The time of value, thus detection speed improved.On the other hand, the increase of carbon dioxide generating speed improves the gas concentration lwevel that flows through detector tube, helps getting rid of the influence that the gas concentration lwevel fluctuation of ambiance Central Plains causes, and has improved the reliability that detects data.But as over-heating, sample temperature is too high, then will kill the part microorganism in the sample, and the content of microorganisms of discharging carbonic acid gas is obviously reduced.So that sample temperature to remain on a suitable scope very important.In general, this scope can be preferably between 20 ℃ to 50 ℃ from 0 ℃ to 65 ℃.The mode of heated sample has multiple, and the contact heating is to make sample directly contact and be heated with Heating element.Contactless heating can be divided into several classes again, and a class is based on the conduction heat exchange mode, i.e. Heating element direct heating sampling receptacle from the outside, and type of thermal communication is crossed barrel and is passed in the interior sample.Second class is based on convective heat exchange, i.e. Heating element elder generation heating fluid medium, and latter's heated sample container, sample is heated in the last tube.The 3rd class is based on radiative transfer, promptly with hertzian wave or ultrasonic wave, and heated sample under the situation that does not contact sample or sampling receptacle.From the homogeneous heating degree, the angle of intensification speed sees that the 3rd class mode is best.But must be pointed out that the higher hertzian wave (as microwave) of hertzian wave, especially frequency acts on sample, except that heat effect, also have non-thermal effect.Experiment shows that microorganism during such as 34 ℃, just may stop division owing to the non-thermal effect of microwave before not reaching the lethal temperature of heating.So, accurate for what guarantee to detect, adopt necessary strict control heating power of hertzian wave heated sample and action time.Make sample temperature preferably be no more than 30 ℃.

Because the heating of sample must form one from the ccontaining cavity of parallel connection, the guiding pipeline is to the apse rate between the carbonic acid gas proofing unit.Because the spread coefficient temperature influence of gas, temperature is high more, spreads fast more.So just helping carbonic acid gas, this enters the carbon dioxide indicator probe fast from concentration and all higher in parallel ccontaining cavity of temperature.

{ 4}, the custom-designed mobile position gradient of carbonic acid gas of being convenient to.Except concentration gradient and thermograde that above-mentioned guiding carbonic acid gas flows, in design, consider the proportion of carbonic acid gas, intentionally be provided with the position gradient, promptly allow the inlet mouth position of probe detector tube be lower than the position, air outlet of sampling receptacle or placer, the position, air outlet of probe detector tube is less than or equal to the inlet mouth position again, makes the carbonic acid gas energy one tunnel that generates from sample enter probe swimmingly.Further accelerated detection speed.

Because the microorganism detection method that the present invention proposes and traditional microorganism are cultivated the mode that afterwards detects earlier bigger difference is arranged.So the preparation work of its sample and usual manner have to a certain degree different.For realizing rapid and precise detection, be necessary to set up the sample standard that is suitable for present method.It thes contents are as follows:

A, sample collecting and preservation

Can detect the standard for manual sampling of stipulating by national related food fully carries out.

The preparation of B, sample and pre-treatment

Usually it is very complicated that the physics and chemistry of food detects pretreatment technology, and the sample pre-treatments technology of microorganism detection is then fairly simple.Conventional way is: by aseptic technique, behind the sample and the abundant mixing of sterile solution (as physiological saline, phosphate buffered saline buffer, nutrient broth etc.) that collect, grind in mortar, its diluent can be for detecting.If sample is a meat, solids such as fish should shred earlier, make behind the homogenate diluted sample liquid with homogenizer and detect.Total number of bacterial colony detection jus gentium or TTC development process such as routine all are first weighing 25 gram samples, add the even liquid that diluent ground to form 1: 10, and then are diluted to 1: 100 and 1: 1,000 even liquid.Select 2-3 suitable extent of dilution to carry out during detection.These conventional detection methods all are that first temperature control is cultivated, more with the naked eye or magnifying glass calculate colony number on the nutrient agar medium plate, be multiplied by extension rate at last, obtain the bacterium colony numerical value in the unit volume.So as not diluting, because amount of bacteria is too big, the colony number on the agar plate must be difficult to counting with many.Thereby can not get correct result.And the new detection mode of utilizing physics or chemical effect, owing to need not carry out enumeration, so generally needn't dilute.In the electric impedance fast detection method (Bactometer) such as French Mei Liai company, earlier aseptic culture medium GPM0.6 milliliter is added sample pool, directly the even liquid of 0.1 milliliter sample is poured into again, close the lid and to put into detector and detect.

