Study On The Processing Characteristics Of Taiwan's Red Flesh Pumelo And The Typical Pulp Pigment

Red flesh pumelo is a variety of Citrus grandis. Osbeck. It is one of popular fruits in Taiwan. In recent years, the red flesh pumelo production increased significantly in Taiwan. Because it is seasonal fruits, during Mid-Autumn Festival period, high temperature and humidity result in product surplus that limit its sale. It is necessary to search for a way to solve the surplus problem. In this study, red flesh pumelo was used to study the color change under normal juice processing conditions. The objective is to search for the mechanism of industrialization process of red flesh pumelo's juice.Through researching the weight changes and acidity of red flesh pumelo stored in normal temperature, according to the index of color difference and researching the affecting factors of the juice's color: citric acid quantity, amount of added sugar, heating temperature and time, exploring the typical pigment and its stability of red flesh pumelo's pulp by using UV-VIS spectrum and exploring the color stability of red flesh pumelo's juice during stored. The following results were obtained:(1) Red flesh pumelo fruit was loses weight very easily at normal temperature. The rate of weight loss reached 25% after stored for 28 days. The rind weight loss was most fast. The acidity of fruit increased gradually during the first two weeks, then decreased slowly. After 28d storage at normal temperature, black spots appeared on the surface.(2) Citric acid quantity (<0.5%) didn't affected obviously on the lightness andredness of red flesh pumelo juice, but affected yellowness (P<0.05). Amount of added sugar affected three color parameters significantly. Heating temperature affected lightness and redness of the juice and its effect on yellowness wad significantly (P<0.01).The effect of heating time on brightness was not obvious (P>0.05), but on redness and yellowness were significant.(3) In regard to the pigment, it is concluded that the typical pigment in red flesh pumelo's pulp is carotenoids, and it is very sensitive to sun light, but not to temperature.(4) The thermal processing affected the lightness, redness and yellowness of red flesh pumelo juice significantly (P<0.01).