Kil Jin Park

Evaluation of drying parameters and desorption isotherms of garden mint leaves (Mentha crispa L.)

Abstract Mint has been used as a medicinal and aromatic plant since ancient times. Its leaves are used for flavoring, tea infusions and spicing. In addition, mint oil is used to treat several diseases. In order to preserve this seasonal plant, and make it available to consumers during the whole year, it undergoes specific technological treatments, such as drying. Here the desorption isotherms of mint leaves were determined at three temperatures. Experimental curves were fitted to three two-parameter equations, three three-parameter equations and one four-parameter equation. All BET, GAB, Oswin and Peleg models could be used to describe the mint desorption isotherms. Experimental data for the drying of mint was obtained at three different temperatures and two different air velocities. The drying process was interpreted through the diffusional model in order to obtain effective diffusivity values, which proved to range from 4.765×10−13 to 2.945×10 −12 m 2 / s . Activation energy was calculated as 82928.5 J/mol assuming an Arrhenius-type temperature reliance. The empirical Page model has shown a better fit to the experimental mint drying data as compared to Ficks model, except for the 50°C–1.0 m/s curve.

Drying of pear d'Anjou with and without osmotic dehydration

Abstract This work compares the drying behavior exhibited by in natura and by osmotic dehydrated pears. The dryer was a convective vertical tray dryer. The drying was analyzed in terms of effective diffusivity and drying rates. The effective diffusivity varied from 1.59×10 −10 to 7.64×10 −10 m 2 /s for in natura pear and from 1.87×10 −10 to 8.12×10 −10 m 2 /s for the pears after osmotic dehydration. In the case of moisture content below 1.0 kg w /kg dm , the drying rates only depends on temperature, as internal resistance to moisture transfer prevails.

Composição físico-química, microbiológica e rendimento do filé de tilápia tailandesa (Oreochromis niloticus)

The fillet yield of Thai-style tilapia and its physicochemical composition, including moisture content, protein, ash lipids and water activity, were determined. The analysis involved 19 specimens of tilapia with average weight and length of 989.6 g and 38.9 cm, respectively. The fish were weighed, measured (length, width and thickness), filleted, and the yield was calculated. The chemical composition presented the following contents: 77.13% moisture, 2.60% lipids, 19.30% protein, 1.09% ash, and 0.983 water activity. The fillet/fish to fish/residue weight ratios presented good linear correlations. The raw fish was also subjected to a microbiological analysis, which indicated that it met the safety limits established by Brazilian legislation and was therefore safe for processing and consumption.

Influence of spray drying conditions on physicochemical properties of chicken meat powder.

The influence of spray-drying conditions on the physicochemical properties of chicken meat hydrolysate powder was studied in this work. Enzymatic reaction, using Alcalase® (Novozymes, Bagsvaerd, Denmark), was carried out at 52.5°C, 4.2 g enzyme/100 g protein, and pH of 8.0 to obtain protein hydrolysate. The spray drying was carried out on a laboratory spray dryer and maltodextrin 10DE was used as carrier agent. A central composite rotatable design was used to evaluate the effect of the independent variables inlet air temperature, feed flow, and maltodextrin concentration on the responses powder moisture content, bulk density, mean particle diameter, and hygroscopicity. All variables had a significant effect on the properties and morphology of protein hydrolysate powder.

Influence of Process Conditions on the Physicochemical Properties of Pequi Powder Produced by Spray Drying

Microencapsulation of extract pequi pulp by spray drying, using Arabic gum as a microencapsulating agent, was studied. Tween 80 was used as a secondary emulsifier. A factorial design was conducted with the following independent variables: inlet air temperature (140 to 200°C), surfactant concentration Tween 80 (0 to 5%), and microencapsulating agent concentration (10 to 20%) on the responses; moisture content (0.3 to 1.9%), hygroscopicity (10.7 to 14.3 g adsorved water/100 g solids), process yield (25.8 to 56.1%), water activity (0.07 to 0.17), vitamin C (113.0 to 306.6 mg ascorbic acid/g pequi solids), and carotenoids content (10.9 to 74.3 mg carotenoids/g pequi solids). Only powder moisture content, hygroscopicity, water activity, and vitamin C content were statistically influenced by independent variables. Spray drying was optimized for maximum vitamin C and carotenoids content and minimal water content and hygroscopicity. Powder obtained under optimum conditions was characterized as to particle morphology, bulk, absolute density, and particle size distribution.

