Studies On Dietary Fiber Of Citrus Fruits

TDF, IDF, SDF, CEL, NDF, ADF, ADL, HC, TP, protopectin and WSP contents were determined in the peel and pulp of lemon (C. limon Burm), pumello (C. grandis(L.) Osbeck), ponken (C. reticulata Blanco), navel orange (C sinensis(L.) Osbeck), satsuma mandarin (C. unshiu Marc) and huyou (Huyou) . Dynamic changes of the contents of different dietary fiber in pumello and satsuma mandarin during different developmental stages were observed. Dynamic changes of the contents of different dietary fiber in satsuma mandarin during different storage period were observed. Lemon dietary fiber and huyou dietary fiber were obtained by alcoholic extraction. Proximate composition, energy value, colour, pH, WHC, WBC, OHC and SWC of fiber products were also determined. The results are as follows:1 Citrus fruits were rich in dietary fiber. Lemon is possessed of the highest TDF, SDF, NDF, ADF, CEL, ADL and WSP. Contents of fiber constituents in peels were higher than in pulp except for the SDF content in the pulp of lemon and navel orange. The variation coefficient was high except TDF and IDF. The variation coefficient in pulp was higher than in peel except HC. Peel and pulp of pumello was the highest in HC. ADL content in citrus fruits was poor.2 TDF and IDF contents in the peel and pulp of pumello and satsuma mandarin decreased slightly during the whole developmental stage; While SDF content was increased with the later stage. WSP content increased quickly during the earlier developmental stage while decreased later. Contents of CEL and ADL decreased gradually during the stage. HC content varied irregularly but decreased in the later stage. Protopectin content decreased most significantly.3 TDF and IDF contents in the peel and pulp of satsuma mandarin decreased slightly during the whole storage period; While SDF content was increased throughout the period. The change of WSP content was consistent with SDF's. In peel SDF content and WSP content reached to the highest at day 40, while in pulp at day 60. Decreases in CEL constituents in peel were slighter than in pulp. HC content varied irregularly but decreased in the later period. TP and protopectin content decreased also, but the loss of protopectin content was significant.4 The physicochemical and biological properties of dietary fiber were associated with physiologyical actions in the small and large intestine, having important implications in human health. These properties include WHC, OHC, SWC and WBC of dietary fiber products. These features may lead to various physiologyical actions such as reducing cholesterol and attenuating blood glucose, maintaining gastrointestinal health, and positively affecting immune function. Moreover, base on their physiochemical properities many of the new dietary fiber products can help improve the organoleptic properties and nutritional value of food. Lemon and huyou dietary fiber products are excellent in WHC, WBC and SWC. They became a gel in water. The size of the product may have an effect on its physicochemical and biological properties. The value of WHC and SWC of the smaller size product is higher. Temperature also affected hydration of dietary fiber. Higher temperature enhanced SWC and WBC. The value of WHC, OHC, WBC and SWC of lemon was higher than huyou's. Insoluble content and soluble content in citrus dietary fiber products were balanced. The products were also low in crude protein v crude faU ash and energy value, thus they can be used as bulking agents in low calorie foods.