Evaluation of bruising susceptibility and response of pears under impact loading through finite element analysis

Mechanical damage and bruising of fruit is a critical problem in the food industry. Minimizing brusing and damage can be achieved by designing energy-absorbing structures and packaging systems in order to ensure the long-term quality of fresh produce. The aim of this study is to investigate the response and bruise susceptibility of pears under impact loading conditions through finite element analysis (FEA) methods. In this paper, three impact heights (0.25 m, 0.5 m, and 1.0 m), four impact material surfaces (poplar wood, rubber, cardboard, and acrylonitrile butadiene styrene (ABS) plastic), two packaging sizes (standard 0.22″ and sandwich lattice 2.1″), and three impact design structures (rigid, corrugated, and honeycomb) are considered. Based on mesh sensitivity analysis, a mesh element of 1.5 mm was adopted for all simulations, assuring the accuracy of results and considering the trade-off between mesh size and computational time. The response surface analysis approach was utilized in order to develop predictive empirical models related to pear bruising. Results revealed that the rubber-based impact platform yielded minimal bruise susceptibility at all heights, while standard-sized corrugated cardboard performed best at a height of 0.25 m. Furthermore, single, double, and triple layers of packaging cardboard were tested. We observed that adding a second soft layer of corrugated cardboard reduced the stress on the pear by around 33%. However, adding a third layer only reduced stress by 5%. The 3D-printed honeycomb ABS has potential as protective packaging but would require further investigations and parameter optimization. Stacking multiple layers of cardboard on top of each other is a cost-effective solution that could improve damping and, therefore, ensure good quality and increase the shelf life of the fresh produce. This study will help decision-makers select the optimal energy-absorbing material for cushioning and packaging designs in order to improve the handling and post-harvesting logistics of fresh produce

The fate of carbon in a mature forest under carbon dioxide enrichment

Atmospheric carbon dioxide enrichment (eCO2) can enhance plant carbon uptake and growth1 5, thereby providing an important negative feedback to climate change by slowing the rate of increase of the atmospheric CO2 concentration6. Although evidence gathered from young aggrading forests has generally indicated a strong CO2 fertilization effect on biomass growth3 5, it is unclear whether mature forests respond to eCO2 in a similar way. In mature trees and forest stands7 10, photosynthetic uptake has been found to increase under eCO2 without any apparent accompanying growth response, leaving the fate of additional carbon fixed under eCO2 unclear4,5,7 11. Here using data from the first ecosystem-scale Free-Air CO2 Enrichment (FACE) experiment in a mature forest, we constructed a comprehensive ecosystem carbon budget to track the fate of carbon as the forest responded to four years of eCO2 exposure. We show that, although the eCO2 treatment of +150 parts per million (+38 per cent) above ambient levels induced a 12 per cent (+247 grams of carbon per square metre per year) increase in carbon uptake through gross primary production, this additional carbon uptake did not lead to increased carbon sequestration at the ecosystem level. Instead, the majority of the extra carbon was emitted back into the atmosphere via several respiratory fluxes, with increased soil respiration alone accounting for half of the total uptake surplus. Our results call into question the predominant thinking that the capacity of forests to act as carbon sinks will be generally enhanced under eCO2, and challenge the efficacy of climate mitigation strategies that rely on ubiquitous CO2 fertilization as a driver of increased carbon sinks in global forests. © 2020, The Author(s), under exclusive licence to Springer Nature Limited

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Not AvailableThermal diffusivities of Indian major carp Catla (Catla catla) and Rohu (Labeo rohita) fish were determined by using a one-dimensional (1D) Fourier equation applied to a cylinder. Experiments were conducted by cooling the different quantities of individual fish with ice in an insulated box. Time–temperature records were used to determine the thermal diffusivity. The values of thermal diffusivities of fish cooling with ice were ranged from 6 6012 to 3 2475 10 8m 2 s 1 and 6 6481 to 5 4267 10 8m 2 s 1 for Catla and Rohu fish, respectively. It was observed that the thermal diffusivity decreases with an increase in the weight of the fish. A logarithmic model adequately described the relationship between thermal diffusivity a and mass of fish m, with values for the coefficient of determination of 0 9949 and 0 9996, and standard errors of 0 088 and 0 0006 for Catla and Rohu fish, respectively.ICA

