**1. Introduction**

400 Food Industrial Processes – Methods and Equipment

Simpson, R., A. A. Teixeira and S. Almonacid. 2007. Advances with Intelligent On-line

Tiansanguankul, J. and P. Limpatanachote. 2000. The Application of Computer Interfacing

Teixeira, A. A. 1992. Thermal Process Calculation. Chapter 11, pp. 563-619. *In* D. R. Heldman

Teixeira, A. A. and J. E. Manson. 1982. Computer Control of Batch Retort Operation with

Teixeira, A. A. and G. S. Tucker. 1997. On-line Retort Control in Thermal Sterilization of

Teixeira, A. A., M. O. Balaban, S. P. M. Germer, M. S. Sadahira, R. O. Teixeira-Nero and A.

*Control*, 18, pp. 821-833.

394

and D.B. Lund (eds). Food

Kasetsart University, Nakhon Pathom.

Engineering Handbook. Marcel Dekker, Inc, New York.

Canned Foods. *Food Control*, Vol. 8, No. 1, pp. 13-20.

Deviations. *Journal of Food Science*, 64, pp. 488-493.

Retort Control and Automation in Thermal Processing of Canned Foods. *Food*

Technique for Fo Determination in Canned Food. 212499 Food Engineering Project. Department of Food Engineering. Faculty of Engineering at Kamphaengsaen.

On-line Correction of Process Deviations. *Food Technology*, Vol. 36, No. 4, pp. 85-90.

A. Vitali. 1999. Heat Transfer Model Performance in Simulation of Process

The ice-temperature storage technology belongs to the no-freezing storage technology, in which the food is stored at a temperature from 0ºC to the freezing point. The fundamental thought of ice temperature storage technology is that the stored product is a living organism. After the cooling disposition on certain conditions, it can reach to an approximate "hibernate" state. Preserved at this state, the product can be maintained in good quality and its life can reach to the longest level since its metabolic rate is the smallest and so is the energy consumption.

The ice-temperature storage technology was originated from Japan. Their found that the freeze point of the snake, frog and meat is below 0°C for the antifreeze substance such as the sugar, the protein and alcohol and they can be kept as a living organism. The results pointed out that the temperature limit of life and death is below zero centigrade and at which temperature, the cell can be kept a living state. The effect of the ice-temperature storage technology on the fresh food mainly includes the followings.


Fig. 2. Curve of temperature change during freezing

**2.1 Influence of reducing sugar on freezing point** 

**2.2 Influence of total sugar on freezing point** 

freezing point. This is just reflected in figure 7 and figure 8.

stage is also relatively steep.

but this relationship is weak.

From the Figure 2, the temperature profile can be divided into three stages:

is small, so the cooling speed is fast and the freezing curve is relatively steep.

the heat in food freezing process is released. So there is a flat segment in the curve.

The first stage: the food's temperature is reduced from the initial temperature to the freezing point, the heat releasing from food is sensible heat. Compared with the total heat, this value

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The second stage: the food's temperature is almost kept at a constant temperature, which value is from 0°C to -5°C. At this stage, most of the water in food is frozen and release a lot of latent heat which is about 50~60 times as much as sensible heat. It is in the second stage that most of

The third stage: the food's temperature reduce from the phase change temperature to the final temperature, the heat released at this time is partly due to ice cooling ,and partly because of the residual small amount of water getting frozen. The freezing curve in this

The freezing point shown in Fig. 3 has an increasing trend with the increase of mass fraction of reducing sugar, which is not apparent. But it doesn't match traditional recognition. Usually the freezing point is believed to drop with the increase of mass fraction of reducing sugar. The tendency of pear's freezing point just reflects the relationship in Fig. 4.The reason maybe that kiwi has a large amount of acid which influence the effect of sugar on

From the trend line of relationship between freezing point and total sugar in Fig. 5 and Fig. 6, we can find that freezing point increases with the increase of mass fraction of total sugar,

Based on these advantages of the ice temperature storage, the study of the ice temperature technology on fruits and vegetables was carried out in our lab. The obtained result shows that the key for the ice temperature preservation is to realize a hibernation state of the product. The "hibernation" process is a cooling process during which the product can reduce its activity ability and energy consumption through the self adaption, starting from the change of components within cells, and at the same time ensuring their own living life characteristics. It is a typical phenomenon of natural adaption. However, the traditional precooling process ignores that and the storage effect couldn't reach to the best level.

Consequently, for the ice temperature storage technology, the prime technical key points are determination of the freezing point, the cooling process and the stability of storage environment. According to these key points, studies of the influence of freezing point, processing and storage environment were carried out.