ESTUDO DE SECAGEM DE PÊRA BARTLETT (Pyrus sp.) EM FATIAS

The drying process aims for the reduction of the in natura products water activity, increasing the shelf life and facilitating the transport, maintenance and storage. Using a convective vertical tray drier, we obtained the drying curves of pear (nine curves) at three different temperatures (50, 60 and 70°C) and three different air velocities (0.5, 1.0 and 1.5m/s). With these results, it was possible to study the drying process determining the effective diffusivities and activation energies.

Influence of Process Conditions on the Mass Transfer Kinetics of Pulsed Vacuum Osmotically Dehydrated Mango Slices

The pulsed vacuum osmotic dehydration of mango slices was studied using a 25–1 fractional factorial design. The process responses were water loss, solids gain, water activity, and the effective diffusivities of the water or solids. Statistical analyses revealed that temperature and solution concentration were significant for all the responses studied. Vacuum time was significant for solids gain and the effective diffusivity of water. Diffusion coefficients were determined using an analytical solution of Ficks unidirectional diffusion equation for flat plates, showing a good fit to the experimental data. Osmotic recirculation and vacuum pressure had no effect on any of the responses studied.

Determinação da difusividade efetiva de raiz de chicória

Inulin is a fructooligosacharide found in diverse agricultural products, amongst them garlic, banana, Jerusalem artichoke and chicory root. Inulin generally is used in developed countries, as a substitute of sugar and/or fat due to its characteristics of fitting as functional and dietary food. Chicory root is usually used as source and raw material for commercial extration of inulin. The experiments consisted on drying sliced chicory roots based on a factorial experimental design in a convective dryer whose alows the air to pass perpendicularly through the tray. Effective diffusivity (dependent variable) has been determined for each experimental combination of independent variables (air temperature and velocity). The data curves have been fitted by the solution of the second Fick law and Pages model. Effective difusivity varied from 3.51 x 10-10 m2 s-1 to 1.036 x 10-10 m2 s-1. It is concluded that, for the range of studied values, air temperature is the only statistically significant variable. So, a first order mathematical model was obtained, representing effective diffusivity behavior as function of air temperature. The best drying condition was correspondent to the trial using the highest drying air temperature.

Obtenção das isotermas de sorção e modelagem matemática para a pêra bartlett (Pyrus sp.) Com e sem desidratação osmótica

Este trabalho aborda o estudo teorico-experimental da atividade de agua de peras in natura e desidratadas osmoticamente a 55oBrix e 40oC. As isotermas foram construidas para tres niveis de temperatura (40oC, 60oC e 80oC) e ajustadas pelos modelos mais usuais: Langmuir, BET, BET linear, GAB, Halsey, Oswin, Peleg, Chung e Henderson. O desvio relativo entre os valores experimentais e os valores estimados foi calculado para cada curva, a fim de se avaliar qual equacao melhor se ajustou aos dados experimentais. O modelo que melhor tratou os resultados das isotermas de dessorcao da pera foi o de Henderson entre os modelos que englobam a temperatura. Em relacao aos modelos que tratam as isotermas isoladamente, os modelos de Peleg, GAB e Oswin apresentaram o melhor ajuste para a pera desidratada e in natura.

Spray Drying of Chicken Meat Protein Hydrolysate: Influence of Process Conditions on Powder Property and Dryer Performance

The influence of operational conditions of a spray dryer on powder properties and equipment performance during spray drying of chicken meat hydrolysate was evaluated by a central composite rotatable design. The independent variables were inlet air temperature (120 to 200°C) and feed flow (0.1 to 0.38 kg/h). Spray dryer performance was assessed through estimation of product recovery, outlet air temperature, thermal efficiency, and energy on the dryer, obtained by mass and heat balance in the dryer system. Powder property was characterized in respect to antioxidant activity. The stable free radical diphenylpicrylhydrazyl (DPPH) was used to estimate the antioxidant activity of protein hydrolysate powder. This response varied from 38.7 to 59.4% and was only affected by inlet air temperature. Moreover, the results demonstrate a significant effect of the processing conditions on dryer performance. The increase of feed flow results in higher thermal efficiency and lower energy on dryer. Higher product recovery values were obtained at lower inlet air temperature and feed flow.