Protein suspension from brewer's grains, method and apparatus for obtaining same

Abstract

The group of inventions relates to the food industry, and more particularly to a method and device for transforming brewer's spent grain (BSG). The invention makes it possible to increase the level of recovery of edible fractions from BSG to 90-95%, and to increase the amount of protein in an edible suspension to not less than 50 wt % dry solids. The underlying principle of the invention is a technique for preparing BSG for nutrient extraction and extracting said nutrients by mechanical processing on a proposed industrial processing line. The essence of the claimed method lies in loosening BSG on a vibratory sieve, grinding the BSG in a colloid mill with the addition of water or centrate in a ratio of from 0.5:1 to 1:1 relative to BSG to produce a paste-like homogeneous mass of BSG, and then processing said mass in a screw extractor for further grinding and separation into two fractions: an edible suspension having a 90-95% moisture content and containing all of the nutrients of BSG, including protein substances; and ground BSG husks having a 60-75% moisture content, suitable for subsequent industrial use. The edible suspension is then mechanically filtered to remove ground husk residue, and the suspension is pumped into a storage tank.

Claims

1. A method for producing a protein suspension having a moisture content equal to or less than 95%; a particle size of equal to or less than 0.5 mm and comprising fat, fiber, ash and protein; wherein the total protein content is of at least 55% dry wt, the method comprising: i) loosening brewer's grains to obtain a homogeneous mass, ii) removing impurities from the homogenous mass; iii) grinding the homogenous mass obtained in ii) with a colloid mill while hydrating the homogenous mass with water or centrate to reach a moisture content of between 90 and 95% and particle size of between 0.1 mm and 0.9 mm to obtain a pasty mass, wherein: the hydrating the homogeneous mass with the water or centrate is for homogeneous humidification of the pasty mass in a volume; and the pasty mass has a viscosity of between 750 cPa.Math.s and 1400 cPa.Math.s that moves by gravity to a screw extractor where the pasty mass is subject to additional grinding and separation to produce the protein suspension with a viscosity of between 1.5 and 3 cPa.Math.s.

2. The method of claim 1, wherein step iii) is performed at a rotor rate of 1,800-3,200 rot./second.

3. The method of claim 1, wherein the additional grinding and separation comprises removing, by the screw extractor, a ground husk from the pasty mass.

4. The method of claim 1, wherein the water or centrate is supplied to a receiving bunker of the colloid mill via openings of the water pipeline located around the circumference of the receiving bunker in its upper part.

5. The method of claim 1, wherein the brewer's grains are loosened, and impurities are removed by means of a vibrating screen with hole size of between 6 and 10 mm, and a screen vibration frequency of between 10 and 50 Hz and an amplitude of between 2 and 20 mm.

6. The method of claim 1, wherein the protein suspension is subject to additional vibrating filtration.

7. The method of claim 6, wherein the additional vibrating filtration is performed with screens having a hole size of between 0.1 and 0.5 mm.

8. The method of claim 4, wherein openings in the water pipeline are uniformly spaced along its length in order to ensure the homogeneous humidification of the pasty mass.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 demonstrates a picture of a part of the pilot production line consisting of a vibrating screen, a conveyor, a colloid mill and a screw extractor for obtaining protein suspension from brewer's grains.

(2) FIG. 2 demonstrates the production line's scheme for implementing the claimed method, where 1 indicates a vibrating screen, 2 indicates a conveyor, 3 indicates a colloid mill, 4 indicates a water pipeline, 5 indicates a screw extractor, 6 and 8 indicate impeller pumps, 7 indicates a vibration filter, 9 indicates a container for collecting protein suspension, 10 indicates a container for collecting husk, 11 indicates a block for processing the protein suspension in order to produce protein concentrate or protein isolate, 12 indicates a tank for centrate.

(3) FIG. 3 demonstrates a scheme of the colloid mill's loading tank. A indicates a layout of constructive elements in the colloid mill's loading tank, B indicates an overhead view of the loading tank, C indicates a cross-section diagram of the colloid mill, where 13 indicates a circular water pipeline, 14 indicates openings in the pipeline for water or centrate supply, 15, 16 and 17 indicate level-sensing devices, 18 indicates a control valve for water supply, 19 indicates a stator, 20 indicates a rotor, 21 indicates a stator shell, 22 indicates a rotor shaft and 23 indicates a loading tank of the colloid mill 3.

EMBODIMENT OF THE INVENTION

(4) Below is a more detailed description of the claimed invention that does not limit the scope of the claimed invention but demonstrates implementability of the invention by means of achieving the claimed technical result.

