Dietary fiber powder from Citrus reticulata Blanco peel and its application

Citrus reticulate Blanco peel is a good source of dietary fiber, total dietary fiber (TDF) content is 52.89 percent dry basis. Its color and aroma are unique character which can use in many food products. Therefore, this research was to study the process and characteristic of Citrus reticulate Blanco peels dietary fiber (DF) powder. Studying of steam blanching effect was found that 2 minutes blanched peel powder had better color than control (p LT= 0.05). To study the drying temperature by hot air oven the levels of temperature were 50, 60 and 70 deg C. The results showed that, temperature effected the color of powder (p L= 0.05), and the optimal temperature were 50 deg C. The comparison of drying method showed that the peel powder which vacuum drying had better color and WHC than hot air drying (p LT= 0.05). Three methods were used for reduce the bitterness of peel powder such as water extraction at 30, 40 50 and 60 deg C, extraction by adjust pH of mixture (peel and water) to 7, 8, 9 and extraction by ethanol at concentration of 35, 55, 75 and 95 percent. The results showed that all methods could reduce the bitterness of peel powder (p LT= 0.05). The comparison of debittering methods found that debittering by adjusted pH of mixture to 7 had highest total acceptance score (p LT= 0.05). The debittered peel powder by freeze-drying method was found that the powder had better color, odor and total acceptance scores than vacuum dried powder (p LT= 0.05). Chemical and physical characteristics of the produced peel DF powder showed quite high TDF content. Water holding capacity, oil holding capacity and total carotenoids were 76.09 percent dry basis, 11.96+-0.30 g water/g dry sample, 1.67+-0.09 g oil/g dry sample, and 216.06+-20.63 micro g/g, respectively. The soluble and insoluble DF ratio was 1:2. The pH, water activity and bulk density of powder were 6.48+-0.01 0.37+-0.01 and 0.16+-0.01 g/mL, respectively. The peel powder had yellow color, tangerine aroma and little bitter taste. Its scanning electron micrograph showed high porosity. Enriched DF cupcakes with 2-6 percent of DF powder had high total acceptance scores which equal to 6.95-7.91.