Preparation of fermented soybean meal by solid state fermentation

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION FACULTY FOR HIGH QUALITY TRAINING GRADUATION PROJECT Thesis code: 2022-18116020 PREPARATION OF FERMENTED SOYBEAN MEAL BY SOLID-

OVERVIEW

Overview of Soybean Meal

Soybean meal (SBM) is a crucial protein source in the poultry and livestock industry, representing approximately two-thirds of global protein feed production Its protein content surpasses that of other plant-based protein sources, establishing it as a benchmark for comparison with alternative protein feeds.

Soybean meal (SBM) is a by-product of oil extraction, primarily classified by its crude protein content for marketing High-protein soybean varieties, derived from hulled seeds, typically contain 47-49% protein and 3% crude fiber In contrast, other soybean meals have less than 47% protein and more than 6% fiber, which includes the shell or part of the cover.

Soybean meal, also known as okara, is the fibrous residue left after soybeans are processed for soy milk and tofu This nutrient-rich byproduct is typically white or yellowish and contains both soluble and insoluble fiber, protein, and essential minerals like calcium, potassium, and niacin Additionally, it retains most of the beneficial isoflavones, B vitamins, and fat-soluble nutrients found in soybeans, including linoleic acid, soy lecithin, phytosterols, linolenic acid, vitamin D, and tocopherol.

Soybean meal (SBM) contains several anti-nutritional factors, including saponins, trypsin inhibitors, and hemagglutinin Fermentation of SBM enhances nutrient digestion and absorption, while also improving its nutritional profile by reducing bean odor and increasing levels of edible fiber, fatty acids, sugars, free amino acids, vitamin B2, vitamin B12, and flavoproteins As a functional food, SBM plays a role in preventing diabetes, hyperlipidemia, and obesity However, due to its high protein and fiber content, along with its perishability, SBM is typically used immediately or requires cooking and freezing for storage.

SBM is particularly appealing due to its low price and low calorie content Recently, okara has gained popularity as an ingredient in cookies, cakes, and various confections, as well as in traditional side dishes Its low-calorie profile makes it an excellent choice for those seeking diet-friendly options.

Soybean meal (SBM) is the leading soybean product utilized in animal diets, complemented by other products such as full-fat soybeans, soy protein concentrate (SPC), soybean oil, soy protein isolate (SPI), and soybean hulls Each of these soybean derivatives possesses distinct nutritional characteristics that cater to the dietary needs of various animals Notably, SBM enhances the amino acid (AA) profile of different grains, making it a valuable ingredient in the food industry Its increasing prevalence in pet food further underscores its significance in animal nutrition.

The size and particle size distribution of SBM were analyzed using the ASAE standard method (1993), revealing that the medium range (0.595 - 2,380 mm) comprises 70% soybean residues and 30% fine grain particles measuring less than 0.595 mm Both normal and log-normal particle size distribution analyses yielded comparable mass-average particle diameters of 0.833 mm and 0.786 mm, respectively.

Humidity significantly influences both actual and bulk density, with increases in humidity leading to a decrease in both densities While particle size impacts bulk density, it does not affect absolute density; finer particles exhibit a higher bulk density compared to coarser particles.

As moisture content increases, the particle shape and dimensional properties, including length, width, thickness, arithmetic mean diameter, and geometric mean diameter, exhibit a linear increase Conversely, sphericity decreases linearly with rising moisture levels Additionally, both grain mass and surface area show a linear increase alongside moisture content, while actual density, bulk density, and porosity decrease linearly as humidity rises.

The nutritional value of soybean meal is influenced by its chemical composition, which can vary based on the processing methods, storage conditions, and the origin of the beans.

The chemical composition of soybean meal varies based on factors such as the latitude of the growing area, light exposure, weather, and environmental conditions during harvest Consequently, soybean meals from leading exporters like the US, Brazil, and Argentina may exhibit significant nutritional differences.

