Venkatesh Meda

Characterization of oil sands naphthenic acids treated with ultraviolet and microwave radiation by negative ion electrospray Fourier transform ion cyclotron resonance mass spectrometry

Naphthenic acids (NAs) are concentrated in oil sand process water (OSPW) as a result of caustic oil sands extraction processes. There is considerable interest in methods for treatment of NAs in OSPW. Earlier work has shown that the combination of ultraviolet (UV) and microwave treatments in the laboratory was effective in reducing the concentration of classical NAs. Here we apply Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to further characterize NAs treated with (a) UV (254 nm) in the presence of TiO(2) catalyst; and/or (b) microwave irradiation (2.45 GHz). FT-ICR MS was used to characterize the NA fraction before and after treatment. Acidic oxygen-containing classes were most abundant in all samples whereas other heteroatomic classes were least abundant or not present in some samples. For example, the SO(2)-containing species were absent in UV- or combined UV- and microwave-treated samples. The O(2) class was dominant in all samples, indicative of NAs. However, samples treated with UV and microwave radiation have a lower relative abundance of other heteroatomic classes. We observed O(2), S(1)O(2), O(3), S(1)O(3), O(4), O(5), and O(6) classes, whereas the species with relatively high O(n) content, namely, the O(3), O(5), and O(6) classes, were present only in UV- and microwave-treated samples. The relatively high O(n) content is consistent with oxidation of the parent acids in treated samples. There may thus be potential implications for environmental forensics. For example, the monitoring of the ratio of SO(2):O(2) or tracking the relative abundances of O(2), O(3), O(4), O(5), and O(6) classes may provide insights for distinguishing naturally derived oil sands components from those that are process-related in aquatic environments.

Impact of Micronization on Rapidly Digestible, Slowly Digestible, and Resistant Starch Concentrations in Normal, High-Amylose, and Waxy Barley

This study determined the effect of micronization (high intensity infrared heating) on the concentrations of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) in normal barley (NB), high-amylose barley (HAB), and waxy barley (WB). The gelatinized starch contents and the thermal properties of the micronized samples also were determined. Samples of each barley type were tempered to each of three moisture contents (approximately 17, 31, or 41%), and then each tempered sample was micronized to each of three surface temperatures (100, 120, or 140 degrees C). Micronized barley samples were substantially lower in RS and in SDS and, therefore, higher in RDS than corresponding unprocessed samples. In general, higher concentrations of RDS and of gelatinized starch were associated with higher initial moisture contents and higher surface temperatures. The lowest concentrations of RS were observed in micronized WB samples. Similar concentrations of RS were observed in corresponding NB and HAB samples. Micronization resulted in slight increases in the onset (To), peak (Tp), and completion (Tc) gelatinization temperatures and in substantial reductions in the gelatinization enthalpy (DeltaH), the latter reflecting the levels of gelatinized starch in micronized samples, particularly in samples micronized at higher moisture contents and to higher surface temperatures. Endothermic transitions were evident only in samples tempered to 17% moisture or 31% moisture (surface temperature of 100 degrees C only).

Optimization of microwave-vacuum drying parameters of Saskatoon berries using response surface methodology.

A combined microwave and vacuum system was used to dry the Saskatoon berries (Amelanchier alnifolia). A central composite rotate design and response surface methodology were used to determine the influence of process variables (microwave power, drying time, and fruit load) and arrive at optimal processing conditions to reduce the moisture content and water activity of the berries to a safe level. It is concluded that the yield of moisture content and water activity can be reduced to 20% and 0.50, respectively, for microwave power 5.7–6 kW, drying time 51.5–55 min, and fruit load 10–9.75 kg.

Drying and Color Characteristics of Coriander Foliage Using Convective Thin-Layer and Microwave Drying

Heat sensitive properties (aromatic, medicinal, color) provide herbs and spices with their high market value. In order to prevent extreme loss of heat sensitive properties when drying herbs, they are normally dried at low temperatures for longer periods of time to preserve these sensory properties. High energy consumption often results from drying herbs over a long period. Coriander (Coriandrum sativum L., Umbelliferae) was dehydrated in two different drying units (thin layer convection and microwave dryers) in order to compare the drying and final product quality (color) characteristics. Microwave drying of the coriander foliage was faster than convective drying. The entire drying process took place in the falling rate period for both microwave and convective dried samples. The drying rate for the microwave dried samples ranged from 42.3 to 48.2% db/min and that of the convective dried samples ranged from 7.1 to 12.5% db/min. The fresh sample color had the lowest L value at 26.83 with higher L values for all dried samples. The results show that convective thin layer dried coriander samples exhibited a significantly greater color change than microwave dried coriander samples. The color change index values for the microwave dried samples ranged from 2.67 to 3.27 and that of the convective dried samples varied from 4.59 to 6.58.

Effect of Microwave Treatment on Starch Digestibility and Physico-chemical Properties of Three Barley Types

Samples of normal, high-amylose, and waxy barleys (NB, HAB, and WB, respectively) were tempered and then microwaved using three treatment protocols at each of three power levels. Microwave treatment increased starch digestibility, as rapidly digestible starch (RDS) concentrations were markedly higher and resistant starch (RS) and slowly digestible starch (SDS) concentrations were significantly lower, in all microwaved samples compared to corresponding unprocessed samples. Levels of RDS, on a dry sample basis, were similar in corresponding microwaved samples of the three barley types but were higher in WB when expressed on a starch basis. Levels of RS were lowest in microwaved WB samples. Microwave treatment was most effective in increasing starch digestibility at higher microwave power levels and when samples were tempered and then stored for 14 days at 4°C prior to microwaving, although the magnitude of the increase may not justify the cost of the storage step and might be achieved more economically through the use of an even higher power level. Increases in starch digestibility were attributed to gelatinization of starch. This conclusion was supported by degree of starch gelatinization, thermal analysis, and pasting data.

