Volume 4, Issue 8

The air-drying kinetics of plum tomato pieces pre-treated with different osmotic solutions were investigated. Four pre-treatment solutions (comprised of salt, sugar and/or calcium lactate), three sample geometries (halves, quarters and eighths) and two air-drying temperatures (55 and 65°C) were studied. In general, the rate of drying over time appeared to fit an exponential curve (R2 values between 0.74 and 0.99). A closer look at the data indicated that the rate of drying appeared to follow two separate falling rate periods. The change from one falling rate period to another was observed for samples at a transition moisture ratio of ~ 0.2, for all geometries and temperatures. Thus, modeling the process was improved by including the two falling rate periods. The drying constant (K) for the two falling rate periods ranged between 0.05 to 0.3 h-1. Moisture diffusivity values ranged from 2.5 x 10-9 to 9 x 10-9 m2 s-1 and were relatively constant during the first falling rate period. During the second falling rate period, the diffusivity increased as the moisture ratio decreased, though this change was less pronounced as the sample size decreased from halves to eighths. The untreated samples had lower diffusivities than those with osmotic pre-treatment but there were no differences amongst the various pre-treatment solutions. In general, moisture diffusivities showed a dependence on the sample size, as the larger tomato samples had higher values of diffusivity. The greater diffusivity seen in the larger samples may be due to the collapse of cell walls in the skin.

Soaking characteristics of white rice grain in water are studied at 25, 40, 60, 70 and 80 °C. The kinetics of mass transfer are modeled using a linear driving force (LDF) approximation with constant diffusivity, which is capable of predicting the moisture ratio profile with time. This approximation is a relatively new approach in food engineering applications for systems in which the rate of mass transfer is controlled by intra-particle diffusion and nonlinear adsorption through porous adsorbent. The mass transfer is also modeled through Fick's law for unsteady-state diffusion using finite difference (FD) method, and compared with the LDF model. In general, the moisture uptake curves calculated with this new approximation compare favorably with the finite difference solution obtained in spherical coordinates, producing results of similar accuracy. Both the methods give a good agreement with the experimental data. The values of the effective diffusion coefficients are between 7.33×10-11 m2/s and 1.43×10-10 m2/s for a temperature of 25 and 80 °C respectively. Although gelatinization of starch is observed at a higher temperature which influences the increase in moisture content, the moisture uptake curves calculated with this new approximation compare favorably with the numerical solution of the non-linear diffusion equation. As such, it can be safely used to predict the unsteady-state moisture absorption kinetics of a rice grain, for the temperature range investigated.

Studies were conducted to find the effects of coagulation temperatures on yield and quality of tofu coagulated with calcium sulfate. Instrumental Textural Analyzer was used to measure the textural properties such as hardness, cohesiveness, adhesiveness, springiness and chewiness of tofu. It was found that hardness, cohesiveness, adhesiveness, springiness, chewiness and yield increase with coagulation temperature. The developed regression equations can be used for predicting these properties in the experimental range satisfactorily.

In this paper, two acetylcholinesterase (AChE) immobilization methods on the surface of a glassy carbon electrode (GCE) were compared. AChE-employed homogenate from chicken brain was home-made in the laboratory. The immobilization methods employed a cross-linking method with glutaraldehyde as a cross-linking agent, bovine serum albumin (BSA) as a protectant, and sol-gel method with tetraethoxysilane (TEOS). AChE was immobilized on chitosan membranes by these two immobilization methods. Then the enzyme membrane was fixed on the surface of GCE to prepare an AChE-GCE amperometric biosensor for the detection of organophosphorus pesticide. Measuring the activity of immobilization AChE by the oxidation current of thiocholine (TCh), produced by hydrolysis of the acetylthiocholine iodide (ATChI) substrate, the results showed that the activity of AChE-employed sol-gel method with TEOS was higher than the cross-linking method with glutaraldehyde. Biosensor sensitivity and reproducibility were statistically evaluated for the different immobilization methods and the most suitable immobilization procedure was selected.

Plums, which have a high water content level, are highly perishable and it is necessary to find alternatives to minimize product deterioration. Osmotic dehydration is one of these effective alternatives. Besides water removal from the product, the process also promotes solid gain due to high concentration of solute. In this study, the effect of different osmotic agents (sugar and sugar-glycerol) was reported. The Magee model could satisfactorily describe the solid gain and water loss during osmosis. Drying was conducted at 45, 55 and 65°C. Osmotic dehydration followed by air drying reduces the drying period. Osmotic dehydration resulted in a decrease in total convective dehydration time. The osmotic dehydration in sugar and sugar-glycerol solution reduced approximately 240 and 120 minutes as compared to the osmo-convective dehydration time of lye-treated plums at 65°C. The drying rate curves contained no constant rate period and showed a linear falling rate throughout the drying process.

