Effect of fermentation with Lactobacillus fermentum FL-0616 on probiotic-rich bean powders

Abstract

Plant-based diets have received considerable attention for balancing human health and environmental sustainability. This study investigated the effects of fermentation with Lactobacillus fermentum FL-0616 on probiotic-rich mung bean, chickpea and tiger skin kidney bean powders. A particle size distribution experiment showed that the particle size of probiotic-rich bean powder was significantly reduced and the specific surface area was increased. This was critical for improving the dissolution rate, wettability and dispersibility. Simultaneously, the angles of repose and slide of the fermented bean powder were significantly reduced. Scanning electron microscopy confirmed that particle size of the bean powder decreased and became more uniform after fermentation. The results of dynamic and static rheology jointly demonstrated that fermentation improved the flowability of probiotic-rich bean powder, which was related to its decreased particle size. This study provides a technical foundation for the deep processing of bean resources.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05668-5.

Introduction

As an important component of human food, beans have made outstanding contributions to the balance of human nutrition worldwide, especially in low-income groups in developing countries (Los et al. 2018; Siddiq et al. 2010). It is a good source of protein and contains active substances, such as phenolic compounds, peptides, amino acids, and unsaturated fatty acids, which are associated with antioxidants, reducing serum cholesterol levels and glucose levels, and preventing cancer (Los et al. 2018; Siddiq et al. 2010). People have become increasingly aware of the excellent functions of sustainable bean food.

In recent years, plant-based diets have received considerable attention for balancing human health and environmental sustainability. Plant-based fermented foods are attractive not only because of the probiotic and industrial potential of their microbes but also as alternative non-dairy food matrices for probiotic administration (Wuyts et al. 2020). Probiotics are generally considered to confer health benefits to hosts when administered in sufficient amounts. Probiotic foods improve the intestinal flora, lower blood lipid levels, prevent cancer, and enhance immunity (Misra et al. 2021). Consuming probiotics containing natural bioactive compounds was a “green” alternative to drugs for maintaining blood pressure, boosting immunity, and eliminating sleep disturbances, especially in the context of the COVID-19 outbreak (Misra et al. 2021). Thus, the food itself could be used as a new vehicle for the traditional (dairy) sale of probiotics to enter new consumer markets.

To date, few studies have been conducted on the development of probiotic-rich bean powders. Bean powder has contributed to the sustainable development of the food industry, in line with new trends and consumption habits (Bento et al. 2021). The development of bean powder could reduce the difficulty in cooking beans, improve their convenience and accessibility, and effectively reduce postharvest losses (Kyomugasho et al. 2021).

In contrast to traditional bean powder, fermented bean powder not only guaranteed the nutritional value of bean powder, but also had a probiotic effect and improved its functional properties (Villacrés et al. 2020). In our earlier study, probiotic-rich bean powder (> 10⁶ CFU/g) was found to be beneficial in promoting human health (Tao et al. 2022). However, its physical, microstructural and rheological properties remain unexplained. In this study, the effects of fermentation with L. fermentum FL-0616 on the physical, microstructural and rheological properties of probiotic-rich bean powders were investigated. This could promote the sustainable development of plant-based diets and further research on bean resources.

Materials and methods

Materials

Mung beans, chickpeas, and tiger skin kidney beans were commercially obtained in Changchun, China. The L. fermentum FL-0616 (L. fermentum FL-0616) strain was isolated from fermented waxy corn and stored at the National Engineering Laboratory for Wheat and Corn Deep Processing (Jilin Agricultural University, China). This strain was identified using 16S rDNA gene sequence analysis. Food grade cellulase (35,767 U/g) and α-amylase (18,291 U/g) were provided by Henan Wanbang Co. Ltd (Henan, China).

