Drying Characteristics and Mathematical Modelling of Cassava Chips

Cassava chips with dimension 5x2x0.4cm were dried at 600C, 700C and 800C in a laboratory tunnel dryer. Kinetics of drying was investigated using Fick’s second law. Drying pattern was observed to be in the falling rate period. Non linear regression analysis was used to fit in the experimental data and the coefficient of determination was found to be greater than 0.97 for all the models. The values of R2, RMSE, MBE and reduced chi square showed that Logarithm model best described the drying behaviour of the samples. The value of activation energy was found to be 30kJ/mol Key word: cassava chips, tunnel dryer, drying, modellin

Optimisation of Microwave Drying of Tomatoes (Solanum lycopersicum L.) Slices Using Taguchi Method

The effect of the processing parameters on the microwave drying of tomatoes was investigated and the process was optimized by using Taguchi technique. Pretreatments (water blanching (WAB), ascorbic acid (ASA) and sodium metabisulphite (SMB)), slice thickness (4 mm, 6 mm and 8 mm) and microwave power level (90W, 180W and 360W) were the parameters used in the study. The increase in microwave power accelerated the drying process, thus shortening the drying time. The drying rate curves indicated the absence of a constant-rate drying rate period in the entire drying process combinations under study. It was found that the pretreatment with SMB along with 4 mm thick tomato slice and 360 W for microwave oven drying were the best processing combination within the experimental domain considered in the present study. Thus, this is the best level that can guarantee minimum drying time and time of exposure of the samples to drying microwave power thereby retaining the qualities of the dried tomatoes. The results found in this study can be applied to industrial designs and operational guides for the microwave drying of tomato slices. Keywords: Optimisation, microwave drying, drying kinetics, tomatoes, Taguchi technique

Determination of moisture-dependent physical and thermal properties of jack bean (Canavalia ensiformis) related to design of processing machines

The study was carried out to investigate the effect of the moisture content on physical properties; axial dimension, seed volume, surface area, arithmetic and geometric mean diameter, aspect ratio, sphericity, true and bulk density, angle of repose and static coefficient of friction, and thermal properties; specific heat capacity, thermal conductivity and thermal diffusivity of Jack beans seeds. The properties were evaluated at six levels of moisture ranged from 10.12% to 30.51% d.b. The physical properties are: major, minor and intermediate diameter (19.42 to 20.78mm, 13.92 to 14.59 mm and 13.92 to 14.59 mm), surface area (152.2 to 167.2mm2), seed volume (446.9 to 595.2mm3), arithmetic mean (14.42 to 15.72mm), geometric mean (13.53 to 14.87mm), sphericity (0.696 to 0.716), aspect ratio (0.72 to 0.70), bulk density (0.677 to 0.376 kg/m3), true density ( 0.55 to 0.94 kg/m3), angle of repose (30.63° to 37.18°), static coefficient of friction for each surface (0.417 to 0.625, 0.438 to 0.692 and 0.357 to 0.459) for aluminium, plywood and glass, respectively. The thermal properties are: thermal conductivity (1.5350 to 4.9295 W/mK), thermal diffusivity (2.82 × 10-5 to 5.63 × 10-5 m2/s), and specific heat (1.3747 to 1.8912 kJ/kgK). The experimental data were satisfactorily fitted as functions of the moisture content using empirical models. Within the range of moisture levels considered, moisture content exhibits a significant great influence on the studied properties.Keywords: Axial dimensions, Jack bean, moisture content, physical properties, thermal propertie

Microwave-assisted extraction proof-of-concept for phenolic phytochemical recovery from Allium Sativum L. (Amaryllidaceous): Optimal process condition evaluation, scale-up computer-aided simulation and profitability risk analysis

Allium Sativum L. (ASL) extract is one of the medicinal and aromatic products used in pharmaceutical, food, cosmetic and perfumery industries. The scientific literature bibliography regarding process scale-up simulation and techno-economics of phenolic extract from ASL Microwave-Assisted Extraction (MAE) is seldom reported. This study presented optimization and techno-economics of phenolic recovery from ASL extraction. Box-benken design extraction experiment was conducted at irradiation power (520 W – 1040 W), extraction time (2- 10 min) and solid-liquid ratio (0.4 – 1 g/100 ml). The extraction conditions that optimized experimental extractible yield and Total Phenolic Content (TPC) evaluated in Box-benken desirability of Response Surface Methodology. Bioactive finger printing of the extract was analyzed using High Performance Liquid Chromatograph (HPLC). Aspen Batch Process Developer was used for the process techno-economic analysis; profitability uncertainty was analyzed using Monte-Carlo Simulation (MCS). Optimal extractible yield (28.62%) and TPC (76.8 mgGAE/g dry extract) were obtained at irradiation time 7.62 min, microwave power 826.67 Watt (63.6%) with solid-liquid ratio 0.55g/100 ml. The HPLC fingerprint revealed bentulinic acid, galic acid, chlorogenic acid, ellagic acid and ferulic acid. Cost of Manufacturing (COM) for 5L, 50L and 500L extractors gave US$1,480, US$ 220 and US$56 respectively. Techno-economic results of 500L extraction capacity with 900 kg/year design gave batch size (0.25 kg), production rate (2 kg/min), cycle time (125 min), discounted net present value (38,133 US$), rate of return (34%) and pay back time (2.94yrs). MCS results show high certainties of achieving base case profitability indices. The study shows that MAE of garlic powder is economically feasible