Kinetic study of lipid oxidation in roasted coffee

1998 ◽  
Vol 4 (1) ◽  
pp. 67-73 ◽  
Author(s):  
M.D. Ortolá ◽  
C.L. Gutiérrez ◽  
A. Chiralt ◽  
P. Fito
Keyword(s):  
Moisture Content ◽  
Lipid Oxidation ◽  
Oxidation Process ◽  
Storage Temperature ◽  
Important Change ◽  
Second Step ◽  
Initiation Mechanism ◽  
Experimental Values ◽  
Second Period ◽  
Kinetics Of

The kinetics of lipid oxidation in ground roast Arabica coffee from Colombia stored under different conditions were studied. Rancidity was controlled by the analysis of the peroxide value at 30-day intervals. The influence of moisture content (26 and 43 g/kg), storage temperature (5, 25 and 35 °C) and packaging conditions (with non-sealed bags, under vacuum, 35 mbar, and packed under CO2 atmosphere) on the kinetics was determined. Experimental values were fitted with a kinetic model for the mechanism of lipid oxidation. Lipid oxidation is described by two steps, which implies a monomolecular and a bimolecular initiation mechanism for the first and second period respectively. The kinetic constants showed that the plastificant effect of water and CO2 lead to an important change in the reactants' mobility within the temperature range. However, the rise in moisture content seems to protect the product from formation of the peroxide. Furthermore, this effect is more important in the second step of the oxidation process.

scholarly journals INVESTIGATING ON EFFECT OF HOT AIR AND WATER TEMPERATURE ON KINETIC OF REHYDRATION OF CELERY BY USING PELEG’S MODEL

2019 ◽  
Vol 49 (4) ◽  
pp. 249-254
Author(s):  
Azadeh Salimi ◽  
Haniyeh Ameri ◽  
Atefe Hajigorbani
Keyword(s):  
Moisture Content ◽  
Water Temperature ◽  
Absorption Capacity ◽  
Water Absorption Capacity ◽  
Hot Air ◽  
Peleg Model ◽  
Experimental Values ◽  
Drying Conditions ◽  
Kinetics Of ◽  
Determine Effect

The Peleg model was used to determine effect of drying conditions and rehydration water temperature on kinetic of moisture content and rehydration ration changes of celery. Celery cubes (1×1×1 cm) were dried at 65ºC in hot air oven. Samples were rehydrated by immersion in water during different periods of time and temperatures (25±2ºC and 100±2ºC). Rehydration kinetic was monitored by measuring samples' weights at regular intervals. Results showed that the highest final moisture content which was observed belonged to the samples which were dried at 70 °C and reydrated at 25°C water temperature, also, dried celeries which were rehydrated at a water temperature of 25°C, had higher levels of RR as a function of physical properties. The Peleg’s e constant (K1), decreased significantly while water temperature increased and in case of the Peleg capacity constant (K2), it increased slightly while water temperature increased. Decreasing of K2 values is a sign of more water absorption capacity. Finally, it was observed that the predicted and experimental values had a good correlation which indicates that the Peleg model is adequate to describe rehydration kinetics of celery cubes.

Drying kinetics of processed natural coffee with high moisture content

2017 ◽  
Vol 12 (3) ◽  
pp. 400 ◽  
Author(s):  
Valdiney Cambuy Siqueira ◽  
Flávio Meira Borém ◽  
Guilherme Euripedes Alves ◽  
Eder Pedroza Isquierdo ◽  
Afonso Celso Ferreira Pinto ◽  
...  
Keyword(s):  
Moisture Content ◽  
Drying Kinetics ◽  
High Moisture Content ◽  
High Moisture ◽  
Kinetics Of

