Heat transfer during forced air precooling of perishable food products

Kumar, Ravi; Kumar, Anil; Murthy, U. Narayana

doi:10.1016/j.biosystemseng.2007.10.012

Cited by 37 publications

(31 citation statements)

References 12 publications

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“…This is because fresh fruits and vegetables continue to deteriorate and shrivel after harvest and their freshness is only short-lived [5,11,71]. To minimize their ultimate loss of quality, the crops are cooled from field temperature to an optimal storage temperature [15,57]. The cooling process retards ripening, suppresses the spoiling physiological, biochemical, and microbiological processes and extends the preservation of the natural properties such as appearance, texture, and flavor during storage [6,42].…”

Section: Introductionmentioning

confidence: 99%

Mathematical Modeling Procedures for Airflow, Heat and Mass Transfer During Forced Convection Cooling of Produce: A Review

2010

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The aim of this review paper is to give comprehensive and detailed mathematical modeling procedures for the airflow, heat and mass transfer occurred during forced convection cooling of produce in order to optimize the cooling process. First, a brief explanation of forced-air precooling process and its importance in improving produce market quality will be given. Then, two main modeling procedures used during the process, namely porous medium approach and direct numerical simulation, will be explored. In addition, various related models available in the literature will be critically discussed together with their capabilities and drawbacks. Finally, a case study for optimizing the process using direct numerical simulation is shown. KeywordsMathematical modeling Á Direct numerical simulation Á Porous medium approach Á Forced-air precooling List of symbols A Surface area (m 2 ) A o Volumetric or specific surface area (1/m) A fs Interfacial area between fluid and solid phases (m 2 ) c Diffusivity in element Peclet number (Pa.s or W/m K) c art Coefficient of artificial diffusion (Pa.s or W/ m K) c p,a Air specific heat capacity (J/kg K) c p,p Produce specific heat capacity (J/kg K) d Hydraulic diameter (m) or pore-level linear length scale (m) d eff Effective produce diameter (m) D Diffusivity of water vapor in air (m 2 /s) or total diffusivity (m 2 /s) D d Dispersion coefficient (m 2 /s) f and g Respiration constants h Element size (m) h sf Interstitial convection heat transfer coefficient (W/m 2 K) I Second-order identity tensor k Mass transfer coefficient (kg/m 2 .s. Pa) k air Air film mass transfer coefficient (kg/m 2 .s. Pa) k 0 air Air film mass transfer coefficient (m/s) k skin Skin mass transfer coefficient (kg/m 2 .s. Pa) k a Air thermal conductivity (W/m K) k p Produce thermal conductivity (W/m K) K 1 and K 2 Constants in Darcy-Forchheimer equation K e Effective thermal conductivity (W/m K) ' Linear length scale for representative elementary volume (m) L Latent heat of evaporation (J/kg) or system dimension (m) _ m Rate of produce moisture loss (kg/s.m 2 ) Nu d Nusselt number (dimensionless) Nu d ¼ h sf d k a P Pressure (Pa)

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Section: Introductionmentioning

confidence: 99%

Mathematical Modeling Procedures for Airflow, Heat and Mass Transfer During Forced Convection Cooling of Produce: A Review

2010

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“…Perlakuan precooling dengan suhu 5 o C selama 30 detik dan buah dipertahankan pada suhu [9][10][11] o C selama 3 hari yang dikombinasikan dengan degreening menggunakan etilen dengan konsentrasi 100 ppm memberikan hasil terbaik untuk menghasilkan warna jingga pada buah jeruk siam dataran rendah. Precooling dapat meningkatkan kandungan padatan terlarut pada buah jeruk.…”

Section: Kesimpulan Dan Saranunclassified

“…Penelitian ini dilakukan dengan perlakuan precooling pada suhu 5 o C selama 30 detik dan suhu jeruk dipertahankan 9-11 o C selama 3 hari karena dianggap telah dapat menurunkan suhu buah secara cepat. Hal ini sejalan dengan penelitian Kumar et al (2008) Perlakuan degreening dilakukan di laboratorium dengan cara jeruk dimasukkan dalam wadah degreening masing-masing sebanyak 28 buah jeruk. Volume wadah telah diketahui sebesar 9.300 ml, jumlah wadah yang digunakan sebanyak 24 buah (sesuai jumlah satuan percobaan).…”

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Precooling dan Konsentrasi Etilen dalam Degreening untuk Membentuk Warna Jingga Kulit Buah Jeruk Siam

