Table 2 Characteristics of different grades of honey
Table 2 Characteristics of different grades of honey (continued)-1
Note: ① The varieties of honey not listed in the table can be determined by each province according to the characteristics of color, fragrance and taste listed in the table. (two) the same honey mixed with low-grade honey, it should be classified as low-grade honey. (3) Any old-fashioned honey extraction method (such as squeezing method and pot cooking method). ) is used to extract honey. Honey with turbid, opaque, dark color and pungent taste can be used as equivalent honey.
The color, state, taste and impurities of heterohoney flowers are dark amber and dark brown translucent viscous liquids or crystals, such as buckwheat and eucalyptus. The taste is cloudy and sweet, without dead bees, larvae, wax chips and other impurities, and it has a pungent taste.
Table 3 Grade specifications of honey (kg/L)
Note: The minimum collection starting point is 1.385kg/L in the north of the Yellow River and 1.370kg/L in the south of the Yellow River.
Table 4 Physical and chemical indexes of honey
Note: ① Enzyme value: namely amylase value, which refers to the number of milliliters of amylase contained in 1 g honey converted into 1% starch standard solution at 40℃1hour. ② Acidity: refers to the number of milliliters of 1 mol/L sodium hydroxide solution needed to neutralize 100 g sample honey.
The main methods to judge the quality of honey are:
① Appearance evaluation
Stir the honey in the container up and down evenly with clean bamboo pieces or wooden sticks, taste it with your mouth and smell it with your nose, check whether there is oily smell and peculiar smell, pay attention to the color and impurities, and pay attention to whether there are crystals and crystals in the honey. Pay special attention to the quality of honey in the lower layer of the container.
② impurity inspection
Take a small amount of honey samples in a test tube, add 5 times of distilled water to dilute and mix them evenly, and let them stand for 12 ~ 24 hours to observe. If precipitation occurs, it means that impurities are mixed in.
③ Examination of starch substances.
Take a little honey sample, add 10 times distilled water into a glass or a large test tube, stir evenly, boil and cool, and add 2 drops of 0.2 mol/L iodine _ potassium iodide solution. If the solution is blue, green or red, it means that the honey is mixed with starch.
④ Inspection of adding sucrose.
Honey reacts with "honey developer" in alkaline solution and appears color. If pure honey reacts with "developer", it will be pale yellow or yellow; If the honey is mixed with sucrose, it is reddish to red; If the sucrose content is high, it is purple-black. Specifically, drop honey 1 into a 20 ml beaker, add 20ml 10% sodium hydroxide solution, stir evenly, take out 1 ml in a graduated test tube, bathe in boiling water for 3-5min, take out and cool to room temperature, and add 1 ml "developer". If the honey solution turns pale red or red, it means honey.
⑤ Inspection of adding maltose.
Take a little honey sample in the test tube, add 4 times of distilled water and mix well, then slowly add 95% alcohol. If white flocs appear, it means that maltose is mixed in this honey sample.
⑥ Heavy metal inspection
When the content of heavy metals in honey exceeds the standard, the color of honey will become darker. When encountering honey with abnormal color, it may be that the heavy metal content is too high. Take a proper amount of honey samples and add a certain amount of tea. If the content of heavy metals in honey samples is high, the color of tea leaves will deepen and even appear brown.
⑦ Inspection of mixed salt
Take a little honey sample in a test tube, add 4 times of distilled water and shake it evenly, then add a few drops of 5% ~ 10% silver nitrate solution. If the honey sample solution produces white precipitate, it proves that salt is mixed.
8 Identification of Alum
Add a little honey sample to the test tube, dilute it with the same amount of distilled water, shake it evenly, and add a few drops of 20% barium chloride solution. If there is a white precipitate, it proves that this honey is mixed with alum.
Pet-name ruby mixed with ammonium salt inspection.
Add 2 ~ 3 ml of honey sample to the test tube, dilute it with the same amount of distilled water, add 2ml 10% sodium hydroxide solution, shake it evenly, and immediately put a wet pH test paper on the mouth of the test tube. If the test paper turns blue, it means ammonium salt is mixed.
(1) moisture determination:
Instruments: Abbe refractometer, super thermostat.
Keep the prism in Abbe refractometer at 40℃ with a super thermostat, calibrate the refractometer with newly-made distilled water according to Table 5 to make the refractive index 1.3305, then adjust the dividing line between light and dark to the center, fix the adjusting screw, start to detect honey, read out the refractive index n, and calculate the percentage of water according to the following formula.