Objetivou-se, com o presente trabalho, propor um novo método de processamento e secagem, assim como avaliar o comportamento dos grãos submetidos a este processo, por meio da taxa de redução de água e do ajuste de diferentes modelos matemáticos aos dados experimentais da secagem. Os frutos colhidos no estágio maduro foram divididos em três lotes. O primeiro foi seco continuamente à temperatura de 40±1 °C. O segundo consiste na secagem do café natural até os teores de água de 0,56±0,02, 0,41±0,02, 0,28±0,02 e 0,20±0,02 decimal (base seca, b.s.), seguido de beneficiamento e secagem contínua nas temperaturas de 35±1 ºC e 40±1 ºC. O terceiro lote correspondeu à secagem contínua do café descascado e desmucilado na temperatura de 40±1 °C. Em todos os lotes, a secagem foi encerrada quando os grãos atingiram o teor de água de 0,12±0,05 (b.s.). Aos dados experimentais da secagem foram ajustados dez modelos matemáticos utilizados para representação da secagem dos produtos agrícolas. Além da representação da cinética de secagem foi avaliada a taxa de redução de água dos grãos. Conclui-se que a taxa de redução de água é maior para a temperatura de secagem de 40±1 °C, especialmente para maiores teores de água. O tempo total de secagem do café beneficiado com alto teor de água é expressivamente reduzido, quando comparado ao tempo de secagem completa do café natural. O modelo de Midilli descreve satisfatoriamente a cinética de secagem do café beneficiado.

scholarly journals Pengaruh Perbedaan Konsentrasi Ekstrak Sargassum sp. dan Lama Penyimpanan terhadap Oksidasi Lemak pada Fillet Ikan Patin (Pangasius sp.)

2017 ◽  
Vol 15 (1) ◽  
pp. 64 ◽  
Author(s):  
Fatin Hidayati ◽  
Y.S Darmanto ◽  
Romadhon Romadhon
Keyword(s):  
Lipid Oxidation ◽  
Research Method ◽  
Storage Time ◽  
Oxidation Process ◽  
Phenol Content ◽  
Flavonoid Content ◽  
High Fat ◽  
Materials Used ◽  
And Storage ◽  
Phenolic And Flavonoid

ABSTRAKIkan patin merupakan ikan air tawar yang mengandung lemak dan protein tinggi sehingga apabila dilakukan penyimpanan rentan terjadi oksidasi yang mengakibatkan ketengikan. Sargassum sp. dengan kandungan fenol dan flavonoid mampu menghambat terjadinya oksidasi pada fillet ikan patin. Penelitian ini bertujuan untuk mengetahui pengaruh perbedaan ekstrak Sargassum sp. dan lama penyimpanan dalam menghambat terjadinya oksidasi pada fillet ikan patin. Materi yang digunakan dalam penelitian ini adalah ekstrak Sargassum sp. dan fillet ikan patin. Metode penelitian yang digunakan adalah experimental laboratories dengan menggunakan Rancangan Acak Lengkap (RAL) faktorial dengan 2 faktor yaitu konsentrasi ekstrak Sargassum sp. (0%, 1%, 1,5% dan 2%) dan lama penyimpanan (hari ke-0, hari ke-2, hari ke-4, dan hari ke-6. Hasil penelitian menunjukkan bahwa perbedaan penambahan konsentrasi ekstrak Sargassum sp. dan lama penyimpanan memberikan pengaruh nyata terhadap nilai PV, nilai TBA, kadar lemak, kadar protein, kadar air serta organoleptik (P < 0,05). Hasil penelitian tahap I didapatkan rendemen Sargassum sp. dengan pelarut etanol 96% sebesar 1,39%, kandungan fenol 1,813%, flavonoid 0,278% dan aktivitas antioksidan 99,1659 ppm (kuat). Hasil penelitian tahap II didapatkan nilai PV berkisar antara 2,03 - 19,82 meq/kg, nilai TBA 0,63 - 6,72 mg.mal/kg. Konsentrasi 1,5% merupakan konsentrasi terbaik ekstrak Sargassum sp. dalam menghambat oksidasi lemak pada fillet ikan patin selama penyimpanan.Kata kunci: Antioksidan, Ekstrak Sargassum sp., Lama Penyimpanan, Oksidasi lemak, Fillet Ikan patinABSTRACTCatfish is a freshwater fish that contain high fat and protein so that if its stored it will susceptible to oxidation process which leads to rancidity. Sargassum sp. with its phenolic and flavonoid content are able to inhibit the oxidation process in catfish fillet. This research was aimed to know the effects of different concentrations of Sargassum sp. extracts and storage time in inhibiting the oxidation process in catfish fillet. The materials used in this research were Sargassum sp. extracts and catfish fillet. This research was using experimental laboratories research method with factorial Completely Randomized Research Design (CRD) of 2 factors which were concentrations of Sargassum sp. extracts (0%, 1%, 1.5%, and 2%) and storage time (0 day, 2 days, 4 days, and 6 days). The results showed that the adding of different concentrations of Sargassum sp. extracts and storage time gave significant effect to the PV value, TBA value, fat content, protein content, moisture content, as well as organoleptic point (P < 0.05). The results obtained from stage I research were the yields of Sargassum sp. with ethanol 96% solvent was 1.39%, phenol content was 1.813%, flavonoid was 0.278%, and antioxidant activity was 99.1659 ppm (categorized as strong antioxidant). The results obtained from stage II research were the PV value were ranged from 2.03 to 19.82 meq/kg, TBA value were ranged from 0.63 to 6.72 mg.mal/kg. The 1.5% concentration was the best concentration of Sargassum sp. extracts in inhibiting the lipid oxidation of catfish fillet during storage.Keywords: Antioxidant, Sargassum sp. Extracts, Storage Time, Lipid Oxidation, Catfish FilletCitation: Hidayati, F., Darmanto, Y.S. dan Romadhon. (2017). Pengaruh Perbedaan Konsentrasi Ekstrak Sargassum sp. dan Lama Penyimpanan terhadap Oksidasi Lemak pada Fillet Ikan Patin (Pangasius sp.). Jurnal Ilmu Lingkungan, 15(1), 64-73, doi:10.14710/jil.15.1.64-73

