Optimization of solid–liquid extraction of phytochemicals from Garcinia indica Choisy by response surface methodology

A central composite rotatable design was employed to study the effect of ultrasound assisted extraction conditions namely sonication amplitude (10–90%), sonication cycle (0.1–1.0 s^?1), solid–liquid ratio (2–10) and extraction time (5–35 min) on the total anthocyanin extraction from Garcinia indica Choisy. Overall extractions of total anthocyanin, acidity and antioxidant activity were considered as response variables. The significant (p < 0.05) response surface models with high coefficients of determination values (R²) ranging from 0.91 to 0.93 were fitted for the experimental data, which indicated that the polynomial response models fitted well for describing the extraction efficiencies of anthocyanin, acidity and antioxidant activity. Based on the design, the optimal conditions for obtaining higher extraction were extraction time 35 min, cycle ranging from 0.44 to 0.48 s^?1, percentage amplitude ranging from 10 to 14%, and solid–liquid ratio 10. The graphical optimization of superimposed contour plots fulfilled the conditions to obtain total anthocyanin (Y₁) ≥ 135 mg/100 g DW, total titratable acidity (Y₂) ≤ 25 g/100 g DW and antioxidant activity (Y₃) ≥ 14.5 M Trolox/100 g DW. The study demonstrated that response surface methodology can be utilized for deriving the optimum conditions for extraction of anthocyanin from G. indica Choisy.     

Thin-layer drying characteristics and modelling of mint leaves undergoing microwave treatment

The effect of microwave drying technique on moisture content, moisture ratio, drying rate, drying time and effective moisture diffusivity of mint leaves (Mentha spicata L.) were investigated. By increasing the microwave output powers (180–900 W) and the sample amounts (25–100 g), the drying time decreased from 12.50 to 3.0 min and increased from 6.60 to 16 min, respectively. To determine the kinetic parameters, the drying data were fitted to various models based on the ratios of the differences between the initial and final moisture contents and equilibrium moisture content versus drying time. Among of the models proposed, the semi-empirical Midilli et al. model gave a better fit for all drying conditions applied. By increasing the microwave output powers and decreasing the sample amounts, the effective moisture diffusivity values ranged from 3.982 × 10⁻¹¹ to 2.073 × 10⁻¹⁰ m² s⁻¹ and from 9.253 × 10⁻¹¹ to 3.162 × 10⁻¹¹ m² s⁻¹, respectively. The activation energy was calculated using an exponential expression based on Arrhenius equation. The relationship between the drying rate constant and effective moisture diffusivity was also estimated; and gave a linear relationship.     

Two-parameter Lorentzian distribution for monitoring physical parameters of golden colored fruits during drying by application of laser light in the Vis/NIR spectrum

Inadequate drying conditions of tropical fruits can alter the cellular structure and chemistry, which can lead to undesirable characteristics of the final product. The purpose of this research is to test the feasibility of light scattering of three laser sources operating in the Vis/NIR range by calculating a two-parameter Lorentzian distribution (LD) for quality assessment of two golden-colored fruits, namely mango and litchi, during drying. Linear mixed models showed that blue light at 473 nm was the most adequate to monitor changes in browning (R² = 0.81) and moisture content (R² = 0.80) of litchi. For mango, NIR light at 785 nm was affected by the hardness (p < 0.001), whereas moisture content showed a strong influence on the calculated LD functions at both 532 (p < 0.001) and 785 (p < 0.05) nm with a good fitting of the prediction model (R² = 0.91). Laser light can provide an economically-effective solution to obtain information from the fruit tissue non-destructively during industrial drying processes.Industrial relevanceConvective drying is still the most common dehydration technique in industrial applications, while many agricultural products remain susceptible to thermal damage. Quality parameters of these products are not only affected by drying conditions, but are also crop-specific. Meanwhile, the use of laser light backscattering is an innovative and rapid technique to estimate a range of quality parameters during drying of agricultural products. The results of this research provide a basis for robust, in-line quality control during industrial drying processes. In this respect, the application of laser backscattering systems presents many advantages: rapid, real-time product information, eradication of laborious and costly destructive analytical methods, continuous monitoring to avoid over-drying (improved energy efficiency) and quality losses, easy integration into existing drying systems and high resistance to harsh conditions typically found in dryers such as high temperatures and dust.     

