Physicochemical Properties and Quality Changes Of Grapefruit (Citrus Paradise. Macf) And Pummelo (Citrus Grandis (L.)) Concentrates During Storage

Abstract

Concentrated citrus juice had been made from two citrus species pummelo and grapefruit for the purpose of studying quality changes and shelf life in different storage conditions. The study intended to estimate the effect of adding citric acid and a high amount of sugar to concentrate juice. Samples were purchased from central market of Khartoum and kept stored in polyethylene bags at room temperature until used and then washed and peeled using a sharp knife removing the outer peel. Juice extraction had been done by hand squeezing after removing the seeds. Commercial sugar e.g. Kennana Sugar (1250 gm) had been added to raise the total soluble solids while powdered citric acid had been added to maintain the bitterness of the juice. Juice had been packed in plastic bottles and stored for three months at refrigerator and room temperatures. Parameters for study included total soluble solids, pH, acidity and Vit. C content. The similar chemical structure of the two species didn\\\\\\\'t show a great difference in the results. The results showed that shelf life of the concentrated juice was only one week at room temperature storage while refrigerator storage expired after two months. The effect of different storage temperatures showed a loss in nutrient content such as degradation of Vit. C and deterioration of Total soluble solids and also color changing was observed. Citric acid played a good role in maintaining the bitter taste, but didn\\\\\\\'t affect the quality of juice, and also kept the acidity low for the first 15 days. Results didn\\\\\\\'t show a significant difference between the two species. Microbial activity was highly effected by the acidity and temperature.