Preparation process of bean powders

Mung beans, chickpeas, and tiger skin kidney beans were mixed with water (1:2, w/w) and soaked at 25 °C. Then, they were ground separately into a slurry. Soon after, enzymatic reactions were performed, by adding 50 U/mL cellulose and 50 U/mL α-amylase to each slurry, and incubated for 3 h at 50 °C. Thereafter, slurries were placed in a boiling water bath for 20 min. After cooling, homogenization was performed using a nano high-pressure homogenizer (AH-BASICI, Shanghai, China). A 0.4% (w/w) sample of L. fermentum FL-0616 was then inoculated into each slurry for fermentation at 37 °C for 6 h. Finally, an experimental spray dryer (Y-PL300, Shanghai, China) was used for spray drying. The spray drying conditions were as follows: inlet temperature was 115 °C, rotation speed was 10 r/min. Spray-dried mung bean powders (MB), chickpea powders (CP), and tiger skin kidney bean powders (TSKB) were placed in sterile bags and immediately tested.

Particle size distribution of bean powders

Three treatments (A1, no probiotics; A2, spray drying directly after adding L. fermentum FL-0616; A3, fermentation with L. fermentum FL-0616) were performed on each bean to obtain different bean powders. The particle size distribution of the bean powders was measured using a BT-9300HT laser particle size analyzer (BT-9300HT, Dandong, China). The samples were uniformly dispersed in distilled water for analysis.

Dissolution rate, precipitation rate and precipitation water absorption rate of bean powders

The prepared bean powder solution (W₀) was placed in a centrifuge tube of known weight (W₂) and centrifuged at 3000× g for 10 min. The supernatant was removed, and the wet weight of the centrifuge tube with the precipitation was measured (W₄). It was placed in an oven at 105 °C to constant weight to obtain the dry weight of the centrifuge tube with precipitation (W₃). Precipitation dry weight W₁ = W₃ − W₂. The formulas used are as follows:

$$\text{Dissolution rate}\left(\%\right)=\left(W_0-W_1\right)/W_0\times 100$$ 1

$$\text{Precipitation rate}\left(\%\right)=W_1/W_0\times 100$$ 2

$$\text{Precipitation water absorption rate}\left(\%\right)=\left(W_4-W_3\right)/W_0\times 100$$ 3

Wettability and dispersibility of bean powders

A 50 mL volume of distilled water (40 °C) was added to a 250 mL beaker, and 1 g of bean powder was spread on the water surface. The time from when the bean powder was placed in the beaker till it was completely wetted was recorded and was called the wetting time. In a beaker, 50 mL of distilled water was added to it, and 1 g of bean powder was spread on the water surface. The mixture was stirred with a magnetic stirrer (600 r/min), and the time at which the bean powder was completely dispersed in distilled water was called the dispersion time.

Angles of repose and slide of bean powders

The angles of repose and slide of bean powders were determined according to the reference method (Zhang et al. 2020a, b). The angle of repose α is calculated as:

$$\alpha =arctan\left(H/R\right)$$ 4

where H is the height from the paper to the outlet of the funnel and R is the radius of the cone.

The angle of slide β is calculated as:

$$\beta =arcsin\left(H/L\right)$$ 5

where L is the length of the glass plate and H is the vertical height between the top of the inclined glass plate and the horizontal line.

Scanning electron microscopic (SEM) analysis of bean powders

The bean powders were evenly coated on the surface of a double-sided conductive adhesive and sprayed with an electroplating layer of approximately 10 nm thickness. Thereafter, bean powders were visualized using scanning electron microscopy (Phenom Pro, Shanghai, China) with an accelerating voltage of 10 kV and 1000× magnification.

Dynamic rheology

The prepared samples were collected, a flat plate measurement system was adopted (model: PP25, diameter: 25 mm), and the plate spacing was set to 1 mm. The test conditions were as follows: the temperature was 25 °C, the strain force was 1%, and the oscillation frequency was 0.1–100 rad/s. The storage modulus (G′) and loss modulus (G′′) were measured with increasing frequency.

Static rheology

The prepared samples were collected, a flat plate measurement system was adopted (model: PP25, diameter: 25 mm), and the plate spacing was set to 1 mm. The test conditions were as follows: the temperature was 25 °C, and the shear rate was increased from 0.1 to 500 s⁻¹. The Herschel-Bulkley model was used for fitting, and the rheological curve was described by the power law τ = k γⁿ + τ₀, where τ is the shear stress (Pa), τ₀ is the initial shear stress (Pa), k is the consistency coefficient (Pa·sⁿ), γ is the shear rate, and n is the flow index.