Modelling of red abalone (Haliotis rufescens) slices drying process: Effect of osmotic dehydration under high pressure as a pretreatment

Simultaneous application of osmotic dehydration and high pressure as a pretreatment to drying process on red abalone (Haliotis rufescens) slices was studied. During drying process the process time was reduced by increasing temperature from 40 to 60 °C along with the application of different pretreatments: high pressure (350 and 550 MPa), pressure time (5 and 10 min), and osmotic solution (10 and 15% NaCl). Effective moisture diffusivity was determined and varied from 4.35 to 9.95 × 10^− 9 m²/s, for both control and pretreated samples (R² ≥ 0.97). The Weibull, Logarithmic and Midilli–Kucuk models were applied to drying experimental data, where Midilli–Kucuk model was found to be the best fitting model. Furthermore, all drying curves were normalized and then modelled by the same three above models showing a R² ≥ 0.96. As to energy consumption and efficiency values for drying processes were found to be in the range of 777–1815 kJ/kg and 8.22–19.20%, respectively. Thus, knowledge on moisture transfer kinetics, energy consumption and data normalization, is needed to manage and control efficiently drying process under different pretreatment conditions.Industrial relevanceThis article deals with the mass transfer modelling and energy consumption during simultaneous high hydrostatic pressure treatment and osmotic dehydration as a pretreatment to drying process of abalone slices. Water and salt transfer during this combined process was satisfactorily simulated with the Midilli–Kucuk model. Results indicated that application of this combined innovative technology improved abalone slices dehydration rates compared to atmospheric pressure operation resulting in a dried abalone with intermediate moisture content ready to be used as input material of further processes. Furthermore, the different energetic features were determined in order to realize the importance of the changes that can influence to alter process time.     

Moisture diffusivity and shrinkage of broad beans during bulk drying in an inert medium fluidized bed dryer assisted by dielectric heating

Drying behavior of broad beans (Vicia faba) was studied in a pilot scaled fluidized bed dryer with inert particles assisted by dielectric heating. The effective diffusion coefficient of moisture transfer was determined by Fickian method at four different air drying temperatures of 35, 45, 55 and 65 °C. Correlations for moisture diffusivity as a function of moisture content and temperature of the drying medium were developed. The values of moisture diffusivity were obtained within the range of 1.27 × 10^?9–6.48 × 10^?9 m²/s and the activation energies for FBD and FBD + DE were found to be 27.71 and 17.10 kJ/mol, respectively. The shrinkage behavior of the broad beans was also investigated by considering the volume ratio of (V/V_O) to be function of moisture content alone and fitting a polynomial of the third order. The dielectric heating power was also found to be effective on the rate of drying.     

Water vapor transport properties during staling of bread crumb and crust as affected by heating rate

In order to develop a mathematical model to simulate mass transfer occurring between the crumb and the crust during bread staling, water vapor sorption properties, i.e., moisture diffusivity, WVP and sorption of bread crumb and crust were investigated at 15 °C. Two types of bread baked with two heating rates (7.39 °C/min and 6.32 °C/min) were considered. Sorption and desorption isotherms were determined using Dynamic Vapor Sorption (DVS) and FF and GAB models were applied in the range of 0–0.95 a_w, to fit isotherm curves. Diffusivity was determined from sorption isotherms by using Fick's law and WVP was measured by two methods (gravimetric and from sorption data). Results exhibited maximum values of D_eff in the range of 0.1 and 0.14 g/g d.b. moisture contents. They varied between 0.88 × 10^? 10 and 0.92 × 10^? 10 m²/s for the crust and between 2.24 × 10^? 10 and 2.64 × 10^? 10 m²/s for the crumb, baked respectively at 220 °C and 240 °C. Results of WVP showed that the crust baked at 240 °C was significantly more permeable than the crust baked at 220 °C. This fact was attributed to the difference in porosity and the molecular structure due to heating effects. Also, the presence of steam in the oven atmosphere enhanced the development of higher porosity in the crust, leading to different structures and properties. Moreover, SEM images showed that starch granules were intact and less swelled in the upper crust when baking at 240 °C, resulting in higher WVP.     

