Thiamine, riboflavin and niacin are essential nutrients and play vital role in oxidation-reduction reaction during energy production in the living cell of the body. Requirement of these vitamins must be met through diet as human body cannot synthesize thiamine and riboflavin. Small amount of niacin is synthesized in the body but major requirement must be met through external diet. Jute leaves are rich in different vitamins and minerals. Different varieties of fresh jute leaves as well as preserved leaves of Corchorus olitorius. L. and Corchorus capsularis L. were evaluated for thiamine, riboflavin and niacin content. Powder jute leaf were prepared through drying of leaves in cold (4 ̊C), oven (100 ̊C) and open air (±30 ̊C) and then ground following preservation at -20 ̊C in freezer. Thiamine content in fresh leaves of C. olitorius is 3.22 – 5.84 mg/g and in C. capsularis is 4.26 – 6.46 mg/g. Jute leaves in both species show riboflavin content 1.00 – 1.35 mg/g. Niacin was found in leaves of C. olitorius 12.01 – 19.12 mg/g and in C. capsularis 12.95 – 23.17 mg/g in different varieties. Preserved leaf powder of C. olitorius and C. capsularis contain 0.37 – 0.58 mg/g thiamine. High amount of riboflavin was found in jute leaf powder of both species. Preserved leaf powder of C. olitorius shows 4.24 – 13.42 mg/g riboflavin and C. capsularis have 9.14 to 19.59 mg/g. Niacin content was found stable in preserved jute leaf powder. Preserved powder leaf of C. olitorius contain 8.4 - 14.8 mg/g niacin and leaves of C. capsularis have 5.8– 8.3 mg/g of niacin. There is no significant difference observed in leaves of different varieties of C. olitorius and C. capsularis regarding thiamine, riboflavin and niacin content. Drying showed different effect on vitamins in jute leaves, it reduced thiamine content, increased riboflavin content but did not affect much on niacin content in jute leaves in comparison to the fresh leaves. Different drying method did not show significant difference in thiamine, riboflavin and niacin content in jute leaves. Fresh jute leaves and preserved jute leaf powder both contain thiamine, riboflavin and niacin.

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Vitamin C, also known as ascorbic acid is essential nutrients that cannot produce in human body and meet up through diet. Jute leaves contain L-ascorbic acid. The amount of L-ascorbic is unknown in different varieties developed by Bangladesh Jute Research Institute. L-ascorbic acid content is affected by cooking or processing and preservation. Therefore, the experiment was conducted to investigate the content of vitamin C in the fresh jute leaves as well as the effect of cooking and preservation methods on L-ascorbic acid content in jute leaves. Fresh jute leaves of different varieties contain different amount of L-ascorbic acid 0.39g/10g to 0.64g/10g in Corchorus olitorius and 0.64g/10g to 0.92g/10g in Corchorus capsularis. C. capsularis contain more amount of L-ascorbic acid than the C. olitorius. Jute leaves of C. olitorius retain 95% L-ascorbic acid and C. capsularis retain 62% L-ascorbic acid after 15 min of boiling. Vinegar soaking leaves release more L- ascorbic acid by 5 min than the fresh leaves and then the L-ascorbic acid content was reduced by 15 min in both the species. Spraying vinegar treatment releases more L-ascorbic acid and increasing up-to 30 min treatment. Both oven dried and cold dried leaves retain small amount of L-ascorbic acid. L-ascorbic acid content was reduced in preserved jute leaf tea and soup powder also in both species. Usually, leafy vegetables are cooked before consumption and sometimes preserved vegetables are consumed when fresh vegetables may not available. So, this study may be useful to know the actual intake of L-ascorbic acid from the processed or preserved jute leaves.