Table 1.1 Chemical composition, amino acid profile, and quality parameters of soybean meal protein and its net energy value 1 [8][10]

Specific analysis, % 1 Soybean meal (Argentina)

1 All results are given for a dry matter content of 88%; 2 Neutral detergent fibre; 3 Urease activity; 4 Protein Dispersibility Index; 5 Protein solubility in KOH; 6 Trypsin inhibitory activity;

7 Net energy is estimated by Noblet et al., 2003.

Bacillus sp

Bacillus sp is a diverse group of aerobic and anaerobic, rod-shaped, spore-forming bacteria found throughout the environment Key species such as B subtilis, B licheniformis, and B pumilus are recognized as the original members of the Bacillus genus.

Fukumoto was the first to isolate Bacillus amyloliquefaciens, a soil bacterium known for producing liquefied amylase This species was later grouped with related species such as Bacillus licheniformis, Bacillus pumilus, and Bacillus subtilis into the "Bacillus subtilis species complex," a classification supported by phylogenetic and genetic evidence due to the highly conserved protein-coding sequences within this complex.

[15] For many years, these closely related species were difficult to classify using classical taxonomic parameters such as morphology, physiology, guanine-cytosine content, and phylogenetic analysis 16S rRNA gene sequencing

Bacillus species, particularly Bacillus velezensis, are increasingly significant in agriculture and the fermentation industry This novel, widely distributed bacterium can be rapidly isolated and cultured, posing no harm to humans or animals while remaining environmentally safe Its metabolites exhibit broad-spectrum antibacterial properties and a strong capacity to mitigate stress, alongside its remarkable ability for fast and stable growth.

As a result, there is more and more research on its properties and applications [16] Bacillus velezensis is an aerobic, gram-positive, endospore-forming bacterium that promotes plant growth

This species thrives in temperatures ranging from 25 to 37 °C and shows rapid adaptation at a neutral pH of 7 Numerous strains have demonstrated the ability to inhibit the growth of various microbial pathogens, including bacteria, fungi, and nematodes.

B velezensis (strain CR-502 T and strain CR-14b) were first isolated from environmental samples gained from the mouth of the Vélez river at Torredelmar in the province of Málaga, Spain Phenotypic tests and phylogenetic analyzes indicate that these strains are members of the genus Bacillus and are closely related to B subtilis and B amyloliquefaciens Further DNA-

DNA hybridization experiments revealed that the new strains had less than 20% similarity to other Bacillus species and, therefore, represented a distinct Bacillus species [19]

Bacillus has been commonly used in animal feed as a microbial additive and a probiotic

Probiotics are beneficial to poultry health by their ability to improve oxidative damage Probiotic

Incorporating Bacillus velezensis into animal feed can enhance health and productivity while promoting a diverse and stable gastrointestinal flora This microorganism, found abundantly in nature, is effective in inhibiting various fungi and bacteria and is also known for its rich array of metabolites.

Supplementing shrimp diets with B velezensis BV007 at a recommended dosage of 10^7 CFU/g can significantly enhance growth performance, boost immune responses, and positively modulate gut microbiota This feed additive is effective in improving both the growth and overall health of shrimp.

Bacillus velezensis DSM 15544 (Calsporin ®) serves as a beneficial feed additive for piglets, including those that are lactating and weaning, as well as for fattening pigs and sows, positively impacting the health of piglets, aquarium fish, dogs, and all poultry species.

Overview of Fermented Soybean meal

Fermentation is an ancient method of processing and preserving food that enhances the nutritional and functional qualities of the original product Various microorganisms, such as Aspergillus oryzae, Lactobacillus subtilis, L plantarum, and Bacillus spp., are employed to ferment soybean meal (SBM) for nutritional improvement The fermentation conditions and nutritional outcomes of fermented soybean meal (FSBM) vary based on the microorganisms used This process increases nutrient bioavailability and reduces antinutritional factors in SBM Fermentation leads to higher protein content, a decrease in trypsin inhibitors, and a shift in protein size distribution, with smaller proteins becoming more prevalent Additionally, soybean fermentation breaks down proteins and carbohydrates into low-molecular-weight, water-soluble compounds, enhancing nutrient digestion and helping to prevent diarrhea in pigs.