The preparation of sample of the present invention and pre-treatment are similar to above-mentioned electric impedance fast detection method, pour in the sampling receptacle after being about to a certain amount of aseptic culture fluid and the even liquid of quantity of sample mixing, and can begin after closing the lid to detect.The aseptic culture fluid here can be the various organic solutions that help microorganism growth that contain carbon atom, and colloid or mixture are such as certain density glucose solution.

The sample standard that C, the present invention adopt

* for be difficult for the uniform solid food of hand lapping (as fresh meat, meat product, fish and shrimp fishery products, some melon and fruit and vegetables, tubers, seaweeds and dry fruit, nut etc.), earlier the sample that collects is shredded or shreds,use 8 again, 000-20, the centrifugal 1-5 of the clarifixator of 000r/min minute, make paste, the mixed that adds glucose solution 10-120 milliliter with per 100 gram pastes becomes sample homogenization again.The concentration of glucose solution is 1-30% (weight ratio).The sample homogenization consumption that detects once is the 25-200 gram.

* for being difficult for hand lapping, also be difficult to solid food (as exsiccant grain and beans etc.), after needing wear into powder with stamp mill earlier, be mixed into sample homogenization with glucose solution again with the homogenizer processing.Its blending ratio, it is the same that glucose solution concentration and homogenate detect consumption.

* for the uniform solid food of easy hand lapping (as vegetables, fruit, cake, bean curd and cereal product), can be directly in aseptic mortar, grind the back and be mixed and made into sample homogenization with glucose solution.Blending ratio, it is the same that glucose solution concentration and homogenate detect consumption.

* for liquid foodstuff that does not contain carbonic acid or beverage (as newborn class, tea, coffee, fruit juice, mineral water, pure water etc.), the mixed that adds glucose 1-30 gram by per 100 grams becomes the even liquid of sample, and the even liquid consumption of sample that detects once is the 25-200 gram.

* the food (as jam, pasta sauce, salad dressing etc.) that forms for solid and liquid mixing is handled by the liquid foodstuff that does not contain carbonic acid.

* for egg-products, bright egg shells the back by the liquid foodstuff processing that does not contain carbonic acid.Powdery or solid-state egg-products are handled by above-mentioned solid food.

* for lipid food, what be in a liquid state under the normal temperature handles by the liquid foodstuff that does not contain carbonic acid.Be solid-state (as butter, oleomargarine) under the normal temperature, handle by the liquid foodstuff that does not contain carbonic acid warm softening back.

* for jar tube food, open jar back and divide liquid and solid to remember the row processing into by above-mentioned liquid and the solid food that does not contain carbonic acid respectively.

* for carbohydrate food (as granulated sugar, brown sugar, Fruit candy etc.), the ratio that adds sterile pure water 20-300 milliliter in per 10 grams is made behind the sugar soln to be checked.The amount of samples that detects once is the 25-200 gram.

* for the solid food (as frozen meat, frozen fish is frozen boiled dumpling, freezes beans etc.) of freezing state, generally thaw earlier, treat to handle by above-mentioned solid food again after temperature is raised to room temperature.

* for freezing one-tenth solid liquid-food (as ice lolly, ice cream, ice-creams etc.), dissolve into earlier liquid state after, handle by the liquid foodstuff that does not contain carbonic acid again.

* for the beverage that contains carbonic acid (as Coca-Cola, carbonated drink etc.), not in sensing range.

Because the carbonic acid gas fluctuation that the carbonic acid gas generating rate of microorganism causes much smaller than testing staff and environment is so accuracy of detection is a key of success.

The present invention takes following measure to guarantee the accuracy of detection and enough precision.

I, the high-quality carbonic acid gas proofing unit of selection.It at first is the type selecting of probe.The probe precision of electrochemistry type is better, but generally has only the several years work-ing life.Non-scattering infra red type (NDIR) probe working stability is reliable, life-span can reach more than 10 years, the resolving power of this carbonic acid gas detector (as the CompuFlow 8610 type products of U.S. Technical Sourcing Internation) of general class is 0.1ppm, precision be+/-50ppm or detect demonstration number+/-3%.The high-grade detection probe of analyzing usefulness, precision can reach 5ppm or lower.The proofing unit that the present invention relates to preferably adopts high-precision electrochemistry type or non-scattering infra red type probe.In addition, when adopting two probes to detect foodstuff samples and blank sample (promptly have only aseptic glucose solution, do not have the sample of food) simultaneously, must consider the matching problem of two probes.Be the resolving power of the two, precision, heat sensitivitys etc. should be consistent as far as possible.The numerical value that shows under similarity condition should be identical.If any minute differences, to guarantee that at least also this difference all is a constant under any circumstance, so that after detection, carry out necessary compensation.

