Method for producing highly soluble soy flour
Patent Information
- Application Number
- JP2024571271
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-02-21
- Filing Date
- 2023-02-20
- Publication Date
- 2026-01-29
Smart Images
Figure 2023156653000001
Abstract
Description
[Technical field]
[0001] The present invention relates generally to the field of the food industry. In particular, the present invention relates to a method for producing soy flour with high solubility, which is particularly suitable for the production of plant-based foods such as soy-based beverages, tofu, and their derivatives. [Background technology]
[0002] In recent years, there has been encouragement to reduce consumption of animal-based foods such as ham and sausages, promoting healthier and more environmentally friendly eating habits to a larger population. As a result, consumers are supplementing their diets with more fruits, grains, legumes and vegetables, of which the soy stands out for its high protein content, protein quality and micronutrients.
[0003] Indeed, among various uses and applications in the food sector, soybeans may be used to manufacture vegetable products including soy beverages, tofu, yogurt, and their derivatives. In addition, soy is highly nutritious, contributes to the regulation of blood sugar and cholesterol levels, and is rich in mineral salts such as calcium and phosphorus, as well as phytoestrogens, which support bone mineralization and slow down processes related to osteoporosis.
[0004] However, soybeans, like other legumes, can have an unpleasant taste, typically due to the presence of antinutritional factors in the legumes. This taste is characterized by a slight bitterness that is generally disliked by consumers, limiting the consumption of soy flour and products derived therefrom.
[0005] In particular, the unpleasant taste of soybeans mentioned above is mainly caused by the action of special enzymes contained in soybeans. In fact, if the enzymes are not properly inactivated, they can leave a bitter taste in the final product that consumers do not like.
[0006] However, the enzyme inactivation that typically occurs during heat treatment or cooking of soybeans is strongly associated with the risk of degrading valuable nutritional phytochemicals in soybeans. To remove this slight bitterness that consumers dislike, various types of traditional methods, both wet and dry, are known in the art.
[0007] In particular, the product of the traditional wet process is a soy extract which is then dried, for example by spray drying, to yield a final product consisting of the soy extract in powder form. The method for preparing the powdered soy extract is also known as the "soy wet extraction method" and includes the following steps:
[0008] Soybeans, possibly dehulled, are soaked in an aqueous solution (usually purified water) for a certain period of time (soaking process). In fact, the step of soybean soaking is necessary to improve the performance of the subsequent step of wet milling the soybeans.
[0009] After wet milling, a suspension of milled soybeans and water is obtained, which then undergoes a separation process, preferably by decanting, where the waste product of the process, the insoluble portion called "okara" (containing soybean fiber, insoluble proteins, oil and carbohydrates), is separated by gravity from the soluble portion of the soybeans.
[0010] The soluble portion of the soybeans is then subjected to a cooking or heat treatment process to inactivate the soybean enzymes, thereby reducing the slight bitter taste that is characteristic of soybeans and which may be objectionable to the end consumer, and to sterilize the final product, thereby reducing the microbial load that may be present therein.
[0011] At the end of the above steps, a soybean extract is obtained, which is then subjected to a drying process, preferably by spray drying, to obtain the powdered soybean extract that constitutes the final product. The spray drying process can be very expensive and unsustainable when carried out on an industrial scale, and further extends the overall process time significantly.
[0012] Instead, the traditional dry process involves dry milling of soybeans, which may have been previously dehulled, to obtain soy flour in a dry manner. Furthermore, these soy flours may be defatted, in particular defatted flours obtained from soybean press residues after oil extraction, which have a very low oil and lecithin content, reducing the nutritional value of the final product, and are characterized by low solubility due to heat treatment and concentration of insoluble fiber.
[0013] The use of soy flours currently on the market is not widespread and has so far been limited by success, since the solubility of these flours is not high enough or sufficient for certain food products that require complete and uniform dissolution of said flour in an aqueous medium, such as soy-based beverages, including soy milk, and tofu.
[0014] In fact, the formation of insoluble solid residues after mixing of the soy flour in an aqueous medium and / or separation of liquid and solid phases in plant products based on the flour can be observed precisely due to the insufficient solubility of these flours in aqueous media.
[0015] Furthermore, the traditional drying process does not effectively inactivate the soy enzymes that cause the slight bitterness characteristic of soybeans, so the soy flour obtained by the dry method still often has a slight bitter taste.
