Search

In the current research, osmotic dehydration of red pitaya (Hylocereus polyrhizusis) cubes using sucrose solution at mild temperature (35ºC) was investigated. Sucrose solution (40, 50 and 60% w/w) was employed for osmotic dehydration process. Responses of weight reduction (WR), solid gain (SG), water loss (WL), color (L* , a* and b* ) and texture (hardness) were evaluated. It was found that sucrose concentration significantly (p < 0.05) affected the mass transfer terms during osmosis process. The results obtained revealed an increase in yellowness (b* ), decrease in lightness (L* ) and redness (a* ) as the sucrose concentration increased. Furthermore, osmotically dehydrated samples were considerably softer than untreated samples. Increasing of sucrose concentration and dehydration time caused softer tissue of dehydrated product compared with the fresh red pitaya.

In this study, osmotic dehydration of seedless guava was studied through response surface methodology. Seedless guava cubes were dehydrated in sucrose solution at different concentration (30–50% w/w), temperature (30–50°C) and immersion time (15–240 min) with respect to weight reduction, solid gain and water loss. A Box–Behnken design was used to determine the optimum processing conditions that yield maximum weight reduction, water loss and minimum solid gain. The models developed for all responses were significant (p<0.05). The response surface plots were constructed to show the interaction of process variables. Optimum process conditions were found to be sucrose concentration of 33.79% w/w, temperature of 30.00°C and immersion time of 240 min through desirability function method. At these optimum points, weight reduction, solid gain and water loss were found to be 0.189 (gg−1), 0.050 (gg−1) and 0.237 (gg−1), respectively.

In the present study, supercritical carbon dioxide (SC-CO2) extraction of seed oil from winter melon (Benincasa hispida) was investigated. The effects of process variables namely pressure (150–300 bar), temperature (40–50 °C) and dynamic extraction time (60–120 min) on crude extraction yield (CEY) were studied through response surface methodology (RSM). The SC-CO2 extraction process was modified using ethanol (99.9%) as co-solvent. Perturbation plot revealed the significant effect of all process variables on the CEY. A central composite design (CCD) was used to optimize the process conditions to achieve maximum CEY. The optimum conditions were 244 bar pressure, 46 °C temperature and 97 min dynamic extraction time. Under these optimal conditions, the CEY was predicted to be 176.30 mg-extract/g-dried sample. The validation experiment results agreed with the predicted value. The antioxidant activity and fatty acid composition of crude oil obtained under optimized conditions were determined and compared with published results using Soxhlet extraction (SE) and ultrasound assisted extraction (UAE). It was found that the antioxidant activity of the extract obtained by SC-CO2 extraction was strongly higher than those obtained by SE and UAE. Identification of fatty acid composition using gas chromatography (GC) showed that all the extracts were rich in unsaturated fatty acids with the most being linoleic acid. In contrast, the amount of saturated fatty acids extracted by SE was higher than that extracted under optimized SC-CO2 extraction conditions.

Ultrasound-assisted extraction (UAE) was applied for the extraction of bioactive valuable compounds from winter melon (Benincasa hispida) seeds. Effects of amplitude (25-75%), temperature (40-60°C) and sonication time (20-60 min) on crude extraction yield (CEY) and radical scavenging activities (RSA, % inhibition of DPPH˙ and ABTS˙+ free radicals) of extracts were determined using complete randomised design (CRD). The results showed that the CEY and RSA of extracts significantly affected by independent variables. The maximum value of CEY (97.14±0.36 mgg-1), scavenging of DPPH˙ radicals (32.12 ± 0.38%) and scavenging of ABTS˙+ radicals (40.52±0.73%) were obtained at the combined treatment conditions of 75%, 55°C and 40 min. The UAE results obtained were compared with those achieved by using conventional Soxhlet extraction (CSE) method. It was found UAE allowed extraction at lower temperature and the extracts obtained posses higher quality compare with CSE. UAE is a promising environment friendly technique for the extraction of bioactive compounds from winter melon (Benincasa hispida) seeds.

