Temperature and Humidity on Transpiration
Effect of temperature and humidity on the transpiration rateof the whole mushrooms
P.V. Mahajan
*
, F.A.R. Oliveira, I. Macedo
Department of Process and Chemical Engineering, University College Cork, Ireland
Abstract
Water loss or transpiration is an important physiological process that affects the main quality characteristics of fresh mushrooms,such as saleable weight, appearance and texture. A loss in weight of only 5% may cause fresh produce to lose freshness and appear wiltedand it is an important parameter to be considered while designing packaging. A setup was developed to monitor the mass loss of mush-rooms under various surrounding temperatures (4, 10 and 16
°
C) and relative humidity (76%, 86% and 96%). Mass loss of whole buttonmushrooms (
Agaricous bisporous
) was measured and transpiration rates were calculated at all the experimental conditions tested. Tran-spiration rate ranged from 0.14 mg/(cm
2
h) to 2.5 mg/(cm
2
h) over all the combinations of temperature and humidity tested. Humiditywas the variable with the greatest effect on transpiration rate. A mathematical model was developed to understand the evolution of waterloss with temperature and relative humidity. The fitting was very good and the distribution of residuals was normal. The model was val-idated at 13
°
C and good agreement was found between experimental and predicted data.
Keywords:
Diffusion; Fruits; Moisture loss; Packaging; Storage; Transpiration rate; Vegetables
1. Introduction
Fresh produce continues to lose water after harvest, butunlike the growing plant it can no longer replace lost waterfrom the soil and so must use up its water content remain-ing at harvest. This loss of water from fresh produce afterharvest is a serious problem, causing shrinkage and loss of weight. When the harvested produce loses 5% or 10% of itsfresh weight, it begins to wilt and soon becomes unusable.To extend the usable life of produce, its rate of water lossmust be as low as possible.
P.V. Mahajan
*
, F.A.R. Oliveira, I. Macedo
Department of Process and Chemical Engineering, University College Cork, Ireland
Abstract
Water loss or transpiration is an important physiological process that affects the main quality characteristics of fresh mushrooms,such as saleable weight, appearance and texture. A loss in weight of only 5% may cause fresh produce to lose freshness and appear wiltedand it is an important parameter to be considered while designing packaging. A setup was developed to monitor the mass loss of mush-rooms under various surrounding temperatures (4, 10 and 16
°
C) and relative humidity (76%, 86% and 96%). Mass loss of whole buttonmushrooms (
Agaricous bisporous
) was measured and transpiration rates were calculated at all the experimental conditions tested. Tran-spiration rate ranged from 0.14 mg/(cm
2
h) to 2.5 mg/(cm
2
h) over all the combinations of temperature and humidity tested. Humiditywas the variable with the greatest effect on transpiration rate. A mathematical model was developed to understand the evolution of waterloss with temperature and relative humidity. The fitting was very good and the distribution of residuals was normal. The model was val-idated at 13
°
C and good agreement was found between experimental and predicted data.
Keywords:
Diffusion; Fruits; Moisture loss; Packaging; Storage; Transpiration rate; Vegetables
1. Introduction
Fresh produce continues to lose water after harvest, butunlike the growing plant it can no longer replace lost waterfrom the soil and so must use up its water content remain-ing at harvest. This loss of water from fresh produce afterharvest is a serious problem, causing shrinkage and loss of weight. When the harvested produce loses 5% or 10% of itsfresh weight, it begins to wilt and soon becomes unusable.To extend the usable life of produce, its rate of water lossmust be as low as possible.