The protective effect of monosodium glutamate on survival of Lactobacillus rhamnosus GG and Lactobacillus rhamnosus E-97800 (E800) strains during spray-drying and storage in trehalose-containing powders

The use of trehalose as a means of preserving Lactobacillus rhamnosus GG (LGG) and L. rhamnosus E-97800 (E800) during spray-drying and the effects of incorporated monosodium glutamate (MSG) in the carrier medium on the survival rates during drying and storage were examined. E800 was more resistant to heat than LGG in 20%, w/w, trehalose; the d-values at 65 °C were 14 s and 5.1 s, respectively. An air outlet temperature of 65–70 °C was taken as optimal for the drying process, as the resultant moisture levels in trehalose containing these bacteria were 4.1% (w/w) and 3.79% (w/w) with corresponding viable counts of 3.65 × 10⁸ cfu mL^?1 and 1.80 × 10⁹ cfu mL^?1, respectively. The presence of MSG increased the final viable counts of LGG and E800 to 3.05 × 10⁹ cfu mL^?1 and 1.30 × 10⁹ cfu mL^?1, respectively. Survival of LGG and E800 remained constant at a minimum level of ～10⁸ cfu mL^?1 during storage at 25 °C in trehalose–MSG medium.     

Modelling kinetics of watercress (Nasturtium officinale) colour changes due to heat and thermosonication treatments

Watercress (Nasturtium officinale) colour changes due to blanching by heat and a combined treatment of heat/ultrasound (thermosonication) were studied in the temperature range of 82.5 to 92.5 °C. The application of thermosonication was intended to enable less severe blanching treatments and, therefore, improve the quality of the blanched product. The thermosonication blanching processes promoted changes of the green colour (aⁿ parameter) at a higher rate (P < 0.05), when compared with the heat blanching processes. No significant differences (P > 0.05) were detected between heat and thermosonication blanching processes in terms of the colour parameters Lⁿ, bⁿ and TCD changes. In both treatments, a fractional first order model fitted well the experimental data for Lⁿ, aⁿ and bⁿ (R_H² = 0.99; R_Ts² = 0.99) and TCD (R_H² = 0.92; R_Ts² = 0.96) colour parameters.The chlorophylls content showed no significant differences (P > 0.05) between thermally treated and thermosonicated watercress samples.The present findings will help to evaluate the effectiveness of thermosonication as a novel process to replace the classical heat treatment.Industrial relevanceConventional blanching commonly results in severe losses or destruction of nutrients due to process intensity and extended process times. Consequently, the attempts to use the synergistic effects of heat and ultrasound (at least) for enzyme inactivation are of high relevance. The results, although not conclusive, indicate, that they may aid optimization of blanching processes.     

High-pressure calorimetric evaluation of ice crystal ratio formed by rapid depressurization during pressure-shift freezing of water and pork muscle

The amount of ice nuclei formed during the pressure release is important for the final formation and development of ice crystals in pressure shift freezing (PSF) frozen products. In this study, a high-pressure (HP) calorimeter was used to evaluate the ratio of ice crystals instantaneously formed by rapid depressurization during PSF of pure water and pork muscle tissue. Experiments were carried out initial pressure levels of 62, 115, 157 and 199 MPa, with corresponding phase change temperatures of −5, −10, −15 and −20 °C, respectively (slightly higher than phase change point of water–ice I). The ice crystal ratio was determined based on calorimetric peak measured and heat balance. The evaluated regression relationship between observed ice crystal ratio (R_ice in %) and pressure (P, MPa) was R_ice–water = 0.115P + 0.00013P² (R² = 0.96, n = 9) for pure water, and R_ice–pork = 0.080P + 0.00012P² (R² = 0.95, n = 11) for pork muscle. Compared to other methods, the calorimetric evaluation does not require any of the pressure-related properties of the test sample. HP calorimetry can thus be used to evaluate ice crystal ratio for PSF of foods even though their pressure related properties may be unknown.     