[0016] It is therefore an object of the present invention to provide a method for producing full-fat soy flour which is characterized by high solubility and high fiber content and at the same time is free of the slight bitter taste typical of this legume. Summary of the Invention
[0017] The present invention solves the above technical problem by providing a method for producing soy flour with high solubility, corresponding to an NSI (Nitrogen Solubility Index) value of more than 95%. The method comprises: i) pre-drying soybeans at a temperature of 40°C to 60°C for 6 hours to 18 hours; a) drying the pre-dried soybeans in a first dryer set at a temperature above 90°C, preferably 92°C to 95°C, for 8 minutes to 18 minutes to obtain dried soybeans having a temperature of 75°C to 85°C; b) a step of obtaining a soybean micropowder having a particle size of 200 μm or less by drying and pulverizing the dried soybeans kept at a temperature of less than 80° C., preferably 0° C. to 80° C.; c) drying the soybean fine powder in a second dryer set at a temperature of 110°C to 130°C for less than 20 seconds, preferably 2 to 10 seconds, to obtain a dried soybean fine powder having a temperature of 75°C to 85°C; d) cooling the dried soybean micropowder to obtain the soybean flour having high solubility. wherein the method does not include a step of soaking the soybeans and / or the micronized soybeans in water or other aqueous solution.
[0018] Preferably, at the end of pre-drying step i), the moisture content of said soybeans is below 13%, more preferably between 10 and 12%. Preferably, at the end of drying step a), the moisture content of the soybeans is less than 10%, more preferably between 7% and 9%.
[0019] Preferably, the second dryer is a flash drying hot air plant. Preferably, after the pre-drying step i) and before the drying step a), said soybeans are subjected to a dehulling step ii).
[0020] Preferably, the highly soluble soy flour has a moisture content of less than 5%, more preferably less than 4%, even more preferably less than 3%. Preferably, the highly soluble soy flour has a particle size of less than 200 μm, more preferably between 190 μm and 5 μm.
[0021] Preferably, the highly soluble soy flour has an NSI value of more than 97%, more preferably more than 98%, and even more preferably between 98.5% and 100%. Preferably, the highly soluble soy flour has a protein content of more than 35%, more preferably between 38% and 45%, on a dry weight basis.
[0022] Preferably, the highly soluble soy flour has a shelf life of more than 6 months at room temperature under vacuum, more preferably between 6 and 12 months. Preferably, said soy flour with high solubility has a lipoxygenase content that is reduced by at least 75% compared to the lipoxygenase content of the soybeans subjected to step a) or step i).
[0023] Preferably, before step b) and after step a), the dried soybeans are cooled to a temperature between 0°C and 30°C. Preferably, the method does not include the step of defatting soybeans.
[0024] The present invention also relates to soy flour with high solubility, corresponding to an NSI (Nitrogen Solubility Index) value of more than 95%, obtainable by the above-described method according to the invention. Preferably, the highly soluble soy flour has a moisture content of less than 5%, more preferably less than 4%, even more preferably less than 3%.
[0025] Preferably, the highly soluble soy flour has a particle size of less than 200 μm, more preferably between 190 μm and 5 μm. Preferably, the highly soluble soy flour has an NSI value of more than 97%, more preferably more than 98%, and even more preferably between 98.5% and 100%.
[0026] Preferably, the highly soluble soy flour has a protein content of more than 35%, more preferably between 38% and 45%, on a dry weight basis. Preferably, said soy flour with high solubility has a lipoxygenase content which is reduced by at least 75% compared to the lipoxygenase content of the soybeans subjected to said step a) or said step i).
[0027] Preferably, the soy flour with high solubility has a shelf life of more than 6 months, preferably between 6 and 12 months, at room temperature under vacuum. The process according to the invention for producing soy flour with high solubility, corresponding to an NSI (Nitrogen Solubility Index) value of more than 95%, advantageously comprises carrying out a drying step (step a)) before a micronization step (step b)) of the soybeans, and carrying out a further drying step (step c)) after said micronization step.
[0028] The method of the invention comprises, before carrying out step a), carrying out a pre-drying step i), which is advantageously carried out at a temperature between 40°C and 60°C, thereby preventing the denaturation of the proteins contained in the soybeans and thus preserving their solubility.
[0029] Advantageously, during drying step a) of the process, the temperature is increased in a controlled manner until the temperature of the soybeans reaches a value between 75°C and 85°C. Advantageously, the drying step a) has the effect of inactivating the soy enzymes and making the soybeans more friable, thus facilitating the subsequent micronization step b).
[0030] In step b) soybeans are dry micronized to a particle size of 200 μm or less to obtain a soy flour that can be easily and homogeneously dissolved in an aqueous medium, for example for the production of soybean-based foods such as soybean drinks, tofu, etc. Advantageously, said micronization step allows for the production of very fine soybean micronized products having particle sizes as described below, which advantageously optimize the solubilization of the soy flour according to the invention in aqueous media, thereby significantly reducing the possible formation of solid residues.
