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Mangosteen Pericarp Processing Technology to Create Economic Value and Reduce Biowaste
(2024-07-01)
Soontornwat, Alisa
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Pongsuttiyakorn, Thadchapong
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Rakmae, Samak
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Sritham, Eakasit
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Sirisomboon, Panmanas
This research comparatively investigates different mangosteen pericarp processing schemes. The experimental pericarp processing schemes were hot air drying (HAD; control), quick freezing/HAD (QF + HAD), slow freezing/HAD (SF + HAD), and slow freezing/freeze-drying (SF + FD). For freezing, the QF temperature was −38 °C for 2 h and that of SF was −25 °C for 2 weeks. For drying, the HAD temperature was 60 °C for 7 h. In the FD process, the primary and secondary temperatures were −20 °C and 50 °C for 48 h. The experimental results showed that the freezing method (i.e., QF and SF) affected the physical properties (moisture content, water activity, and color) of dried mangosteen pericarp. The antioxidant activities (DPPH and ABTS) of the SF + HAD scheme (28.20 and 26.86 mg Trolox/g DW of mangosteen pericarp) were lower than the SF + FD scheme (40.68 and 41.20 mg Trolox/g DW of mangosteen pericarp). The α-mangostin contents were 82.3 and 78.9 mg/g DW of mangosteen pericarp for FD and HAD, respectively; and the corresponding TPC were 1065.57 and 783.24 mg GAE/g DW of mangosteen pericarp. The results of this study suggest that the drying process had a negligible effect on bioactive compounds. Essentially, the SF + HAD technology is the most operationally and economically viable scheme to process mangosteen pericarp.
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Effects of heat transfer surface temperature on liquid egg yolk fouling
(2024-01-01)
Sritham, Eakasit
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Nunak, Navaphattra
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Suthanupaphwut, Worapanya
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Somlitsopak, Badin
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Chaishome, Jedsada
This study was aimed at investigating the effects of different surface temperatures (60-80°C) on the formation of egg yolk deposits on heat transfer surface. Experimental data from the fouling period were fitted with zero- and first-order reaction models and the reaction kinetics of fouling was obtained using the Arrhenius equation. Egg yolk fouling curves exhibited an asymptotic pattern showing only fouling and post-fouling periods. The fouling resistance at transition point increased with the increasing surface temperature. The zero-order reaction model was well describing the reaction rate of egg yolk fouling. The obtained activation energy of 85.47 kJ/mol was less than that for thermal denaturation of egg yolk proteins. The fouling process of egg yolk was mainly controlled by the deposition reaction.
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Development of Mathematical Model to Predict Soymilk Fouling Deposit Mass on Heat Transfer Surfaces Using Dimensional Analysis
(2023-04-01)
Sritham, Eakasit
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Nunak, Navaphattra
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Ongwongsakul, Ekarin
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Chaishome, Jedsada
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Schleining, Gerhard
The formation of fouling deposits on heat exchanger surfaces is one of the major concerns in thermal processes. The fouling behavior of food materials is complex, and its mechanism remains, in general, unclear. This study was aimed at developing a predictive model for soymilk fouling deposit formed on heated surfaces using dimensional analysis. Relevant variables affecting fouling deposit mass could be grouped into six dimensionless terms using Buckingham’s pi-theorem. Experimental data were obtained from a lab-scale plate heat exchanger. A simple model developed using the experimental data under the process conditions with the product inlet temperature, the product outlet temperature, and plate surface temperature in the ranges of 50–55 °C, 65–70 °C, and 70–85 °C, respectively, exhibited a good performance in the prediction of soymilk fouled mass. The correlation coefficient between the predicted and experimental values of fouled mass was 0.97 with an average relative error of 9.03%. Within the ranges of product inlet temperature and plate surfaces temperature studied, this model offers an opportunity to estimate soymilk fouling mass with acceptable accuracy.
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Tensile properties of PLA/PBAT blends and PLA fibre-reinforced PBAT composite
(2018-08-14)
Sritham, Eakasit
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Phunsombat, Phakaimat
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Chaishome, Jedsada
The tensile properties of PLA/PBAT blends, PLA fibre reinforced PBAT composite (PLAF) at room temperature and -18°C were investigated. The concentrations of PLA in the blends were 10%, 20%, 30% and 40% (by volume). There was an improvement of elastic modulus (E) for PLA/PBAT blends when PLA was 40%. There was no significant difference of ultimate tensile strength (UTS) among the blends. For the same concentration of PLA (40%) in PLA-PBAT mixture, PLAF exhibited higher values of E and UTS than that of PLA/PBAT blends. Elongation of PLA/PBAT blends rapidly decreased upon the addition of PLA to the blends. The values of E and UTS for PLA/PBAT blends and composite, neat PLA, and PP increased with the decreasing of temperature from room temperature to -18°C. The effect of decreasing temperature was not observed on elongation. It was appeared from the results obtained for FTIR and DSC measurements that PLA and PBAT were immiscible, separating into two phases.