Oxidation Kinetics of Hazelnut Shelf-Life Prediction Model

2012 ◽  
Vol 200 ◽  
pp. 466-469
Author(s):  
Wen Li Dong ◽  
Xue Gong ◽  
Jing Dong ◽  
Ling Jin ◽  
Yu Xiang Wei
Keyword(s):  
Prediction Model ◽  
Shelf Life ◽  
Peroxide Value ◽  
Storage Temperature ◽  
Order Kinetic ◽  
Shelf Life Prediction ◽  
Changing Patterns ◽  
Kinetics Of ◽  
Life Prediction Model

The changing patterns of filbert peroxide value through the determination of different storage temperature conditions,research the dynamics characteristics of oxidative rancidity of filbert. By regression analysis base on the storage time and the logarithm of peroxide value,it concluded the grease oxidation reaction first-order kinetic equation of filbert.Using Arrhenius equation and Q10 model for 5 ~ 35 °C temperature within the shelf life of any temperature prediction model.

scholarly journals Experimental Study on the Softening Characteristics of Sandstone and Mudstone in Relation to Moisture Content

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Gui-chen Li ◽  
Chong-chong Qi ◽  
Yuan-tian Sun ◽  
Xiao-lin Tang ◽  
Bao-quan Hou
Keyword(s):  
Moisture Content ◽  
Vertical Displacement ◽  
Surface Porosity ◽  
Shear Tests ◽  
Moisture Contents ◽  
Dynamic Finite Element ◽  
Rock Types ◽  
Underground Roadway ◽  
The Stability ◽  
Kinetics Of

The kinetics of fluid-solid coupling during immersion is an important topic of investigation in rock engineering. Two rock types, sandstone and mudstone, are selected in this work to study the correlation between the softening characteristics of the rocks and moisture content. This is achieved through detailed studies using scanning electron microscopy, shear tests, and evaluation of rock index properties during exposure to different moisture contents. An underground roadway excavation is simulated by dynamic finite element modeling to analyze the effect of moisture content on the stability of the roadway. The results show that moisture content has a significant effect on shear properties reduction of both sandstone and mudstone, which must thus be considered in mining or excavation processes. Specifically, it is found that the number, area, and diameter of micropores, as well as surface porosity, increase with increasing moisture content. Additionally, stress concentration is negatively correlated with moisture content, while the influenced area and vertical displacement are positively correlated with moisture content. These findings may provide useful input for the design of underground roadways.

