Question

The life of fruit is terminated by the oxygen content. Allowable oxygen limit is 15 ppm. 30g nuts are packaged in a vacuum packed (9cm *7cm) of 1mm thickness coated cellophane, what is the shelf life? Permeability coefficient is of O2 is 2ml/(m^2*24*atm)

Answer 1

Allowable oxygen limit = 15 ppm (15 parts per million)

Allowable oxygen content = 30 * 15 * 10^-6 gm = 0.00045 gms

Molecular wt. of oxygen = 32 gm

Volume of 1 mole of oxygen in standard condition = 22.4 L or 22400 ml

Volume of 0.00045 gm oxygen ==> (0.00045 / 32 ) * 22400 = 0.315 ml

Area of package = 0.09m * 0.07m = 0.0063 m²  

Permeability coefficient = 2ml / m² * 24hr * 1 atm

Let time required to penetrate oxygen content be t hrs then

0.315 ml = (2ml / m² * 24hr * 1 atm) * 0.0063 m2 * t * 1 atm

0.315 = (2 / 24) * 0.0063 t

t = (0.315 * 24) / (2 * 0.0063) = 600 hrs

t = 25 days