Elsevier

Food Chemistry

Volume 84, Issue 4, March 2004, Pages 577-584
Food Chemistry

Date seeds: chemical composition and characteristic profiles of the lipid fraction

https://doi.org/10.1016/S0308-8146(03)00281-4Get rights and content

Abstract

The seeds of two date palm (Phoenix dactylifera L.) cultivars, Deglet Nour and Allig, from the Degach region—Tunisia, were analysed for their main chemical composition. Studies were also conducted on properties of oil extracted from date pits. The following values (on a dry-weight basis) were obtained for Deglet Nour and Allig cultivars, respectively: protein 5.56 and 5.17%, oil 10.19 and 12.67%, Ash 1.15 and 1.12% and total carbohydrate 83.1 and 81.0%. Gas–liquid chromatography revealed that the major unsaturated fatty acid was oleic acid (41.3–47.7%), while the main saturated fatty acid was lauric acid (17.8%) for the Deglet Nour cultivar and palmitic acid for the Allig cultivar (15.0%). Capric, myristic, myristoleic, palmitoleic, stearic, linoleic and linolenic acids were also found. Thermal profiles of both date seed oils, determined by their DSC melting curves, revealed simple thermograms. Sensorial and physical profiles of Deglet Nour and Allig seed oil were based on studies of the CieLab (L, a, b) colour, oxidative stability, viscosity and microstructure. Results showed that date seed oil could be used in cosmetic, pharmaceutical and food products.

Introduction

The date (Phoenix dactylifera L.) has been an important crop in arid and semiarid regions of the world. It has always played an important part in the economic and social lives of the people of these regions. The fruit of the date palm is well known as a staple food. It is composed of a fleshy pericarp and seed.

The chemical composition and nutritional value of date flesh have been reported (Al-Hootii et al., 1995, Fayadh and Al-Showiman, 1990, Hussein et al., 1976, Mohamed et al., 1983, Rygg, 1946, Salem and Hegazi, 1971, Vandercook et al., 1977, Youssif et al., 1976). Few works have been published on date palm seeds (Al-Hootii et al., 1995, Al-Showiman, 1990, Devshony et al., 1992, El-Shurafa et al., 1982, Hamada et al., 2002). However, these were focused on their chemical composition only and not their thermal and sensorial properties. Pits of date palm (seed) are a waste product of many industries, after technological transformation of the date fruits (Al-Hooti et al., 1997, Hobani, 1998, Khatchadourian et al., 1983, Youssif et al., 1990, Youssif and Alghamdi, 1999, Youssif et al., 1996) or their biological transformation (Abou Zied et al., 1991, Abou Zied and Baghlef, 1983, Abou Zied and Khoja, 1993, Al-Obaidi and Berry, 1976, Nacib et al., 1997, Nacib et al., 1999).

In some date-processing countries, such as Tunisia, date seeds are discarded or used as fodder for domestic farm animals. In Tunisia, the mean annual yield of date fruits is about 100,000 tons. From this, around 1000 tons of date seeds oils would be extracted. The aim of this study was to evaluate the chemical composition of date seeds from two important cultivars grown in Tunisia and to determine fatty acid profiles, thermal profiles and sensorial profiles of their lipid fraction.

Section snippets

Seed material

Date palm fruits were obtained from the National Institute of Arid Zone (Degach, Tunisia). The seeds of the two cultivars under investigation (Deglet Nour and Allig) were directly isolated from 50 kg of date fruit having the same origin, collected at the “Tamr stage” (full ripeness) and kept at 10 °C for a week. The seeds were soaked in water, washed to get rid of any adhering date flesh, and then air-dried. Their relative percentage weight compared with the weight of the fresh fruits was about

Chemical composition of date seed

Table 1 presents the average compositions of Phoenix dactylifera L. date seed of the two studied cultivars. Date pits from Deglet-Nour and Allig cultivars contained 9.4 and 8.6% moisture, respectively. The ash, protein and fat contents (dry weight basis) in Deglet-Nour and Allig seeds were 1.15 and 1.12%; 5.56 and 5.17% and 10.19 and 12.67%, respectively. Accordingly, total carbohydrate content of date pits ranged from 83.1% for Deglet-Nour to 81.0% for Allig. These results were in general

Conclusion

Considering the protein, fat, mineral and carbohydrate contents of date seed, we can conclude that date pits could be used to meet part of the nutritional requirements of animal feeds. This by-product of date processing industries could be regarded as an excellent source of food ingredients with interesting technological functionality that could also be used in food as an important source of dietary fibre.

This preliminary study shows that date seed oils contain high relative percentages of

Acknowledgements

We thank Mr. Fakhfakh Zouheir responsible for U.S.C.R. Microscopy for observations in S.E.M. and Mr. Hammami Mohamed, responsible for U.S.C.R. spectrometry, for chromatographic analysis.

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