IIF CHARACTERISTICS OF OYSTER EMBRYOS AND EGGS DETERMINED BY A FEEDBACK CONTROLLED DIRECTIONAL CRYOMICROSCOPE Ta-Te Lin, Ken Lung Department of Agricultural Machinery Engineering, National Taiwan University, Taipei, Taiwan, R.O.C.

l OBJECTIVES l MATERIALS AND METHODS l RESULT AND ANALYSIS l CONCLUSIONS

OBJECTIVES n To design and construct a feedback controlled directional cryomicroscope system. n To determine the IIF characteristics of oyster embryos and eggs at subfreezing temperatures. n To compare and analyze the IIF characteristics of oyster embryos and eggs with a stochastic model.

MATERIALS AND METHODS n THE DIRECTIONAL CRYOMICROSCOPE SYSTEM n PREPARATION OF OYSTER EGGS AND EMBRYOS n EXPERIMENTS l TESTS ON THE CRYOMICROSCOPE SYSTEM PERFORMANCE l OBSERVATION OF IIF PROCESS DURING FREEZING

MATERIALS AND METHODS n THE DIRECTIONAL CRYOMICROSCOPE SYSTEM n PREPARATION OF OYSTER EGGS AND EMBRYOS n EXPERIMENTS l TESTS ON THE CRYOMICROSCOPE SYSTEM PERFORMANCE l OBSERVATION OF IIF PROCESS DURING FREEZING

MATERIALS AND METHODS n THE DIRECTIONAL CRYOMICROSCOPE SYSTEM n PREPARATION OF OYSTER EGGS AND EMBRYOS n EXPERIMENTS l TESTS ON THE CRYOMICROSCOPE SYSTEM PERFORMANCE l OBSERVATION OF IIF PROCESS DURING FREEZING

n THE DIRECTIONAL CRYOMICROSCOPE SYSTEM n PREPARATION OF OYSTER EGGS AND EMBRYOS n EXPERIMENTS l TEST ON CRYOMICROSCOPE PERFORMANCE l OBSERVATION OF IIF PROCESS DURING FREEZING MATERIALS AND METHODS

RESULTS n TIME AND TEMPERATURE DEPENDENCE OF IIF n THE STOCHASTIC MODEL FOR IIF PHENOMENON n SIMULATION AND ANALYSES

Comparison on the probability of IIF for oyster eggs and embryos at subfreezing temperatures

Simulation on the relative probability of instantaneous IIF and time-dependent IIF mechanisms for oyster embryos.

Simulation on the relative probability of instantaneous IIF and time-dependent IIF mechanisms for oyster eggs.

Test on the isothermal temperature control of the directional cryomicroscope.

Set point temperature and the experimental temperature measured with the thermocouple under linear cooling rate controlled protocol.

Comparison on the IIF experimental results of oyster embryos and the fitted curves of the modified stochastic model

Comparison on the IIF experimental results of oyster eggs and the fitted curves of the modified stochastic model

Comparison on the IIF experimental results of oyster embryos and the fitted curves of the stochastic model

Comparison on the IIF experimental results of oyster eggs and the fitted curves of the stochastic model

Time and temperature dependence of IIF process for oyster eggs.

Time and temperature dependence of IIF process for oyster embryos.

THE STOCHASTIC MODEL P{ IIF } = { 1 - exp[ - ( T / T 0 ) ] } + { 1 - [1 - exp( -(T / T 0 ) )]} [1 - exp(-t / t 0 )] = 1 - exp [ - ( T / T 0 ) - (t / t 0 )] 1 / t 0 = (T) = ( T / t 0 ) (Pitt et al., 1991) + INSTANTANEOUS IIF + TIME-DEPENDENT IIF

(Modified model) P{ IIF } = { 1 - exp[ - ( T / T 0 ) ] } + { exp[ - ( T / T a ) ] - exp[ - ( T / T 0 ) ] } [ 1 - exp( -t / t 0 ) ] 1 / t 0 = (T) = ( T / t 0 ) THE STOCHASTIC MODEL

THE DETERMINED KINETIC PARAMETERS

THE DETERMINED KINETIC PARAMETERS (Modified model)

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SCHEMATIC DIAGRAM OF THE DIRECTIONAL CRYOMICROSCOPE

CONCLUSIONS n An integrated, feedback controlled directional cryomicroscope system was developed. n IIF temperatures of oyster eggs and embryos were determined using the cryomicroscope system. The IIF process of oyster embryos and eggs was found to be both time and temperature dependent. The median IIF temperature of embryos and eggs were determined to be C and C, respectively. The transition temperature zone of IIF appeared to be broader for embryos than that of eggs. n The IIF data were further analyzed with a stochastic model and the kinetic parameters were determined.