Change regime of aroma active compounds in response to pulsed electric field treatment time,sour cherry juice apricot and peach nectars,and physical and sensory properties

Regime (direction, amount, rate, and pattern) of change in aroma active compounds was quantified as a function of four pulsed electric field (PEF) treatment times, three fruits, and 10 physical and eight sensory properties using the best-fit multiple linear regression (MLR) models. The PEF treatment times did not deteriorate 94% of the sensory properties and 70% of the physical properties and significantly change 57% of a total of 73 aroma active compounds detected for sour cherry juice, and apricot and peach nectars. The best performing MLR models belonged to 1-methyl-4-prop-1-en-2-ylcyclohexene as a function of fruit type, treatment time, and titratable acidity (= 49 mg/L; R_adj² = 95.7%; R_cv² = 94.9%) and to 2-[(2S,5S)-5-ethenyl-5-methyloxolan-2-yl]propan-2-ol as a function of fruit type, and treatment time (SE = 157 mg/L; R_adj² = 98.2%; R_cv² = 98.0%), respectively (n = 48; p < 0.001).Industrial relevancePulsed electric field (PEF) is one of the leading nonthermal food technologies especiallyfor processing of high acid low viscosity foods with satisfactory quality and microbial inactivation. It was shown in this study that PEF with different treatment times can successfully be applied in the pasteurization of sour cherry juice, and apricot and peach nectars with minimum loss of aroma active compounds and sensory and physical properties. Both PEF processing conditions and results can be used as a guide to determine PEF processing parameters for industrial scale processing of juices/nectars.     

Prediction of moisture content uniformity of microwave-vacuum dried mangoes as affected by different shapes using NIR hyperspectral imaging

The prediction of moisture content uniformity on mango slices as affected by four different shapes (square, rectangle, regular triangle, and round shape) during microwave-vacuum drying (MVD) was investigated using near-infrared hyperspectral imaging in combination with multivariate chemometric analysis. Applying spectral pretreatment of a 2nd derivative followed by mean-center to raw spectra was found to be greatly beneficial for the reduction of noise and scattering levels. Seven wavelengths (951, 977, 1138, 1362, 1386, 1420, and 1440 nm) with larger absolute values of regression coefficients derived from a partial least square regression model were identified as feature variables for moisture prediction. An optimized model based on the selected wavelengths was developed using multivariate linear regression, achieving a high prediction accuracy with R_p² = 0.993 and RMSEP = 1.282%. From the moisture distribution map, a similar non-uniform drying pattern was found on square, rectangle and regular triangle-shaped samples, while round-shaped mango slices achieved better drying results.Industrial relevanceThe current study suggested that NIR hyperspectral imaging was a promising technique in predicting the moisture content of mango slices during MVD, and non-uniformity of moisture distribution and the effect of sample geometry should be taken into account when the microwave-vacuum method is implemented in drying.     

Monitoring nisin desorption from a multi-layer polyethylene-based film coated with nisin loaded HPMC film and diffusion in agarose gel by an immunoassay (ELISA) method and a numerical modeling

Polyethylene-based films coated with nisin loaded HPMC films were put in contact with food simulants, i.e. agarose gels with 5 or 30% (w/w) fat. Nisin desorption from the multi-layer films and diffusion in agarose gels were monitored by ELISA (Enzyme Linked ImmunoSorbent Assay). The data obtained after 2 or 6 days of contact between antimicrobial films and agarose gels were employed to determine nisin mass transfer by numerical modeling following Fick's second law. The values were in the range from 0.87 × 10^? 3 m s^? 1 to 4.30 × 10^? 3 m s^? 1 and 6.5 × 10^? 11 m² s^? 1 to 3.3 × 10^? 10 m² s^? 1, for nisin apparent desorption and diffusion coefficients, respectively. The diffusion process was governed by interactions between food matrix simulant and nisin. Moreover, it was observed that the polymer in the coating did not modify plastic film initial mechanical resistance and water vapor permeability.Industrial relevanceThis paper concerns active packaging, considered as a new approach to preserve food shelf life. Active packaging is a real gain for plastic and Food industrials. The paper deals with coating as a manner to activate packaging. The impact of coating on film properties is investigated.Also, predictive models are proposed to determine antimicrobial agent desorption and diffusion during some storage conditions.     

A risk characterization model of Salmonella Typhimurium in Irish fresh pork sausages

A second-order simulation model was built to estimate the risk of Salmonella Typhimurium associated with the consumption of Irish fresh pork sausages. To select appropriate hazard characterization models, an initial appraisal of the current dose-response models was conducted. The cooking modality of grilling was associated with a higher mean risk of infection per serving (1.399 × 10^? 6; 95% CI: 7.54 × 10^? 7–2.65 × 10^? 6) than frying (6.246 × 10^? 7, 95% CI: 2.78 × 10^? 7–1.17 × 10^? 6). When the risk was extrapolated over the consumption in a year period, the mean risk of infection increased considerably to 8.541 × 10^? 5 with an expected number of infections and illnesses of 184.3 (95% CI: 26–664) and 17 (95% CI: 2–63), respectively. Results highlighted the importance of consumer education, as scenario analysis predicted that, for the current level of Salmonella in pork sausage, decreasing the product's cold storage by approximately 8 h and cooking for an additional half minute can reduce the current risk level by ～ 50%.     

