Combined effect of operational variables and enzyme activity on aqueous enzymatic extraction of oil and protein from soybean

Production of a water-soluble fertilizer containing amino acids by solid-state fermentation of soybean meal and evaluation of its efficacy on the rapeseed growth

Soybean meal is a by-product of soybean oil extraction and contains approximately 44% protein. We performed solid-state fermentation by using Bacillus subtilis strain N-2 to produce a water-soluble fertilizer containing amino acids. Strain N-2 produced a high yield of protease, which transformed the proteins in soybean meal into peptide and free amino acids that were dissolved in the fermentation products. Based on the Plackett-Burman design, the initial pH of the fermentation substrate, number of days of fermentation, and the ratio of liquid to soybean meal exhibited significant effects on the recovery of proteins in the resulting water-soluble solution. According to the predicted results of the central composite design, the highest recovery of soluble proteins (99.072%) was achieved at the optimum conditions. Under these conditions, the resulting solution contained 50.42% small peptides and 7.9% poly-γ-glutamic acid (γ-PGA). The water-soluble fertilizer robustly increased the activity of the rapeseed root system, chlorophyll content, leaf area, shoot dry weight, root length, and root weight at a concentration of 0.25% (w/v). This methodology offers a value-added use of soybean meal.

Effect of β-cyclodextrin complexation on solubility and enzymatic hydrolysis rate of icariin

Objective:

The aim of this work was to investigate the effect of β-cyclodextrin complexation on the solubility and hydrolysis rate of icariin.

Material and Methods:

The inclusion complex of icariin at the molar ratio of 1:1 was obtained by the dropping method and was characterized by differential scanning calorimetry. The solubility of icariin complex in water at 37°C was 36 times greater than that of free icariin. Enzymatic hydrolysis conditions were tested for the bioconversion of icariin by mono-factor experimental design.

Methods:

The inclusion complex of icariin at the molar ratio of 1:1 was obtained by the dropping method and was characterized by differential scanning calorimetry. The solubility of icariin complex in water at 37°C was 36 times greater than that of free icariin. Enzymatic hydrolysis conditions were tested for the bioconversion of icariin by mono-factor experimental design.

Results:

The enzymatic hydrolysis experiment showed that icariin can be transformed into baohuoside I. The optimum conditions determined were as follows: pH 5.0, 50°C, the ratio of cellulase/substrate (0.6), the concentration of icariin 20 mg/ml, and reaction time 12 h. Under these enzymatic conditions, 98.2% transforming rate of baohuoside I from icariin in inclusion complexes was obtained.

Conclusion

The aqueous solubility and enzymatic hydrolysis rate of icariin were improved owing to the inclusion complexation.

Simultaneous extraction of oil and antioxidant compounds from oil palm fruit (Elaeis guineensis) by an aqueous enzymatic process

Oil palm (Elaeis guineensis) fruit was treated with enzymes to facilitate simultaneous recovery of oil and bioactive compounds. Tannase from Paecilomyces variotii, cellulase and pectinase were evaluated for their influence on oil recovery and antioxidant capacity (DPPH), oxidative stability (Rancimat), fatty acid profile, total phenols, total carotenoids and tocols of the oil. Maximum oil recovery (90-93% total oil) was obtained with central composite design using 4% of enzyme preparation (w/w) as 80 U of tannase, 240 U of cellulase and 178 U of pectinase, pH 4, ratio of solution to pulp of 2:1 and 30 min of incubation at 50 °C. Tannase improved the phenolic compounds extraction by 51% and pectinase plus cellulase improved carotene extraction by 153%. Samples treated with tannase showed a 27% and 53% higher antioxidant capacity for the lipophilic and hydrophilic fractions.

Effect of β-cyclodextrin complexation on solubility and enzymatic conversion of naringin

In the present paper, the effect of beta-cyclodextrin (beta-CD) inclusion complexation on the solubility and enzymatic hydrolysis of naringin was investigated. The inclusion complex of naringin/beta-CD at the molar ratio of 1:1 was obtained by the dropping method and was characterized by differential scanning calorimetry. The solubility of naringin complexes in water at 37 ± 0.1 °C was 15 times greater than that of free naringin. Snailase-involved hydrolysis conditions were tested for the bioconversion of naringin into naringenin using the univariate experimental design. Naringin can be transformed into naringenin by snailase-involved hydrolysis. The optimum conditions for enzymatic hydrolysis were determined as follows: pH 5.0, temperature 37 °C, ratio of snailase/substrate 0.8, substrate concentration 20 mg·mL(-1), and reaction time 12 h. Under the optimum conditions, the transforming rate of naringenin from naringin for inclusion complexes and free naringin was 98.7% and 56.2% respectively, suggesting that beta-CD complexation can improve the aqueous solubility and consequently the enzymatic hydrolysis rate of naringin.

