| Vacuum impregnation (VI) is a new way of adding mineral substances, vitamins, and other physical active components into fresh fruits or vegetables. VI pretreatment before freezing can enhance quality of frozen fruits and vegetables. Yellow peaches (prunus persicu L. Batsch.) are the local special fruits of Guangming town of Shanghai, which have a high value because of their abundant nutrient contents. However, peaches are very perishable fruits, with a short shelf life of only 3-7 days, therefore, it's important to timely process peaches. The research is sponsored by Expo fund(No.05dz05824).In this paper, using vacuum impregnation technology with high-methoxy pectin(HMP), honey and calcium lactate on the yellow peaches, imposing different vacuum pressure, followed by frozen storage, then evaluating the effect of yellow peaches with different processing. Main research results are as follows:1. Developed an experiment vacuum impregnation system, and discussed the feasibility of strengthen mineral nutrients of fruits and vegetables, via pre-experiment then decided the vacuum impregnation solution and physico-chemical property indicators.2. Comparing weight change, moisture content, soluble solids content, pH, titratable acid, drip loss and water activity before and after vacuum impregnation under different vacuum conditions, the study found that vacuum impregnation is useful to preserve products'nature properties.3. Discussed the color changes, mechanical properties before and after vacuum impregnation. Using the L*a*b* Color System to study the color, the Physical Property Analyzer to study mechanical properties, when analysising the firmness of different treatments using a novel method, integration of force by time, statistically and more accurately to reflect the changes of the firmness.4. Using Atomic Absorption Spectrophotometry to test the calcium's strengthen and distribution. The results confirmed that vacuum impregnation can well achieve or enhance calcium content.
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