Preliminary investigations on the effects of ageing and cooking on the Raman spectra of porcine longissimus dorsi

The influence of ageing and cooking on the Raman spectrum of porcine longissimus dorsi was investigated. The rich information contained in the Raman spectrum was highlighted, with numerous changes attributed to changes in the environment and conformations of the myofibrillar proteins.Predictions equations for shear force and cooking loss were developed from the Raman spectra of both raw and cooked pork. Good correlations and standard errors of prediction were obtained for both WB shear force and cooking loss, with the raw and the cooked samples showing almost identical results R² = 0.77, root mean standard error of prediction (RMSEP)% of mean = 12% for shear force; R² = 0.71, RMSEP% of mean = 10% for cooking loss. The Raman spectra were also able to predict the extent of cooking that occurred within the pork (R²_val = 0.94, RMSEP% of range = 5.5%).Raman spectroscopy has considerable potential as a method for non-destructive and rapid determination of pork quality parameters such as tenderness. Raman spectroscopy may provide a means of determining changes during cooking and the extent to which foods have been cooked.     

Migration of α-tocopherol from LDPE films to corn oil and its effect on the oxidative stability

The migration of α-tocopherol (α-T) from low density polyethylene (LDPE) films, added with 20 (film A) and 40 mg g^?1 (film B) to corn oil for 12 weeks at 5, 20 and 30 °C was determined. A LDPE film added with no α-T was used as control (film C). Diffusion coefficient (D) values for the film A system were 1.4 × 10^?11, 7.1 × 10^?11 and 30.3 × 10^?11 cm² s^?1 at 5, 20 and 30 °C, respectively. Meanwhile, D values for the film B system were 1.3 × 10^?11, 9.6 × 10^?11 and 51.1 × 10^?11 cm² s^?1 at the same temperatures. The activation energy (E_a) for the diffusion of α-T was 126.5 (film A) and 105.9 kJ mol^?1 (film B). The effect of the migration of α-T on the oxidative stability of corn oil was evaluated by monitoring hexanal content by solid phase micro-extraction (SPME) and gas chromatography. The hexanal content in the oil showed that both films added with α-T resulted suitable to maintain the oxidative stability of the oil for about 16 weeks at 30 °C, compared to 12 weeks for the oil in contact with the film C.     

Optimization of the associative growth of novel yoghurt cultures in the production of biomass, β-galactosidase and lactic acid using response surface methodology

The associative growth of Streptococcus thermophilus 95/2 (St 95/2) and Lactobacillus delbrueckii ssp. bulgaricus 77 (Lb 77) isolated from the Toros mountain region of Turkey was investigated with respect to lactic acid, biomass and β-galactosidase enzyme production using response surface methodology (RSM). The ratio (St 95/2:Lb 77) of the strains and media formulation had significant effect on all responses (p < 0.001). The predicted enzyme activity (2.14 U mL^?1), lactic acid (22.50 g L^?1) and biomass (7.11 g L^?1) production at optimum conditions were very close to the actual experimental values (2.14 U mL^?1, 22.94 g L^?1 and 7.86 g L^?1, respectively). The optimum conditions were to use these cultures in a ratio of 1.66:1.62 (St 95/2:Lb 77) in a medium containing whey (5%), corn steep liquor (4%), potassium phosphate (2%) and peptone (2%) at 43 °C for 8 h. The associative growth provided 6.4% and 39% more β-galactosidase activity and 8.73% and 44% more lactic acid compared with the results obtained using pure St 95/2 and Lb 77 strains, respectively.     