scholarly journals A Logistic Approach for Kinetics of Isothermal Pyrolysis of Cellulose

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 551
Author(s):  
Jorge López-Beceiro ◽  
Ana María Díaz-Díaz ◽  
Ana Álvarez-García ◽  
Javier Tarrío-Saavedra ◽  
Salvador Naya ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Time Derivative ◽  
Inert Atmosphere ◽  
Second Step ◽  
Rate Parameter ◽  
Thermogravimetric Data ◽  
Different Temperatures ◽  
Parameter Values ◽  
Kinetics Of ◽  
Logistic Functions

A kinetic model is proposed to fit isothermal thermogravimetric data obtained from cellulose in an inert atmosphere at different temperatures. The method used here to evaluate the model involves two steps: (1) fitting of single time-derivative thermogravimetric curves (DTG) obtained at different temperatures versus time, and (2) fitting of the rate parameter values obtained at different temperatures versus temperature. The first step makes use of derivative of logistic functions. For the second step, the dependence of the rate factor on temperature is evaluated. That separation of the curve fitting from the analysis of the rate factor resulted to be very flexible since it proved to work for previous crystallization studies and now for thermal degradation of cellulose.

Research of drying kinetics of prepared wheat flour

2021 ◽  
Vol 9 (16) ◽  
pp. 212-220
Author(s):  
Liubomyr Khomichak ◽  
◽  
Inha Kuznietsova ◽  
Svetlana Vysotska ◽  
Sergiy Tkachenko ◽  
...  
Keyword(s):  
Moisture Content ◽  
Wheat Flour ◽  
Raw Materials ◽  
Control Sample ◽  
Raw Material ◽  
Convective Drying ◽  
Kinetic Dependence ◽  
Vital Functions ◽  
Kinetic Coefficients ◽  
Kinetics Of

Introduction. Processing of grain raw material with influence on starch or albumens by application of heat treatment creates the variety of functional properties of a product and is perspective in the modern terms vital functions of man. Research methods and methods. The flour obtained from wheat of the Ascanian wheat and from wheat of the soft varieties: Sophia ("sweet wheat"), Blond (soft) and Chornobrova (enriched with micro- and macronutrients) were used in the study. Thermal modification of flour samples was carried out in a convective manner. The control sample for determining the quality indicators is obtained in industrial conditions, extruded wheat flour produced by LLC "AS groups, LTD". Research results. The obtained kinetic dependence shows the gradual loss of moisture standards with different speed which accordingly influences on duration of drying. The moisture content of the drying agent most affects the intensity at the initial stage of the constant drying rate. With an increase in the moisture content of the coolant, the period of constant drying increases and the amount of evaporated moisture increases during this period. With the subsequent removal of moisture from raw materials, the degree of influence of this parameter on the intensity decreases. The nature of the drying curves is the same and the recommended process for obtaining modified flour is the process duration of 300 minutes or 5 hours. It was determined microscopically, that the samples of dried wheat flour have a purpose and are partially destroyed by starch granules and amorphization of biocomposite materials. Based on the data on the kinetics of drying flour samples, the kinetic coefficients and values of the critical moisture content for drying wheat flour were calculated, which is 1.18-1.30 %. It was determined that for the sensorial indicators the obtained samples have indicators characteristic of the varietal characteristics of wheat, from which the flour was taken. In terms of physical and chemical parameters, the modified wheat flour samples are not inferior to the well-known industrial sample of extruded flour. Conclusions. Use of flour, obtained from the wheat with different correlation of amilose and amylopectin, positively influences on a technological process and allows to extend the assortment of modified starch products, and accordingly, food products. Kinetics of the convective drying standards of the flour is investigated. Researches showed that a it is physically modified flour obtained from the different sorts of the soft wheat is not inferior in quality to the extruded wheat flour.

scholarly journals PENGARUH PERBEDAAN KONSENTRASI EKSTRAK Sargassum sp. DAN LAMA PENYIMPANAN TERHADAP OKSIDASI LEMAK PADA FILLET IKAN PATIN (Pangasius sp.) (The Effect of Different Concentrations Extract Sargassum sp. and Storage Time of Lipid Oxidation at Catfish (Pangasius sp.))

