**2.5 Regression of freezing point and mass fraction**

Based on the experimental data, the linear regression of the relationship between freezing point and the mass fraction of each component were carried out shown in Eq.(1) and Eq.(2) as follows.

Kiwi:

406 Food Industrial Processes – Methods and Equipment

Seen from Fig.9 and Fid.10, the freezing point has a downward tendency with the increase of mass fraction of soluble solid, but the decline rate of kiwi's freezing point is smaller than

From the curve relationship between above four kinds of nutrition and freezing point, it can be found that there is a strong relationship between freezing point and the nutritional proportions for a defined fruit. The experimental results show that freezing point of fruits is related with multiple nutritional proportions, among which the interaction effect may influence the changes in freezing point. For example, the acid has a reverse effect on sugar. In general, the freezing point will drop accordingly as sugar content increases. However, this effect becomes weak in the role of acid, which can be verified by the relationship between the freezing point and reducing sugar and total sugar shown in Fig. 3 and Fig.5.

Based on the experimental data, the linear regression of the relationship between freezing point and the mass fraction of each component were carried out shown in Eq.(1) and Eq.(2)

**2.4 Influence of soluble solid on freezing point** 

Fig. 9. freezing point of kiwi vs. soluble solid

Fig. 10. freezing point of pear vs. soluble solid

as follows.

**2.5 Regression of freezing point and mass fraction** 

that of the pear.

```
117198.0 055817.0 095504.0 07142.0 97913.2 t   x sugar reducing   x sugar total   xacidity   x solid soluble  (1)
```
Pear:

39643.0 213383.0 746773.5 14007.0 669404.0 *t x* sugar reducing *x* sugar total *x*acidity *x* solid soluble (2)

By the checking, calculation, the freezing point of pear by Eq.(1) is calculated, the maximum error is 15%and the minimum error is 1.7%,while calculated by Eq.(2),the maximum error of pear is 25% and the minimum error is 1%. The predicted results coincide better with experimental ones.
