MANUFACTURING OF EXTRUDATES HAVING IMPROVED MICROBIAL QUALITY

Abstract

The present invention relates to extrudates comprising water-soluble vitamins and other micronutrients. They are obtainable by adiabatic extrusion. During extrusion, temperature is controlled by the viscosity of the composition which is being extruded. Pasteurization temperature is reached, i.e. the extrudates of the invention meet the requirements set out in microbiological guidelines.

Claims

1. Extrudate, obtainable by extrusion of a composition comprising at least 10 weight-% starch powder, based on the total weight of the composition, at least 10 weight-% semolina, based on the total weight of the composition, and water, wherein the weight ratio between said starch powder and said semolina is from 5:1 to 1:5.

2. Extrudate according to claim 1, wherein said composition further comprises water-soluble vitamins and wherein said composition comprises preferably vitamin B12, folic acid and/or niacinamide.

3. Extrudate, according to claim 1, obtainable by extrusion of a composition comprising at least 20 weight-% starch powder, based on the total weight of the composition, at least 20 weight-% semolina, based on the total weight of the composition, at least 5 weight-% of at least one water-soluble vitamin, based on the total weight of the composition, preferably at least 1 weight-% of at least one lubricant such as medium-chain triglycerides (MCT), based on the total weight of the composition and 10-30 weight-% water, based on the total weight of the composition wherein the weight ratio between said starch powder and said semolina is from 4:1 to 1:4, preferably from 3:1 to 1:3 and most preferably from 2:1 to 1:2.

4. Method for manufacturing extrudates, said method comprising the extrusion of a composition comprising at least 10 weight-% starch powder, based on the total weight of the composition, at least 10 weight-% semolina, based on the total weight of the composition, and water, wherein the weight ratio between said starch powder and said semolina is from 5:1 to 1:5.

5. Method according to claim 4, wherein the particle size of said starch powder and the particle size of said semolina is chosen such that a temperature of at least 70 C. is reached at the extruder's die not later than 30 minutes after the start of adiabatic extrusion, when a Rheomex PTW16/25 OS Twin Screw extruder is used (length/diameter ratio=25; screw speed=200 rpm; feed rate: 300 g/h).

6. Use of a mixture comprising starch powder and semolina for controlling temperature during adiabatic extrusion, wherein the weight ratio between said wheat starch and said semolina is from 5:1 to 1:5.

7. Use according to claim 6, wherein said mixture comprises water-soluble vitamins and wherein said mixture comprises preferably vitamin B12, folic acid and/or niacinamide.

8. Extrudate according to claim 1, wherein the viscosity of a mixture consisting of 10 weight-% of said starch powder and 90 weight-% water, based on the total weight of said mixture, is at least 0.4 Pa.Math.s when measured at temperature of 60 C. on the Malvern Rheometer AR G2 using a concentric rotary cylinder with a bob diameter of 27.99 mm and a length of 42.10 mm at a shear rate of 100 s.sup.1 and/or wherein the viscosity of a mixture consisting of 10 weight-% of said semolina and 90 weight-% water, based on the total weight of said mixture, is at least 0.04 Pa.Math.s when measured at temperature of 70 C. on the Malvern Rheometer AR G2 using a concentric rotary cylinder with a bob diameter of 27.99 mm and a length of 42.10 mm at a shear rate of 100 s.sup.1.

9. Extrudate according to claim 1, wherein the viscosity of a mixture consisting of 10 weight-% of said semolina and 90 weight-% water, based on the total weight of said mixture, is lower at 85 C. than the viscosity of the same mixture at 75 C. when measured on the Malvern Rheometer AR G2 using a concentric rotary cylinder with a bob diameter of 27.99 mm and a length of 42.10 mm at a shear rate of 100 s.sup.1, and/or wherein the viscosity of a mixture consisting of 10 weight-% of said starch powder and 90 weight-% water, based on the total weight of said mixture, is lower at 85 C. than the viscosity of the same mixture at 75 C. when measured Malvern Rheometer AR G2 using a concentric rotary cylinder with a bob diameter of 27.99 mm and a length of 42.10 mm at a shear rate of 100 s.sup.1.

10. Extrudate according to claim 1, wherein said semolina has a particle size d(0.9) from 300m to 500m when measured on the Malvern Rheometer AR G2 using a concentric rotary cylinder with a bob diameter of 27.99 mm and a length of 42.10 mm at a shear rate of 100 s.sup.1, and/or wherein said starch powder has a particle size d(0.9) from 10m to 300m when measured on the Malvern Rheometer AR G2 using a concentric rotary cylinder with a bob diameter of 27.99 mm and a length of 42.10 mm at a shear rate of 100 s.sup.1.