The presence of common enterobacterial genes (wec E, F), the ubiquitous plant chloroplast gene of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL), maize intrinsic zein (Ze1) and recombinant cry1Ab genes in the gastrointestinal (GI) contents, peripheral blood mononuclear cells (PBMC) and visceral organs of mice and their progeny were examined by PCR. The wec E, F or rbcL were detected inconsistently in the PBMC, visceral organs, milk or liver of suckling mice, while Ze1 or cry1Ab were not detected. These results suggest that feed derived plant or enterobacterial DNAs were incompletely degraded in the GI tract, and part of them were absorbed into organs or milk as a source of transfer into suckling mice, but cry1Ab was not transferred. Detection of bacterial genes also suggested the influence of the immune system through stimulation of Toll-like receptor 9.

Some physical and aerodynamic properties of two varieties of sesame seeds (Yandev -55 and E8) were determined at varied moisture content levels. These properties are factors in the design and selection of sesame seed-cleaning machines. For the Yandev-55 and E8 varieties, major diameters ranged from 2.8 mm to 3.3 mm and 3.4 mm to 3.8 mm, intermediate diameters ranged from 1.8 mm to 2.1 mm and 2.2 mm to 2.5 mm, and minor diameters ranged from 0.7 mm to 0.9 mm and 0.6 to 0.9 mm, respectively. Their geometric means ranged from 1.5 to 1.8 mm and 1.7 to 2.0 mm, their spheroids ranged from 0.5 to 0.6 and 0.5 to 0.6, and their frontal areas ranged from 1.8 to 2.6 and 2.2 to 3.2, respectively. The terminal velocities of Yandev-55 were 2.9, 3.6, 4.7 and 5.4, while the terminal velocities of E8 were 3.4, 4.12, 5.1 and 6.3 at a moisture content level of 8.0, 10.3, 15.9 and 21.2 % (w.b.), respectively. The drag coefficients were in the range of 0.4 to 2.7 while Reynolds number varied from 2775.0 to 7840.7. The terminal velocities of the associated materials within the seeds were 1.5, 2.3, 3.1, and 3.6 at a moisture content level of 8.0, 10.3, 15.9 and 21.2%, respectively. The studied properties significantly varied with the varieties of sesame seeds. Also, the effects of moisture content are non negligible.

In this study, the drying kinetics of apple (control, blanching and blanching in 1% potassium meta bisulphate) in a tunnel dryer was studied at 50, 60, and 70°C air temperatures. The drying of apple slices occurred in a falling rate period. It was found that treated apple slices dried faster. Six thin layer-drying models were fitted to the experimental moisture ratio. Among the mathematical models evaluated, the logarithmic model satisfactorily described the drying behaviour of apple slices with high r2 values. The effective moisture diffusivity (Deff) of apple slices increased as the drying air temperature increased. The Deff values were higher for the treated samples than for the control.

Vacuum drying of liquid honey was carried out using three additives, i.e., maltodextrin (drying agent), glycerol monostreate (flowability agent) and tricalcium phosphate (anti-caking agent). The drying experiments were conducted through a central composite rotatable (CCR) type experimental design with three levels and five variables to study the effect of the additives on the vacuum dried honey powder properties. The maximum and minimum level of malto dextrin, glycerol monostreate and tricalcium phosphate used in the experiments were 0.6-0.35 kg.kg dry honey solid-1, 0.02-0.01 kg.kg dry honey solid-1 and 0.02-0.01 kg.kg dry honey solid-1, respectively. The amount of maltodextrin, glycerol monostereate, and tricalcium phosphate required to reduce powder stickiness and caking and increase powder flowability were optimized based on the commercially available honey powder properties. At the optimum ranges of maltodextrin (0.429-0.55 kg.kg dry honey solid-1), glycerol monostereate (0.0121-0.0157 kg.kg dry honey solid-1), and tricalcium phosphate (0.0147-0.0156 kg.kg dry honey solid-1), the range of powder properties were: hygroscopicity= 8.33-10.27%; degree of caking=10.24-11.50%; flowability=22-24.56s; overall colour difference=5.8-7.9 and sticky point temperature = 45.5-50.65°C.

Papain, a proteolytic enzyme was purified from latex of Carica papaya by a variety of techniques such as two-step salt precipitation, organic solvent precipitation (ethanol) and ion exchange chromatography. Fold purity obtained using ion exchange chromatography was in the range of 4.5 to 5 times as compared to the precipitation techniques. The purified papain was entrapped in ionotropically cross-linked alginate beads, in order to develop formulation for site-specific delivery of papain in intestine. The entrapment efficiency for papain in alginate beads was found to be in excess of 86%. Drying at low temperature and low air velocity results into maximum retention of papain activity; however, drying time increases significantly. The dissolution study shows the possible use of alginate beads for site-specific intestinal delivery of papain. The shelf-life of papain can be improved significantly by entrapment in alginate matrix, which was confirmed by an FTIR study.