In the present study, ultrasound-assisted extraction of crude oil from winter melon seeds was investigated through response surface methodology (RSM). Process variables were power level (25–75%), temperature (45–55 °C) and sonication time (20–40 min). It was found that all process variables have significant (p < 0.05) effects on the response variable. A central composite design (CCD) was used to determine the optimum process conditions. Optimal conditions were identified as 65% power level, 52 °C temperature and 36 min sonication time for maximum crude yield (108.62 mg-extract/g-dried matter). The antioxidant activity, total phenolic content and fatty acid composition of extract obtained under optimized conditions were determined and compared with those of oil obtained by the Soxhlet method. It was found that crude extract yield (CEY) of ultrasound-assisted extraction was lower than that of the Soxhlet method, whereas antioxidant activity and total phenolic content of the extract obtained by ultrasound-assisted extraction were clearly higher than those of the Soxhlet extract. Furthermore, both extracts were rich in unsaturated fatty acids. The major fatty acids of the both extracts were linoleic acid and oleic acid.

In this study, the effect of different solvent including ethanol, n-hexane and ethyl acetate on antioxidant activity and total phenolic content (TPC) of winter melon (Benincasa hispida) seeds extract was investigated using conventional Soxhlet extraction (CSE). DPPH and ABTS scavenging activity and TPC results indicated that the seed extracts obtained using ethanol possessed the highest antioxidant activity and followed by ethyl acetate and n-hexane. By considering obtained results, it was clear that there was a high positive correlation between TPC and antioxidant activity. Linoleic acid forms a significant percentage of unsaturated fatty acids of the seed extract (60.6%). It is well known that essential fatty acids including linoleic acid and linolenic acid which are detected in extracts play important roles in preventing many disease and abnormal differentiation problems. B. hispida seeds are potential source of natural antioxidant compounds to replace synthetic antioxidants.

Osmotic dehydration is a viable process for the partial removal of water in which cellular materials are placed in a concentrated solution of soluble solute. The initial results showed that the values of mass transfer terms (0.2 (g/g) water loss and 0.03 (g/g) solid gain) at the studied range of process variables including temperature of 33 ºC, sucrose concentration of 30% w/w and 180 min of immersion time were not in accordance with an efficient osmotic dehydration process which 40–60% water loss and <10% solid gain are mostly aimed. Thus, feasibility of ultrasonic wave in order to improve the rate of mass transfer was investigated. Ultrasonic treatment was carried out with 20 kHz frequency in the amplitude range of 25-75% for different lengths of sonication time (10-30 min). The highest amounts of water loss (0.42 (g/g)) and solid gain (0.073 (g/g)) were obtained by application of ultrasonic treatment. These increases can be attributed to increased cell wall permeability, facilitating transport of water and solute, as evidenced by the excess conductivity of ultrasonically treated samples as compared with a control condition. The results revealed that ultrasonic technology can be carried out to improve rate of mass transfer during osmotic dehydration.

Conventional Soxhlet extraction (CSE) and Ultrasound-assisted extraction (UAE) methods were applied for the extraction of total phenolic compounds (TPC) from winter melon (Benincasa hispida) seeds. Effects of different UAE variables such as amplitude (25-75%), temperature (45-65 °C) and sonication time (20-60 min) on the TPC of extracts was determined using complete randomised design (CRD). The results showed that the TPC of extracts obtained UAE process significantly affected by independent variables. The maximum value of TPC (22.12 ± 1.23 mg GAE/g extract) was obtained at the combined treatment conditions of 75%, 55 °C and 40 min. The UAE results obtained were compared with those achieved by using conventional Soxhlet extraction (CSE) method. It was found UAE allowed extraction at lower temperature and the extracts obtained posses higher quality compare with CSE. UAE is a promising environment friendly technique for the extraction of bioactive compounds from winter melon (Benincasa hispida) seeds.