11. Extrudate according to claim 1, wherein said starch powder is not flowable and/or wherein said starch powder is wheat starch powder.

12. Extrudate according to claim 1, wherein said semolina is durum semolina.

13. Extrudate according to claim 1, wherein said semolina has a refusal to sieve 200m of less than 40% (m/m), of preferably less than 30% (m/m) and most preferably of less than 20% (m/m) and/or wherein said starch powder has a refusal to sieve 200m of less than 5% (m/m), of preferably less than 3% (m/m) and most preferably of less than 1% (m/m).

14. Extrudate according to claim 1, wherein said weight ratio between said starch powder and said semolina is from 4:1 to 1:4, preferably from 3:1 to 1:3 and most preferably from 2:1 to 1:2.

15. Container comprising extrudate according to claim 1, wherein said container is preferably a sachet or a stick pack.

Description

FIGURES

[0179] FIG. 1 shows the temperature dependency of the viscosity of aqueous semolina type 1 and aqueous semolina type 2, respectively. Viscosity is shown on the y-axis in [Pa.Math.s] whereas temperature is shown on the x-axis in [ C.]. For further details, see below example 1.

[0180] FIG. 2 shows the temperature dependency of the viscosity of aqueous wheat starch type1 and aqueous wheat starch type 2, respectively. Viscosity is shown on the y-axis in [Pa.Math.s] whereas temperature is shown on the x-axis in [ C.]. For further details, see below example 2.

[0181] FIG. 3 shows the temperature at the extruder's die from the start of the extrusion (t=0) to the end of extrusion at a feed rate of 300 g/h. Temperature is shown on the y-axis in [ C.] whereas time is shown in minutes on the x-axis. For further details, see below example 3.

[0182] FIG. 4 shows the temperature at the extruder's die from the start of the extrusion (t=0) to the end of extrusion at a feed rate of 500 g/h. Temperature is shown on the y-axis in [ C.] whereas time is shown in minutes on the x-axis. For further details, see below example 4.

[0183] FIG. 5 shows the temperature at the extruder's die from the start of the extrusion (t=0) to the end of extrusion at a feed rate of 300 g/h. Temperature is shown on the y-axis in [ C.] whereas time is shown in minutes on the x-axis. For further details, see below example 5.

EXAMPLE 1

Semolina

[0184] Two different types of semolina were tested: Type 1 has a smaller particle size than type 2. Accordingly, when semolina type 2 is sieved, more particles remain in the sieve (200m) than when semolina type 1 is sieved. Details are given in TABLE 1.

[0185] Semolina type 1 was mixed with water. The obtained mixture consisted of 10 weight-% of said semolina and 90 weight-% water, based on the total weight of said mixture.

[0186] Similarly, semolina type 2 was mixed with water. The obtained mixture consisted of 10 weight-% of said semolina and 90 weight-% water, based on the total weight of said mixture.

[0187] Then, the viscosity of both mixtures is measured on a Malvern Rheometer AR G2 using a concentric rotary cylinder with a bob diameter of 27.99 mm and a length of 42.10 mm at a shear rate of 100 s.sup.1. The 10% suspension was heated stepwise from 25-85 C. and the viscosity measured 7 times at each temperature step and then averaged. The results of both tests are shown in FIG. 1.

TABLE-US-00001 TABLE 1 Semolina, as tested in Example 1. Semolina Type 1 Semolina Type 2 Description Granular product, Granular product, obtained from milling obtained from milling and sieving of wheat and sieving of wheat refusal to sieve 10 5% (m/m) 75 5% (m/m) 200 m flowability yes yes Density 670 g/l 753 g/l

[0188] FIG. 1 shows that the increase in viscosity depends on the particle size of semolina. The viscosity of the mixture comprising semolina type 1 (small particle size) starts increasing at lower temperature than the viscosity of the mixture comprising semolina type 2 (large particle size).

[0189] Furthermore, maximum viscosity of the mixture comprising semolina type 1 (small particle size) is reached at lower temperature than maximum viscosity of the mixture comprising semolina type 2 (large particle size).

[0190] Surprisingly, the differences between the two types of semolina are most prominent in a temperature range between 55 C. and 80 C. This temperature range is particularly important for the extrusion of vitamins (cf. examples 3, 4 and 5).

[0191] At a temperature between 60 C. and 70 C., the mixture comprising semolina type 1 (small particle size) has a higher viscosity than semolina type 2 (large particle size). Without wishing to be bound to a particular theory, it is believed that smaller particles are more susceptible for gelatinization than larger particles.

[0192] At a temperature between 75 C. and 85 C., however, aqueous semolina type 1 (small particle size) has a lower viscosity than aqueous semolina type 2 (large particle size). It is believed that the observed decrease in viscosity helps to make sure that a pre-determined maximum temperature is not exceeded during adiabatic extrusion.