Nyctanthes arbor-tristis (Harshingar, Parijat) belongs to the family Oleaceae. The flower has white petals with an orange calyx. Nyctanthes stems have been found to be a rich source of antioxidant. The aqueous extracts of the flower, calyx and petals were evaluated and found to be dose-dependent and showed an increase in DPPH free radical scavenging activity in vitro. The extracts, which showed strong DPPH radical scavenging activity, are in the order Calyx > flower > petals. This signifies that the main antioxidant activity is in the orange colored calyx of the flower. We have attempted an innovative study with the Nyctanthes flower as a part of an exploration for a cheap natural source of antioxidants which can be used at the industrial scale of the food industry.

Lactobacillus acidophilus is one of the major microorganisms which are famous for their effects on cholesterol. In this study, we have investigated the effect of L. acidophilus ATCC 1643 on removing the milk cholesterol and additionally, we have immobilized L. acidophilus ATCC1643 cells in sodium-alginate and observed its effect on milk cholesterol removing. Also, we have researched about the effect of some factors including: bacteria cells number (both free and immobilized cells) and immobilized cells bead size on cholesterol removing rate and ultimately the extracted results were compared together. The results indicated that free cells could reduce cholesterol to lower than 0.5mg/100ml milk. Also, smaller bead size resulted higher cholesterol reduction. Increasing the number of immobilized cells showed significant effect on cholesterol removal to about 86%. Also, reusability of the beads showed that immobilized cells are active in cholesterol processing for three times.

A novel process has been developed for the recovery of phytochemicals such as, ? -HCA from kokum (Garcinia indica choisy) rinds using hot water pressurized with carbon dioxide, followed by its purification. The performance of the pressurized hot water extraction (PHWE) process has been evaluated to ascertain the optimum process parameters for maximizing the recovery of ? -HCA. A systematic parametric study has been undertaken by varying the important parameters in the ranges of 30-120 °C for temperature, 1-20 atm for pressure, 30-60 min of extraction time, 4 - 22 ml/g of water to feed ratio, 1-3 number of stages , 0-350 rpm of stirring, presence of salt, nature of feed, and grinding. Ethanol is added to the aqueous extract from kokum rinds for the removal of pectinous materials by precipitation. Quantification of ? -HCA in the product has been carried out by the titration method with 0.1N NaOH solution. The maximum recovery is obtained when PHWE is carried out at 90 °C above which the recovery decreases. Pressure does not have much effect on the recovery of ? -HCA beyond a certain pressure required to maintain the extractant in the liquid phase. More ?-HCA is recovered by 2-stage PHWE from ground dry kokum than from salty kokum rinds.

Experiments were undertaken to study the relationship between the drying constant and the shrinkage constant of food products during drying. Three particular geometrical shapes of parallelepiped, cylindrical and spheres were selected from potatoes (aspect ratio = 1:1, 2:1, 3:1), cut beans (length: diameter = 1:1, 2:1, 3:1) and peas, respectively. The volumetric shrinkage behaviour and drying behaviour of food particulates were studied in a batch fluidised bed dryer connected to a heat pump dehumidifier system at three different drying temperatures of 30, 40 and 50 °C. Shrinkage constant was evaluated with non-dimensional moisture and compared with the drying constant for all materials at these three temperatures to understand the effects of the drying constant on the shrinkage constant for each material under investigated drying conditions. Simple mathematical models were obtained for the relationship between the volumetric shrinkage constant and the drying constant.

The effectiveness of the antioxidant properties of fresh and dry rhizomes of two tropical turmeric species (Curcuma longa) – long and short varieties – and dry turmeric spice powder have been evaluated with 1,1-Diphenyl-2-picryl-hydrazyl(DPPH) and beta - carotene bleaching radical-generating systems. The results showed that the aqueous extract of fresh rhizomes showed higher antioxidant properties as compared to the extracts from dry rhizomes, while the commercially available dry turmeric powder, commonly sold and used as a spice in Indian markets and used as a very common spice in Indian cooking, had the least antioxidant properties. A comparison of the two different species in their two different physical states of rhizomes-fresh and dry, showed considerable loss in antioxidant properties in dry powders. The order of reactivity is curcuma-long (dry) < dry spice turmeric powder < curcuma-long (wet) < curcuma-short(dry) < curcuma-short(wet). The loss of antioxidant properties during the dry spice preparation thus signifies that its beneficial pharmacological activities were definitely reduced. It is therefore recommended that fresh Curcuma longa rhizome be preferred for consumption to get its maximum benefit.