Statistical analysis

All test results are the average of three repeated tests. Origin 8.1 was used for data analysis and graphing. Statistical analyses were performed using SPSS (version 19.0). Multivariate analysis (MANOVA) of variance and Duncan’s multiple comparison method were used to analyze the differences between bean powders.

Results and discussion

The particle size distribution of bean powders

The particle size distribution of bean powders after different treatments are shown in Table 1. Particle size distribution was an important physical factor for spray-dried powders, as it has a large impact on powder flowability, portability, and retention of biological activity (Zhang et al. 2020a, b). As shown in Table 1, the particle size of bean powders after A3 treatment was the smallest. This was like due to the fermentation by L. fermentum FL-0616. The particle size of bean powder after A2 treatment was larger than that after A3 treatment, because L. fermentum FL-0616 only had a minor fermentation effect on the bean slurry before spray drying. As a lactic acid bacterium, the bean powder fermented with L. fermentum FL-0616 decreased anti-nutrient factors (Online Resource 1) and reduced stachyose and raffinose (Online Resource 2), which are responsible for flatulence. The L. fermentum can degrade macromolecular substances in bean powder, such as carbohydrates, proteins and phytic acid. By extracting and measuring enzyme activity, it was found that pectinase, cellulase, xylanase, amylase and protease were produced during the L. fermentum FL-0616 fermentation process (Online Resource 4), and the production of pectinase was the highest, measuring at 239.33 U/mL. These enzymes likely degraded large molecules in bean powder, such as carbohydrates and proteins, thus reducing its particle size. Similar studies have found that lactic acid bacteria can secrete a variety of extracellular enzymes such as amylase, α-glucosidase, and cellulase (Huang et al. 2019), that play a role in the degradation process. Studies have found that lactic acid bacteria have considerable glycosyl hydrolases and carbohydrate—degrading capabilities, and can selectively degrade specific polysaccharides (Wuyts et al. 2020). Fermentation can degrade mineral-complexed phytic acid into calcium and phosphorus because it can increase the activity of phytase (Olukomaiya et al. 2020). In addition, enzymes produced by microorganisms can hydrolyze proteins to a certain extent, thereby reducing the molecular weight of sample proteins during the fermentation process (Olukomaiya et al. 2020). Fermentation can also convert bound phenols to free phenols, thereby increasing their bioavailability (Olukomaiya et al. 2020). Table 1 shows that the particle size order of the three bean powders under the same treatment was: TSKB > CP > MB, and the difference was related to the type of bean used. Specific surface area was inversely proportional to the volume mean diameter of the bean powder. After A3 treatment with the same fermented bean powder, the specific surface area was the largest. Small particles are required in food formulations to ensure uniformity and better quality (Alves et al. 2016). Particle size has a significant effect on the digestibility of food in the gastrointestinal system. The larger the particle size, the smaller will be the specific surface area and the lower will be the digestibility (Ahmed et al. 2019). Thus, the reduced particle size of probiotic-rich bean powder aids gastrointestinal digestion.

Table 1.