[0031] A further advantage of the dry micronization step b) according to the method of the present invention is that it further enhances the enzyme inactivation of the treated soybeans. As used herein, the expression "dry micronized" refers to the micronization of dried soybeans, i.e. soybeans having a moisture content of less than 13%.
[0032] In particular, the soy flour obtainable by the method of the present invention has a particle size distribution in which at least 98% of the particles have a particle size less than 200 μm, preferably between 190 μm and 5 μm. In particular, 90% of the particles have a particle size between 150 μm and 10 μm, 70% of the particles have a particle size between 80 μm and 15 μm, and 50% of the particles have a particle size between 45 μm and 16 μm.
[0033] Furthermore, the drying step c) is preferably a flash drying hot air treatment, which advantageously dries the soybean micropulverized material and reduces the surface moisture of the micropulverized material without significantly increasing the temperature of the micropulverized material, thereby avoiding the damage to the soybean sensory properties caused by high temperatures and at the same time promoting enzyme inactivation of the treated soybeans.
[0034] Moreover, said process steps advantageously promote a complete and uniform dissolution of the soy flour of the invention in aqueous media by increasing the hydration capacity of the soy flour. Furthermore, the drying step c) ensures the chemical and physical stability of the soy flour throughout its shelf life.
[0035] According to one embodiment of the invention, the soybeans are subjected to a dehulling step ii) before said step a) and after the pre-drying of said step i). Advantageously, the dehulling step ii) discards the soybean hull (or skin), which consists mainly of vegetable fibre, making it possible to obtain soy flour with a high protein content.
[0036] Furthermore, the dehulling step ii) facilitates the performance of the subsequent step of micronization of the soybeans, since the absence of the soybean hull (or skin) makes it possible to obtain a micronized soybean product having the advantageous characteristic of a smaller average particle size compared to the micronized product obtained from undehulled soybeans.
[0037] According to an equally preferred embodiment of the present invention, the soybeans of the present invention are whole, unhulled soybeans. Soy flour obtained from unhulled soybeans has a lower protein content and a larger particle size compared to soy flour obtained from dehulled soybeans and is preferably used advantageously to increase the fiber intake in vegetable products based on this particular flour type. Soy flour obtained from unhulled soybeans can also advantageously increase the absorption of water, thereby resulting in vegetable products with a particularly homogeneous and creamy consistency.
[0038] Advantageously, steps a) to c) of the present invention are carried out whilst maintaining the soybeans and soy micronized material at a controlled temperature, in particular below 85°C, to provide effective enzyme inactivation and enhance solubility of other ingredients without damaging or rendering the soy protein insoluble.
[0039] Indeed, soy enzymes and soluble soy proteins differ in their sensitivity to temperature, in particular enzyme inactivation begins at lower temperatures compared to the inactivation temperature of soluble soy proteins.
[0040] Additionally, the micronization process increases the solubility of soybeans and at the same time aids in enzyme inactivation. Advantageously, said steps of the method of the present invention are advantageously carried out dry and, indeed, the method of the present invention advantageously does not include a step of soaking soybeans and / or soybean fines in water or other aqueous solution.
[0041] Unlike the conventional methods of soybean wet extraction described above which specifically teach at least one soybean soaking step, the method of the present invention has the following advantages: The process of the present invention does not involve an extraction step, thus reducing the associated plant costs and shortening the production time on an industrial scale of the soy flour according to the present invention.
[0042] As the method of the present invention does not involve a step of extracting and / or soaking soybeans in water, a further advantage of the method is that no production waste is generated and all parts of the soybeans are used and subjected to all steps a) to c) of the present invention.
[0043] Furthermore, the method of the invention advantageously makes it possible to improve the yield of the final product, as well as its quality in terms of organoleptic and nutritional properties, as well as its microbiological stability properties over its shelf life, as will be explained in more detail below.
[0044] Indeed, whereas in traditional wet processes, okara (which represents a waste product of the process) can constitute more than 50% w / w of the raw soybean, the process of the invention has the advantage that all parts of the soybean can be used without producing waste, thus allowing 100% of the raw soybean to be used.
[0045] In embodiments of the process of the present invention that use dehulled soybeans, the process waste consists essentially of soybean hulls only. Furthermore, compared to traditional methods of obtaining soy flour by dry processes, the soy flour obtained according to the invention is characterized by a better solubility, which makes it advantageously particularly suitable for the production of soy-based vegetable products.
[0046] The process according to the invention is preferably carried out as a continuous process. According to this method, by carrying out a drying step prior to the micronization of the soybeans and a further drying step after the micronization of the soybeans, it is advantageous to obtain soy flours, in particular full fat soy flours, which have a high solubility (corresponding to an NSI value of more than 95%) and a neutral taste, i.e., substantially free of the slight bitterness typical of soybeans, which characteristics make them particularly suitable for use in the field of the production of soy-based food products.