Controlling moisture transport in a cereal porous product by modification of structural or formulation parameters

Equilibrium and dynamic water sorption properties of sponge cakes with varying porosity (86–52%) and fat content (0–0.30 g/g d.b.) were determined using a water vapour sorption microbalance. Contrary to porosity, addition of fat decreased equilibrium moisture contents. The effective moisture diffusivity (D_eff) was identified from a numerical solution of Fick’s second law, taking into account an external mass transfer coefficient and the swelling of the solid matrix. D_eff increased from 1.61 to 8.67 × 10⁻¹⁰ m²/s with moisture content, reached a threshold at moisture content 0.15 g/g d.b. and then decreased until water saturation. D_eff decreased from 8.67 to 2.97 × 10⁻¹⁰ m²/s with decreasing porosity. This effect was attributed to a change of water diffusion mechanism, from predominant vapour to liquid. D_eff decreased from 8.67 to 2.12 × 10⁻¹⁰ m²/s with increasing fat content. Addition of fat had an effect on the water diffusion in two ways, decreasing porosity (sagging of the foam) and increasing tortuosity.     

Prediction of linolenic and linoleic fatty acids content in flax seeds and flax seeds flours through the use of infrared reflectance spectroscopy and multivariate calibration

Infrared spectroscopy was used for multivariate determination of linoleic (LA) and linolenic (ALA) acids in yellow and brown flax seed samples, using partial least square regression (PLSR). The models were developed by correlating near-(NIR) and mid-infrared (MIR) spectroscopic signals with the acid content determined by GC-FID. For the flax seed samples, the best models for both, LA (R² = 0.90, Standard Error of Prediction (SEP) = 1.61) and ALA (R² = 0.86, SEP = 0.63) were obtained by processing the NIR spectral data. For samples of flax seed flours, the best models for prediction of the ALA (R² = 0.99, SEP = 1.21) and LA content (R² = 0.88, SEP = 0.76) were developed by processing the NIR and MIR spectral region, respectively. This report demonstrates that NIR and MIR spectroscopies are efficient techniques for the determination and quantification of LA and ALA in flax seed and flax seed flours.     

The influence of multi stage alginate coating on survivability of potential probiotic bacteria in simulated gastric and intestinal juice

The probiotics, Lactobacillus acidophilus PTCC1643 and Lactobacillus rhamnosus PTCC1637, were encapsulated into uncoated calcium alginate beads and the same beads were coated with one or two layers of sodium alginate with the objective of enhancing survival during exposure to the adverse conditions of the gastro-intestinal tract. The survivability of the strains, was expressed as the destructive value (decimal reduction time). Particle size distribution was measured using laser diffraction technique. The thickness of the alginate beads increased with the addition of coating layers. No differences were detectable in the bead appearance by scanning electron microscopy (SEM). The alginate coat prevented acid-induced reduction of the strains in simulated gastric juice (pH 1.5, 2 h), resulting in significantly (P < 0.05) higher numbers of survivors. After incubation in simulated gastric (60 min) and intestinal juices (pH 7.25, 2 h), number of surviving cells were 6.5 log cfu mL^?1 for L. acidophilus and 7.6 log cfu mL^?1 for L. rhamnosus by double layer coated alginate microspheres, respectively, while 2.3 and 2.0 log cfu mL^?1 were obtained for free cells, respectively.     

Dual-enzymatic synthesis of lactulose in organic-aqueous two-phase media

Lactulose has been successfully synthesized by dual-enzymatic method in organic-aqueous two-phase media using lactose and fructose as the raw materials. Cyclohexane–buffer system C₆H₁₂:buffer = 95:5 (v/v) was employed as the organic-aqueous media for the reaction. The dual-enzymatic system was consisted of immobilized lactase (IL) and immobilized glucose isomerase (IGI). Immobilized lactase was prepared by cross-linking the free lactase into Fe₃O₄-chitosan magnetic microspheres. The main enzymatic reaction parameters were investigated, including reaction temperature (T), pH value and reaction time (t). Under the optimum reaction conditions, i.e., lactose 0.8 g mL^?1, fructose 0.1 g mL^?1, IL 0.1 g mL^?1, IGI 0.05 g mL^?1, T = 30 °C, pH = 8.0 and t = 2 h, the obtained highest lactulose yield was approximately 151 g L^?1 and the corresponding productivity was 75.5 g L^?1 h^?1. Experimental results indicated that the organic-aqueous media can significantly promoted the transglycosidation activity of lactase and therefore improve the lactulose yield. The possible reaction mechanism of the synthesis of lactulose using IL and IGI in two-phase system was also proposed.