The particle size distribution of bean powders

Treatments1,2,3	D10 (μm)	D50 (μm)	D90 (μm)	Area mean diameter (μm)	Volume mean diameter (μm)	Specific surface area (m2/kg)
MB(A1)	3.53 ± 0.08bZ	24.92 ± 0.89aZ	72.05 ± 0.78aZ	8.20 ± 0.07aY	31.59 ± 0.26aZ	223.37 ± 0.74cX
MB(A2)	2.91 ± 0.02bY	18.28 ± 0.78aY	70.81 ± 0.86aY	8.17 ± 0.58aY	28.17 ± 0.86aY	241.40 ± 0.80cY
MB(A3)	2.89 ± 0.10bX	16.64 ± 0.98aX	64.66 ± 0.55aX	8.04 ± 0.47aX	25.77 ± 0.68aX	254.43 ± 0.81cZ
CP(A1)	2.84 ± 0.08aZ	26.19 ± 0.95bZ	95.51 ± 0.90bZ	8.46 ± 0.09aY	39.11 ± 0.75bZ	228.60 ± 0.36bX
CP(A2)	2.83 ± 0.02aY	25.65 ± 0.73bY	90.64 ± 0.40bY	8.38 ± 0.06aY	38.87 ± 0.72bY	230.00 ± 0.44bY
CP(A3)	2.66 ± 0.08aX	21.18 ± 0.87bX	89.70 ± 0.45bX	7.79 ± 0.04aX	36.14 ± 0.66bX	248.37 ± 0.31bZ
TSKB(A1)	3.97 ± 0.05cZ	37.48 ± 0.55cZ	98.50 ± 0.27cZ	11.52 ± 0.20bY	45.28 ± 0.32cZ	167.90 ± 0.69aX
TSKB(A2)	3.94 ± 0.04cY	27.93 ± 0.59cY	95.66 ± 0.78cY	11.47 ± 0.13bY	40.26 ± 0.35cY	168.83 ± 0.32aY
TSKB(A3)	3.80 ± 0.01cX	22.09 ± 0.32cX	91.71 ± 0.86cX	11.14 ± 0.16bX	36.52 ± 0.60cX	173.63 ± 0.95aZ

¹ MB, mung bean powders; CP, chickpea powders; TSKB, tiger skin kidney bean powders

² A1: no probiotics; A2: spray drying directly after adding L. fermentum FL-0616; A3: fermentation with L. fermentum FL-0616

³ a, b, and c were used to identify the statistical differences (P < 0.05) among the different beans under the same treatment; X, Y, and Z were used to identify the statistical differences (P < 0.05) among the same beans under different treatments

Analysis of physical properties

The dissolution rate is one of the main parameters used to judge the quality of powder products. Compared with A1 treatment, the dissolution rate of the bean powder after A2 treatment was significantly enhanced, but less than that of the A3 treatment (Table 2). This was related to fermentation by L. fermentum FL-0616. The production of acetic acid and lactic acid by lactic acid bacteria during fermentation results in proteolytic degradation of gluten, moderate hydrolysis of starch and increased solubility (Elkhalifa et al. 2005). Fermentation induced inactivation of anti-nutritional factors in bean powder can also an promote increased dissolution rate (Elkhalifa et al. 2005). Fermentation also results in partial removal of the protein barrier on the surface of starch granules, making it easier for starch to leach out, thereby increasing the dissolution rate (Park et al. 2020). The increased dissolution rate might also be related to the weakening of the binding capacity between starch granules caused by fermentation (Odey and Lee 2019). The A3 treatment effectively decreased the precipitation rate because of its higher dissolution rate. In addition, the precipitation water absorption rate decreased, because less precipitation resulted in less water being absorbed.

Table 2.

The physical properties of bean powders

Treatments1,2,3	Dissolution rate (%)	Precipitation rate (%)	Precipitation water absorption rate (%)	Wettability (s)	Dispersibility (s)
MB(A1)	95.90 ± 0.06aX	4.10 ± 0.06bZ	19.85 ± 0.12bZ	84.33 ± 0.58cZ	51.67 ± 0.58cZ
MB(A2)	95.93 ± 0.04aY	4.07 ± 0.04bY	19.21 ± 0.28bY	73.67 ± 0.29cY	46.33 ± 0.58cY
MB(A3)	96.46 ± 0.04aZ	3.54 ± 0.04bX	18.40 ± 0.01bX	68.00 ± 1.00cX	38.33 ± 0.58cX
CP(A1)	96.19 ± 0.08bX	3.81 ± 0.08aZ	17.78 ± 0.11aZ	42.33 ± 0.76aZ	34.00 ± 1.00aZ
CP(A2)	96.26 ± 0.02bY	3.74 ± 0.02aY	17.50 ± 0.14aY	39.00 ± 1.00aY	32.67 ± 0.58aY
CP(A3)	96.63 ± 0.04bZ	3.37 ± 0.04aX	16.89 ± 0.10aX	32.33 ± 0.29aX	30.33 ± 1.26aX
TSKB(A1)	95.82 ± 0.03aX	4.18 ± 0.03bZ	23.39 ± 0.15cZ	77.67 ± 0.58bZ	42.67 ± 0.76bZ
TSKB(A2)	95.94 ± 0.06aY	4.06 ± 0.06bY	22.83 ± 0.14cY	66.67 ± 0.29bY	41.67 ± 0.58bY
TSKB(A3)	96.40 ± 0.01aZ	3.60 ± 0.01bX	21.33 ± 0.09cX	63.33 ± 0.58bX	35.33 ± 0.58bX