This study evaluated the effect of some process parameters and selected enhancement techniques on the kinetics of mass transfer as well as selected quality attributes for osmotic dehydration of seedless guava. Experimental results revealed that higher values of solution concentration and temperature resulted in higher flows of water (39%) and solids (8%) through the seedless guava. In all cases, Peleg equation adequately (R2>0.92) described the kinetics of mass transfer during osmotic dehydration. Total color difference increased up to 21% while hardness decreased around 32% with increase process variables. A zero order kinetic model was fitted to the experimental data adequately for quality parameters (R2>0.88). The osmotic dehydration process was optimized for maximum water loss, weight reduction and minimum solute gain through response surface methodology. Results suggested optimum processing conditions of 30% w/w sucrose concentration at 33 ºC after 179 min would result in 0.15 gg-1 weight reduction, 0.2 gg-1 water loss and 0.03 gg-1 solid gain. Results showed that at the studied range of process parameters, the values of mass transfer terms were not in accordance with an efficient osmotic dehydration process in which 40–60% water loss and <10% solid gain are expected (Eren and Kaymak-Ertekin, 2007). In order to improve the rate of mass transfer a number of enhancement methods such as hot water blanching, thermosonication, ultrasound and centrifugal force were applied. The effect of hot water pretreatment at the temperature range of 80-95°C was evaluated and compared with osmotic dehydration at optimum condition. It improves the kinetics of mass transfer in terms of weight reduction, solid gain, water loss and normalized moisture content up to 15-30%, 2-6%, 16-46% and 7-20% at the temperature range of 80-90 °C, respectively. Traditional blanching lead to 17% increase and 54% decrease in total color difference and hardness values, respectively. For the first time

The present work aimed to study kinetics of osmotic dehydration of seedless guava in terms of solid gain and water loss, which was evaluated at three sucrose concentration levels (30, 40 and 50% w/w), three temperature levels of osmotic solution (30, 40 and 50°C) for 240 min. The experimental data was fitted to different empirical kinetic models including Peleg, Page and Azuara. Determination of coefficient (R 2 ), root mean square error (RMSE) and mean relative deviation modulus (E) were used for determination of the best suitable model. The present work shows that the Peleg empirical model satisfactorily described the dehydration kinetics with the highest R 2 ( > 0.95) and the lowest RMSE ( < 0.003) and E ( < 5.20%). Moreover, the effect of solution concentration and temperature was also studied and it was found that initial water loss and solid gain are related to solution concentration and temperature whereas equilibrium contents are related to sucrose concentration. From the experimental data it is possible to estimate the equilibrium content of water and solid.

In this study, the effects of pressure (100–300 bar), temperature (40–60ºC) and co-solvent flow rate (3–9 g/min) on antioxidant activities of supercritical carbon dioxide (SC-CO²) extracts of spearmint leaves were determined using full factorial in the frame of complete randomize design (CRD). The antioxidant activity of SC-CO² extracts was determined by DPPH radical scavenging method. The results showed that extraction pressure, temperature and co-solvent flow rate had significant effect (P < 0.05) on antioxidant activity of extracts obtained. The highest antioxidant activity (71.00 ± 2.65%) was obtained at 200 bar pressure, 50ºC and 6 g/min co-solvent flow rate. However, all of the extracts obtained in this study had significantly higher antiradical activities varying from 35.62 ± 0.34% to 72 ± 3.17% compared to butylated hydroxytoluene (BHT) as a reference. These results indicated that supercritical carbon dioxide is a promising alternative process for recovering compounds of high antioxidant activities from spearmint leaves.

This study aims to evaluate the effect of heat and the simultaneous application of heat (80-95°C) and ultrasonic waves (thermosonication) on the inactivation kinetic of peroxidase and vitamin C degradation in seedless guava. Ultrasonic wave’s amplitudes except 25 and 100% had significant (P<0.05) effect on peroxidase inactivation rate. The thermal and thermosonication inactivation of peroxidase was described well by first-order kinetics (R2>0.98). In the heat blanching process, the peroxidase inactivation rate constant increased from 1.1×10-2 to 4.6×10-2 s-1. However, the inactivation rate of peroxidase was increased by 1.5–3 times in the temperature range 80–95ºC, with the 50 and 75% ultrasonic wave amplitudes, respectively. Decreases in vitamin C contents due to blanching treatments were found. Blanching processes at high temperature and short time resulted in higher vitamin C retention. It was found that thermosonication treatment inactivates seedless guava peroxidase at less severe blanching conditions and consequently retains vitamin C content at higher levels. The present findings will help to design the blanching conditions in order to reduce the severity of conventional thermal treatments and, therefore, improving the quality of the thermally treated product.