[0193] In the adiabatic extrusion of example 5 (vide infra), semolina type 1 (small particle size) was used. It appears that the temperature dependency of the viscosity of semolina type 1 (small particle size) triggers a quick temperature increase at the beginning of adiabatic extrusion which ensures that the temperature does not go beyond 100 C. Temperatures of more than 100 C. would be detrimental to vitamins.

EXAMPLE 2

Wheat Starch Powder

[0194] Two different types of wheat starch powders were tested. Both powders were white in appearance and, in contrast to semolina, not flowable: Type 1 has a lower d(0.9) value than type 2, indicating a smaller particle size.

[0195] The d(0.9) value was measured on a Malvern Mastersizer 2000 connected to a Scirocco 2000 dry dispenser unit with a 60% vibration feed, 0.1 bar dispersive air pressure and measured with a continuous obscuration (7.01%) over 35 s.

[0196] Details about the two types of wheat starch powder are given in TABLE 2.

[0197] Wheat starch powder type 1 was mixed with water. The obtained mixture consisted of 10 weight-% of said wheat starch and 90 weight-% water, based on the total weight of said mixture.

[0198] Similarly, wheat starch powder type 2 was mixed with water. The obtained mixture consisted of 10 weight-% of said wheat starch and 90 weight-% water, based on the total weight of said mixture.

[0199] Then, the viscosity of both mixtures was measured as described in example 1.

[0200] The result of both tests is shown in FIG. 2.

TABLE-US-00002 TABLE 2 wheat starch powder, tested in Example 2. Wheat starch Wheat starch powder Type 1 powder Type 2 Description very fine powder that creaks White powder when pressed between the fingers d(0.9) value approx. 50 m approx. 400 m Flowability no no density More than 568 g/l Approx. 523 g/l

[0201] FIG. 2 shows that the increase in viscosity depends on the particle size of wheat starch powder. As the temperature is being raised, the viscosity of the mixture comprising wheat starch powder type 1 (small particle size) increases a lot more than the viscosity of the mixture comprising wheat starch powder type 2 (large particle size).

[0202] Furthermore, maximum viscosity of the mixture comprising wheat starch powder type 1 (small particle size) is a lot higher than maximum viscosity of the mixture comprising wheat starch powder type 2 (large particle size).

[0203] The differences between the two types of wheat starch powder are most prominent in a temperature above 55 C.

[0204] At a temperature above 55 C., wheat starch powder type 1 (small particle size) has a higher viscosity than semolina type 2 (large particle size). Without wishing to be bound to a particular theory, it is believed that smaller particles are more susceptible for gelatinization than larger particles.

[0205] At a temperature of above 65 C., however, the viscosity of the mixture comprising wheat starch powder type 1 (small particle size) begins to decrease. It is believed that the observed decrease helps controlling the maximum temperature during adiabatic extrusion.

[0206] In the adiabatic extrusion of example 5 (vide infra), wheat starch powder type 1 (small particle size) was used in combination with semolina type 1 (small particle size). It appears that the temperature dependency of the viscosity of such mixture triggers a quick temperature raise at the beginning of adiabatic extrusion and prevents at the same time that temperature goes beyond 100 C. Temperatures of more than 100 C. would be detrimental to vitamins.

EXAMPLE 3

Matrix Type 2

[0207] Extrudates were obtained by extrusion of a composition shown in TABLE 3. As a matrix, wheat starch powder type 2 of example 2 and semolina type 2 of example 1 was mixed in a weight ratio 1:1.

TABLE-US-00003 TABLE 3 composition being extruded in Example 3 Place of content in weight-%, based on the compound insertion total weight of the composition wheat starch Barrel #1 35.64 powder type 2 semolina type 2 35.64 Vitamins and 14.59 minerals water Barrel #2 10.54 MCT Barrel #4 3.59

[0208] A Rheomex PTW16/25 OS Twin Screw extruder with a length/diameter ratio 25, fitted with a 0.8 mm die consisting of 15 holes (Thermo Fischer, Karlsruhe), has been used. A Haake Polylab drive (Thermo Fischer, Karlsruhe) unit was connected to the extruder.

[0209] A blend of wheat starch powder, semolina and all the water-soluble active ingredients (i.e. vitamins and micronutrients) were added into the first barrel of the extruder (feed rate: 300 g/h). Water was then added in a second barrel of the extruder, said second barrel being located downstream of said first barrel. The lubricant (i.e. MCT) was then added into barrel 4 of the extruder, said barrel being located downstream of said barrel 2.

[0210] The screw of the extruder had two stress zones for ensuring adequate mixing. Stress zone one was located after barrel 2 whereas a second stress zone was located after barrel 4.