Certain microorganisms in fermented products may inhibit the colonization of diarrhea-causing pathogens in pigs, which is crucial for swine production as it lowers the risk of Escherichia coli infections and enhances feed efficiency Soybean meal (SBM) can undergo fermentation through single-stage or two-stage processes, with submerged fermentation and solid-state fermentation being the two most popular methods.

In Vietnam, research on soybean meal fermentation focuses on its application in animal feed, particularly through the isolation and selection of Lactobacillus spp to enhance soybean fermentation This fermented soybean meal serves as a viable alternative to fishmeal in the diets of pangasius and tilapia, thereby boosting aquaculture profitability Additionally, the fermentation of soybean meal with Trichoderma fungus is explored for its benefits in fertilizing plants, improving soil quality, and promoting healthy root development.

Research indicates that fermented soybean meal (FSBM) can effectively replace soybean meal (SBM) in pig diets without negatively impacting their performance Notably, FSBM has been shown to reduce post-weaning diarrhea in newly weaned pigs Additionally, studies highlight that feeding non-ruminants with FSBM offers several advantages over SBM, such as enhanced daily weight gain, improved growth performance, better protein digestibility, and a reduced immune response, while also preventing undesirable morphological changes Furthermore, two-stage fermentation of SBM using B subtilis has been explored for its potential benefits.

E.faecium effectively reduced antinutritional factors (soybean antigenic proteins, neutral detergent fiber, and phytic acid) in corn-SBM mixed feeds It increased the content of trichloroacetic acid-soluble protein (TCA-SP) and crude protein (CP) Furthermore, the high lactic acid concentration and low pH during inoculated feed fermentation inhibited the proliferation of Enterobacteriaceae According to L Chen et al., 2021, Two-stage fermentation of SBM with B velezensis can change the nutritional characteristics of SBM significantly based on the degradation of ANFs (soybean antigenic protein, cellulose, and hemicellulose), alteration of physicochemical properties and metabolites function while L plantarum mainly works to lower the pH to produce lactic acid concentration to inhibit pathogens and preserve animal feed.

The reason for creating the topic

Soybean meal (SBM), a high-protein agricultural by-product from tofu and soy milk production, serves as a crucial source of vegetable protein in the animal feed industry However, the presence of macromolecular proteins and anti-nutritional factors (ANFs) in SBM can hinder digestion and absorption, particularly in young animals To enhance these digestive processes, microbial fermentation has emerged as an effective solution Thus, our graduation thesis focuses on the "Preparation of fermented soybean meal by solid-state fermentation."

Research content

Use finely ground soybean meal for carrying out fermentation Investigate the growth ability of microorganisms and evaluate their proteolytic activity to select an excellent microbial strain

Soybean residues were fermented over five days at intervals of 0, 24, 48, 72, and 96 hours, followed by drying and preservation This process aimed to analyze the alterations in chemical composition and the concentration of decomposed proteins, as well as the protein molecular weight changes resulting from fermentation.

MATERIALS AND METHODS

Materials, chemicals and equipment

ROBIKA Hai Long produces a variety of essential products, including Argentine soybean meal, Xilong casein, glucose, and agar Additionally, the company utilizes Himedia's nutrient broth environment and Bomei's bovine serum albumin Key reagents such as NaOH, Folin-Ciocalteu's, and complex-forming agents like Na2CO3, CuSO4·5H2O, and C4H4O6KNa·4H2O are also part of their offerings Furthermore, they provide a phosphate buffer at 50 nM (pH 7.0) and K2SO4 for various applications.