Arzam

Hidayati

Poerwanto

et al. 2016

J.Hort

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Naskah diterima tanggal 24 Desember 2014 dan disetujui untuk diterbitkan tanggal 22 Mei 2015 ABSTRAK. Degreening pada buah jeruk tropika dataran rendah seringkali gagal menghasilkan buah jeruk berwarna jingga, tetapi kuning. Warna jingga terbentuk dari campuran dua pigmen kulit jeruk, yaitu β-cryptoxanthin (kuning) dan ß-citraurin (kuning kemerahan). ß-citraurin sering kali tidak terbentuk pada buah jeruk tropika dataran rendah karena pembentukannya terjadi apabila buah terpapar suhu rendah saat pertumbuhannya. Precooling buah jeruk tropika dataran rendah diharapkan dapat mendorong pembentukan ß-citraurin karena jeruk yang sudah dipanen masih melakukan metabolisme. Konsentrasi etilen adalah salah satu faktor pembatas keberhasilan degradasi klorofil dalam degreening. Penelitian ini bertujuan untuk mengetahui pengaruh precooling sebelum degreening dan konsentrasi etilen terbaik pada degreening buah jeruk siam. Buah dipetik di kebun jeruk rakyat di Jember dan perlakuan degreening dilaksanakan di Laboratorium Pascapanen, Pusat Kajian Hortikultura Tropika, Institut Pertanian Bogor pada bulan Februari 2014. Penelitian menggunakan rancangan acak kelompok dua faktor. Faktor pertama adalah perlakuan precooling (dengan precooling dan tanpa precooling). Faktor kedua adalah konsentrasi etilen (0, 100, 200, 300 ppm). Perlakuan degreening buah jeruk siam asal Jember yang diawali dengan perlakuan precooling pada suhu 5 o C menghasilkan jeruk berwarna jingga, sedangkan yang tanpa precooling menghasilkan warna kuning. Etilen 100 ppm adalah konsentrasi terbaik dalam degradasi klorofil. Perlakuan precooling dan degreening tidak berpengaruh buruk pada kandungan asam dan gula buah jeruk. Katakunci: Degradasi klorofil; ß-citraurin; β-cryptoxanthin; Citrus color index; HueABSTRACT. Degreening on lowland tropical citrus fruits is often fail to generate orange color of citrus peel, but yellow. Orange color is generated by a mixture of two pigments of citrus peel, that are β-cryptoxanthin (yellow) and ß-citraurin (reddish yellow). ß-citraurin is not established oftenly in tropical citrus fruit grown in lowland because it is only established when the fruits are exposed to low temperatures during their growth. Precooling of lowland tropical citrus fruit is expected to encourage the formation of ß-citraurin because the fruits still doing metabolism after harvested. Concentration of ethylene is one of the factors in the successfull of chlorophyll degradation in degreening. This study aimed to determine the affect of precooling before degreening and best ethylene concentration in degreening of tangerine citrus fruit. Citrus fruit was picked in citrus garden in Jember and degreening treatment was conducted in Postharvest Laboratory, Research Center for Tropical Horticulture, Bogor Agricultural University in February 2014. This study used a randomized block design with two factors. The first factor was treatment of precooling (with precooling and without precooling). The second factor was the concentration of ethylene (0, 100, 200, 300 ppm). Ta...

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“…Although analytical models are still used (Becker and Fricke 2004;Erdogdu 2005;Erdogdu 2008;Kumar et al 2008;Cuesta and Lamúa 2009;Raval et al 2011), in the recent years many works use numerical solutions to describe the cooling kinetics of agricultural products. Campanõne et al (2002) used an implicit finite-difference scheme to describe the simulation of food refrigeration.…”

Section: Introductionmentioning

confidence: 99%

Calculation of the convective heat transfer coefficient and thermal diffusivity of cucumbers using numerical simulation and the inverse method

Silva

2012

J Food Sci Technol

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Cooling of fruits and vegetables, immediately after the harvest, has been a widely used method for maximizing post-harvest life. In this paper, an optimization algorithm and a numerical solution are used to determine simultaneously the convective heat transfer coefficient, h H , and the thermal diffusivity, α, for an individual solid with cylindrical shape, using experimental data obtained during its cooling. To this end, the one-dimensional diffusion equation in cylindrical coordinates is discretized and numerically solved through the finite volume method, with a fully implicit formulation. This solution is coupled to an optimizer based on the inverse method, in which the chi-square referring to the fit of the numerical simulation to the experimental data is used as objective function. The optimizer coupled to the numerical solution was applied to experimental data relative to the cooling of a cucumber. The obtained results for α and h H were coherent with the values available in the literature. With the results obtained in the optimization process, the cooling kinetics of cucumbers was described in details.

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Heat transfer during forced air precooling of perishable food products

Cited by 37 publications

References 12 publications

Mathematical Modeling Procedures for Airflow, Heat and Mass Transfer During Forced Convection Cooling of Produce: A Review

Mathematical Modeling Procedures for Airflow, Heat and Mass Transfer During Forced Convection Cooling of Produce: A Review

Precooling dan Konsentrasi Etilen dalam Degreening untuk Membentuk Warna Jingga Kulit Buah Jeruk Siam

Calculation of the convective heat transfer coefficient and thermal diffusivity of cucumbers using numerical simulation and the inverse method

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