Table 5 distilled water refractive index table
Moisture (%) =100-[78+390.7 (n-1.4768)]
② Determination of reducing sugar-Lingfei method;
Reagent:
Lin Fei solution A (copper sulfate solution): Weigh 34.639 grams of copper sulfate (CuSO 45 H2O), dissolve it in a small amount of distilled water, and dilute it to 500 ml. Ling Fei solution b (alkaline potassium sodium tartrate solution): weigh 173g potassium sodium tartrate and 50g sodium hydroxide, dissolve them in a small amount of distilled water, and then dilute them to 500ml. 10% sodium hydroxide solution. 0.5% glucose solution. 0. 1% methylene blue indicator, stored in a brown bottle.
Calibration of Linfei solution titre: accurately suck 5ml of Linfei solution A and 5ml of solution B into a 125ml triangular beaker, add 2ml of 0.5% glucose solution, and put it in an electric furnace or alcohol lamp to boil. If the blue color is unchanged, continue to drop it to light blue with glucose solution, add 2 drops of 0. 1% methylene blue indicator, and continue to titrate with glucose solution until the blue color disappears.
10 ml of Feyning's solution is equivalent to reducing sugar (g) = 0.005× a.
Where a is the standard amount of sugar used to titrate 10 ml of Fehling solution.
Preparation of test solution: weigh 1g honey sample, dissolve it in a small amount of water, adjust it to weak alkalinity with 10% sodium hydroxide solution, and adjust the volume to 100ml with distilled water to be tested.
Determination steps: accurately absorb 5ml of solution A and solution B, put them in a 125ml triangular flask, shake them evenly, put them in an electric furnace or alcohol lamp for boiling, then add 2ml of prepared test solution into a burette and boil them again. If the color does not change, continue to add the test solution drop by drop while boiling with a burette until the blue color disappears, and add 0. 1% methylene.
Calculation:
Where w is the weight of the sample.
③ Determination of sucrose-Lingfei method:
Reagent: 20% hydrochloric acid solution; 20% sodium hydroxide solution; 1% methyl orange indicator; Lin feijie a (ibid.); Lin Fei's plan B (same as above); 0. 1% methylene blue indicator.
Determination steps: use 100 ml volumetric flask to suck 50 ml of prepared test solution, and put it in a water bath to heat it to 70℃; Add 20% hydrochloric acid 10 ml, keep heating at 70℃ for10min; Take out the volumetric flask, cool it to room temperature (20℃), add 1 drop methyl orange indicator, neutralize it with 20% sodium hydroxide, then add distilled water to dilute it to scale, and shake it evenly to obtain the test solution for determining sucrose content; Accurately suck 5ml of Felling's solution A and 5ml of Felling's solution B into a 125ml triangular flask, and put them in an electric furnace or alcohol lamp for heating and boiling; When boiling, add 2ml of test solution into the burette. When boiling, if the blue color remains unchanged, add the test solution drop by drop. When it is close to blue, add 2 drops of methylene blue indicator and continue to use the test solution until the blue disappears when boiling, and record its dosage.
Calculation:
Where w is the sample weight (g);
B—— the number of milliliters of test solution consumed during titration;
A-10 ml of Feyning's solution is equivalent to grams of reducing sugar.
Sucrose (%) = (invert sugar%-reducing sugar %)×0.95
0.95 means that 0.95g sucrose can convert 1g monosaccharide.
④ Determination of amylase value:
Reagent:
0.05 mol/L sodium hydroxide: dissolve 2g sodium hydroxide in 1000ml distilled water.
0. 1 mol/L sodium chloride solution: dissolve 0.59 g sodium chloride in 100 ml distilled water.
0.2 mol/L acetic acid solution: dilute 0.6 ml of 20% acetic acid with distilled water to 100 ml.
1% starch solution: weigh 1.00g (dry state) soluble starch, put it in a beaker, add a little distilled water to make it slurry, add 60ml boiling distilled water, and boil 1 ~ 2min with stirring to make the starch solution transparent. Slightly cool, rinse with distilled water, so that the starch solution is completely poured into the 100 ml volumetric flask, cooled, diluted with distilled water to the marking line, and shaken well for use.