(5) The source brewer's grains with the humidity level of 70-90% are subject to treatment in the course of 3 hours after they are produced (from the moment they are obtained as a waste product in the brewing industry). The temperature of such brewer's grains at the moment of their receipt form the production facility varies from 2° C. to 80° C. The brewer's grains are loaded manually or by means of any mechanical method on a vibrating screen 1 (FIGS. 1, 2) with the hole size of 6-10 mm equipped with a magnetic catcher where the brewer's grains are subject to loosening and removal of any mechanical and metallic foreign impurities. Treatment by means of this vibrating screen implies sieving of the brewer's grains with the vibration frequency from 10 to 50 Hz and the amplitude of 2-20 mm within 2-10 seconds in order to produce a raw material without lumps and of a homogeneous composition for the further processing stage when the material is subject to grinding. It is possible to obtain a homogeneous mass with removal of mechanical impurities in the course of loosening the brewer's grains not only by means of a vibrating screen but also by means of any prior art device or a set of devices performing the mentioned functions. For the purpose of grinding, the conveyor 2 takes the loosened brewer's grains to the colloid mill 3 (FIG. 3) or another grinding machine capable of producing 0.005-0.5 mm particles. At the same time, the raw material is loaded in the colloid mill's tank step-by-step and water is added in order to provide for homogeneous humidifying of the raw materials in volume that can be performed both in a continuous mode and in a pulsating mode. As a rule, the ratio of the supplied water to the brewer's grains in mass is from 0.5:1 to 1:1. The amount and rate of water supply can be calculated in advance based on the measured initial humidity parameters of the brewer's grains delivered for processing taking into account humidity losses in the course of sieving the brewer's grains by means of the vibrating screen. The humidity level of the brewer's grain subject to treatment in the colloid mill shall preferably be within the range of 90-95%. The colloid mill 3 performs its homogeneous mixing (and/or homogenization) in order to produce a homogeneous pasty mass (pulp) with the viscosity of preferably 750-1,400 cPa.Math.s that moves by gravity to the screw extractor 5 where the mass is subject to additional grinding and division into suspension with the humidity level of 90-95% and the viscosity of 1.5 3 cPa.Math.s and husk with the particle size from 0.01 mm to 1.0 mm and the humidity level of 60-75%. The temperature of the brewer's grains subject to treatment in the colloid mill and the screw extractor can vary from 2° C. to 90° C. The brewer's grains can be supplied to the colloid mill by means of any prior art technical device, for example by means of a screw conveyor, or a belt conveyor, or a drag conveyor.

(6) Grinding of the brewer's grains in the colloid mill 3 takes place in the shell 21 between working surfaces of the rotor 20 and the stator 19, for example, in the course of rotation of the mill's rotor 20 at the rate of 1,800-3,200 rot./second what enables to produce thick, homogeneous, but sloppy consistency of the pulp for the maximum extraction of a nutritional fraction from the source raw material at the screw extraction stage. It is preferable to use centrate produced in the course of the food suspension's further treatment (in case of its concentrating) for its supply to the colloid mill 3 instead of water what provides for better extraction of the nutritional fraction remaining in the centrate and provides for avoiding a necessity of the centrate disposal, thus, for saving of resources necessary in case of the centrate disposal for purification before its discharge to the sewerage system. Water or centrate from blocks 5 or 12 is supplied to the V-shaped tank (receiving bunker) 23 of the colloid mill 3 via openings 14 of the water pipeline 13 located around the circumference of the tank in its upper part above the mark indicating the maximum tank load with raw materials. Amount of the supplied water or centrate can be regulated by means of the valve 18.

(7) The openings 14 in the pipeline are preferably uniformly spaced along its length what ensures the total homogeneous humidifying (thinning) of the brewer's grains in the course of processing.

(8) After grinding in the colloid mill 3 the pulp is subject to treatment in the screw extractor 5 with the screw rotation rate from 2 rot./minute to 8 rot./minute what enables to separate the food suspension from its waste product, barley's husk, in as short a time as possible, within 1-2 seconds. For this purpose, the pasty mass (pulp) produced by the colloid mill 3 fell by gravity into the screw extractor 5 where it was separated from the husk in order to produce the main product, the food suspension with the humidity level of max. 95%, and a waste product, barley's husk, with the humidity level of 60-75% and 1.0-5.0 mm husk particles. Since after treatment in the screw extractor 5 the suspension still contains 2-5% of small husk particles from 0.01 to 1.0 mm, this suspension is delivered by means of the impeller or another pump 6 designed for work with food suspension with the impurity level of up to 5% represented by small vegetable fractions of max. 1.0 mm, for the next purification stage to the vibration filter 7 with the filter holes of 0.2-0.5 mm what practically provides for removal from the food suspension of husk remaining after the screw extraction stage. After the vibration filter 7 the suspension is pumped to the collection tank 9 by means of the impeller pump 8. The produced protein suspension with the protein content of 50-65% wt (dry solid) can be the final product that can be used as a food or feed supplement and it can also be frozen for its further use. The produced protein suspension can be sent for its further processing treatment to the block 11 for the purpose of producing protein concentrate with the protein content of 60-80% wt or protein isolate with the protein content of min. 80% wt.