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Not AvailableThe internal cooling of fish has been studied on the basis of Newton’s cooling law. Experiments were conducted by cooling of the Indian major carp (Catla catla) of different weights with ice in an insulated box. Exponential model describing cooling of objects having irregular shape has been investigated. The developed model could predict the fish cooling with ice within a percent error of 0.74. The thermal properties of fish cooling with ice have been evaluated. The cooling data such as cooling coefficients, average surface heat transfer coefficient, thermal resistance, thermal capacitance, half cooling time and seven-eighth cooling time were determined for individual fish. The results show that the half cooling time and seven-eighth cooling time increased and the cooling rate decreased with increase in the weight of fish, respectively. Thermal resistance was independent of fish weight and having an average value of 1. 22 C W-1. Thermal capacitance increased with fish weight and ranged from 665.8 to 4639.3 J C-1. The average surface heat transfer coefficient of fish cooling with ice ranged from 11.68 to 34.41 W m-2 C-1.Not Availabl

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Not AvailableThe drying behavior of prawn and chelwa fish (Indian minor carp) has been studied under open sun drying (OSD). The drying rate curves contained no constant rate period and showed a linear falling rate throughout the drying process. An asymptotic regression precisely represents the open sun drying behavior with the coefficient of determination and mean square of deviation as 0.9996 and 0.33 · 10 4 for prawn and 0.9993 and 0.58 · 10 4 for chelwa fish, respectively. Effective moisture diffusivity values were estimated from Fick’s equation. The hourly effective moisture diffusivity has an exponential relation with the hourly mean moisture content of fish. The average effective moisture diffusivities were 11.11 · 10 11 and 8.708 · 10 11 m2 s 1 for prawn and chelwa fish drying, respectively.ICA

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Not Availableduration of eight days. Textural parameters, viz. skin hardness, toughness and stiffness has been evaluated on a texture analyzer for the different day of iced fish. The abruptly reduction in skin hardness (bio-yield point) and toughness was observed after fifth day of storage. The skin hardness ranged between 86.911 and 95.656 N within five days of storage and thereafter reduced within the range from 48.714 to 65.920 N. The stiffness ranged between 3.1474 and 4.6340 N mm 1 and toughness, 588.9–713.2 N mm for five days. After five days of storage, the stiffness and toughness reduced in the range of 2.0030–2.8111 N mm 1 and 415.0–526.3 N mm, respectively. During this storage period the pH of fish flesh was also determined with pH meter. The pH increased from 6.10 to 6.90 during the period of storage. Exponential regression presents the relationship between fish flesh stiffness Fs and pH with coefficient of determination 0.9695 and standard error 0.167. The results of skin hardness curve were fitted to modified Maxwell model. The modified Maxwell model could satisfactorily described relationship between skin hardness and compression time for iced fish with the coefficient of determination ranged from 0.9910 to 0.9967 and standard error ranged from 1.184 to 2.014. The coefficients of Maxwell model were further fitted in exponential expression to relate with the days of storage. Thus, the developed Maxwell model could predict the skin hardness for fish with an error of 0.06%, which was within the limit of experimental uncertainty of 5.54%.ICA

Design of Packaging Vents for Cooling Fresh Horticultural Produce

ReviewThis review focuses on the design of vents in packages used for handling horticulture produce. The studies on vent designs that are conducted to obtain fundamental understanding of the mechanisms by which different parameters affect the rate and homogeneity of the airflow and the cooling process are presented. Ventilated packages should be designed in such a way that they can provide a uniform airflow distribution and consequently uniform produce cooling. Total opening area and opening size and position show a significant effect on pressure drop, air distribution uniformity and cooling efficiency. Recent advances in measurement and mathematical modelling techniques have provided powerful tools to develop detailed investigations of local airflow rate and heat and mass transfer processes within complex packaging structures. The complexity of the physical structure of the packed systems and the biological variability of the produce make both experimental and model-based studies of transport processes challenging. In many of the available mathematical models, the packed structure is assumed as a porous medium; the limitations of the porous media approach are evident during vented package design studies principally when the container-to-produce dimension ratio is below a certain value. The complex and chaotic structure within horticultural produce ventilated packages during a forced-air precooling process complicates the numerical study of energy and mass transfer considering each individual produce. Future research efforts should be directed to detailed models of the vented package, the complex produce stacking within the package, as well as their interaction with adjacent produce, stacks and surrounding environment. For the validation of the numerical models, the development of better experimental techniques taking into account the complex packaging system is also very important. © 2012 Springer Science+Business Media, LLC