The Effect of Extraction Method, Bleaching and Clarification Processes on Quality Second Grade Siwi Date Dibs

Abstract

Second grade Siwi date palm fruits in Baharia Oasis were used forproduction of high quality date syrup (Dibs). Physical and chemical characteristics of Siwi date fruits (second grade) as well as quality parameters of Siwi date extract as affected by bleaching and clarification treatments were investigated. Also, quality parameters of the obtained dibs by different methods and treatments were examined. Physical and chemical characteristics of Siwi date illustrated that, fruit weight, flesh/pit ratio, fruit length, fruit diameter, T.S.S, total and reducing sugars, crude protein, ash, soluble pectin and tannins were 10.0g, 6.40, 3.46 cm, 2.22 cm, 81.40%, 91.41%, 86.78%, 2.76%, 0.83%, 1.55% and 0.27%, respectively. Granular activated charcoal (G.A.C) is more effective bleaching treatment than powder activated charcoal (P.A.C), Also, liming phosphatation is more effective clarification treatment than centrifugation with filtration. Quality dibs results indicated that, the highest values of T.S.S, total and reducing sugars and date syrup yield were recorded for the dibs samples extracted at 75°C and 96°C and concentrated under vacuum while the lowest values were recorded for commercial sample(except yield), also, clarification processed sample recorded the lowest browning index, ash and pectin contents, while the highest values of these parameter were recorded for commercial sample. Sensory quality parameters demonstrated that, the highest taste and flavor scores were recorded for the extracted sample at 96°C with bleaching by GAC then concentrated under vacuum while the extracted sample by blender at room temperature (with or without clarification treatment) had the highest color scores. In relation to microbial quality, results showed that, microwave extraction followed by concentration at 100% power level recorded the highest microbial quality (the lowest counts of bacteria, yeast and mould, and coliform group) followed by sample extracted at 96°C and then concentrated under vacuum.