[0047] As used herein, the term "soybean" refers to the species Glycine max, Glycine soja, or any species derived from Glycine max, preferably the white-eyed soybean cultivar of the Glycine max species.
[0048] As used herein, the terms "soybean powder," "soybean meal," and "soy flour" are used interchangeably. The expression "soy flour" as used herein means full fat soy flour, i.e. soy flour characterized by containing all the macronutrients characteristic of soybeans (lipids, proteins, carbohydrates and fiber); in fact, the soy flour of the present invention is not defatted.
[0049] The term "NSI" or "Nitrogen Solubility Index" as used herein means a measure of the solubility of protein in a material. In accordance with the present invention, to determine the NSI value of soy flour, the methodology of Araba, M. & Dale, NM (1990) "Evaluation of protein solubility as an indicator of overprocessing soybean meal" Poultry Science 69;76-83 was followed.
[0050] The soy flour obtainable by the method of the invention has an advantageously high protein content, in particular between 40% and 42% by dry weight, a feature which makes its use particularly advantageous for the manufacture of vegetable food products.
[0051] Indeed, such a high protein content not only accelerates the tofu coagulation process, but also significantly increases the protein content of the plant-based beverage, thereby making it comparable to the corresponding product obtained from milk.
[0052] The expression "protein content" as used herein refers to the protein content of a material measured using the MP / C / 35 (rev2 2017) method. By the above-mentioned method of the present invention, which includes only a drying step, the moisture content of the soybeans is gradually reduced from the initial moisture content of 13% before step a) to the moisture content of soybean flour with high solubility of less than 5%, preferably 1% to 3%.
[0053] The expression "moisture content" as used herein refers to the amount of moisture in a material and is determined using the method of ISTISAN 1996 / 34 (page 7 MetB). A further advantage of the method of the present invention is that the soy flour obtained according to the present invention has an advantageously fine particle size, i.e. less than 200 μm, preferably between 190 μm and 5 μm, as calculated by a Verder Scientific Microtrac Turbosync model instrument.
[0054] In particular, 90% of the particles have a size between 150 μm and 10 μm, 70% of the particles have a size between 80 μm and 15 μm, and 50% of the particles have a size between 45 μm and 16 μm. A further advantage of the process of the invention is that the soy flour obtained according to the invention has a shelf life of several months, in particular 6 to 12 months, at room temperature, preferably under vacuum and in packaging suitable for light-sensitive products.
[0055] In particular, in fact, the soy flour obtained according to the method of the present invention is chemically stable throughout its shelf life since it is not subject to primary oxidative rancidity caused by the oxidation of unsaturated fatty acids of triglycerides by oxygen and the catalysis of the enzyme lipoxygenase.
[0056] The lipoxygenase content of the soy flour described herein is advantageously reduced by at least 75% relative to the lipoxygenase content of the starting soybeans. In particular, the average nutritional value of the soy flour obtained by the method of the present invention is as follows (Table 1):
[0057] [Table 1]
[0058] Advantageously, the soy flour obtained according to the method of the present invention has a high water absorption capacity due to its particle size, low moisture content, as well as soluble fiber content properties, as defined above. The soy flour-based vegetable product dissolved in an aqueous medium is therefore characterized by a soft, homogeneous texture and a pleasant mouthfeel, and furthermore, since the soy flour has a neutral taste, the vegetable product advantageously does not have the slight bitter taste typical of soybeans.
[0059] Furthermore, the soy flour obtained by the process of the present invention is advantageously "clean label", i.e., it consists only of powdered soybeans and does not contain any food additives or preservatives. As a result, the soy flour can be conveniently used in the preparation of plant-based foods such as, for example, tofu, fruit-based products, beverages, soups, baby foods, yogurt, ice cream, pasta, bars, meat substitutes, snacks, frozen foods, confectionery, and bakery products. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0060] Detailed Description of the Invention Further features and advantages of the present invention will become apparent from the following examples, which are given herein as non-limiting examples.
[0061] Example 1 - An example of a method according to the present invention. 1. Pre-drying, sorting, and washing 120,000 kg of soybeans with a moisture content of 22% (measured using a Zetalab Thermo120 thermobalance) were continuously fed into a Petkus DU4000-24 heat recovery cascade dryer.
[0062] A pre-drying step is then carried out at a temperature of 60° C. for 694 minutes. The soybeans were roughly cleaned using a Cimbria Delta 146 sieving unit with 11 mm round top and 3 mm bottom sieve meshes, then cooled by a circulating flow of dehumidified cold air from a Marcold refrigerator outside the silo and stored in the silo at a moderate temperature (15°C).