2017 ◽  
Vol 12 (2) ◽  
pp. 116
Author(s):  
Fatin Hidayati ◽  
Y.S. Darmanto Y.S. Darmanto ◽  
Romadhon Romadhon
Keyword(s):  
Lipid Oxidation ◽  
Research Method ◽  
Storage Time ◽  
Oxidation Process ◽  
Phenol Content ◽  
Flavonoid Content ◽  
High Fat ◽  
Materials Used ◽  
And Storage ◽  
Phenolic And Flavonoid

ABSTRAK Ikan patin merupakan ikan air tawar yang mengandung lemak dan protein tinggi sehingga apabila dilakukan penyimpanan rentan terjadi oksidasi yang mengakibatkan ketengikan. Sargassum sp. dengan kandungan fenol dan flavonoid mampu menghambat terjadinya oksidasi pada fillet ikan patin. Penelitian ini bertujuan untuk mengetahui pengaruh perbedaan ekstrak Sargassum sp. dan lama penyimpanan dalam menghambat terjadinya oksidasi pada fillet ikan patin. Materi yang digunakan dalam penelitian ini adalah ekstrak Sargassum sp. dan fillet ikan patin. Metode penelitian yang digunakan adalah experimental laboratories dengan menggunakan Rancangan Acak Lengkap (RAL) faktorial dengan 2 faktor yaitu konsentrasi ekstrak Sargassum sp. (0%, 1%, 1,5% dan 2%) dan lama penyimpanan (hari ke-0, hari ke-2, hari ke-4, dan hari ke-6. Hasil penelitian menunjukkan bahwa perbedaan penambahan konsentrasi ekstrak Sargassum sp. dan lama penyimpanan memberikan pengaruh nyata terhadap nilai PV, nilai TBA, kadar lemak, kadar protein, kadar air serta organoleptik (P<0,05). Hasil penelitian tahap I didapatkan rendemen Sargassum sp. dengan pelarut etanol 96% sebesar 1,39%, kandungan fenol 1,813%, flavonoid 0,278% dan aktivitas antioksidan dengan Ic 50 sebesar 99,1659 ppm (kuat). Hasil penelitian tahap II didapatkan nilai PV berkisar antara 2,03–19,82 meq/kg, nilai TBA 0,63–6,72 mg.mal/kg. Konsentrasi 1,5% merupakan konsentrasi terbaik ekstrak Sargassum sp. dalam menghambat oksidasi lemak pada fillet ikan patin selama penyimpanan. Kata kunci: Antioksidan, Ekstrak Sargassum sp., Lama Penyimpanan, Oksidasi lemak, Fillet Ikan patin  ABSTRACT Catfish is a freshwater fish that contain high fat and protein so that if its stored it will susceptible to oxidation process which leads to rancidity. Sargassum sp. with its phenolic and flavonoid content are able to inhibit the oxidation process in catfish fillet. This research was aimed to know the effects of different concentrations of Sargassum sp. extracts and storage time in inhibiting the oxidation process in catfish fillet. The materials used in this research were Sargassum sp. extracts and catfish fillet. This research was using experimental laboratories research method with factorial Completely Randomized Research Design (CRD) of 2 factors which were concentrations of Sargassum sp. extracts (0%, 1%, 1.5%, and 2%) and storage time (0 day, 2 days, 4 days, and 6 days). The results showed that the adding of different concentrations of Sargassum sp. extracts and storage time gave significant effect to the PV value, TBA value, fat content, protein content, moisture content, as well as organoleptic point (P < 0.05). The results obtained from stage I research were the yields of Sargassum sp. with ethanol 96% solvent was 1.39%, phenol content was 1.813%, flavonoid was 0.278%, and antioxidant activity was 99.1659 ppm (categorized as strong antioxidant). The results obtained from stage II research were the PV value were ranged from 2.03 to 19.82 meq/kg, TBA value were ranged from 0.63 to 6.72 mg.mal/kg. The 1.5% concentration was the best concentration of Sargassum sp. extracts in inhibiting the lipid oxidation of catfish fillet during storage. Keywords: Antioxidant, Sargassum sp. Extracts, Storage Time, Lipid Oxidation, Catfish Fillet 