(9) Husk is a waste product of the brewer's grains processing and in the course of the screw extractor's operation husk naturally falls in the collection bunker from which it is delivered to the collection tank by means of a screw conveyor, or a spiral conveyor or any other conveyor. The claimed machine can be used for producing protein suspension with the protein content of max. 50% wt, for example 40, 42, 47 and 49% wt (with a lower energy value) in case of respective settings of devices enabling to produce suspension particles of the upper level of the claimed size range (more than 0.5 mm). Such product can be used in fields where there are no requirements to achieving the greatest possible quantitative content of protein in a protein product, for example, when it is used as animal food stuff.

(10) Food protein suspension in the amount of 337 litres was produced by means of the claimed method with its further drying for analysis.

(11) For this purpose 260 kg of brewer's grains with the humidity level of 75.59% (original composition, energy value of 150 kcal) were manually loaded on the vibrating screen 1 represented by the vibrating table unit XFZ1020 with a single-level screen and 10 mm holes, with the table unit length of 2,000 mm, with the table unit width of 1,000 mm, with the vibration frequency of 20 Hz and the vibration amplitude of 8 mm. From the vibrating screen 1 the mass by means of the belt conveyor 2 was supplied to the colloid mill 3 represented by the unit KDDJ-1,5 with the power capacity of 11 kW, with the rotation rate of 2,200 rot./minute of the rotor 20 that can also be equipped with a device for supplying drinking water from the block 4. In the colloid mill, the brewer's grains were humidified by means of water with the design amount of 170 litres (0.67:1) that was supplied to the colloid mill at the rate of 15 litres per minute. At the same time, the humidified brewer's grains were subject to grinding in order to obtain the faction of 0.1-0.9 mm. The process of supplying the source raw materials and water to the loading tank 23 of the colloid mill 3 was controlled by means of three level-sensing devices 15, 16 and 17 built in the shell of the loading tank 23 and a microcontroller located close to the level-sensing devices at the frame of the table on which the colloid mill was installed. At the same time one of the level-sensing device, the upper one, 17 was used for controlling the maximum possible load of the raw material in the bunker (85-90% in volume of the maximum capacity of the bunker); when this level was reached a command to stop the loading conveyor was given; the second level-sensing device, the middle one, 16 was used for controlling the minimum level of the loaded raw material (25-30% in volume of the maximum capacity of the bunker); when this level was reached a command to start the loading conveyor and to supply the raw material was given what provided for continuous operation of the colloid mill. The third level-sensing device, the lower one, 15 was installed near the loading bunker's bottom at the distance of 15 cm from the bottom and it was used for controlling the minimum possible load of the raw material in the bunker (10-15% in volume of the maximum capacity of the bunker); if this level was not reached the colloid mill stopped until another portion of the raw material was supplied. After the colloid mill, the produced pulp with the viscosity of 900-1,200 cPa and the humidity level of 95% was delivered to the screw extractor 5 represented by the machine of KDLZ-1,5 model with the power capacity of 4 kW, with the rotation rate of 4.5-10 rot./minute. The output was the main product, food suspension with the humidity level of 95% and the viscosity of 2.013 cPa, and a waste product, barley's husk, with the humidity level of 70.84%. By means of the impeller pump 6 with the power capacity of 0.25 kW with the rotation rate of 1,200 rot./minute the food suspension was delivered to the vibration filter 7 of XZS-1200-1S model with the power capacity of 0.75 kW with 0.3 mm openings. After filtration by means of the impeller pump 8 with the power capacity of 0.25 kW with the rotation rate of 1,200 rot./minute the food suspension was pumped to the collection tank 9. The husk naturally fell in the collection tank 10. Thus, the food suspension with the humidity level of 93%, with the viscosity of 1.907 cPa and the particle size of 0.005-0.3 mm was produced. In order to assess its composition, 12 litres of suspension were dried in the spray-type drier HT-RY1500 during 8 hours at the temperature of 200° C. until the humidity reached the level of 10% (capacity of this spray-type drier HT-RY1500 amounts to 1,500 ml of suspension per hour). The analysis showed that the obtained food suspension (sample 1) is characterized by nutritional energy value of 250 kcal and the following composition, % wt (dry solid) (Table 1):

(12) TABLE-US-00001 TABLE 1 Brewer's grains (original Food suspension, composition), % wt Composition % wt (sample 1) Protein 18.98 51.16 Fats 7.9 4.9 Fibre 13.6 4.5 Ash 2.2 0.8 at the same time protein from brewer's gains is rich in the following amino acids: Arginine 1.07 4.27 Lysine 0.86 2.37 Tyrosine 0.61 2.55 Phenylalanine 1.23 3.57 Histidine 0.66 1.8 Isoleucine 0.79 3.79 Leucine 0.57 Methionine 0.5 1.5 Valine 1.06 2.62 Proline 2.05 4.21 Threonine 0.77 2.26 Serine 0.89 1.79 Alanine 0.94 3.6 Glycine 0.79 2.19 Cystine 0.46 1.91 Glutamic acid 4.57 8.63 Asparaginic acid 1.35 2.06 Total amount of amino acids 19.17 49.12

(13) The total time for processing 260 kg of brewer's grains amounted to 25 minutes.

