DE19615044C2 - Process for the continuous production of yogurt - Google Patents

Description

The invention relates to a method for producing Yogurt, covering the entire manufacturing process of yogurt the temperature-time course of the output milk has only a maximum and an increase the dry mass of milk through flash evaporation is made, preheating the milk first is then heated to a maximum temperature becomes and finally a flash evaporation Subject to cooling and thereby concentrating.

A method of this kind is known (milk science 26 (9), 1971, pages 533 to 536).

The industrial production of yogurt and yoghurt Certificates usually run according to the following procedure (see e.g. H. J. Klupsch: Sour milk products, milk mixed drinks and desserts, pages 60-84 and 315-357, Verlag Th. Mann, Gelsenkirchen-Buer, 2nd edition 1992) from: First, the raw or pasteuri provided  milk with fat content. To the later Water binding ability and thus the strength in puncture-resistant or the viscosity in the stirred end product usually increases in the next step Increasing the dry matter, increasing the absolute casein content is of the greatest importance. A steady increase in all dry matter stocks parts is by evaporating the milk or by Addition of milk concentrates reached while at Addition of skimmed milk powder only the components of the fat-free milk solids can be added. The Jo ghurt consistency can also be targeted by adding certain milk protein products can be improved. For heat-treated yogurt products or milk mixers Products made from yoghurt can also be used in milk Contain hydrocolloids or sugar.

The introduction of skimmed milk powder, but especially also that of special milk protein products or hydro colloid, requires a suitable device to make a to achieve complete dispersion in milk.

Degassing is then often required Lich. The addition of concentrates starts with one previous evaporation. When evaporating the whole Milk, e.g. B. in the downdraft evaporator, this is first heated up and then concentrated under vacuum. Then, if necessary, there is another one Correction of fat and dry matter.

After evaporation, concentrate or powder addition, the Yogurt milk cooled to approx. 6-8 ° C then heat-treated delt and homogenized. The concentrate is on heated to approx. 85-95 ° C and kept hot for up to 30 min. Homogenization takes place before heating (septic) or one or two after keeping hot (aseptic)  staged. Before adding the prepared yoghurt culture, cooling to approx. 42-48 ° C is required. It is not uncommon for the process milk to continue to rise cooled about 6-8 ° C and only re-opened when needed Incubated temperature of about 42-45 ° C warmed and mixed with the culture.

After the culture has been added, incubation takes place until desired pH. Happens with stubborn yogurt this only after filling in the final packaging, at In contrast, stir yogurt in a sterile tank before bottling. Here the gelatin is usually one more Sheared to a smoother consi to achieve stenz, then immediately bring it down to approx. 20 ° C cooled and then bottled. The packs of the finished end product are placed in the cooling tunnel cooled about 10 ° C.

The description of the yogurt production shows that up to numerous energy-consuming products Temperature control steps must be carried out so that only the put lactic acid bacteria into effect and that End product in the desired quality is created. Ver simplifications of the current procedures - without qualification Loss of crime - should therefore be aimed at.

It is an object of the present invention, the number the thermal treatment steps and thus the To significantly reduce energy expenditure, too is aimed at the cost of a system with which the method according to the invention is to be carried out minimize, the procedure compared to the previous known methods should run more time-saving.  

The object is achieved according to the invention in that for the continuous production of yoghurt Yogurt culture only through the pressure difference between the outlet of the flash tank and the Culture container in the cooled and concentrated Milk is introduced.

The advantage of the method according to the invention is in that to form the pressure difference between the exit of the relaxation tank and the cultural heritage container no previous dosing pump required is what is called a reduction in energy gi effort leads to the implementation of the method and according to the task, the system costs for implementation of the inventive method with simultaneous Time savings in execution are reduced.

Advantageous refinements of the invention result from the subclaims.

According to FIG. 1, a plant with which yoghurt can be produced by the method according to the invention consists of the following components:

• a) from a heater, in which the heating of the cold raw milk to the desired maximum temperature takes place in several departments by indirect heat transfer (via plate, tube bundle, spiral heat exchangers). The first section 3 also serves as vapor vapor condenser, in which the vapor vapor formed in the expansion tank 8 is deposited by means of cold milk. The condensate formed is pumped out with the aid of a vacuum pump 18 . In the second and third sections 4 , 6 , the raw milk, preheated to approx. 42 - 46 ° C, is heated to the maximum temperature using hot water or steam. Serves hot water as a heat transfer medium, this is set in the separate hot water circuit by a direct steam injection 17 to the desired temperature. The maximum temperature of the milk is set and regulated via a steam control valve in the hot water circuit. Between the second and third department, a hot holder 5 a can also be installed, so that the milk can be kept hot (for at least 2 min) after the second department at 90-95 ° C. Keeping hot with almost complete denaturation of the whey proteins has a positive effect on the structure and viscosity of the end product;
• b) from a hot tube holder 5 b after reaching the maximum temperature, at the end of which immediately before entering the expansion tank, a pressure maintaining valve 7 works to maintain the required pressure in the entire heating system;
• c) from an expansion tank 8 in which a vacuum is set and maintained by means of the vacuum pump 18 and the vapor vapor condenser 3 via the vapor vapor suction line. In the expansion tank, the liquid milk phase is separated from the vapor formed by reducing the pressure (relaxation). The feed of the milk / steam mixture (two-phase flow) can be carried out both tangentially and axially ( Fig. 2);
• d) from a container for the yoghurt culture 9 , which is connected via a line to the outlet of the relaxation container;
• e) from a static mixer 10 , which is installed behind the outlet of the expansion tank and in which the lactic acid bacteria of the operating culture are evenly dispersed in the concentrated milk;
• f) from a pump 11 which conveys the concentrated and mixed milk into the buffer tank;
• g) from a buffer tank 12 for the short-term interim stacking of the concentrated and mixed milk;
• h) from a pump 13 , which promotes the concentrated and mixed milk from the buffer tank to the bottling plant;
• i) from an aseptically working filling system 14 , in which the concentrated and mixed milk is filled into the final packaging and this is then closed ver.