The laboratory is equipped with advanced instruments including the Hitachi UH-5300 UV-Vis Spectrophotometer from Japan, a Sartorius 4-digit analytical balance from Germany, and a centrifuge machine Essential tools such as beakers, Erlenmeyer flasks, pipettes, micropipettes, volumetric flasks, petri dishes, and heat-resistant plastic containers are also available Additional equipment includes an autoclave, laboratory inoculation chamber, incubator, drying chamber, convection drying cabinet, and a heat magnetic stirrer, along with a pH meter for precise measurements.

Research Methods

The enzyme-producing microorganisms were cultured in a nutrient medium, specifically Nutrient Broth (NBC), which contained 0.01% (w/v) sodium caseinate A sterilized 100 mL of NBC medium was prepared, to which 1.0 mg of dry inoculum was added The culture was incubated for 24 hours at 37°C with continuous shaking at 200 rpm This microorganism will subsequently be utilized for the solid-state fermentation of soybean meal (SBM) in the next steps.

Microorganisms were cultured on NBC agar for 24 hours and incubated at 37˚C to develop colonies This method is utilized for screening proteolytic activity.

LM 1 Microbial Bacillus subtilis sample

LM 2 Microbial Bacillus subtilis sample

LM 3 Microbial Bacillus velezensis sample

LM 4 Microbial Bacillus pumilus sample

2.2.2 Investigation of the growth ability of microbial strains

The nutrient medium for culturing enzyme-producing microorganisms consisted of 0.01% (w/v) sodium caseinate (NBC) To evaluate the bacterial growth rate, samples of the bacterial suspension were taken hourly, and absorbance was measured at λ600 nm.

The proteolytic activity was evaluated by monitoring casein hydrolysis on agar plates enriched with YNB medium, which contained 0.5% casein, 0.5% glucose, and 2.2% agar at pH 7.0 Biomass was inoculated at the center of the plates and incubated at 37˚C for 24 to 72 hours, after which the formation of a clear zone around the biomass was observed.

2.2.4 Solid-state fermentation (SSF) in soybean meal

Figure 2 1 Solid-state fermentation process SBM

Experiments were carried out under three different conditions:

 Condition 1: 10g SBM (10 g) is sterilized before fermentation

 Condition 2: SBM (1.0 kg) is sterilized before fermentation

 Condition 3: SBM (10 g)has no sterilization prior to fermentation

Prepare sterilized Petri dishes or heat-resistant plastic containers with 10g or 1.0 kg of SBM, ensuring they are clean Weigh the SBM and sterilize it at 121˚C for 15 minutes to eliminate microorganisms and lower antinutrient levels After sterilization, measure 2-5g of the sample using an infrared moisture-drying scale to assess moisture content Calculate the necessary water addition to achieve a final moisture content of 40%, incorporating 1% molasses and 5% microorganisms by weight of SBM in the water.

To calculate the amount of water needed to achieve a desired moisture level in a sample, use the formula: \[x = f\left(\frac{(1-b\%) \times 100\% \cdot m}{(b\% - a\%)}\right)\]where \(x\) represents the volume of water to be added in milliliters, \(a\%\) is the current moisture content of the sample, \(m\) is the mass of the sample in grams, and \(b\%\) is the target humidity level.

SBM was subjected to semi-solid fermentation for five days at 37˚C During the fermentation process, samples were collected at intervals from 0 to 96 hours and dried using convection at temperatures between 50-60˚C until the moisture content fell below 10%, which took place overnight The dried samples were then finely ground (FSBM) and stored in an airtight container at 4˚C.

The total protein content of the samples was measured using the Kjeldahl method For water-soluble protein analysis, 0.5g of the sample was diluted in 21.0g of distilled water, mixed thoroughly, and centrifuged at 4500 RPM for 20 minutes to obtain the supernatant, which was then analyzed using the Lowry method.

 Lowry method (used to determine the water-soluble protein content of SBM or FSBM samples)

The most reliable technique for measuring protein concentration is acid hydrolysis, which is succeeded by amino acid analysis Other methods often depend on the amino acid composition of proteins and may not yield absolute concentrations For calculating soluble protein content, the Lowry method should be employed, ensuring that sensitivity remains within an acceptable range.