Combined effect of ohmic heating and enzyme assisted aqueous extraction process on soy oil recovery

This research describes a new technological process for soybean oil extraction. The process deals with the combined effect of ohmic heating and enzyme assisted aqueous oil extraction process (EAEP) on enhancement of oil recovery from soybean seed. The experimental process consisted of following basic steps, namely, dehulling, wet grinding, enzymatic treatment, ohmic heating, aqueous extraction and centrifugation. The effect of ohmic heating parameters namely electric field strength (EFS), end point temperature (EPT) and holding time (HT) on aqueous oil extraction process were investigated. Three levels of electric field strength (i.e. OH600V, OH750V and OH900V), 3 levels of end point temperature (i.e. 70, 80 and 90 °C) and 3 levels of holding time (i.e. 0, 5 and 10 min.) were taken as independent variables using full factorial design. Percentage oil recovery from soybean by EAEP alone and EAEP coupled with ohmic heating were 53.12 % and 56.86 % to 73 % respectively. The maximum oil recovery (73 %) was obtained when the sample was heated and maintained at 90 °C using electric field strength of OH600V for a holding time of 10 min. The free fatty acid (FFA) of the extracted oil (i.e. in range of 0.97 to 1.29 %) was within the acceptable limit of 3 % (oleic acid) and 0.5-3 % prescribed respectively by PFA and BIS.

Lunasin and Bowman-Birk protease inhibitor concentrations of protein extracts from enzyme-assisted aqueous extraction of soybeans

Lunasin and Bowman-Birk protease inhibitor (BBI) are two soybean peptides to which health-promoting properties have been attributed. Concentrations of these peptides were determined in skim fractions produced by enzyme-assisted aqueous extraction processing (EAEP) of extruded full-fat soybean flakes (an alternative to extracting oil from soybeans with hexane) and compared with similar extracts from hexane-defatted soybean meal. Oil and protein were extracted by using countercurrent two-stage EAEP of soybeans at 1:6 solids-to-liquid ratio, 50 °C, pH 9.0, and 120 rpm for 1 h. Protein-rich skim fractions were produced from extruded full-fat soybean flakes using different enzyme strategies in EAEP: 0.5% protease (wt/g extruded flakes) used in both extraction stages; 0.5% protease used only in the second extraction stage; no enzyme used in either extraction stage. Countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes was used as a control. Protein extraction yields increased from 66% to 89-96% when using countercurrent two-stage EAEP with extruded full-fat flakes compared to 85% when using countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes. Extruding full-fat soybean flakes reduced BBI activity. Enzymatic hydrolysis reduced BBI contents of EAEP skims. Lunasin, however, was more resistant to both enzymatic hydrolysis and heat denaturation. Although using enzymes in both EAEP extraction stages yielded the highest protein and oil extractions, reducing enzyme use to only the second stage preserved much of the BBI and Lunasin.

Enzymatic hydrolysis and extraction of arachidonic acid rich lipids from Mortierella alpina

A novel method for efficient arachidonic acid rich lipids extraction was investigated. Six different enzymes (papain, pectinase, snailase, neutrase, alcalase and cellulase) were used to extract lipids from Mortierella alpina. The effects of enzyme concentration, temperature and hydrolysis time on oil recovery were evaluated using factorial experimental design and polynomial regression for each enzyme. Hydrolysis time is found to be the most important parameter for all enzymes. The ratios of enzyme mixtures were also studied. It showed that the mixtures of pectinase and papain (5:3, v/v), pectinase and alcalase (5:1, v/v) were better combined effects on oil yields. The effects of hydrolysis time and temperature were then analyzed by response surface methodology, and oil recoveries were satisfactory (104.6% for pectinase and papain and 101.3% for pectinase and alcalase). In the whole process, the lipid composition was not affected by the enzyme treatments according to fatty acid profile.

Characterization of fibrous residues from agrowastes and the production of nanofibers

Oil palm trunk (OPT), oil palm frond (OPF), and okara are agrowastes generated abundantly by the palm oil and soy industries. There are vast potentials for these fibrous biomass rather than disposal at landfills or incineration. Fibrous materials (FM) and alkali-treated fibrous residues (FR) were produced from the selected wastes and subsequently characterized. Functional properties such as emulsifying properties, mineral-binding capacity, and free radical scavenging activity were also evaluated for possible development of functional products. Supernatants (FS) generated from the alkaline treatment contained soluble fractions of fibers and were also characterized and used for the production of nanofibers. Okara FM had the highest (P < 0.05) protein (31.5%) and fat (12.2%) contents, which were significantly reduced following alkali treatment. The treatment also increased total dietary fiber (TDF) in okara by 107.9%, in OPT by 67.2%, and in OPF by 25.1%. The increased fiber fractions in FR enhanced functional properties such as water-holding capacities and oil-holding capacities. Okara displayed the highest (P < 0.05) emulsifying properties compared to OPT and OPF. High IDF content of OPT and OPF contributed to high antioxidant activities (377.2 and 367.8% higher than that of okara, respectively; P < 0.05). The soluble fraction from alkali treatment of fibers was successfully electrospun into nanofibers, which can be further developed into nanoencapsulants for bioactive compound or drug delivery.

Mechanisms of aqueous extraction of soybean oil

Aqueous extraction processing (AEP) of soy is a promising green alternative to hexane extraction processing. To improve AEP oil yields, experiments were conducted to probe the mechanisms of oil release. Microscopy of extruded soy before and after extraction with and without protease indicated that unextracted oil is sequestered in an insoluble matrix of denatured protein and is released by proteolytic digestion of this matrix. In flour from flake, unextracted oil is contained as intact oil bodies in undisrupted cells, or as coalesced oil droplets too large to pass out of the disrupted cellular matrix. Our results suggest that emulsification is an important extraction mechanism that reduces the size of these droplets and increases yield. Protease and SDS were both successful in increasing extraction yields. We propose that this is because they disrupt a viscoelastic protein film at the droplet interface, facilitating droplet disruption. An extraction model based on oil droplet coalescence and the formation of a viscoelastic film was able to fit kinetic extraction data well.