[0211] The extrusion took place under adiabatic conditions, i.e. the extruder was neither cooled nor heated and the compounds being inserted into the extruder (e.g water) had room temperature. The temperature was measured at the die of the extruder during the complete extrusion (60 minutes); the result is shown in FIG. 3.

[0212] Die face cutting began once a cuttable extrusion strand appeared that the die. Sample were taken at regular intervals and the sample was then dried on a fluid bed dryer. The dried extrudates had residual water of about 5 weight-%, based on the total weight of the dried extrudate.

[0213] FIG. 3 shows that the temperature of the die increased and then remained stable a 60 C. FIG. 3 also shows that it took approx. 30 minutes to reach a temperature of approx. 60 C.

EXAMPLE 4

Matrix Type 2

[0214] Example 3 was repeated. This time, however, feed rate was increased from 300 g/h to 500 g/h.

[0215] Similar to example 2, the extrusion took place under adiabatic conditions, i.e. the extruder was neither cooled nor heated and the compounds being inserted into the extruder (e.g. water) had room temperature. The temperature was measured at the die of the extruder during the complete extrusion (90 minutes); the result is shown in FIG. 4.

[0216] In contrast to example 3, the temperature kept raising.

[0217] Probably because a higher feed rate (500 g/h vs. 300 g/h) had been applied, a temperature high enough to ensure pasteurization was reached. However, it took almost approx. 50 minutes to reach a temperature high enough for pasteurization. Thus, similar to example 3, the increase in temperature at the beginning of the adiabatic extrusion was relatively slow.

[0218] Extrudates being produced at temperature below 70 C. (i.e. extrudates produced in the first 30 minutes) had to be discharged.

EXAMPLE 5

Matrix Type 1

[0219] Example 3 was repeated (i.e. feed rate: 300 g/h). This time, however, wheat starch powder type 1 of example 2 (instead of type 2) and semolina type 1 of example 1 (instead of type 2) was used. For details, reference is made to TABLE 4.

TABLE-US-00004 TABLE 4 composition being extruded in Example 5 Place of content in weight-%, based on the compound insertion total weight of the composition wheat starch Barrel #1 35.64 powder type 1 semolina type 1 35.64 Vitamins and 14.59 minerals water Barrel #2 10.54 MCT Barrel #4 3.59

[0220] Again, the extrusion took place under adiabatic conditions, i.e. the extruder was neither cooled nor heated and the compounds being inserted into the extruder (e.g water) had room temperature. The temperature was measured at the die of the extruder during the complete extrusion (130 minutes); the result is shown in FIG. 5.

[0221] Surprisingly, a temperature plateau of approx. 82 C. was reached although a feed rate of 300 g/h only was applied.

[0222] Furthermore, said temperature plateau was reached very quickly. In example 4, it took almost 50 minutes to reach a temperature of approx. 82 C. In example 5, a similar temperature was reached after about 30 minutes.

[0223] Thus, using a mixture of type 1 semolina and type 1 wheat starch powder allows to reach pasteurization temperature quickly and prevents at the same time unacceptable high temperatures.

EXAMPLE 6

Application in Food

[0224] Porridge was prepared. Approx. 40 extrudates of example 5 were sprinkled over the warm porridge. After stirring with a spoon, no extrudates could be discovered upon visual inspection, i.e. the extrudates had been disintegrated. Porridge is easy-to-swallow.

EXAMPLE 7

Microbial Quality

[0225] The microbial quality of the semolina type 1 as used in example 1 was tested. The test revealed that total aerobic bacteria count (measured in CFU/g) was about 50 times higher than the regulatory limit. Yeasts and moulds (measured in CFU/g) was also above regulatory limit. Furthermore, a significant amount of Salmonella spp. and staphylococcus aureus was detected.

[0226] Applicable regulatory limits are shown in below Table 5. CFU refers to colony forming units.

TABLE-US-00005 TABLE 4 regulatory limits Parameter Limit Unit Total aerobic bacteria count 1000 CFU/g Yeats & Moulds 100 CFU/g E. coli absent in 10 g Salmonella spp. absent in 50 g Staphylococcus aureus absent in 10 g

[0227] The microbial quality of the extrudate produced in example 5 was then tested. In said example, semolina type 1 was used. Extrudates being produced below pasteurization temperature were discharged.

[0228] In said extrudate, that total aerobic bacteria count (measured in CFU/g) was about 500 times lower than in the semolina as such and thus, fulfilled the regulatory limit. Yeasts and moulds (measured in CFU/g) was also below regulatory limit. Neither Salmonella spp. nor staphylococcus aureus was detected in the extrudate.

[0229] Thus, example 7 shows that a temperature high enough to manufacture extrudate of good microbial quality can be reached under adiabatic conditions when the composition of the invention is used.