¹ MB, mung bean powders; CP, chickpea powders; TSKB, tiger skin kidney bean powders

²A1: no probiotics; A2: spray drying directly after adding L. fermentum FL-0616; A3: fermentation with L. fermentum FL-0616

³a, b, and c were used to identify the statistical differences (P < 0.05) among the different beans under the same treatment; X, Y, and Z were used to identify the statistical differences (P < 0.05) among the same beans under different treatments

Table 2 also lists the wettability and dispersibility of the bean powders obtained using different beans under different treatments. Wettability refers to the rate at which the sample particles are wetted and sunk, while dispersibility refers to the rate at which the sample particles are completely dissolved and uniformly dispersed in the preparation solution. Under the same treatment conditions, CP exhibited the best wettability and dispersibility, followed by TSKB and MB. The main reason was that, compared with MB and TSKB, CP particles were looser, and the powder was not easy to stick. This was conducive to improving the penetration of water into the powder, making it easier to wet and disperse in water, and resulting in a better dissolution effect. Compared with the A1 treatment, the wettability and dispersibility of the bean powder improved the most after A3 treatment. This might be because fermentation can induce structural changes in proteins and starches, which are easier to disperse into finer particles, and easier to wet and disperse (Elkhalifa et al. 2005; Park et al. 2020). Fermentation led to smaller particle sizes and larger surface areas for the same bean powder. The structure was loose, more hydrophilic groups were exposed, and the contact area between the particles and water increased, resulting in enhanced wettability and dispersibility.

The angles of repose and slide of bean powders

The angle of repose of the same bean powder was significantly different under different treatments (Table 3). The smaller the angle of repose, the better the flowability of the particle (Qian et al. 2020). Compared with the A1 treatment, the A2 and A3 treatments significantly reduced the angle of repose of the bean powder, which was the smallest for the bean powder fermented by L. fermentum FL-0616. It is generally believed that the flowability of a powder is affected by various properties of the particles, such as particle size and its distribution, particle shape, surface roughness, and other interparticle forces (Wang et al. 2017). Flowability is important for the transportation and handling of powders. Angles of repose up to 30° indicated excellent flow, and angles above 55° implied very poor flow (Kaur et al. 2022). After A3 treatment, the angle of repose of the bean powder was higher than 30°, but lower than 55° (Table 3). This suggests that the probiotic-rich bean powder had good flowability. Compared with A1 treatment, the angle of slide of the same bean powder was significantly reduced after A3 treatment because fermentation reduced the particle size of the bean powder. Particle size distribution is a very important property of powder and might have a significant effect on its flowability (Hussain et al. 2018). Smaller particles with smaller angles of repose and slide had better flow properties, which were more conducive to the formation of a homogeneous mixture. A similar result was obtained for ultra-fine ginger powder (Zhao et al. 2009). The reduced angles of repose and slide of the probiotic-rich bean powder improved the flowability and enhanced the anti-caking ability, thus promoting the dispersibility and solubility of the bean powder.

Table 3.