The process is a continuous one process in which the temperature-time curve only a single maximum over the entire process and at the same time has a yogurt consistency Promoting increase in dry matter by evaporating the Yogurt milk is done.

This procedure is for yogurt making intended starting milk adjusted in fat content in continuous flow initially to approx. 90-95 ° C warmed up, hot at this temperature for at least 2 min held and then further heated to 120-140 ° C and kept hot for a few seconds. During the subsequent After cooling down to 43-48 ° C a relaxation takes place  evaporation down to the vacuum range at which Deduction of the vapor vapor formed a dry mass milk increases. After this cooling down of the thickened milk continuously approx. 3-8% one Yoghurt culture added. This happens in the Way that in a separate sterile container culture in the vacuum area of the relaxation dosing tank via a separate line becomes. Then the milk mixed with culture from the vacuum area through a static mixer promoted to even distribution of milk to ensure acid bacteria.

In the manufacture of firm yogurt then over a sterile expansion tank aseptic filling in the final packaging. Acidification up to a certain pH value runs in the locked its final packaging in the culture given Temperature range from approx. 42 to 45 ° C. At Rührjo ghurt, on the other hand, joins the static mixer a tank for incubation before filling in later the final packaging follows. With the invention Manufacturing process becomes a continuous, ener pour-saving and recontamination-free process reali siert. By thermal pretreatment of the output milk with keeping warm at approx. 90-95 ° C and a Maximum temperature between 120 and 140 ° C becomes a very low-germ or even aseptic milk, which is produced in the subsequent flash evaporation and simultaneous Cooling down and the addition of culture no longer recontami is renated. With aseptic filling in a sterile Final packaging is then guaranteed to the end the minimum shelf life of yogurt no growth unwanted microorganisms is possible.  

The for heating the raw milk to the ge desired maximum temperature is necessary energy largely in the following process steps tet. This applies in particular to the relaxation process, where inevitably the pressure reduction Heat content of those previously heated to maximum temperature Milk used for partial evaporation of milk water becomes. This will make both the technologically necessary Increase in dry matter as well as the required Cooling achieved without additional energy supply. The Thermal energy of the formed after the phase transition Evaporated steam is used to preheat cold milk used during the heating phase. So that becomes a further energy savings both through the elimination of the cooling capacity required for vapor condensation as well as by reducing the energy required supply achieved during the heating process.

The yoghurt culture is sucked in exclusively Lich by the pressure difference between the outlet of the Relaxation tank and the culture tank and benö therefore does not require an additional culture feed pump. With With the help of a simple control valve and a mass current registration device can dose the Culture to be set and regulated precisely. The Container for the yogurt culture is replaced by one running piston cover airtight from above. This ensures that during the dosing phase no outside air is sucked in and the set one Vacuum in the expansion tank remains stable.

The manufacturing process also includes a tempered brood chamber in which the filled and sealed packs remain until the acidification process has led to the desired pH. A ventilation system 20 is used for tempering the incubation chamber, in which the thermal energy of the vapor vapor condensate produced during yogurt production and the overflow from the hot water circuit is additionally used. The subsequent rapid cooling of the yogurt after incubation can e.g. B. can be reached in a cooling tunnel (not included in Fig. 1).

When using a high-pressure heat transfer system for preheating the raw milk 3 , e.g. B. in the form of a tubular heat exchanger 23 , and the use of a high-pressure piston pump 22 in the feed area of the output milk, there is the possibility of homogenizing it by ent speaking installation of a homogenizing valve 21 ( Fig. 3).

Should be made yogurt instead of non-stick yogurt the components described in a) -f) remain unchanged. The concentrated and with culture spiked milk is then not stored in a buffer tank, but driven into a heated sterile tank, in which the incubation takes place up to the desired pH finds. After mechanical shear to a to achieve a smooth consistency, and cooling to approx. 20 ° C then the aseptic filling and others Cooling to below 10 ° C.

example

This example describes how to make a stitch firm whole milk yogurts (at least 3.5% fat) from concentrated centered milk according to the procedure described.