The method utilizes the Biuret reaction, where protein peptide bonds react with copper in alkaline conditions, resulting in Cu\(^+\) that interacts with the Folin reagent Additionally, the Folin-Ciocalteau reaction, which remains somewhat unclear, involves the reduction of phosphomolybdotungstate to polypdenum blue through copper-catalyzed oxidation of aromatic amino acids This series of reactions yields a deep blue color, influenced significantly by the tyrosine content.

The blue complex formed during the reaction can be measured at 675 nm, with color intensity directly proportional to protein concentration Protein content in the sample can be calculated using a standard protein graph, typically based on bovine serum albumin crystals This method demonstrates a sensitivity of approximately 0.01 mg protein/mL and is most effective for solutions containing 0.01–1.0 mg/mL of protein.

The standard curve for the calculation of protein concentration by the Lowry method was performed according to a published method [34]

Stand at room temperature 30-60 min

Figure 2 2 Procedure for measuring soluble protein according to the Lowry method

Prepare chemicals and explain the procedure as follows:

Complexing reagent: mix three solutions of compounds X, Y, and Z in the ratio of 100:1:1, respectively Solution X: 2% (w/v) Na2CO3 dissolved in distilled water Solution Y: 1% (w/v)

CuSO4 5H2O is soluble in distilled water Solution Z: 2% (w/v) C4H4O6KNa 4H2O is soluble in distilled water

Dilute 2N NaOH solution, prepare 1N Folin reagent, prepare standard solution means use BSA standard protein solution containing 4 mg/mL protein diluted with sand water and store at - 20˚C

Prepare standard solutions with different concentrations according to Table 2.2

Table 2 2.Standard curve construction table of Lowry method

Take 0.5 mL of sample to be measured or standard solution, and add 0.5 mL of 2N NaOH solution Leave the hydrolysate solution at 100˚C for 10 minutes in a thermostatic bath or pot of boiling water Then, cool the hydrolyzed solution to room temperature, and add 5 mL of the complexation reagent mixture Let the mixture stand at room temperature for about 10 minutes Add over 0.5 mL of Folin compound to the mixture, shake the solution well and leave at room temperature for about 30-60 minutes (not more than 60 minutes) Take the mixture to measure UV-Vis at two wavelengths, 550 nm, and 750 nm Read results at 750 nm if the protein concentration is below 500 μg/ml or at 550 nm if the protein concentration is between 100 and

2000 μg/ml Next, draw a standard absorbance curve as a function of the initial protein concentration and use it to determine the unknown protein concentration of the sample to be measured

 Kjeldahl method (used to determine total protein content in SBM or FSBM samples

The Kjeldahl process involves the conversion of total organic nitrogen into ammonium sulfate through decomposition in concentrated sulfuric acid This process generates ammonia, which is then distilled into a boric acid solution under alkaline conditions.

The Kjeldahl method involves a three-step approach to protein quantification: digestion, distillation, and titration Organic matter digestion is achieved by using concentrated, heated

The process involves using H2SO4 and K2SO4 to elevate the boiling point, along with a catalyst like selenium to accelerate the reaction, effectively converting nitrogen in the sample to ammonium sulfate To neutralize the decomposer, NaOH is added, transforming ammonium sulfate into ammonia, which is then distilled and collected in a flask containing excess boric acid, resulting in the formation of ammonium borate.

The borate anions were titrated using standardized hydrochloric acid to determine the nitrogen content indicative of the sample's crude protein Since most proteins consist of approximately 16% nitrogen, a conversion factor of 6.25 is applied It's important to note that nitrogen from non-protein additives or contaminants, such as melamine found in milk, is also included in the measurement.