The angles of repose and slide of bean powders

Treatments1,2,3	Angle of repose (°)	Angle of slide (°)
MB(A1)	47.05 ± 0.79bZ	32.34 ± 0.73cY
MB(A2)	46.15 ± 0.96bY	32.07 ± 0.08cY
MB(A3)	44.42 ± 1.24bX	30.33 ± 1.06cX
CP(A1)	45.96 ± 1.03aZ	22.68 ± 1.35aY
CP(A2)	43.60 ± 0.56aY	21.64 ± 1.24aY
CP(A3)	42.43 ± 0.90aX	21.02 ± 0.82aX
TSKB(A1)	50.18 ± 1.62cZ	28.38 ± 0.75bY
TSKB(A2)	48.30 ± 0.33cY	28.29 ± 0.65bY
TSKB(A3)	45.62 ± 0.64cX	27.50 ± 0.17bX

¹ MB, mung bean powders; CP, chickpea powders; TSKB, tiger skin kidney bean powders

²A1: no probiotics; A2: spray drying directly after adding L. fermentum FL-0616; A3: fermentation with L. fermentum FL-0616

³a, b, and c were used to identify the statistical differences (P < 0.05) among the different beans under the same treatment; X, Y, and Z were used to identify the statistical differences (P < 0.05) among the same beans under different treatments

The microstructure of bean powders

Real shot and SEM images (1000 ×) of the different bean powders are shown in Online Resource 3. The real shot images showed that the color of the bean powder tended to be white and bright after the addition of L. fermentum FL-0616. Fermentation can improve product color (Ma et al. 2021). A similar study found that adding pea powder to a probiotic fermented beverage increased the L value (Zare et al. 2012). CP was looser than MB and TSKB. Compared with A1 treatment, MB particles were partially damaged, CP microparticles partially disappeared, and TSKB particles appeared to be smaller after A2 treatment. This is related to the short-term fermentation of L. fermentum FL-0616. However, the particles of the bean powder after A3 treatment were smaller and more uniform from Online Resource 3(b), confirming the particle size distribution results. The L. fermentum FL-0616 might use the macromolecular components of bean powder for growth and reproduction, resulting in the degradation of macromolecular substances. The similar effect of fermentation was consistent with some reported findings, for example, solid-state fermentation could degrade lupin proteins and fermentation of L. fermentum could significantly reduce the particle size of longan pulp polysaccharide (Huang et al. 2019; Olukomaiya et al. 2020).

The rheological properties of bean powders

Compared with A1 treatment, both the G' and G" values of bean powder decreased after the addition of probiotics (A3 treatment) (Fig. 1). It is generally believed that the smaller the G' value, the weaker is the recovery ability, and the smaller the G" value, the weaker is flow resistance of materials. Compared with A1 treatment, the G' and G" values of the bean powder significantly decreased after A3 treatment, so the ability to recover and resist the flow of fermented bean powder was weakened. This was because fermentation likely led to the destruction of the protein network structure that then loosened, resulting in a decrease in viscoelasticity (Ma et al. 2021). A similar study found that fermentation could partially offset the increase in G' and G'' values during whole wheat dough production (AlioĞLu and Özülkü 2021). The reduced flow resistance of fermented bean powder contributed to improving the flowability of the probiotic-rich bean powder, which was associated with its improved wettability, dispersibility and dissolution rate. At the same time, it was found that the G" values of the three bean powders were much lower than their G' values, and both G' and G" increased with increasing angular frequency, which represented typical weak gel rheological properties. The difficulty in forming a gel of bean powder is related to its improved solubility. The flowability differences between different bean powders after the same treatment were related to the bean type and bean powder particle size.

Fig. 1.

The dynamic rheological properties of bean powders. a, c and e show storage modulus (G') measurements; b, d and f show loss modulus (G") measurements. a and b: mung bean powders; c and d: chickpea powders; e and f: tiger skin kidney bean powders. A1: no probiotics; A2: spray drying directly after adding L. fermentum FL-0616; A3: fermentation with L. fermentum FL-0616

