Akinbode A. Adedeji

Effect of Pretreatments on Drying Characteristics of Okra

This study was conducted to evaluate the effect of different pretreatment methods (blanching, microwave, and pulsed electric field [PEF]) on drying and rehydration behavior of okra. Drying rates were significantly (P < 0.05) influenced by the different pretreatments. The control samples had the lowest coefficient of diffusivity while samples pretreated with PEF at maximum energy input (4 kV/cm, 500 nF) had the highest coefficient. A simple exponential model used for describing the drying behavior of okra gave moisture diffusivity values ranging between 4.56 × 10−10 and 8.05 × 10−10 m2/s and the coefficient of determination values were between 0.94 and 0.98. Rehydration capacities of the control and pretreated samples were significantly different.

A Comparative Study on the Effect of Chemical, Microwave, and Pulsed Electric Pretreatments on Convective Drying and Quality of Raisins

In order to discourage the use of chemicals in raisin processing, the effect of microwave and pulsed electric field (PEF) pretreatments on the drying rate and other quality parameters like color, total soluble solids, bulk density, appearance, and market quality were compared with that of chemically pretreated raisins dried at 65°C. The untreated and pretreated samples had a statistically significant difference in drying rate (P < 0.05). The drying rate of chemically pretreated raisins was the highest when compared to others. The results showed that the PEF and microwave-treated samples had a significantly high Total Soluble Solids (TSS), along with good appearance and market quality.

Drying Characteristics of Pulsed Electric Field-Treated Carrot

This study was designed to establish the interaction effect of various components of pulsed electric field (PEF) system on drying characteristics of carrot, a vegetable rich in carotenoid. Carrots were treated in PEF system of 0.5, 1, and 1.5 kV/cm electric field strength, 0.5 and 1 μF capacitance, and pulse numbers of 10, 30, and 50. The samples were subsequently dried at 70°C until reaching an acceptable moisture content level. Drying rates were significantly (P < 0.05) influenced by PEF treatment. Variation in drying constant was not significantly influenced by the interaction effect of electric field components but by the energy per pulse. The Henderson and Perry model was fitted to the drying curve and it gave correlation coefficients ranging between 0.86 and 0.96.

3-D Imaging of Deep-Fat Fried Chicken Nuggets Breading Coating Using X-Ray Micro-CT

Food coatings are used to add value to deep-fat fried foods and to control heat and mass transfer during frying. They impart special characteristics such as crispiness and flavor to fried products while they also form a barrier to moisture and fat transfer during frying. Development of structure during frying plays an important role in defining the performance of batter/bread coatings. Food structural properties such as porosity have been associated with fat uptake in fried foods. A good understanding of the microstructural properties is necessary in order to produce high quality fried foods. X-ray micro-computed tomography (X-ray micro-CT) is a unique technique for imaging food non-invasively, requiring no or minimal sample preparation and 3-D rendition of high resolution images. The technique is capable of providing morphological details under a natural environment, which gives some advantages over the conventional imaging techniques such as microscopy. Study on chicken nuggets provided useful information relating frying conditions to structural changes in the breading-batter coating using X-ray micro-CT technique. Chicken nuggets were fried at 180°C for different frying durations after which the products were scanned using X-ray micro-CT. Images were reconstructed and analyzed, and 2-D and 3-D renditions of the coating images confirmed porosity changes with frying time. Numerical slicing of the 3-D images with image analysis software showed the degree of interconnectivity of pores, pore shape and pore count under different conditions of frying. The effect of frying time on microstructural parameters is significant. X-ray micro-CT shows great prospect in characterizing microstructural properties of foods especially coated fried products. This technique could be used in optimizing mass transfer during deep-fat frying by providing quantitative information on structural properties such as porosity, pore size distribution and pore connectivity.

Microstructural Properties of Deep-Fat Fried Chicken Nuggets Coated with Different Batter Formulation

A study on batter formulation effect on microstructural and physicochemical properties of deep-fat fried chicken nuggets coating was carried out. Two flour (wheat and rice) mixes at 5 ratios (100:0, 70:30, 50:50, 30:70, and 0:100) and two carboxymethyl cellulose ratios (0 and 1%) were combined. Samples were fried at 180°C for four min. Fried samples were then scanned with x-ray micro-computed tomography, and the obtained images were analyzed. Inclusion of hydrocolloid into the batter system significantly influenced their microstructural parameters. The number of pores, fragmentation index, and structure model index (shape) of the fried coating increased with the addition of hydrocolloid while porosity decreased. The proportions of rice or wheat flours in the batter affected porosity. Viscosity, batter pickup, color, texture, moisture, and fat content of the batter systems were significantly affected by the formulation. Some correlations were shown between the physicochemical properties of the batter system and the fried coating.

Shrinkage of Chicken Nuggets During Deep-Fat Frying

Apparent density and apparent volume shrinkage of chicken nuggets were analyzed at three frying temperatures (160, 170, and 180°C) at 16 time intervals between 0 and 300 s. A linear relation was found for particle densities with moisture loss. Apparent density decreased from about 1080 to 980 kg/m3 during frying. The regression of volumetric shrinkage as a function of moisture loss gave coefficient of determination value (R2) values ranging between 0.90 and 0.94. Temperature effect on apparent density was not significant, while its effect on shrinkage was quite pronounce (P < 0.05). The influence of moisture loss, frying time and temperature on density and shrinkage during deep-fat frying of chicken nuggets was established.