The control of II, temperature effect and compensation.Temperature Influence shows two aspects: the one, and the temperature variation of sampling receptacle and ccontaining cavity in parallel can influence the rate of diffusion of carbonic acid gas, so the heating of sample is control accurately, make the temperature variation in sampling receptacle and the ccontaining cavity in parallel as far as possible little.This need take into full account when selecting type of heating and element at the design detector.Another influence of temperature is the interference that non-scattering infra red type (NDIR) is detected, and general temperature is high more, and the data that obtain are more little than actual value, so must compensate.Concrete method be in the carbonic acid gas exploring tube or near detect the carbon dioxide gas stream temperature enter in the pipe with the highly sensitive temp probe, find out with the difference DELTA T of predetermined work temperature (generally being 20 ℃) (℃),

By following formula offset value calculation

δ(ppm)：δ＝+/-0.003ρΔT (1)

Wherein ρ is the gas concentration lwevel value (ppm) that instrument shows.It is pointed out that some carbonic acid gas proofing unit or transmitter itself have had temperature compensation function.

The elimination of III, environment and the influence of testing process cumulative carbonic acid gas.The influence that the main tested person personnel of the variation of environment gas concentration lwevel breathe.Breathing can cause the concentration of regional area up to 1,000-2,000ppm.In addition, testing process may cause carbonic acid gas to be trapped in ccontaining cavity in parallel, in guiding pipeline and the carbonic acid gas proofing unit, also can cause interference to detect next time, so must eliminate.When instruments design, should take into full account.The simplest way is, scavenger pump or ventilator are set, and before detecting each time, earlier remaining carbonic acid gas in the ccontaining cavity of parallel connection, guiding tube and the carbonic acid gas proofing unit taken away.Make the gas concentration lwevel in the probe be lower than environmental concentration slightly, and can in for some time, keep this concentration constant substantially.So begin this moment to detect, can be with interference reduction to minimum.

In IV, the testing process, the strict seal of equipment unit and junction.Its objective is that the carbonic acid gas that guarantees microorganisms does not leak, the carbonic acid gas in the outside air does not enter detection probe influences accuracy of detection.

V, water vapour interferential are eliminated.Water vapour in the carbon dioxide gas stream can cause interference to accuracy of detection.If the sample Heating temperature is higher, must has on a small quantity and enter in the detector tube with carbon dioxide gas stream from the water vapour in nutrient solution and the sample.The method that overcomes is: strict control Heating temperature, must not be too high, and preferably be no more than 50?In addition, can before the detector tube import of carbonic acid gas proofing unit, add a water vapour strainer, with siccative (as silica gel particle) filling.Make through wherein water vapour and fully adsorbed, carbonic acid gas then passes through.

VI, the various electronic filterings of employing and anti-electromagnetic interference measure make detection noise and interference drop to minimum level.

Blank contrast under VII, the same terms.So-called blank contrast is meant adopts the same specimen inspection system of two covers, and a cover is used for formal sample detection, and another set of is used for contrast, promptly is not the dress sample homogenization in sampling receptacle, but only adorns aseptic glucose solution.Two cover systems are in identical envrionment conditions (comprising initial temperature, initial gas concentration lwevel etc.), adopt identical equipment to heat, and detect and the data analysis processing.Last comparative result, its difference is exactly the carbon dioxide effect of microorganisms in the sample, and it should have positive correlation with content of microorganisms.Adopt this mode can overcome the influence that factors such as envrionment temperature and gas concentration lwevel are brought more completely.

The calibrating procedure of VIII, strictness.What the detection method that the present invention proposes obtained is that indirect content of microorganisms characterizes, for being converted into real content of microorganisms, must demarcate with traditional detection method, promptly to same sample to be checked, adopt present method and traditional method (as jus gentium or TTC development process) to detect simultaneously, with result contrast, thereby derive conversion relation between the former carbonic acid gas variation characteristic and the latter's microbe colony sum.For making conversion relation accurately and reliably, this demarcation notes following points:

* preferably food is classified, respectively varieties of food items is demarcated by the mode in the aforementioned sample standard.At least solid and liquid foodstuff should be demarcated respectively.The benefit of doing like this is to make demarcation more reasonable and accurate.

