3
of Oyster mushroom, that were still rare, to choice the right kind of bag plastic or to
design the proper packaging system. Therefore, the aim of this work is to study
the physiological behaviors of Oyster mushroom on several variations of
temperature storage and gas concentration.
2. Theoretical Approach
2.1 Respiration Respiration
is the
oxidative breakdown of complex substrate normally
present in plant cells -such as starch, sugars, and organic acids- to simpler
molecules such as CO
2
and H
2
O. Concomitant with this catabolic reaction is
the production of energy and intermediate molecules that are required to sustain the
myriad of anabolic reactions essential for the maintenance of cellular organization
and membrane integrity of living cells Kader and Saltveit, 2003. Oxygen which
is needed for oxidation must be available in the course of respiration process.
Respiration on fresh produce located on free atmosphere can be considered that
availability of oxygen is unlimited, therefore availability of oxygen does not
inhibits
the respiration.
Otherwise, limitation of oxygen availability on
surrounding atmosphere suppresses the rate of respiration Kader and Saltveit,
2003.
Depletion of
oxygen and
accumulation of carbon dioxide inhibit the reaction on internal tissue. Respiration is
enzymatic reaction that has common characteristic such as depend on substrate
concentration, pH, and temperature and of course the concentration of enzyme that
catalyses the reaction Metzler, 2002. Enzyme needs pH range 5.5 to 7.5 to
perform optimum activity on reaction. Besides, enzyme needs optimum reaction
temperature also Kader and Saltveit, 2003. Enzyme can be inactivated if the
reaction temperature very low otherwise enzyme will be denaturalized on too high
reaction temperature Belitz, Grosch, Schiberle, 2009. So, three factors that
influence the activity of enzyme are substrates concentration, pH and reaction
temperature. Heat is released
during respiration, 686 kcal or 2870 kJ heat is
released per 1 mole of glucose. Besides, 0.8-1 fraction of heat released is used to
heat the surrounding atmosphere or to increase temperature of product
Ooraikul and Stiles, 1991.
2.2 Respiratory quotient Respiratory quotient is defined as ratio
of production rate of CO
2
to consumption rate of O
2
. According to respiration equation in which mole O
2
consumed is equal to mole of CO
2
produced indicated by coefficient of every species that involve
in reaction.
+ 6 6
+ 6 +
Ooraikul and Stiles, 1991. From the definition it can be concluded
that the respiratory quotient is preferable to evaluate the respiration. Increasing on
magnitude of respiratory quotient indicates respiration is approaching to anaerobic
respiration or production rate of CO
2
is higher than consumption rate of O
2
. Kader 2002 suggested that respiratory quotient
on aerobic respiration range between 0.8 to 1.3 and the exact value is depending on the
intrinsic properties of product and the storage condition.
3. Method