Physical Properties of Canadian Grown Flaxseed in Relation to Its Processing

The average flaxseed length, width, thickness and 1000 seed mass were 4.64 mm, 2.37 mm, 1.0 mm and 5.77 g, respectively. The average surface area was 15.49 mm2 while the sphericity and aspect ratio were 0.48 and 51.04%, respectively. The average bulk density was 652.16 kg/m3 while the true density was 784.36 kg/m3, and the corresponding porosity was 16.83%. The angle of repose for flaxseed was 24.40 while the terminal velocity was 2.9 m/s. The results showed that the mean value of static coefficient friction was least in case of plastic sheet while it is highest for rubber sheet.

Drying Kinetics anD Quality characteristics of Microwave-vacuuM DrieD sasKatoon Berries

Saskatoon berry (Amelanchier alnifolia) is a high moisture content fruit crop, harvested at 75–80% moisture content (w. b.) and dried to lower moisture contents for a safe, extended shelf-life and for further usage in food applications. Saskatoon berries were driedfrom an initial moisture content of 75.5% to around25% (w.b.) using microwave-vacuum drying. In this study, saskatoon berries were dried at different microwave power levels P10 (745 W), P7 (514 W) andP5 (374 W) and vacuum pressure levels V20 (67.0 kPa) and V10 (33.5 kPa). The vacuum pressure levels did not greatly influence the drying time of the saskatoon berries compared to the microwave power levels. Increasing the microwave power level produced faster drying times for the samples. After 12 min of drying at power level P10, the moisture contents of the samples at vacuum pressures of 33.5 and 67.0 kPa were 29.74 and 31.24%, respectively. However, after dryingfor 12 min at vacuum pressure of 33.5 kPa, the moisture contents atpower levels P10, P7 andP5 were 29.74, 51.41 and 61.95%, respectively. Polynomial and exponential models were fitted to the drying data. The exponential model provided a better fit for the drying data at the lower vacuum pressure, with higher R2 and lower SE compared to the polynomial model. On the other hand, the polynomial model provided a better fit for the drying data at the higher vacuum pressure. The vacuum pressure and the microwave power levels did not significantly change the yellowness of the samples at indicated by the Ab values. However, microwave-vacuum drying produced significant color changes in the L (white = 100 to black = 0) and a (green = -a to red = +a) values as indicated by AL and Aa. Total color difference was dependent on microwave power and vacuum pressure levels. Water activity of the samples after drying ranged from 0.61 to 0.75 for moisture content range of 15.68 to 29.03%.

The effect of different formulations on physical properties of cakes baked with microwave and near infrared-microwave combinations.

The aim of this study was to determine the effect of different formulations on color and textural characteristics of different cakes during baking in microwave and near infrared-microwave combination ovens. For comparison, cakes were also baked in conventional ovens. Color and hardness for both types of baking schemes were found to be dependent on formulation. Cakes containing Simplesse™ a fat replacer consisting mostly of whey protein, baked in microwave and near infrared-microwave combination ovens were found to be the firmest cakes.

Microwave treatment of naphthenic acids in water.

Naphthenic acids (NAs) are natural constituents of bitumen and crude oil. These compounds are concentrated as part of the oil sands process water (OSPW) during petroleum refining and separation from oil sands. NAs are considered among the major water contaminants in OSPW due to their toxicity and environmental recalcitrance. A laboratory scale microwave system was developed and experiments were conducted to determine the efficiency of NA degradation during microwave treatment. The effects of water source and quality (deionized lab water and river water) and of TiO2 catalyst in the degradation process were also investigated. Degradation kinetic parameters for both total NAs and individual z-family were calculated. The microwave system degraded OSPW NAs and commercial Fluka NAs in river water in the presence of TiO2 rapidly, producing half-life values of 3.32 and 3.61 hours, respectively. Toxicity assessments of the NA samples pre-and post-treatment indicated that the microwave system reduced overall toxicity of water containing Fluka NAs from high (5 min. IC50 v/v = 15.85%) to moderate (5 min. IC50 v/v = 36.45%) toxicity levels. However, a slight increase in toxicity was noted post-treatment in OSPW NAs.

Dehydrating of Flax Fiber with Microwave Heating for Biocomposite Production

The feasibility of microwave dehydrating flax fiber was evaluated using a commercial domestic microwave oven at four power settings representing 200, 300, 400 and 500 Watt (W) power level. Due to the possibility of local heating and consequent fiber degradation, the changes in color of the flax fiber at different levels of temperature were also investigated. The dehydration processes at various power levels were simulated by Page model. Based on visual inspection, color analysis and scanning electron microscopy (SEM) of the fiber, it was revealed that discoloration of the fiber occurred at about 170°C. At 200 and 300 W power level, after 10 minutes of dehydrating, the moisture content of the fiber reached from initial 7.9% close to 2.0 and 1.0%, respectively. For 400 W power level, the moisture content of the fiber dropped to 0.10% in about 9.5 minutes. Major discoloration of the fiber was noticed when dehydration was proceed beyond 4.5 minutes for 500 W treatment. The Page model very well fitted the experimental data. The coefficients of determination calculated from the model and the experimental data increased with increase in applied microwave power.