* the demarcation of same food is preferably under the different condition (as differing temps time) and carries out repeatedly respectively, to obtain the most rational result.

* same food, the calibration experiment under the similarity condition, preferably also doing several times so that obtain more rational conversion relation by mathematical statistics more.

* the most handy two or more traditional detection mode and present method compares demarcation, again with check and inspection as a result, to eliminate the deficiency that only exists with a kind of traditional method.

IX, raising enter the gas concentration lwevel in the detector tube air-flow.Because all there is certain sensitivity problem in transmitter, high gas concentration lwevel helps the raising of accuracy of detection, and low excessively concentration might not reach the minimum door that makes working sensor

Value, causing detection signal is zero.In the present invention, strengthen the amount (as increasing to 100 grams) of sample to be checked and sample heated, the gas concentration lwevel that enters in the detector tube will be improved from 25 grams.

The elimination of microbial contamination in X, the operating process.Remove in specimen preparation, loading and unloading, detect wait observe outer each detection of conventional aseptic rules in the operation before, each parts of instrument must the thorough disinfection sterilization.The mode of disinfection has multiple, and the simplest method is to adopt the UV-lamp irradiation, but need to guarantee not have in sampling receptacle and the ccontaining cavity in parallel according to less than the dead angle.Adopting photocatalysis sterilization also is a kind of mode of considering, it need smear thenano level TiO 2 particles of one deck at ccontaining cavity of parallel connection and carbonic acid gas receiver internal surface, also needs the UV-irradiation of specific wavelength.So not as directly convenient with ultra-violet sterilization.

The present invention needs the carbon dioxide effect of contained microorganisms in the sample is detected analyzing and processing and storage.Such as:

(a), will be constantly 0 to being divided into the some time interval constantly between the t, write down each spaced points and enter gas concentration lwevel value in the detector tube, i.e. r₀, r₁, r₂, r₃, r '_iR '_T-1, and r_tThe length in the timed interval is relevant with the detection probe performance, can not wait by several minutes from the several seconds.Total detection time, t can be according to concrete food and specimen in use amount, sample Heating temperature and deciding.Can not wait from several minutes to a few hours.

(b), write down each point in timed interval flow through detector tube gas flow temperature, T₀, T₂, T₃, T_iT_T-1, and T_t

(c), the temperature data of each point of obtaining according to detection in timed interval, by above-mentioned formula (1), calculate also storage through compensating the carbonic acid gas data r ' of revised each timed interval point₀, r '₁, r '₂, r '₃, r '_iR '_T-1, and r '_t

(d), calculate and store the time dependent function relation curve of gas concentration lwevel, i.e. r '-t curve.

(e), calculate and the time dependent function relation curve of storage gas concentration lwevel rate of rise, promptly (dr '/dt)-the t curve.

Carbonic acid gas increment r ' when (f), writing down moment ti_I-r '₀

(g), record moment t_iThe time the carbonic acid gas rate of rise (r '_I-r '₀)/t_i

(h), record moment t_iMaximum value, minimum value and the difference between them of preceding gas concentration lwevel.

(i), record moment t_iThe average of preceding gas concentration lwevel

(j), for blank comparison system, also carry out similar detection by foregoing fully, record, storage and handle.

(k), adopt digital filtering technique, handle detecting data, reject irrational numerical value, reduce noise jamming, to obtain the optimum detection result.

(l), relatively, analyze relation curve and some carbonic acid gas increment and rate of rise constantly that two cover systems obtain, find out main difference, with this carbonic acid gas variation characteristic that causes as microorganism.

(m), according to microbe colony sum in the carbonic acid gas variation characteristic that obtains in advance and the derivation of the conversion relation between the microbe colony sum sample, store data then.

The detection technique that the present invention proposes is made of following key step:

(1), according to a conventional method carry out the sampling and the preservation of food, under aseptic condition, carry out specimen preparation;

(2), with UV-lamp to sampling receptacle, to container and the ccontaining cavity in parallel sterilising treatment that carries out disinfection, and with heating unit simultaneously with sampling receptacle, to container and ccontaining cavity preheating in parallel;

According to above-mentioned design, the workflow of detector is as follows.

(1), plug circumscripted power line, turn on the power switch detector preheating and self check.