[0063] Impurities, foreign objects, and abnormal beans were then removed and the best beans were selected, as described below. Specifically, the cooled soybeans were fed into a continuous cleaning and sorting plant with a capacity of 6 tonnes per hour. The plant consisted of: Mechanical rotary separator with a frequency of 50Hz manufactured by Brambati spa An automatic air recirculating destoner from Brambati spa with a 15° inclination weighing surface and operated by two eccentric motor vibrators with a 5° reverse inclination Cimbria density measuring table GA210 with variable air conditioning, x-axis tilt of 2° and y-axis tilt of 4° Chromex optical sorter from Sea Cimbria, with an optical resolution of 0.06 mm, set to the following values: dark = 3 (sensitivity index of the optical sorter), light brown = 2 (sensitivity index of the optical sorter), transducer 1 speed = 60 Hz, transducer 2 speed = 65 Hz, transducer 3 speed = 67 Hz, transducer 4 speed = 64 Hz, transducer 5 speed = 65 Hz A sieve calibrator (Cimbria) with an upper sieve with a diameter of 7 mm, a middle slot sieve with a diameter of 4.5 mm and a lower round sieve with a diameter of 4 mm.
[0064] The machines are part of a single plant and processing takes place through a bucket elevator, screw conveyor and pneumatic system. Soybeans were obtained and shipped from a sorting plant with a moisture content of 13% as measured by a Zetalab Thermo 120 thermobalance.
[0065] 2. Peeling The sorted beans are fed into a Satake VTA10DW(2)-T model dehuller set at 70 amps.
[0066] 3. Drying The dehulled soybeans were then subjected to a drying process, resulting in a moisture content of 8.96% and a protein content of 40.9%.
[0067] Moisture content was measured using a Zetalab Thermo 120 thermobalance. Protein content was measured using a FOSS Infratec 1241 protein analyzer.
[0068] The 1,000 kg batch of soybeans was then loaded into a Brambati BR600 / 1000 toaster set according to the following parameters: Duration: 15 minutes 32 seconds -Toaster temperature (drum outlet): 93.6℃
[0069] The toaster was connected to a software with a toasting / drying curve from Brambati, specially developed to continuously control and monitor the temperature of the product and increase the temperature until the product temperature reached 80°C.
[0070] Once the soybeans reached a temperature of 80°C, they were removed and cooled to room temperature by a special air system built into the toaster. The following values for the toasted soybeans were measured:
[0071] The moisture content was 7.91% as measured using a Zetalab Thermo 120 thermobalance, and Protein content was 41% as measured using a FOSS Infratec 1241 protein analyser.
[0072] 4. Micronization Prior to the milling process, the soybeans are fed into an iron impurity control system equipped with a 1T (10,000 Gauss) magnetic cylinder compartment made of stainless steel AISI304 to prevent metal objects from entering the mill.
[0073] The soybeans were then cooled to room temperature on a Cimma cryogenic screw conveyor made of stainless steel AISI 304 with an inverter variable flow rate up to 4 t / hr and then fed into a Cimma vertical shaft mill with air separator, model pps-1000-tx, set at a flow rate of 1.1 t / hr, 195 amps, separator frequency of 31 Hz, mill rotor frequency of 49 Hz and ventilation frequency of 49 Hz.
[0074] At the outlet of the two filtering cyclones of the crusher there is a feed rotary valve INOX304-0.37kw-Atex20 / 22 and a PT100 temperature sensor for measuring the temperature of the soybeans (80°C).
[0075] At the end of the micronization process, at a temperature of 75° C., a soybean micronized product was obtained having the following percentile particle size distribution, as shown in Table 2:
[0076] [Table 2]
[0077] 95% of the soy micronized material had a particle size less than 190 μm, according to the results shown in Table 2. Particle size distribution was measured using a Microtrac turbosync from Verder Scientific.
[0078] 5. Thermopneumatic treatment The soybean micropulverized material was then fed into a hot air processing plant (Brambati) and flash dried.
[0079] Specifically, micronized soybeans are dispersed inside the plant into a stream of air heated to 120°C. Using the heat of the airflow, the soybean micronized material is dried as soon as it is delivered to the plant.
[0080] When the soybean micronized material left the thermopneumatic plant, the moisture content was 2% and the temperature was 79.4°C. The thermopneumatic plant line has three PT100 temperature sensors to check compliance with the parameters.
[0081] 6. Cooling The soybean micropowder was then placed in the dehumidification and cooling system described below and cooled. Specifically, soybean micropowder was stored in a standard 1200m AHU (air handling unit) unit with a relative humidity of 40% and a temperature of 16°C. 3 1,000m per hour (Brambati) 3 / hr flow rate.