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Feasibility study on using evaporator condensate to subcool refrigerant in a vapor-compression refrigeration system
(2018-08-14)
Roonprasang, Kiattisak
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Sritham, Eakasit
A computer simulation based on MATLAB was developed to investigate the effectiveness of using evaporator condensate to subcool refrigerants in a vapor-compression refrigeration system. Three different types of refrigerant including R22, R410a, and R134a were studied. The simulation clearly showed the effectiveness of the technique to subcool refrigerant using evaporator condensate. Throughout the RH range of surrounding in this study, 40%-100%RH, the vapor-compression model system using R22 as a refrigerant provided the highest COP linearly ranging from 3.40 to 3.76. The greatest improvement in COP was found in the model system with R410a where the COP values increased by 3.33% to 15.36.
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Enthalpy relaxation in sucrose-maltodextrin-sodium citrate bioglass
(2017-10-01)
Sritham, Eakasit
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Gunasekaran, Sundaram
Glass transition characteristics of sucrose (SC)-maltodextrin (MD)-sodium citrate (NaCit) bioglass system were investigated using differential scanning calorimetry. Samples were formulated with different SC:MD (7:3, 5:5 and 3:7 by mass) and NaCit/SC (0, 0.1 and 0.2 by mole) ratios, and were equilibrated to residual moisture contents of 0.27–0.35 %wb. Isothermal aging experiments were conducted with the degree of undercooling from 12 to 57 °C and aging times of 8, 20, 47 and 71 h. In general, the Kohlrausch-Williams-Watts (KWW) decay function fit well with the experimental enthalpy relaxation data. The enthalpy relaxation time (τKWW) and the time required for 50% completion of theoretical possible maximum enthalpy relaxation at constant temperature (t<inf>ϕ(t)=0.5</inf>) increased with increasing MD content; lowering the aging temperature had similar effects on τKWW and t<inf>ϕ(t)=0.5</inf>. In the system with high SC and NaCit concentrations (SC:MD = 7:3 and NaCit/SC = 0.2), a substantial increase in τKWW and t<inf>ϕ(t)=0.5</inf> were observed when aging temperature <inf>decreased slightly;</inf> these systems also exhibited the greatest apparent activation energy. The findings reveal that NaCit can enhance the stability of low-moisture bioglass by primarily interacting with SC and form large less-mobile clusters, which helps to improve glass transition temperature and restrict the matrix mobility.
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FTIR spectroscopic evaluation of sucrose-maltodextrin-sodium citrate bioglass
(2017-09-01)
Sritham, Eakasit
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Gunasekaran, Sundaram
A model bioglass system was composed with sucrose (SC), maltodextrin (MD), and sodium citrate (NaCit). Samples were prepared with different SC/MD ratios (7:3, 5:5 and 3:7, by mass) and NaCit/SC ratios (0, 0.1 and 0.2, by mole) at low (0.27–0.49 %wb) and high (2.83–4.4 %wb) levels of moisture content. The effects of system constituents were investigated using the Fourier transform infrared (FTIR) spectroscopy. Hydrogen bonding interactions analyzed by studying the OH-stretching absorption band in the FTIR spectra indicated that there was no noticeable effect of moisture on the bioglass. The matrix of the system with high concentration of MD was loosely packed. NaCit interacted with both SC and MD through carboxylic groups, as evidenced by the shifting of antisymmetric (ν<inf>as</inf>(COO−)) and symmetric (ν<inf>s</inf>(COO−)) stretching bands of carboxyl groups. However, NaCit tended to interact more strongly with SC rather than with MD as evidenced by the strongest hydrogen-bonded network observed in the system with highest concentrations of SC (i.e., SC/MD = 7:3) and NaCit (i.e., NaCit/SC = 0.2).
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Rheological and microstructure evaluations of amorphous sucrose-maltodextrin-sodium citrate mixture
(2017-01-01)
Sritham, Eakasit
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Gunasekaran, Sundaram
Rheological properties and the mechanical relaxation behavior of rubbery amorphous sucrose-maltodextrin-sodium citrate systems were studied at room temperature using the small amplitude oscillatory shear test in the frequency range of 0.1 - 150 Hz. The system with high sucrose concentration exhibited viscous-dominant relaxation, while the system with high maltodextrin concentration exhibited elastic-dominant relaxation. The addition of sodium citrate could retard molecular mobility presumably due to its molecular interaction with sucrose rather than with maltodextrin. The technique was capable to detect changes in molecular process even with a small variation in the matrix components. Evidences obtained with scanning electron micrographs suggested the possible effect of sodium citrate to interfere with molecular interactions in the system with high maltodextrin concentration, i.e. the system tended to be more brittle.
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Estimation of thermal conductivity and thermal diffusivity of biological materials using thermographic camera
(2014-01-01)
Nunak, Navaphattra
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Sritham, Eakasit
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Songthai, Maethinee
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Suesut, Taweepol
This study proposes a method to estimate thermal conductivity and thermal diffusivity using a thermoelectric device and a thermographic camera. The experimental results were compared with others literatures. Three different materials including acrylic, apple, and potato were tested. The proposed method has proved to be effective. The experimental results for all selected materials are in comparable range with literature values. The proposed method can be a useful tool for determining thermal properties of solid biological materials with low thermal conductivity and diffusivity values.

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