Application of Room Cooling and Thermal Insulation Materials to Maintain Quality of Okra during Storage and Transportation

A combination of room cooling and the use of thermal insulation materials to maintain okra quality under simulated storage and transportation was evaluated. Okra pods were packed in plastic baskets and either cooled at 18 °C or not cooled in a room for 2 h. After either room cooling or no cooling, the okra pods were covered with three different materials: (1) perforated linear low-density polyethylene (P-LLDPE), (2) two layers of heat-reflective sheet with thin nonwoven (HRS+TNNW), and (3) metalized foam sheet (MFS). Typical handling (TP) without cooling and covering with P-LLDPE was used as the control. The six treatments were conducted during simulated storage (18 °C for 48 h) and transportation (30 °C for 15 h). Results showed that MFS gave the best insulation properties (Qx and R-values), followed by HRS and TNNW. After room cooling, both HRS+TNNW and MFS materials delayed the time for pulp temperature to reach 18 °C (10 h), compared to P-LLDPE (2 h). TP presented the highest mass loss (17.8%) throughout simulated conditions, followed by cooling plus P-LLDPE (15.2%) and either of the thermal insulation materials with or without room cooling (3.6% to 5.2%), respectively. TP, cooling plus P-LLDPE, and no cooling plus MFS (44% to 56%) showed the highest percentage of decay, while cooling combined with both HRS+TNNW and MFS gave the lowest decay incidence (11–21%). Findings demonstrated that room cooling combined with HRS+TNNW had the highest efficiency for preserving cool temperature and reducing decay, compared to TP and room cooling plus MFS.

Download Full-text

Performance of Thermal Insulation Covering Materials to Reduce Postharvest Losses in Okra

Horticulturae ◽

10.3390/horticulturae7100392 ◽

2021 ◽

Vol 7 (10) ◽

pp. 392

Author(s):

Jutarat Rattanakaran ◽

Rattapon Saengrayap ◽

Nattapol Aunsri ◽

Sirada Padee ◽

Chureerat Prahsarn ◽

...

Keyword(s):

Mass Loss ◽

Thermal Insulation ◽

Temperature Profiles ◽

Linear Low Density Polyethylene ◽

Heat Temperature ◽

Chain Management ◽

Temperature Changes ◽

Pulp Temperature ◽

Alternative Material ◽

Postharvest Loss

The efficiency of different thermal insulation covers in minimizing temperature fluctuations in cool chain management was investigated to reduce postharvest loss and maintain okra quality during storage and transportation. The four thermal insulation covering materials: (1) heat reflective sheet with thin nonwoven (HRS + TNNW), (2) heat reflective sheet with thick nonwoven (HRS + TKNW), (3) metalized Tyvek® (MTyvek) and (4) metalized foam sheet (MFS) were studied and compared with perforated linear low-density polyethylene (P-LLDPE) as the typical handing package for okra distribution alongside no covering as the control. The material properties, transpiration rate, vital heat, temperature profiles (air and pulp temperatures), relative humidity, mass loss and incidence of decay were determined throughout a simulated supply chain. Results exhibited that HRS + TNNW and HRS + TKNW covers had the lowest thermal heat energy (Qx) and moderate R-value. These two covers maintained low temperature fluctuation with the lowest rate of air and pulp temperature changes, reflecting in lowest mass loss and decay in okra. The HRS + TNNW cover yielded less decay (1%) in okra, compared to commercial covers; MTyvek (16%) and MFS (9%). Results showed that HRS + TNNW exhibited great potential as a thermal insulation cover to reduce postharvest loss in okra (5%) compared to typical handling (11–18%) and could be considered as alternative material to reduce the use of foam sheets in cool chain management distribution packaging of okra under ambient environment conditions.

Download Full-text

Identification of the LLDPE Constitutive Material Model for Energy Absorption in Impact Applications

Polymers ◽

10.3390/polym13101537 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1537

Author(s):

Luděk Hynčík ◽

Petra Kochová ◽

Jan Špička ◽

Tomasz Bońkowski ◽

Robert Cimrman ◽

...

Keyword(s):

Strain Rate ◽

Material Model ◽

Low Density Polyethylene ◽

Low Density ◽

Linear Low Density Polyethylene ◽

Stress Strain ◽

Rate Dependent ◽

Constitutive Material Model ◽

Principal Directions ◽

Constitutive Material

Current industrial trends bring new challenges in energy absorbing systems. Polymer materials as the traditional packaging materials seem to be promising due to their low weight, structure, and production price. Based on the review, the linear low-density polyethylene (LLDPE) material was identified as the most promising material for absorbing impact energy. The current paper addresses the identification of the material parameters and the development of a constitutive material model to be used in future designs by virtual prototyping. The paper deals with the experimental measurement of the stress-strain relations of linear low-density polyethylene under static and dynamic loading. The quasi-static measurement was realized in two perpendicular principal directions and was supplemented by a test measurement in the 45° direction, i.e., exactly between the principal directions. The quasi-static stress-strain curves were analyzed as an initial step for dynamic strain rate-dependent material behavior. The dynamic response was tested in a drop tower using a spherical impactor hitting a flat material multi-layered specimen at two different energy levels. The strain rate-dependent material model was identified by optimizing the static material response obtained in the dynamic experiments. The material model was validated by the virtual reconstruction of the experiments and by comparing the numerical results to the experimental ones.

Download Full-text

Photo-selective shade nets on the production and quality of sugarcane plantlets

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v23n5p366-371 ◽

2019 ◽

Vol 23 (5) ◽

pp. 366-371 ◽

Cited By ~ 1

Author(s):

José J. F. Cordeiro Júnior ◽

Héliton Pandorfi ◽

José A. D. Barbosa Filho ◽

Alex S. Moraes ◽

Luiz A. de Almeida Neto ◽

...

Keyword(s):

Solar Radiation ◽

Substrate Temperature ◽

Principal Component ◽

Global Solar Radiation ◽

Saccharum Officinarum ◽

Low Density Polyethylene ◽

Low Density ◽

Randomized Design ◽

Completely Randomized Design

ABSTRACT Brazil is the world’s largest producer of sugarcane (Saccharum officinarum L.) and research aimed at propagation has promoted higher quality in production. The objective of this study was to investigate the effect of the variation of micrometeorological elements on the survival and quality of pre-sprouted sugarcane plantlets. The study was carried out in a protected environment (UFRPE). Plantlets of the cultivar RB92579 were obtained by the technique of production of pre-sprouted plantlets. The protected environments were divided into four modules covered with low-density polyethylene plastic + photo-selective shade nets and one module without shade net. Micrometeorological data of global and photosynthetically active solar radiation, air temperature, substrate temperature, relative humidity and the solar radiation spectrum were recorded in each module. The experiment was conducted in a completely randomized design and the principal component analysis was used to verify the association between the cultivation modules, micrometeorological variables and crop variables. Anti-UV low-density polyethylene plastic + freshnet led to lower transmittance of global solar radiation, higher percentage of photosynthetically active radiation and lower plantlet mortality. Substrate temperature above 30.2 °C resulted in higher plantlet mortality. Larger spectrum in the red range led to the production of better quality plantlet. The use of freshnet shade net promoted adequate conditions for the cultivation of sugarcane plantlets and allows obtaining better quality plantlets.

Download Full-text