(14) Thus, the protein suspension produced by means of the claimed method is characterized by a high protein content with preservation of the amino acid composition of the brewer's grains and a low content of fats and fibres. The method is easy to implement and does not take a lot of time: the time from loading raw material in the machine to obtaining the final product in the form of suspension, for example when calculated for 100 kg of brewer's grains, takes from 5 to 10 minutes with the equipment's capacity from 20 to 500 tonnes/day; at the same time, the amount of centrate being a waste product and subject to disposal is minimal and it is equal to max. 1% of the capacity of the brewer's grain processing line of kg/1 minute.

(15) Brewer's grains delivered from five different manufacturing facilities were processed by this machine in accordance with the claimed method. The quantitative content of ingredients in the brewer's grains compositions was different from the original composition specified in table 1 within the limit of 1-5%. Table 2 shows compositions of protein suspensions with the optimal content of key components.

(16) TABLE-US-00002 TABLE 2 Parameters Food suspension sample 2 sample 3 sample 4 sample 5 sample 6 nutritional energy 245 kcal 260 kcal 258 kcal 255 kcal 265 kcal value (dry solid) humidity 91% 93% 92% 93% 95% particle size 0.005- 0.005- 0.005-0.3 0.005- 0.005- 0.5 mm 0.1 mm 0.4 mm 0.1 mm Composition content (% wt) Protein 51.1 62.19 58.3 55.4 64.7 Fats 3.7 4.9 3.2 3.8 4.7 Fibre 2.4 3.8 4.2 3.1 4.5 Ash 0.4 0.82 0.56 0.7 1.0 Amino acid composition: Arginine 3.93 4.27 4.6 4.0 5.3 Lysine 1.95 3 2.72 2.87 3.17 Tyrosine 2.15 3.85 2.53 2.23 3.72 Phenylalanine 3.5 4.97 4.47 3.68 4.17 Histidine 2.1 2.9 2.1 1.85 2.1 Isoleucine/Leucine 2.23 3.79 2.05 2.89 3.82 Methionine 2.43 2.55 2.1 1.97 2.1 Valine 2.84 2.62 2.9 2.75 3.16 Proline 3.85 4.73 4.1 3.95 5.1 Threonine 1.79 3.12 3.7 3.17 3.7 Serine 1.98 2.3 2.4 1.95 2.4 Alanine 2.84 4.1 4.3 3.97 4.3 Glycine 2.98 2.49 3.1 2.94 3.1 Cystine 2.62 2.1 2.4 1.95 2.4 Glutamic acid 7.7 9.8 8.5 7.94 10.3 Asparaginic acid 2.35 3.2 2.6 2.27 3.4 Total amount of 47.24 59.79 54.57 50.38 62.24 amino acids

(17) Table 3 include parameters of processing brewer's grains (samples 2-6).

(18) TABLE-US-00003 TABLE 3 Processing parameters sample sample sample sample sample Equipment 2 3 4 5 6 Colloid mill/rotor 1.800 3,000 2,500 2.000 3,200 rotation rate (rot./second) Vibrating screen 10/10, 15 5/40, 10 7/30, 20 8/20, 15 6/50, 8 screen hole size (mm)/vibration frequency (Hz and mm) Screw extractor/ 3 8 5 7 10 rotation rate (rot./second) Filtration/hole 0.5 0.1 0.3 0.4 0.1 size (mm)

(19) Based on the above-given data it can be concluded that a protein product in the form of suspension with a high protein content is produced despite the fact that various plants use different types of barley, have various technologies for manufacturing brewer's malt, various malt mix recipes for manufacturing beer etc. The two-stage processing of brewer's grains (in the colloid mill and in the screw extractor) without using multi-step compression processes and thermochemical treatment enables to obtain a protein product with the humidity level of max. 95% and the particle size of max. 0.5 mm with the protein content of min. 50.0% wt (dry solid) and without gluten.

(20) This method of producing protein suspension is universal and enables to preserve all valuable biologically active agents of the source brewer's grains. The rich chemical composition of brewer's grains with the minimal content of hydrocarbons predetermines its prospects in the food-processing industry, in particular its use as an albuminous vitamin-mineral additive in manufacturing of pastry products.