The product-carrying system was steamed before the attempt sterilized. The intended raw milk was initially  skimmed and then adjusted to 3.15% fat. The Protein content was 3.46%, the dry matter was 12.1 %. The milk was fed through a high pressure piston pump at 55 kg / h heated to 93 ° C in a preheater, then flowed in a tube hot holder with a dwell time of approx. 2 min and was then in the downstream Heating department (spiral heat exchanger) continues heated to approx. 121 ° C. After 10 s in the holding tube came the milk in the relaxation vessel. Here the cooled Milk to 48 ° C and at the same time gave water as Steam vapor off. When leaving the relaxation vessel the fat content had increased to 3.51% fat, protein and dry matter content to 3.89 and 13.5%, respectively. In order to was the amount of water withdrawn based on the Initial water volume of milk, approx. 11.8% and the Evaporation or thickening degree about 1.12. To the same effect through the addition of skimmed milk powder would have 1.3% in the raw milk must be added. However, this would have one around 0.4% higher fat content, i.e. must have 3.55%, so that the end product reaches 3.5% fat.

The thickened milk, the relaxation with 49 kg / h was left immediately at the age of 25 g / min (1.5 kg / h, i.e. approx. 3%) 8 ° C cold company culture metered in continuously.

The company culture was in autoclaved whole milk according to the regulations with a quick acidic, classic Yogurt culture produced (yogurt 709 Visbyvac series 50, Wiesby, Niebüll).

After the milk was inoculated, it passed one static mixer to ensure an even distribution of Ensure culture.  

The yogurt milk was then piped to one sterile filling bench with sterile room air. There was a three-way tap in the Yogurt cup (polypropylene, 150 g content). According to Ver the cup was closed by crimped aluminum foil place them in an incubator at 42 ° C. After about The incubation was stopped at 2: 45 hours after 3 examined cups the desired pH of 4.60 was reached. The cups were soaked in water from 5 ° C, then in a room at the same temperature further cooled. After 24 hours, 25 out of 50 filled cups measured the pH values. they layed between 4.30 and 4.45. The yogurt showed no whey casual, was sufficiently firm and creamy. In terms of sensors, it showed no defects.

When tested again after 14 days of storage at 5 ° C no yeast or mold reinfection was detected bar. Even now, no whey neglect was determined poses. The acidification resulted in a change different, but still sensory flawless taste.  

Reference list

1

Flow tank

2nd

positive feed pump

3rd

Heat recovery department I (vapor condenser) (heater)

4th

Heat recovery department II (heater)

5

a Preheat holder, at least 2 min (heater)

5

bHeat holder (heater)

6

Heating department (heater)

7

Pressure control valve (heater)

8th

Relaxation tank

9

Culture storage container with dosing control unit

10th

Dosing device for culture with static mixer

11

Pump to the buffer tank

12th

Buffer tank

13

Pump to the filling machine

14

aseptic filling machine

15

Hot water expansion tank

16

Hot water circulation pump

17th

Steam injector

18th

Vacuum pump

19th

Hatchery

20th

Ventilation system for the hatchery

21

Homogenizing valve

22

High pressure piston pump

23

Tube vapor condenser (high pressure version)
---- Product management
-------- water / condensate
.._.._ .. steam / vapor
........Air
..._..._Culture
Fruit preparation

Claims (7)

1. Process for the production of yogurt, in which the temperature-time profile of the starting milk has only a maximum over the entire production process of the yoghurt and in which an increase in the dry mass of the milk is carried out by flash evaporation, the milk being preheated and subsequently heated to a maximum temperature and finally subjected to flash evaporation for cooling and thereby concentrated, characterized in that for the continuous production of the yoghurt the yoghurt culture is introduced into the cooled and concentrated milk solely by the pressure difference between the outlet of the flash tank and the culture tank. 2. The method according to claim 1, characterized in that that the cooled, concentrated and with yogurt cultures added milk using a static mixer to be led.   3. The method according to claim 1 or 2, characterized records that the preheating of the raw milk takes place in a pressure-resistant tubular heat exchanger, and is homogenized in the process. 4. The method according to any one of the preceding claims, characterized in that the preheating of the milk to a temperature of 90 to 95 ° C for 2 to 15 min., in particular over 5 to 10 minutes. 5. The method according to any one of the preceding claims, characterized in that the maximum temperature is between 120 and 140 ° C. 6. The method according to any one of the preceding claims, characterized in that to obtain puncture-resistant Yogurt the cooling of the milk at the place of relaxation voltage step by regulating the vacuum to a Temperature of 44 to 48 ° C takes place, so that after Dosing of the yoghurt culture and a subsequent one Filling in a final packaging an optimal brew temperature of 42 to 45 ° C of the yoghurt reached becomes. 7. The method according to any one of the preceding claims, characterized in that stirrable to obtain Yogurt the cooling of the milk at the place of relaxation voltage step by regulating the vacuum to a Temperature is in the range of 43 to 46 ° C, so that after adding the yoghurt culture and one closing transfer to a sterile tank optimal incubation temperature of 42 to 45 ° C reached becomes.