Biochemical Characteristics of Maturing Date Cultivars

Abstract

This work was carried out to study chemical properties of Sudanese date cultivars Barakawi, Gondela and Tamoda from the Northern State at four different stages of fruit maturity at kimri, khalal, Rutab and Tamr stages, as well as varieties Mishrig Wad laggai, Mishrig wad khateb and Barhi from Khartoum State at three stages of fruit maturity for kimri, khalal and rutab stages. The chemical analysis studies included moisture content, protein, fat, crude fiber, ash content, carbohydrates, and total sugars, reducing sugars, starch, total polyphenols and tannins content. The moisture content of date samples at harvest were determined. The rest of values were expressed on dry weight bases. The protein content was generally high during the early stages of maturity which registered the highest values as 3.0-3.4% at the khalal stage and lower values as 1.91-2.1% at the rutab stage and 1.86-2.0% at the Tamr stage. Generally the protein decreased as the fruits developed and matured. The highest values of crude fiber content was observed at kimri stage which ranged between 9.59-10.67% and its lower values at rutab stage ranging between 2.03-3.37% and 2.43-3.14% at the tamr stage. The ash content was high at kimri stage which varies viii between 1.07-4.76% and then it decreased to low levels at rutab stage to 1.87-3.97% and at tamr stage to 2.2-2.9%. The highest amount of total sugars was found at tamr stage which ranged from 66.93-77.0% of date cultivars from Nile State area. Barakawi, Gondela and Tamoda on the other hand dates from Khartoum State showed highest amount of total sugars at rutab stage ranging from 41.04-85.0% and the lowest amount of total sugars for all six cultivars was found at kimri stage which ranged from 7.5-11.74%, generally there was an increase in total sugars as fruits ripe, the highest values of reducing sugars was found at the tamr stage for dates from Nile State area which ranged from 33.77-56.0% except gondela cultivar was 42.0% at rutab stage, higher than the value of the next tamr stage, 33.77%. The highest value of reducing sugars for Khartoum State area date cultivars was at rutab stage. The amount of sucrose have its lower value at kimri stage which ranged between 0.31-01.76% for all the six date cultivars and then increased gradually to reach the maximum values at tamr stage for Nile State cultivars which, ranged between 24.86-32.71 and at Khalal stage for Khartoum state cultivars which ranged between 3.38- 5.76%. The amount of total polyphenols which declined significantly from 241.48-1404.92 mg/100g at kimri stage to 87.73-145.80 mg/100g at rutab stage and 86.63-109.0 mg/100g at the tamr stage, while the tannin content was high at kimri stage, which ranged from ix 1.5-9.3% and it decreased to lower levels at rutab stage, which ranged from 0.1-2.5% and 0.7-1.7% at Tamr stage. The study showed a decrease in moisture, crude protein, crude fat, ash content, crude fiber, starch, polyphenols and tannins content, with increasing maturity. While carbohydrate, total sugar, reducing sugar and sucrose significantly increased with fruit development.