Drying Kinetics of Deglet Enour Date Seeds, Antioxidant, Antibacterial, Antidiabetic and Bio-preservative Potencies

Abstract

The effect of four drying temperatures (50, 60, 70 and 80 °C) on drying kinetics, colorimetric parameters, the total phenol, flavonoid, tannin and carotenoid contents and antioxidant activities of date seeds extract (water- acetone- ethanol, v/v/v) was investigated. Drying at 60 °C is the most suitable to preserve color and antioxidants of date seeds. The extract of date seeds dried at 60 °C had the highest phenol (6.6 ± 0.09 g GAE/100 g DM), flavonoid (5.64 ± 0.14 g QE/100 g DM), tannin (9.73 ± 0.16 g CE/100 g DM) and carotenoid contents (0.65 ± 0.002 mg β-carotene E/100 g DM). The extract of date seeds dried at 60 °C shows an interesting α-amylase inhibition and antibacterial activities against eight foodborne pathogens and this was associated to its richness in epicatechin and procyanidin identified by UHPLC-DAD-ESI/MS. The potential bio-preservative activity of the extract, at different concentrations was confirmed in UHT- cow milk matrix model, inoculated with Staphylococcus aureus and monitored for 7 days at 4 °C. Moreover, the addition of 50 and 100 mg/mL of dried date seeds extract showed good overall acceptability scores of non-inoculated milk. The addition of 50 mg/mL of dried date seeds extract significantly (p < 0.05) increased the total phenols, the total flavonoids and enhanced the antioxidant potency of non-inoculated milk.

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ORIGINAL PAPER
Waste and Biomass Valorization
https://doi.org/10.1007/s12649-025-02911-2
Introduction
Achieving a circular bio-economy is among the most sus-
tainable development goals for governments and businesses
worldwide. A circular economy supports multiple societal
needs by developing tools to combat climate change and
minimize biodiversity loss [1, 2]. Revalorization of agro-
industrial fruit and vegetable byproducts, could promote the
achievement of economic development and environmental
protection and the establishing a sustainable ecosystem.
The date palm (Phoenix dactylifera L.) belonging to the
palm family (Arecaceae), remains one of the major fruit
crops produced in arid and semi-arid regions of the world
such as North Africa and the Middle East [3, 4]. Tunisia is
considered as one of the leading date producing countries
[5, 6]. This plant constitutes the main source of remunera-
tion for the people living in Tunisian Sahara [7].
The date seed is the main byproduct generated dur-
ing date processing (date juice, date honey, date jam, date
vinegar, and date pastes). The approximate annual yield of
Statement of novelty: This study presents a methodological
approach allowing to produce bioactive extracts from dried date seeds
(Deglet Enour variety) with a potential valorization as natural bio-
preservative and dietary food supplement. Drying at 60 °C improves
the quality attributes of date seeds powder, the extractability of the
phytochemical and enhances the antioxidant activity of the extract.
The ternary mixture solvent (water: ethanol: acetone) extract of dried
date seeds at 60 °C display anti-diabetic, antibacterial activities and
bio-preservative capacity in milk.
Amal Dbeibia
amaldbeibia@gmail.com
Nourhene Boudhrioua
nourhene.boudhrioua@isbst.uma.tn
1 Laboratory of Physiopathology, Food and Biomolecules,
LR17ES03, Higher Institute of Biotechnology of Sidi Thabet,
University of Manouba, Ariana 2020, Tunisia
2 Research and Technology Center of Energy, B.P. 95 2050,
Hammam-Lif, Tunisia
3 VACPA Boudjebel, Km 2 Route de Menzel Bouzelfa, C42,
Béni Khalled 8021, Tunisia
Abstract
The eect of four drying temperatures (50, 60, 70 and 80 °C) on drying kinetics, colorimetric parameters, the total phenol,
avonoid, tannin and carotenoid contents and antioxidant activities of date seeds extract (water- acetone- ethanol, v/v/v)
was investigated. Drying at 60 °C is the most suitable to preserve color and antioxidants of date seeds. The extract of
date seeds dried at 60 °C had the highest phenol (6.6 ± 0.09 g GAE/100 g DM), avonoid (5.64 ± 0.14 g QE/100 g DM),
tannin (9.73 ± 0.16 g CE/100 g DM) and carotenoid contents (0.65 ± 0.002 mg β-carotene E/100 g DM). The extract of
date seeds dried at 60 °C shows an interesting α-amylase inhibition and antibacterial activities against eight foodborne
pathogens and this was associated to its richness in epicatechin and procyanidin identied by UHPLC-DAD-ESI/MS.
The potential bio-preservative activity of the extract, at dierent concentrations was conrmed in UHT- cow milk matrix
model, inoculated with Staphylococcus aureus and monitored for 7 days at 4 °C. Moreover, the addition of 50 and 100 mg/
mL of dried date seeds extract showed good overall acceptability scores of non-inoculated milk. The addition of 50 mg/
mL of dried date seeds extract signicantly (p < 0.05) increased the total phenols, the total avonoids and enhanced the
antioxidant potency of non-inoculated milk.
Keywords Date Seeds · Drying · Color · Phenols · Antioxidant Activity · α-Amylase Inhibition · Antibacterial
Potency · Bio-preservative · Phenolic Prole
Received: 23 September 2024 / Accepted: 11 January 2025
© The Author(s), under exclusive licence to Springer Nature B.V. 2025
Drying Kinetics of Deglet Enour Date Seeds, Antioxidant, Antibacterial,
Antidiabetic and Bio-preservative Potencies
AmalDbeibia1· RamlaKhiari1· DaouedMihoubi2· NahlaZeghonda3· NourheneBoudhrioua1
1 3
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