RESULTS

Selection of microorganisms with intense protease activity

Figure 3 1 Growth curve of strain LM 1 Figure 3 2 Growth curve of strain LM 2

Figure 3 3 Growth curve of strain LM 3 Figure 3 4 Growth curve of strain LM 4

Assessing the growth capacity of bacterial strains involves surveying their growth curves Additionally, evaluating the casein hydrolysis ability of microbial strains is conducted by measuring the diameter of the proteolytic zone These two experiments are essential for selecting the most suitable strains for fermentation processes.

The growth rates of four microbial strains in NBC medium at 37°C exhibit significant differences, as indicated by the four growth curve plots Notably, LM 1 has a brief log phase duration with a relatively low peak, leading to a rapid transition into the death phase.

LM 2 and LM 4 strains, the lag phase period is long, and the growth rate of the microorganisms slows down over time and falls into a period of rapid death phase, while the LM 3 strain started growing at the 3rd hour and stabilized at 15 hours and lasted for 8 hours before entering the death phase (after 24 hours of microbial culture, the bacterial content in the medium was 2.7 ×

The LM 2 and LM 4 strains exhibited a significantly higher bacterial density during the stationary phase compared to the LM 1 and LM 3 strains Additionally, all four strains—LM 1, LM 2, LM 3, and LM 4—reached the stationary phase in 12 hours.

Table 3 1.Diameter size (mm) hydrolysis of 4 microbial strains on YNB agar plate at 37˚C

Different values printed in the same row indicate a statistically significant difference

Screening for proteolytic activity revealed that strain LM 3 exhibited a significantly larger casein hydrolysis diameter of 88.90 mm after 72 hours, outperforming other strains In contrast, strain LM 4 showed an indistinct hydrolytic diameter, while strains LM 1 and LM 2 demonstrated vigorous colony growth but limited hydrolytic diameters of 12.42 mm and 6.48 mm, respectively Notably, strain LM 3 completely hydrolyzed the casein in the agar plate, indicating its superior proteolytic capacity Consequently, strain LM 3 was selected for further experiments, and identification confirmed it as a Bacillus velezensis strain.

The strain of Bacillus velezensis (LM 3) will be used by us for further research

Figure 3 5 The zone of clearance on YNB agar plates by strain LM 1 at 37˚C for 24h, 48h,

Figure 3 6 The zone of clearance on YNB agar plates by strain LM 2 at 37˚C for 24h, 48h, 72h

Figure 3 9 Results of identification of microorganisms of strain LM3.

Chemical composition of soybean meal (SBM)

The raw SBM sample exhibits various nutritional components, including crude protein content, water-soluble protein, protein solubility in KOH, and nitrogen solubility index, with values of 46.65 g/100g, 8.06 g/100g, 86.66 g/100g, and 17.28 g/100g, respectively Additionally, it contains crude fiber (3.58 g/100g), fat (1.3 g/100g), crude ash (6.2 g/100g), moisture (8.7 g/100g), and volatile matter content at 103˚C The trypsin inhibitor activity is measured at 2.75 mg TID/g.

ARG Sample SBM raw material

LM 10 SBM is sterilized; 0h solid-state fermentation, sample weight 1.0kg

Table 3 3 Chemical composition of SBM and FSBM

Indicators ARG LM 10 LM 124 LM 148 LM 172 LM 196

Water soluble protein/crude protein (%) 17.28 10.10 13.33 36.88 31.26 35.54

Fermented soybean meal (FSBM) exhibits a notable enhancement in crude protein, water-soluble protein, and nitrogen solubility index compared to raw soybean meal (SBM), along with a slight increase in crude ash content Conversely, FSBM shows a reduction in KOH-soluble protein and trypsin inhibitory activity, while the levels of crude fat and fiber remain largely unchanged.

The crude protein content of fermented soybean meal (FSBM) increased significantly at 24, 48, 72, and 96 hours, showing rises of 2.85%, 3.7%, 3.95%, and 4.65%, respectively, compared to standard soybean meal (SBM) During bacterial growth, carbohydrates are utilized for cellular respiration, generating energy while converting carbohydrates into carbon dioxide and water This process leads to a reduction in carbohydrate content in FSBM, which in turn results in a higher percentage of crude protein due to the decreased carbohydrate levels.

