چكيده لاتين :
The aim of this research was to determine shelf life stability of un-pasteurized lemon juice filled in
clear or dark green glass bottles. Presence of light, time and temperature affect the ascorbic acid retention in
citrus juices. Bottles were stored at room temperature (27±3°C) and in the refrigerator (3±1°C). Total soluble
solids, total titrable acidity and pH value were measured every three weeks and analysis was carried out on
ascorbic acid content by means of titration method in the presence of 2,6-dichlorophenol indophenol. The
study was carried out for 12 weeks after which slight changes in color, taste and apparent texture in some
samples were observed and ascorbic acid content reduced by 50%. Soluble solids content, pH value and total
acidity were 5.5 0 Brix, 2.73 and 5 gil 00 mL, respectively which appeared not to be significantly influenced by
storage time or conditions. Ascorbic acid content initially at 38.50 mgll 00 mL was sharply reduced to about
22 mg/l 00 mL within the first three weeks of storage. The final ascorbic acid content of all samples was about
15 mg/l 00 mL. The deteriorative reaction of ascorbic acid in the juice at all conditions followed a first-order
kinetic model with activation energy of 137 cal mol-I.
