glucose, starch, urea, sucrose, hydrolyzed protein, powdered oils, antibiotics, antisepsis, accumulated in production practice. Agent and mastitis milk test.
Keywords: fresh cow (goat) milk; adulteration; inspection
The rapid methods of decerming about adulterated matter in milk
Han qi-weng1 Qin li-hu2 Sun wu-bin3
(1.Baoji huiming dairy group corp,Baoji 721305,China;2.Xian oriental dairy factory,Xian 710065,China; 3.Shanghai hesibi chemistry corp,shanghai 210000,china)
Abstract:In this paper we mainly introduce the rapid technology methods of decerming the basicity matter, nitrite, strache, bactericide, preservative, carbamide, sugar in adulterated milk.
Key words: Milk; adulterating; decerming
0 INTRODUCTION At present, the competition of major dairy companies in China has focused on the competition for milk resources in various places. Due to their own economic interests, dairy farmers often adulterate fresh milk, which will inevitably affect the inherent quality and economic benefits of dairy product processing companies, and it will certainly damage the health of consumers. The author has worked in dairy products for many years and has accumulated some technical methods for testing adulterated milk and abnormal milk. Now he has compiled some experience in controlling the quality of fresh milk purchase for reference by his peers.
1 Measuring proportion
1.1 The purpose of measuring the proportion of purpose is to determine whether the fresh milk is mixed with water, the specific gravity of fresh milk will decrease after mixing. According to a sample survey of some cattle in the Baoji area of ​​Shaanxi Province, the proportion of normal milk should be 1.028 to 1.032. Therefore, milk with a specific gravity of less than 1.028 can be considered as abnormal milk.
1.2 Detection methods
1.2.1 Apparatus and equipment hydrometer (20°C/4°C); thermometer (100°C, rod mercury thermometer); glass graduated cylinder (250mL).
1.2.2 Operation method Mix fresh milk thoroughly, sample 400-500 mL, slowly pour into the cylinder wall, then gently insert the hydrometer into the cylinder and wait until it is stationary. At the same time, the milk temperature is measured and the specific gravity value is finally calculated.
1.3 Explain that using the method of measuring specific gravity to determine whether milk is mixed with water does not actually measure the freezing point method to determine whether or not the water is added. However, it has a simple operation and can guarantee the powder extraction rate of the powdered milk processing enterprises, and therefore it has been widely used in actual production. .
2 Alkaline substances
2.1 Purpose The common basic substances are soda, alkaline and so on. Because milk is rich in nutrients, microorganisms are prone to reproduction, especially in the summer, which is the most vulnerable to rancidity. In addition, sheep's milk mixed with milk is also prone to rancidity. Dairy farmers often add alkali in order to cover up rancidity. The purpose of measuring alkali is to find this part of abnormal milk.
2.2 Detection method
2.2.1 Principles The bromothymol blue indicator changes color from yellow to blue in an alkaline solution with a pH of 6.0-7.6.
2.2.2 Reagents
0.04% Bromothymol blue ethanol solution.
2.2.3 Operation method Take 2mL milk sample in the test tube, tilt the test tube, carefully add 0.04% bromothymol blue ethanol solution 0.6mL along the wall, then slowly turn 3~5 times, stand for 2 minutes, observe the interface Ring color changes.
2.2.4 The result is judged by the change of color of the ring layer (see Table 1).
2.3 Test Methods (Radic Acid Color Reaction)
2.3.1 Principle Rhodiola acid is also an acid-base indicator. Its PH value ranges from 6.9 to 8.0. When alkaline milk is encountered, it changes from brownish yellow to rose red. The reaction is sensitive and easy to detect.
2.3.2 Reagents
A 0.2% erythrosine alcohol solution was weighed and 200 mg of rose acid indicator was dissolved in 95% 100 mL alcohol solution.
2.3.3 Method of operation Take 1 mL of the tested milk and normal milk into two test tubes, then add 0.2% Rhodiola alcohol solution (1mL) dropwise, and observe the changes after shaking. If the milk contains alkali, it is rose-red. The greater the alkali content, the brighter it is. The alkali-free milk is brownish (cinnamon).
In addition, the following rapid test method can also be used: in the pit of the white porcelain titer plate, a drop of the tested milk and one of the above indicators is dropped, and the mixture is evenly mixed. If the rose is red, the milk contains alkaline substances.
3 Determination of nitrite and nitrate
3.1 Purpose Nitrite and nitrate are often used as preservatives and color formers for meat foods. However, excessive intake of the human body can produce toxic effects. Therefore, the nitrite and nitrate content must be monitored during the acquisition of fresh milk. However, since nitrates are reduced to nitrites by the action of bacteria (nitrite bacteria), we can basically control both nitrite-containing abnormal milks so that they do not exceed the standards in the finished product.
3.2 Nitrite detection method
3.2.1 Principle Under weak acidic conditions, nitrite and sulfanilic acid are diazotized and then coupled with α-naphthylamine to form a purple-red dye.
3.2.2 Reagent preparation 0.1 g of α-naphthol, 0.2 g of α-naphthylamine and 0.6 g of sulfanilic acid were dissolved in 400 mL of 50% glacial acetic acid and stored in brown bottles in the dark.
3.2.3 Operation method Take 2 mL of milk sample in a test tube, and then add 1.5 mL of nitrite reagent. Shake for 2 minutes and observe the phenomenon.
3.2.4 The results are judged according to the color depth (see Table 2).
3.3 Nitrate detection method
3.3.1 Principles Nitrate in fresh milk is reduced to nitrite and then reacted with sulfanilic acid and methamphetamine to form a red azo compound.
3.3.2 Reagents
A. 44 g of barium nitrate as a reducing agent, 5 g of manganese sulfate, and 2 g of cadmium acetate.
2 grams of zinc powder, mixed together after drying, ground into fine powder and stored in a brown advertising bottle.
B. The display agent is the same as the reagent for determining nitrite.
3.3.3 Operation method Take milk sample 2mL in a small test tube, add a small spoon of reducing agent (about 0.3g), shake well, add color reagent 2mL, shake and observe for about 3 minutes.
3.3.4 Judgment The results are judged by the depth of shade (see Table 3).
3.3.5 Description (1) This method can be used to determine the nitrate content in fresh milk at the same time as the method of measuring nitrite.
(2) As a dairy manufacturer controlling the quality of fresh milk purchase, this method has the advantages of convenience, rapidity, and accuracy. When the milk is purchased, as long as the nitrate is measured, the content of both nitrate and nitrite in the milk can be controlled. Can effectively guarantee the quality of fresh milk purchase.
(3) The phenomenon of this experiment is sometimes aggravated by the incorporation of low-desalination whey powder in fresh milk.
Rapid adulteration test for fresh milk (1)
Rapid Inspection Technology of Fresh Milk Adulteration Han Qiwen 1 Qin Lihu 2 Sun Wubin 3