The water-soluble protein of FSBM increased significantly at 48, 72, and 96 hours, respectively, 10.51, 7.76, and 10.17% compared to SBM The nitrogen solubility index of FSBM

At 96 hours, the protein levels in the Bacillus velezensis sample more than doubled compared to the SBM sample This significant increase suggests that Bacillus velezensis effectively hydrolyzed crude protein, transforming it into smaller, water-soluble protein molecules and oligopeptides.

Soybean meal samples were classified into five groups based on KOH protein solubility: less than 75%, 75-80%, 80-85%, 85-90%, and greater than 90% Additionally, they were categorized by ureatic activity into five levels: 0, 0.01, 0.011-0.05, 0.051-0.1, and greater than 0.1 Excessive processing can adversely affect amino acid digestibility, as some amino acids may be destroyed or converted into indigestible compounds The ideal KOH solubility range for soybean meal is typically between 70-85%, indicating high protein quality The KOH soluble protein content of soybean meal was measured at 86.66%, suggesting inadequate heat treatment Notably, after fermentation, this content decreased by 8.41% at 48 hours and 11.66% at 96 hours compared to the initial soybean meal sample.

A high TI value (trypsin inhibitor activity) can negatively affect protein digestion in animals

During solid-state fermentation (SSF), the trypsin inhibitor (TI), a protein-based anti-nutritional factor (ANF), is gradually degraded by proteases secreted by Bacillus velezensis The activity of the trypsin inhibitor decreased from 2.78 mg TID/g in raw samples to 1.78 mg TID/g after 24 hours, and further to 1.23 mg TID/g after 96 hours.

The fermentation time significantly influences the ash ratio of fermented soybean meal (FSBM), with crude ash content rising from 6.2% in the initial soybean meal (SBM) sample to 6.9% after five days of fermentation This increase in ash content is attributed to a corresponding decrease in the carbohydrate ratio.

The fermentation process significantly increases the percentage of water-soluble protein relative to total protein, surpassing that of raw soybean meal (SBM) after 48 hours In soy, the predominant protein type is globulin, followed by albumin, with glutelin and prolamin present in smaller amounts Globulins and albumins are particularly susceptible to heat denaturation, which can lead to reduced water solubility Consequently, the proportion of soluble protein in raw samples of ARG (17.27%) is higher than in LM 10 (10.10%) and LM 124 (13.33%) This indicates that an increase in water-soluble protein correlates with a higher degree of protein hydrolysis.

Enzyme-degrading protein concentration

❖Total and water-soluble protein content of the sample

The results of total protein and water-soluble protein content of SBM and FSBM samples are shown in Tables 3.3, Table 3.4, Table 3.5, and Table 3.6

LM 3T SBM is sterilized; sample with a mass of 10g

LM 3K SBM is not sterilized; sample with a mass of 10g

LM 0 SBM is sterilized; 0h solid-state fermentation, sample weight 10g

LM 00 SBM is not sterilized; 0h solid-state fermentation, sample weight 10g

LM 3T1 SBM is sterilized, sample with a mass of 1.0kg

TT 50 Samples of fermented soybeans (FSBM) market 50

Table 3 5 Results of total protein and water-soluble protein content of SBM samples sterilized at condition 1 (Appendix 4)

Water soluble protein/crude protein (%)

Different values printed in the same column indicate a statistically significant difference (p

Tiêu đề	Preparation of Fermented Soybean Meal by Solid-State Fermentation
Tác giả	Tran Kieu Huong, Luong Thi Ngoc Sang
Người hướng dẫn	Assoc. Prof. Trinh Khanh Son
Trường học	Ho Chi Minh City University of Technology and Education
Chuyên ngành	Food Technology
Thể loại	Graduation project
Năm xuất bản	2022
Thành phố	Ho Chi Minh City

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Số trang	65
Dung lượng	5,56 MB