[0082] After dehumidification, the pulverized material was introduced into a Brambati pneumatic cooling line set at a temperature of 12°C. At the end of the cooling step, a soy flour according to the invention was obtained, which had a moisture content of 2.7% as measured using a Zetalab Thermo 120 thermobalance, an NSI value of 95% and a percentile particle size distribution as shown in Table 2 above.
[0083] NSI values were determined according to the methodology of Araba, M. & Dale, NM (1990) “Evaluation of protein solubility as an indicator of overprocessing soybean meal” Poultry Science 69;76-83.
[0084] Example 2: Characterization of soy flour obtained by the method of the present invention. The characteristics of soy flour samples obtained by the method described in Example 1 according to the following operating parameters are given below.
[0085] Sample A: Operating parameters -I (current intensity) absorbed by the mill of the grinder model pps-1000-tx (Cimma) = 183 Amperes 1.1 tonnes / hour Crusher model pps-1000-tx (Cimma) sorter frequency = 25Hz Grinder model pps-1000-tx (Cimma) mill frequency = 48Hz Crusher model pps-1000-tx (Cimma) fan frequency = 50Hz Qualitative parameters: ·Moisture (Thermo120 thermobalance, Zetalab)=3.36% ·Particle size distribution (Microtrac turbosync, Verder Scientific):
[0086] [Table 3]
[0087] Sample B: Operating parameters -I (current intensity) absorbed by the mill of the grinder model pps-1000-tx (Cimma) = 183 Amperes 1.1 tonnes / hour Crusher model pps-1000-tx (Cimma) sorter frequency = 27Hz Crusher model pps-1000-tx (Cimma) mill frequency = 50Hz Crusher model pps-1000-tx (Cimma) fan frequency = 50Hz Qualitative parameters: ·Moisture (Thermo120 thermobalance, Zetalab) = 2.9% ·Particle size distribution (Microtrac turbosync, Verder Scientific):
[0088] [Table 4]
[0089] Example 3 - Comparative Study 1. Comparison sample The following samples were evaluated and compared for peroxide concentration, shelf life, and oxidation of linoleic acid by lipoxygenase enzyme:
[0090] - "p2" and "p3" samples: dehulled soy flour obtained according to example 1, except that the soybean micronization was not subjected to a drying step by hot air pressure treatment. p2 is a mixture of soy flour belonging to Proteix and Mentor varieties, and p3 belongs to PR91M10 variety.
[0091] - "p4" and "p5" samples: whole soy flours obtained according to example 1, except that the soybeans were not dehulled and the soybean micronisation was not subjected to a drying step by hot air pressure treatment. p4 is a mixture of soy flours belonging to the Proteix and Mentor varieties, and p5 belongs to the PR91M10 variety.
[0092] Each sample had three subsamples: Approximately 2 kg of samples (number of samples: 4): Pilot test of the production of plant-based beverages using Roboqbo Qb8-4 Approximately 1 kg of samples (number of samples: 4): Nutritional analysis, lipoxygenase activity, and peroxide count Approximately 1 kg sample (12 samples): further divided into 3 subsamples, evacuated and analysed at 0, 30, 60 and 180 days to determine the number of peroxides.
[0093] "p2E" and "p3E" samples: dehulled soy flour obtained according to example 1. - "p4E" and "p5E" samples: whole soy flour obtained according to example 1 except that the soybeans were not dehulled.
[0094] Each sample has three subsamples: Approximately 2 kg of samples (6 samples): Pilot test of the production of plant-based beverages using Roboqbo Qb8-4 Approximately 1 kg of samples (6 samples): Nutritional analysis, lipoxygenase activity, and peroxide count Approximately 1 kg sample (18 samples): further divided into 3 subsamples, evacuated and analysed at 0, 30, 60 and 180 days to determine the number of peroxides.
[0095] - Controls: soybean of PR32M10 variety and soybean of Proteix variety. The p2E, p3E, p4E and p5E samples are in accordance with the present invention since they undergo a step of hot air pressure treatment, unlike the p2, p3, p4 and p5 samples, respectively. In the present invention, the peeling step is optional.
[0096] 2. Method Nutritional analysis: dry sample (Method 930.15, AOAC 2000); crude protein (Method 976.05, AOAC 2000), crude fat (Method 954.02, not acid hydrolyzed, AOAC 2000), ash (Method 942.05, AOAC 2000), total dietary fiber (Method 991.43, AOAC 2000) Measurement of peroxides (Shantha & Decker, J. AOAC Int. 1994, 77, 421-424) Measurement of lipoxygenase activity (Salcedo et al., 2010, Food Research International 2010, 43, 1187-1197) All results are expressed as the mean of three independent determinations.
[0097] 3.Results -Nutritional information of raw materials Table 5 shows the nutritional content (g / 100 g dry sample) of the samples tested.