The variation in shear stress and shear rate of the probiotic-rich bean powders is shown in Fig. 2. The shear stress of the bean powders increased with an increase in shear rate, which is characteristic of a pseudoplastic fluid. By fitting the Herschel-Bulkley model, the power law τ = k∙γⁿ + τ₀ can be used to describe the rheological curve. Through univariate nonlinear regression, the k, τ₀ and n values, as well as the correlation coefficient (R²) of the probiotic-rich bean powder were obtained (Table 4). k is the consistency coefficient. When k decreases, the initial viscosity of the solution system also decreases, resulting in a lower flow resistance (Zhang et al. 2018). The k value of bean powder decreased after A3 treatment, indicating that fermentation led to a decrease in initial viscosity and flow resistance. Consequently, the flowability of the bean powder improved, which was consistent with the dynamic rheology results. This also verified the inference that the particle size reduction of the probiotic-rich bean powder could improve the flowability of the bean powder. The R² in Table 4 shows that the power law fits the rheological curve of the bean powder well.

Fig. 2.

The static rheological properties of mung bean powders (a), chickpea powders (b), and tiger skin kidney bean powders (c). A1: no probiotics; A2: spray drying directly after adding L. fermentum FL-0616; A3: fermentation with L. fermentum FL-0616

Table 4.

The rheological parameters of the Herschel-Bulkley model

Treatments1,2,3	τ0 (Pa)	k (Pa·sn)	n	R2
MB(A1)	0	85.546	0.140	0.9877
MB(A2)	61.308	21.315	0.247	0.9985
MB(A3)	1.579	0.085	0.698	0.9917
CP(A1)	3.545	1.934	0.339	0.9978
CP(A2)	1.422	0.772	0.482	0.9984
CP(A3)	0.701	0.024	0.903	0.9989
TSKB(A1)	1.883	0.684	0.494	0.9994
TSKB(A2)	0.994	0.604	0.533	0.9972
TSKB(A3)	0.292	0.153	0.633	0.9991

¹ MB, mung bean powders; CP, chickpea powders; TSKB, tiger skin kidney bean powders

²A1: no probiotics; A2: spray drying directly after adding L. fermentum FL-0616; A3: fermentation with L. fermentum FL-0616

³τ: shear stress (Pa); τ₀: initial shear stress (Pa); k: consistency coefficient (Pa·sⁿ); γ: shear rate; n: flow index

Conclusion

This study investigated the effects of fermentation on the physical, microstructural and rheological properties of bean powders. Fermentation could significantly reduce the particle size of bean powder through self-degradation and enzymatic hydrolysis. Simultaneously, fermentation improved the dissolution rate, wettability, and dispersibility of bean powder, and decreased their angles of repose and slide. This was inevitably related to the reduction in particle size of the bean powder by L. fermentum FL-0616 fermentation. This might improve the flowability of the probiotic-rich bean powder. The SEM results confirmed that fermentation caused smaller and more uniform bean powder particles. Finally, it was confirmed through the dynamic and static rheology of probiotic-rich bean powder that the flow resistance decreased and the flowability improved. The development of probiotic-rich bean powder may promote the sustainable development and utilization of bean resources.

Supplementary Information

Below is the link to the electronic supplementary material.

Abbreviations

MB

Mung bean powders

CP

Chickpea powders

TSKB

Tiger skin kidney bean powders

Author Contributions

LT involved in conceptualization, data curation, formal analysis, investigation, methodology, software, validation, visualization, writing—original draft and writing—review and editing; JYW, QYZ and JWZ involved in data curation, investigation, methodology and validation; YFL involved in formal analysis, investigation, methodology and validation; SXS involved in formal analysis, methodology and supervision; LY involved in formal analysis, funding acquisition, project administration, resources, supervision, writing—original draft and writing—review and editing.

Funding

This work was supported by the Science and Technology Development Plan of Jilin Province (Grant Numbers: 20190301028NY).

Availability of data and material

The original images and raw analytical data are provided in manuscript and supplementary files.

Code availability

Not applicable.

Declarations

Conflicts of interest

The authors confirm that they have no conflicts of interest with respect to the work described in this manuscript.

Ethics approval

Not applicable.

Consent to participate

All authors participated the collaborated project, and contributed to the research works of the project.

Consent for publication

All authors are aware of the manuscript submission to the Journal of Food Science and Technology.