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Food Bioscience

journal homepage:www.elsevier.com/locate/fbio Physico-chemical and functional properties of dried male date palmowers

Sirine Karra

a , Haifa Sebii a , Chema Borchani a , Sabine Danthine b , Christophe Blecker b

Hamadi Attia

a , Souhail Besbes a , Mohamed Ali Bouaziz a a

Laboratory of Analysis Valorisation and Food Safety, Department of Biology, National School of Engineers of Sfax, University of Sfax, 3038, Sfax, Tunisia

b

Laboratory of Food Science and Formulation, Gembloux Agro-Bio Tech, University of Liège, 5030, Gembloux, Belgium

ARTICLE INFO

Keywords:

Male date palmowers

Phoenix dactyliferaL.

Nour variety

ABSTRACT

The physico-chemical, microstructure, thermal and functional properties of Deglet Nour male date palmowers

(MDPF) ofPhoenix dactyliferaL. were studied. The main objective was to add value to this discarded by-product

as a functional raw material and assess its suitability to be incorporated into foods. The pollen-freeowers were

dried at 40 °C. Then, a milling step was used to obtain the powdered MDPF. The results showed high amounts not

only of dietarybres (68%), especially insolublebre (64%), but also of proteins (14.8%), which conrmed the

nutritional value of the MDPF and its possible use in dietetic products. The physical properties showed that dried

MDPF were safe from deterioration, had a light colour suitable for incorporation, had an amorphous structure

helpful for preservation and were thermally stable suggesting that MDPF could be a natural stabilizer. Moreover,

MDPF showed interesting functional properties expressed by relatively high swelling values, and water and oil

holding capacities (6.3ml/g dry sample, 4.95 g water/g dry sample and 4.42 g oil/g dry sample, respectively),

which may be helpful in foods to minimize some technical problems (e.g., improving emulsion stability in fatty

products and avoiding syneresis).

1. Introduction

Date palm (Phoenix dactyliferaL.) is a dioecious species with sepa- rate male and female trees belonging to the Arecaceae family. It is a principal source of food for the arid and semiarid regions of the world. Moreover, it is essential to the economy of many oases by providing many other products. In Tunisia, according to the Tunisian Technical Centre of Dates, there are about 4.2 million productive date palms of which 63% are of the Deglet Nour variety. The date palm provides not only dates but also other derivatives that can be used for various tra- ditional and industrial activities, e.g., the roasted date seeds can pro- vide a coee substitute, the trunk is used for carpentry and asrewood, and the palms are found in fences, under roofs and in basketwork. The oasis farmer has to wait for 6 -8yr until therstowers to know the sex of the plants (Aberlenc-Bertossi, 2012). Thereafter, if the tree is male, that will minimize date yield. However, male date palmowers are needed for pollination. In general, 2 to 4 male trees that are good pollinators are sucient to pollinate 100 female trees (Sedra, 2003) which means that farmers keep about 3% of male date palm. According toHalimi (2004), a good pollinator palm could provide 500g of pollen,

and relying on laboratory based estimates (result not shown), bothpollen andower production mean values represent 2 and 50%, re-

spectively, of the harvest. Consequently,12.5kg ofowers could be provided/male date palm. If 3% of date palms are male, the annual production ofowers in Tunisia could reach 1575 tonnes/yr. These are currently discarded or used in animal feeding (Rhouma, Nasr, Ben Salah, & Allala, 2005). Actually, the maleowers are usually creamy white with a characteristic odour of bread dough. They are arranged on an abundantly branched spadix surrounded by a large single spathe (El

Hadrami & Al-Khayri, 2012

). Eachower has a slightly elongated shape and consists of a short calyx, three welded sepals, and a corolla com- posed of three petals and 6 stamens (Sedra, 2003). Many studies have used the female date palm, whereas there is little data on the male date palm, especially of the male date palmowers (MDPF) ofP. dactylifera L. The current work aims at characterizing the pollen-free MDPF by identifying the composition, the structure (X-ray), the microstructure (SEM), the thermal stability (TGA and DSC) and the functional prop- erties (solubility index, swelling capacity, WHC and oil holding capa- city). This study is arst step in extracting functional compounds and determining if MDPF is potentially useful in the food industry. Received 26 March 2018; Received in revised form 20 July 2019; Accepted 21 July 2019

Corresponding author. Laboratory of Analysis Valorisation and Food Safety, Department of Biology, National School of Engineers of Sfax, Soukra road, 3038, Sfax,

Tunisia

E-mail address:karra.sirine@gmail.com(S. Karra).

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