[0098] It is clear that the p2E, p3E, p4E and p5E samples have the advantage of having significantly lower moisture contents compared to the corresponding samples that were not subjected to a final drying step by hot air pressure treatment (i.e., p2, p3, p4 and p5 samples).
[0099] [Table 5]
[0100] Rancidity due to primary oxidation during shelf life. Table 6 shows the peroxide values (PV, MeqO2 / kg oil) of the samples evaluated at time zero (T0), after 30 days (T30), 60 days (T60) and 180 days (T180) to assess the stability and shelf life (life at room temperature) of the samples at these times.
[0101] [Table 6]
[0102] According to the results shown in Table 6, the p2E, p3E, p4E, and p5E samples are more stable than the corresponding p2 and p3 samples over the 180 days tested, especially the p2 sample, which already shows signs of oxidative rancidity after 30 days.
[0103] Lipoxygenase activity The reduction in the oxidation of linoleic acid catalyzed by the enzyme lipoxygenase extracted from the above soy flour samples was evaluated.
[0104] The analysis was performed using a spectrophotometer UV-VIS (Shimadzu model UV-1601) and linoleic acid as substrate, following the methodology used by Salcedo et al., 2010, Food Research International 2010, 43, 1187-1197.
[0105] Briefly, 2 g of soy flour sample was ground, added with 10 ml of Na3PO4 0.2 mol / L buffer (pH = 7.8), and centrifuged at 10,000 g for 20 min at 4 °C. Afterwards, 1 μL of the supernatant was added to a solution containing 4 μL of 10 mmol / L linoleic acid solution and 1 ml of Na3PO4 0.05 mol / L buffer (pH = 6.5) at 25 °C. The absorbance was evaluated at a wavelength of 234 nm against a blank (linoleic acid and buffer solution, no supernatant) and measured at 30 s intervals for 2.5 min.
[0106] Lipoxygenase catalyzes the dioxygenation of polyunsaturated fatty acids containing cis,cis-1,4-pentadiene structures to produce the corresponding fatty acid hydroperoxides. The activity of linoleic acid hydroperoxidation at 25°C was then assessed spectrophotometrically by monitoring the increase in A234 caused by the conversion of linoleate to the corresponding hydroperoxides (Axelrod, 1981).
[0107] The oxidation was calculated over the entire analysis interval (180 seconds) by calculating the area under the curve (AUC). The CTR sample (control) refers to the soybeans at the start. The results are shown in Tables 7 and 8.
[0108] [Table 7]
[0109] [Table 8]
[0110] Lipoxygenases (LOX) can affect the color, aroma (the generation of off-flavors due to the oxidation of fatty acids) and nutritional properties of foods, particularly affecting pigments and vitamins. The results show that the p2E, p3E, p4E, and p5E samples, as well as the p2, p3, p4, and p5 samples, had significantly reduced lipoxygenase activity compared to the control.
[0111] Furthermore, reduced lipoxygenase activity is observed in the p2E, p3E, p4E and p5E samples compared to the p2, p3, p4 and p5 samples. Considering the results of the above comparative tests, it is evident that the p2E, p3E, p4E and p5E samples obtained according to the method of the present invention are obviously chemically stable and have much lower moisture content compared to the p2, p3, p4 and p5 samples which, unlike the p2E, p3E, p4E and p5E samples, were not subjected to the hot air pressure treatment step.
[0112] Example 4 - Method for producing tofu from soy flour according to the present invention 8 kg of dehulled soy flour obtained according to the method described in Example 1 was added to 92 liters of purified water at 75° C. in an Enoop Multimix homogenizer. Mixing was carried out for 10 minutes at a speed of 6000 rpm until the temperature reached 85° C.
[0113] The mixture thus obtained was poured into a Mase tank (a tofu coagulation plant) with the addition of steam to keep the temperature at 82°C, and the typical coagulation process was carried out using a Mase machine for tofu production.
[0114] The machine consisted of nine containers that moved clockwise at three-minute intervals. One container was dosed with 16 grams of MgCl2 per kilogram of soy flour. At the end of the coagulation process, the product was placed into a coagulation box and then pressed in a Mase press for 12 minutes. Finally, the tofu was cooled to 4°C in a designated cooling room.
[0115] At the end of the above process, 24 kg of tofu made from the soybean flour of the present invention was obtained. Table 9 shows the nutritional value of the tofu obtained according to Example 4:
[0116] [Table 9]
[0117] As shown in Table 9, the tofu of the present invention has a fiber content of 7 grams per 100 grams of tofu, which is significantly higher than the fiber content of commercially available tofu, i.e., 2 grams per 100 grams of tofu. Furthermore, according to the method described in this Example 4, 1 kg of peeled soybean flour according to the present invention can be used to obtain 3 kg of tofu, whereas the conventional tofu production method using wet milling can only obtain 1 to 1.6 kg of tofu from 1 kg of soybean grains (input wet milling).