New Insights into the Kinetics of the Gas-Phase Oxidation of Hexafluoropropene

2016 ◽  
Vol 41 (4) ◽  
pp. 418-427 ◽  
Author(s):  
David Lokhat ◽  
Maciej Starzak ◽  
Deresh Ramjugernath
Keyword(s):  
Gas Phase ◽  
Oxidation Process ◽  
Flow Reactor ◽  
Packed Column ◽  
Phase Reaction ◽  
Analytical Technique ◽  
Tubular Flow Reactor ◽  
Gas Phase Oxidation ◽  
Tubular Flow ◽  
Kinetics Of

The gas-phase reaction of hexafluoropropene and molecular oxygen was investigated in a tubular flow reactor at 450 kPa and within a temperature range of 463–493 K using HFP/O2 mixtures containing 20–67% HFP on a molar basis. Capillary and packed column chromatography served as the main analytical technique. The reaction yielded HFPO, COF2, CF3COF, C2F4 and c-C3F6 as gas-phase products. High molecular weight oligomers were also formed. The oligomers were found to have a polyoxadifluoromethylene structure according to elemental and 19F NMR analysis. At 493 K HFP is proposed to undergo oxygen-mediated decomposition to difluorocarbene radicals, yielding greater quantities of difluorocarbene recombination products. Kinetic parameters for a revised model of the oxidation process were identified through least squares analysis of the experimental data.

scholarly journals Drying Kinetics of Noni Seeds

2019 ◽  
Vol 11 (5) ◽  
pp. 250 ◽  
Author(s):  
Wellytton Darci Quequeto ◽  
Osvaldo Resende ◽  
Patrícia Cardoso Silva ◽  
Fábio Adriano Santos e Silva ◽  
Lígia Campos de Moura Silva
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Diffusion Coefficient ◽  
Moisture Content ◽  
Mathematical Models ◽  
Effective Diffusion Coefficient ◽  
Effective Diffusion ◽  
Information Criterion ◽  
Drying Kinetics ◽  
Kinetics Of

Noni seeds have been used for years as an important medicinal source, with wide use in the pharmaceutical and food industry. Drying is a fundamental process in the post-harvest stages, where it enables the safe storage of the product. Therefore, the present study aimed to fit different mathematical models to experimental data of drying kinetics of noni seeds, determine the effective diffusion coefficient and obtain the activation energy for the process during drying under different conditions of air temperature. The experiment used noni seeds with initial moisture content of 0.46 (decimal, d.b.) and dehydrated up to equilibrium moisture content. Drying was conducted under different controlled conditions of temperature, 40; 50; 60; 70 and 80 &ordm;C and relative humidity, 24.4; 16.0; 9.9; 5.7 and 3.3%, respectively. Eleven mathematical models were fitted to the experimental data. The parameters to evaluate the fitting of the mathematical models were mean relative error (P), mean estimated error (SE), coefficient of determination (R2), Chi-square test (c2), Akaike Information Criterion (AIC) and Schwarz&rsquo;s Bayesian Information Criterion (BIC). Considering the fitting criteria, the model Two Terms was selected to describe the drying kinetics of noni seeds. Effective diffusion coefficient ranged from 8.70 to 23.71 &times; 10-10 m2 s-1 and its relationship with drying temperature can be described by the Arrhenius equation. The activation energy for noni seeds drying was 24.20 kJ mol-1 for the studied temperature range.

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