Note: the above starch solution should be freshly prepared when used, and its pH value is about 4.8 ~ 5.5. Take about 0.2 ml and dilute it to 30 ml with distilled water. When adding 1 drop of 0.2 mol/L iodine solution, it should be pure blue.
0. 1 mol/L iodine solution: dissolve 12.69 g redistilled iodine and 13 g potassium iodide in distilled water and dilute to 1000 ml.
Phenolphthalein indicator: 1% ethanol solution.
Determination steps: Weigh the sample 10g (accurate to 0.0 1g) and dissolve it in 50 ~ 70ml distilled water, add 2 ~ 3 drops of phenolphthalein indicator and neutralize it with 0.05mol/L sodium hydroxide solution. Pour this solution into a 100 ml volumetric flask and dilute it with distilled water to scale. Take 12 test tubes with the same size, mark them with serial numbers, and add honey sample solution, distilled water, 0. 1 mol/L sodium chloride solution, 0.2 mol/L acetic acid solution and 1% starch solution according to Table 5, and immediately immerse all test tubes in a water bath at 45 ~ 50℃ after shaking them evenly, so that the liquid level of the test tubes is lower than that of the test tubes. Immediately after taking it out, cool it in ice water, then add 1 drop of 0.2 mol/L iodine solution to each test tube, shake it well and observe it immediately. At this time, the color in each test tube changes from yellow to red, from purple to purple, and from purple to blue. According to the number of purple test tubes, the amylase values are shown in Table 6.
Table 6 Honey Amylase Value Table
Note: The distilled water used in this test should be boiled and cooled in advance.
⑤ Acidity determination:
Reagent: 0. 1 mol/L sodium hydroxide standard solution: dissolve 4 g sodium hydroxide in 1000 ml boiled and cooled distilled water, and calibrate its specified concentration with potassium hydrogen phthalate.
Weigh 0.8 ~ 0.9g (accurate to 0.0002g) of analytically pure potassium hydrogen phthalate dried at 65438 025℃ in advance, put it in a 250ml conical flask and dissolve it with 50ml distilled water. Add 2 ~ 3 drops of phenolphthalein indicator, titrate with sodium hydroxide standard solution to pink, and calculate the calibration concentration (m) of sodium hydroxide standard solution according to the following formula:
M=G/V×0.2042
Where g refers to the weight (grams) of potassium hydrogen phthalate;
V—— the amount of sodium hydroxide standard solution consumed in titration (ml).
Phenolphthalein indicator: 1% ethanol solution.
Determination steps: Weigh 10g (accurate to 0.00 1g) sample, dissolve it in 75ml of boiled and cooled distilled water, add phenolphthalein indicator, and titrate with sodium hydroxide standard solution until it is light pink (10s does not fade).
Calculate the acidity according to the following formula:
Acidity =V×M/W× 100
Where, V is the amount of sodium hydroxide standard solution consumed in titration (mL);
M—— calibrated concentration of sodium hydroxide solution;
W—— sample weight (gram).
The allowable error of parallel test results is 0. 1.
⑥ Fischer reaction:
Reagent:
1% resorcinol hydrochloric acid solution: dissolve 0. 1 g resorcinol in 10 ml concentrated hydrochloric acid (density: 1. 19 kg/L), and the solution should be colorless (freshly prepared when the solution is used).
Ether: It should be free of peroxide, moisture and alcohol. The resorcinol hydrochloric acid solution should be colorless after dripping, and there should be no residue after volatilization. If necessary, dry with calcium chloride, distill, and add metallic sodium for later use.
Attention: When handling ether, the distilled water bottle must not evaporate. Adding metallic sodium means anhydrous ether, otherwise there will be explosion danger.
Determination steps:
Grinding method: take 5.0 grams of sample and put it in a mortar with an outer diameter of about 7 cm at the bottom. Add 3 ml of ether, grind with a bowl hammer until the ether is completely volatilized (about 1 minute and a half), then add 3 ml of ether each time to grind 1 minute (about 60 times) until about 1 ml of ether remains, pour it into a porcelain evaporating dish with a smooth inner surface and a diameter of about 7 cm, grind it for 3 times, and collect it all in the evaporating dish. Drop 3 ~ 4 drops of resorcinol hydrochloric acid solution, vortex immediately to completely moisten the residue, stand for 65438 0 hours, and observe. If there is cherry red, it is a positive reaction.