[0118] Example 5 - Method for producing beverages from soy flour according to the present invention 12 kg of soy flour obtained according to the method described in Example 1 were added to 88 liters of purified water (temperature 75° C.) in an Enoop Multimix homogenizer.
[0119] Mixing was carried out at 6000 rpm for 10 minutes until the temperature reached 85°C. At the end of mixing, the protein content of the resulting plant-based beverage was 5% w / w.
Claims
1. 1. A method for producing soy flour having a high solubility corresponding to an NSI (Nitrogen Solubility Index) value of greater than 95% as measured by the methodology of Araba, M. & Dale, N. M. (1990) "Evaluation of protein solubility as an indicator of overprocessing soybean meal," Poultry Science 69; 76-83, said method comprising: i) pre-drying soybeans at a temperature of 40°C to 60°C for 6 to 18 hours; a) drying the pre-dried soybeans in a first dryer set at a temperature above 90°C, preferably 92°C to 95°C, for 8 to 18 minutes to obtain dried soybeans having a temperature of 75°C to 85°C; b) dry-pulverizing the dried soybeans maintained at a temperature of less than 80°C, preferably 0°C to 80°C, to obtain a soybean micropowder having a particle size of 200 μm or less; c) drying the soybean micronized material in a second dryer set at a temperature of 110°C to 130°C for less than 20 seconds, preferably 2 to 10 seconds, to obtain a dried soybean micronized material having a temperature of 75°C to 85°C; d) cooling the dried soybean micronized material to obtain the soybean flour having high solubility. wherein the method does not include a step of soaking the soybeans and / or the micronized soybeans in water or other aqueous solution.
2. 2. The method of claim 1, wherein at the end of the pre-drying step i), the moisture content of the soybeans is less than 13%, more preferably 10-12%.
3. 3. The method according to claim 1 or 2, wherein at the end of the drying step a), the moisture content of the soybeans is less than 10%, more preferably between 7% and 9%.
4. 3. The method according to claim 1 or 2, wherein the second dryer is a flash dry hot air plant.
5. 3. The method according to claim 1 or 2, wherein after the pre-drying step i) and before the drying step a), the soybeans are subjected to a dehulling step ii).
6. 3. The method of claim 1 or 2, wherein the soy flour with high solubility has a moisture content of less than 5%, preferably less than 4%, more preferably less than 3%.
7. The method according to claim 1 or 2, wherein the soy flour with high solubility has a particle size of less than 200 μm, preferably between 190 μm and 5 μm.
8. The method according to claim 1 or 2, wherein the soy flour with high solubility has an NSI value of more than 97%, preferably more than 98%, more preferably between 98.5% and 100%.
9. 3. The method according to claim 1 or 2, wherein the soy flour with high solubility has a protein content of more than 35%, preferably between 38% and 45%, on a dry weight basis.
10. 3. The method according to claim 1 or 2, wherein the soy flour with high solubility has a shelf life of more than 6 months, preferably between 6 and 12 months, at room temperature under vacuum.
11. 3. The method of claim 1 or 2, wherein the soy flour with high solubility has a lipoxygenase content that is reduced by at least 75% relative to the lipoxygenase content of the soybeans subjected to step a) or step i).
12. 3. The method of claim 1 or 2, wherein before step b) and after step a), the dried soybeans are cooled to a temperature of from 0°C to 30°C.
13. The method according to claim 1 or 2, which does not include a step of defatting the soybeans.
14. Araba, M. & Dale, N. M. (1990) "Evaluation of protein solubility as an indicator of overprocessing soybean meal," Poultry Science 69; 76-83, and having a high solubility corresponding to an NSI (Nitrogen Solubility Index) value of greater than 95%, and having a moisture content of less than 4% and a particle size of less than 200 μm, wherein the average nutritional value of said soybean meal is Table 1 wherein the soy flour is obtainable by the method according to claim 1 or 2 and has a lipoxygenase content that is reduced by at least 75% relative to the lipoxygenase content of the soybeans subjected to step a) or step i).
15. 15. The soy flour with high solubility of claim 14 having a moisture content of less than 3%.
16. The soy flour with high solubility according to claim 14, having a particle size of 190 μm to 5 μm.
17. 15. The soy flour with high solubility according to claim 14, having an NSI value of more than 97%, preferably more than 98%, more preferably between 98.5% and 100%.
18. 15. The soy flour with high solubility according to claim 14, having a shelf life of more than 6 months, preferably 6 to 12 months, at room temperature under vacuum.