“…The estimate of LOU for the 'Granny Smith' apples at 20°C in this work (0.79 kPa) was within the 95% confidence interval of values for anaerobic compensation point reported for 'Cox's Orange Pippin' apples at 24°C (0.70-0.79 kPa; Yearsley et al 1996) and slightly lower than estimates obtained on the basis of RQ (1.04-1.20 kPa; Yearsley et al 1996). Use of surface coatings at a range of concentrations therefore provides the potential to identify LOU values without resort to resourceintensive controlled atmosphere experiments.…”
Section: Fitting Of Equation 6 To Experimental Data Inmentioning
confidence: 52%
“…Benefit can be expressed as reduction in P t ' uo whilst the principal risk arises from the potential for excessive depression of p' O2 in the coated commodity. Values approaching or below the internal lower O2 limit (LOL 1 , Beaudry et al 1992;Yearsley et al 1996) indicate that fruit are at risk from anaerobiosis. This approach is used to compare suitability of three surface coating materials for reducing weight loss in apples in the experimental study described below.…”
Section: Separable Mechanisms For Benefits and Risksmentioning
confidence: 99%
“…Assuming that the respiratory quotient (RQ) of fruit when O2 is non-limiting is unity (Yearsley et al 1996) …”
Section: Development Of New Modelmentioning
confidence: 99%
“…A sensitivity analysis of parameters k\,k2, £3, £4, and £5 indicated that there was quite a limited range (e.g., 10-20% of final values) for each parameter within which reasonable overall visual fit could be obtained. An estimate of LOU for the fruit (0.79 kPa) was obtained as the p' Ol value at which calculated RQ = 1.1 (Yearsley 1996) i.e., when:…”
A mathematical model predicted that final water vapour permeance in surface-coated fruits would depend upon water permeance of the coating but not the proportion of pores blocked on the fruit surface. In contrast, predicted final oxygen (O 2 ) permeance depended upon numbers of pores blocked but not O 2 permeance of the coating. Predicted variation in internal atmosphere composition caused by coatings that blocked different proportions of pores on the model fruit surface was consistent with data from two experiments on coated apples (Malus domestica Borkh.). A new equation was developed to characterise the relationship between internal carbon dioxide (CO 2 ) and O 2 levels resulting from different coating treatments. Two graphical approaches to assess surface coatings for fresh fruits are presented. In the first, a plot of water vapour permeance against internal O 2 was used to identify the most suitable of three surface coatings for reducing water loss in 'Royal Gala' apples at 20°C. The second method used a plot of internal CO 2 versus internal O 2 in coated fruit to identify the crop's internal lower O 2 limit (LOL i ), which lies just below the optimum internal O 2 level for modified atmosphere effects. Coatings containing different concentrations of carboxymethyl cellulose produced internal O 2 levels ranging from almost H96074
“…The estimate of LOU for the 'Granny Smith' apples at 20°C in this work (0.79 kPa) was within the 95% confidence interval of values for anaerobic compensation point reported for 'Cox's Orange Pippin' apples at 24°C (0.70-0.79 kPa; Yearsley et al 1996) and slightly lower than estimates obtained on the basis of RQ (1.04-1.20 kPa; Yearsley et al 1996). Use of surface coatings at a range of concentrations therefore provides the potential to identify LOU values without resort to resourceintensive controlled atmosphere experiments.…”
Section: Fitting Of Equation 6 To Experimental Data Inmentioning
confidence: 52%
“…Benefit can be expressed as reduction in P t ' uo whilst the principal risk arises from the potential for excessive depression of p' O2 in the coated commodity. Values approaching or below the internal lower O2 limit (LOL 1 , Beaudry et al 1992;Yearsley et al 1996) indicate that fruit are at risk from anaerobiosis. This approach is used to compare suitability of three surface coating materials for reducing weight loss in apples in the experimental study described below.…”
Section: Separable Mechanisms For Benefits and Risksmentioning
confidence: 99%
“…Assuming that the respiratory quotient (RQ) of fruit when O2 is non-limiting is unity (Yearsley et al 1996) …”
Section: Development Of New Modelmentioning
confidence: 99%
“…A sensitivity analysis of parameters k\,k2, £3, £4, and £5 indicated that there was quite a limited range (e.g., 10-20% of final values) for each parameter within which reasonable overall visual fit could be obtained. An estimate of LOU for the fruit (0.79 kPa) was obtained as the p' Ol value at which calculated RQ = 1.1 (Yearsley 1996) i.e., when:…”
A mathematical model predicted that final water vapour permeance in surface-coated fruits would depend upon water permeance of the coating but not the proportion of pores blocked on the fruit surface. In contrast, predicted final oxygen (O 2 ) permeance depended upon numbers of pores blocked but not O 2 permeance of the coating. Predicted variation in internal atmosphere composition caused by coatings that blocked different proportions of pores on the model fruit surface was consistent with data from two experiments on coated apples (Malus domestica Borkh.). A new equation was developed to characterise the relationship between internal carbon dioxide (CO 2 ) and O 2 levels resulting from different coating treatments. Two graphical approaches to assess surface coatings for fresh fruits are presented. In the first, a plot of water vapour permeance against internal O 2 was used to identify the most suitable of three surface coatings for reducing water loss in 'Royal Gala' apples at 20°C. The second method used a plot of internal CO 2 versus internal O 2 in coated fruit to identify the crop's internal lower O 2 limit (LOL i ), which lies just below the optimum internal O 2 level for modified atmosphere effects. Coatings containing different concentrations of carboxymethyl cellulose produced internal O 2 levels ranging from almost H96074
“…This set point is often close to the anaerobic compensation point, the O 2 partial pressure at which the CO 2 production rate is at its minimum. The optimal gas composition is critical, as too low an O 2 partial pressure in combination with too high a CO 2 partial pressure induces a fermentative metabolism in the fruit (Beaudry, 1999;Yearsley et al, 1996). This causes off-flavours (e.g., ethanol) and storage disorders (e.g., core breakdown in pear).…”
Abstract:The success of controlled atmosphere storage of fruit critically depends on the gas composition of the storage atmosphere. Gas transport models can be used advantageously to evaluate the effect of gas composition on product quality and to optimise and control the storage process. In this paper we will discuss gas and moisture transport models of increasing complexity. We will focus on recent advances in multiscale transport models. Such models are basically a hierarchy of models which describe the transport phenomena at different spatial scales in such a way that the submodels are interconnected. We will pay particular attention to methods to measure product topology and material properties at the micro-and nanoscale.
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