(2), open the sampling receptacle sealing cover, cover the detector loam cake, send instruction by central control unit, open UV-lamp automatically, to sampling receptacle and its ccontaining cavity sterilization in parallel.Simultaneously send instruction by central control unit, detect temperature in the ccontaining cavity in parallel automatically, whether decision starts heating unit is heated to predefined temperature for ccontaining cavity in parallel.(meanwhile, detection person can carry out the preparation work of specimen preparation and contrast nutrient solution)

(3), after sterilization and ccontaining cavity preheating in parallel finish,, open loam cake, take out sampling receptacle, add sample and contrast nutrient solution according to the display screen prompting.Cover sealing cover and loam cake.Send instruction by central control unit, open air interchanger automatically, discharge last time detecting the carbonic acid gas that remains in the carbonic acid gas proofing unit.Begin formal detection then.Detect data and analyze, handle and record by central control unit.Meanwhile,,, make sample in testing process, keep constant temp substantially by starting or stoping heating unit at any time according to the detection of temp probe.

(4), according to predefined detection time, stop to detect, show net result by display screen.Data transmission is preserved or is printed in computer.

(5), as then detect next time, need not shut down, take out sampling receptacle after, put into new empty tube, restart sterilization and preheating.

Claims

1. microbe content in food method for quick is characterized in that: adopt two covers specimen inspection system in parallel, a cover is used for food samples and detects, and another set ofly is used for contrast; Two cover systems are in identical envrionment conditions, comprise initial temperature, initial gas concentration lwevel, adopt identical heating unit to heat, the carbonic acid gas that two cover systems are produced is transported to downwards in the same carbonic acid gas proofing unit of two covers through guiding tube respectively and is detected, data analysis is handled after testing, compares the detected result of two cover systems, and content of microorganisms has positive correlation in its difference and the food samples; Draw microbe colony sum in the food samples according to the conversion relation between carbonic acid gas variation characteristic that obtains in advance and the microbe colony sum.

2. microbe content in food method for quick according to claim 1 is characterized in that following steps are arranged:

3. microbe content in food method for quick according to claim 1 and 2 is characterized in that: the mode of above-mentioned heating can be the conduction heat exchange mode, and the convective heat exchange mode is or/and the radiative transfer mode.

4. microbe content in food method for quick according to claim 1 and 2, it is characterized in that: the conversion relation between above-mentioned carbonic acid gas variation characteristic and the microbe colony sum is demarcated with traditional detection method, promptly to same sample to be checked, adopt the present invention and traditional method simultaneously, traditional method such as jus gentium or TTC development process, detect,, thereby derive conversion relation between the former carbonic acid gas variation characteristic and the latter's microbe colony sum result contrast.

5. a microbe content in food rapid detection instrument is provided with supply socket, power switch that connects central control unit and the interface that is connected outer computer on cabinet, it is characterized in that:

Sampling receptacle with container is connected with the carbonic acid gas proofing unit with the water vapour strainer through guiding tube respectively; The carbonic acid gas proofing unit comprises the detector tube that is positioned at inlet mouth and carbonic acid gas probe, change-over circuit and the air outlet that the carbonic acid gas detection signal can be changed into voltage or current signal, the air outlet is through the pipe connection air interchanger, and the air outlet of air interchanger is located on the cabinet; The data output end of above-mentioned change-over circuit is connected with the data input pin of central control unit, and the data output end of central control unit is connected with display screen.

6. microbe content in food rapid detection instrument according to claim 5 is characterized in that: above-mentioned carbonic acid gas probe is non-scattering infra red type probe or electrochemistry type probe.

7. microbe content in food rapid detection instrument according to claim 5, it is characterized in that: above-mentioned water vapour strainer is a filling siccative in body, body one end has inlet mouth, and the other end has the air outlet, is provided with filter at the inlet mouth and the place, air outlet of body lid.

8. microbe content in food rapid detection instrument according to claim 5 is characterized in that: above-mentioned heating unit be connected by power source circuit, temperature detection amplifying circuit, pilot circuit and the constant temperature control circuit that flip-flop circuit connects to form.

9. microbe content in food rapid detection instrument according to claim 5 is characterized in that: above-mentioned sampling receptacle is the encloses container of with closure, and the air outlet in the sealing cover is communicated with the carbonic acid gas proofing unit of below through guiding tube and water vapour strainer.

10. microbe content in food rapid detection instrument according to claim 5, it is characterized in that: above-mentioned sampling receptacle is the open container of the ventilative aperture of band, ccontaining cavity in parallel has sealing cover, each ccontaining cavity bottom in parallel has the air outlet, and the air outlet is communicated with the carbonic acid gas proofing unit of below through guiding tube and water vapour strainer.