| Summary: | 碩士 === 中興大學 === 食品暨應用生物科技學系 === 95 === Alkaline foods are good for health. Most of alkaline foods are vegetable and fruits products, Mei fruit is also one kind of them. Mei fruits(Japanese apricot; Prunus mune Sieb. Et Zucc.), which contains little sugar and taste very sour and bitter, are not suitable to be eaten fresh. It is usually processed to be a semi-product to export for further processing. Bacterial cellulose synthesized by A. xylinum has the properties of high degree of crystallization, mechanical strength and water absorption capacity.
The traditional process for the production of crisp Mei products necessitated the addition of large doses of preservatives and sulfur dioxide; thus, the popularity of these products has declined steadily due to the health risk posed by these preservatives. This research investigated the effect of processing conditions, such as concentration of sugar, preservatives, amount of acetic acid and application of A. xylinum and bacterial cellulose on the safety and quality of candied mei fruits. The objectives for this study are to know the quality of candied fruits made from mei fruits and quality evaluation of preserved mei fruits during processing and storage.
The results showed the inoculated spoilage microorganisms could be inhibited for up to 20 weeks if 1.5% acetic acid was added in the presence of sucrose ranging from 30 to 50 °Brix. Moreover, the acetic acid bacterium A. xylinum could be adapted to growing in high concentration of sucrose(25%) by increasing the sucrose concentration stepwise.
After a pretreatment, green Meis were soaked in high sucrose solution and the then divided into four groups, each group was treated with either one of the following treatments, i.e. application of A. xylinum fermentation broth with or without cellulosic pellicle, addition of acetic acid or preservatives. Combination of sucrose and granular sucrose was used for soaking method. Concentration of sucrose were stepwise increased at 5% increment every 3~4 days until the final sucrose concentrations (35, 45and 55 °Brix) were attained. The candied Mei were then stored at room temperature for up to 52 weeks. The results showed that no spoilage of Mei occurred during both soaking and storage periods. In conclusion, uses of preservatives, fermentation broth with or without cellulosic pellicle of A. xylinum, or acetic acid alone all could effectively inhibit growth of spoilage microorganisms. Both sanitation and safety of Mei products during processing and storage were effectively improved and insured.
|
|---|
