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Titre : Functional characterization of alkaline digested date-pits : residue and supernatant fibers.

Auteur : Al-Hasniyah, Muna Khalfan.

Université de soutenance : Sultan Qaboos University

Grade : Master of Science (MS) in Food Science and Nutrition 2021

Résumé partiel
Date-pits are waste from the date-fruit processing factory. The objective of this study was to develop date-pits fibers having hygroscopic characteristics with molecular structural damage and easy to digest. In this work, two types of date-fibers were prepared by alkaline digestion of date-pits at 70oC for 24 h. Two fractions of date-pits fibers were developed, one from the residue and other one from the supernatant after digestion of date-pits. The physico-chemical and molecular characteristics, proton mobility, and health functionality of these fiberes were measured. Date-pits showed FTIR absorption peaks at 3422 cm-1 (O-H stretching), 2924 cm-1 (asymmetric C-H stretching), 2856 cm-1 (symmetric C-H stretching), 1744 cm-1 (C=O vibration acetyl and ester linkages), 1656 cm-1 and 1638 cm-1 (C=C vibration aromatic region), 1532 cm-1 and 1458 cm-1 (C=C stretching of aromatic skeletal mode). Other peaks were at 1384 cm-1 (C-H stretching of cellulose), 1252 cm-1 (C-O-H deformation and C-O stretching of phenolic), 1146 cm-1 (C-O-C vibration of cellulose and hemicellulose), 1113 cm-1 , 1059 cm-1 (C-O stretching vibration of cellulose and hemicellulose), 885 cm-1 , 814 cm-1 , 610 cm-1 , and 495 cm-1 , respectively. The alkaline treated residue and supernatant date-pits fibers showed similar peaks. The structural damage of the residue and supernatant fibers was evaluated from the missing and new peaks, and increased or decreased intensity values at specific peaks. This indicates that treated fibers could have the ability to make inter links when it is used in food products and other applications. Therefore, residue and supernatant fibers showed higher hygroscopicity as compared to the date-pits powder (p<0.05), while there was no difference between them (p>0.05). Similar trends were also observed for water absorption and solubility, and showed higher interactions of the fibers with water as compared to the date-pits. Proton mobility was measured by Low-Frequency Nuclear Magnetic Resonance (LFNMR) and three pools of the protons were identified : rigid protons, semi-rigid protons, and mobile protons..

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