Document

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

Identifier
Al-Hasniyah, Muna Khalfan (2021). Functional characterization of alkaline digested date-pits : residue and supernatant fibers (Master thesis, Sultan Qaboos University, Muscat, Oman).
Publisher
Sultan Qaboos University.
Gregorian
2021
Language
English
English abstract
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. At low similar moisture content (1.5 g/100 g sample), the relaxation time of the rigid protons of residue (21.8 s) and supernatant (24.3 s) fibers xi was significantly higher as compared to the date-pits (11.1 s) (p<0.05). In the case of semi-rigid protons, relaxation tioms of the residue (0.22 ms) and supernatant (0.33 ms) fibers decreased as compared to the date-pits (1.30 ms). Similarly, relaxation times of mobile protons decreased in the cases of residue (7.01 ms) and supernatant (9.94 ms) fibers as compared to the date-pits (59.78 ms). It is expected that the relaxation time of protons in the macromolecules should be increased (i.e. higher mobility) with structural damage unless protons are interfering each other. The decrease of relaxation times in the case of semi-rigid and mobile protons indicated that these pools of protons were interfering each other causing a decrease instead of increase in relaxation. In the case of same water activity (i.e. 0.90) samples, rigid proton showed similar trends as the samples with similar moisture content. However, in the case of semi-rigid protons, both residue and supernatant showed increased relaxation times, while in the case of mobile protons, relaxation time decreased for residue and it increased for supernatant. The moisture content of residue and supernatant fibers was 3.8 time higher than the datepits. Therefore, large pools of water protons were exited with the protons of the macromolecules and interacted differently. In general, alkaline treatment damaged the molecular structure of the fibers and affected their mobility. The supernatant fibers were effective in reducing in-vitro aluminum toxicity as observed by the decrease of oxidized glutathione (OG). In the case of 0.01 g/ml supernatant fibers, OG increased with the reaction time at 37oC, while OG decreased in the cases of 0.03 and 0.05 g/ml fibers addition. However, reduction of toxicity reached equilibrium after 30 min and remained until 2 days as used in this study. Overall, the improved functionality observed in the residue and supernatant fibers could be used to determine the proper applications of these fibers in different products, such as fiber supplements, use of fibers as ingredient in food products, and bio-composites. In the case of bio-composites, date-pits could be used when non-hydroscopic and low water soluble rigid particles are required as fillers. The residue and supernatant fibers could be used in food products due to its structural damage and higher ability to interact with the other food components; and easy digestibility.
Arabic abstract
نوى التمر هو نفاية من مصنع معالجة التموروالفاكهة. كان الهدف من هذه الدراسة هو تطوير ألياف نوى التمر لديها خصائص استرطابية مع تلف بنيوي ويكون سهل الهضم. وفي هذه الدراسة تم تحضير نوعين من ألياف التمر عن طريق الهضم القلوي لنوى التمر عند 70 درجة سليزية لمدة 24 ساعة. تم تطوير نوعين من ألياف نوى التمر بعد الهضم القلوي، أحدهما من البقايا واالخر من المادة الطافية. تم قياس الخصائص الفيزيائية والكيميائية والجزيئية، وحركة البروتون والوظائف الصحية لهذه األلياف. -1 أظهرت نوى التمر قمم االمتصاص عند 3422 سم سم 2924 ،)O-H تمديد )1- )تمدد H-C غير المتماثل( سم 2856 1- سم 1744 ، )متماثل C-H تمدد )1- )O=C اهتزاز أسيتيل وروابط استر( ، 1656 سم 1- و 1638 -1 سم -1( المنطقة العطرية لالهتزاز C=C ،)1532 سم )C=C تمدد وضع الهيكل العظمي العطري(، 1458 سم - 1 )C=C تمدد وضع الهيكل العظمي العطري(، 1384 سم 1- )H-C تمتد من السليلوز(، 1252 سم 1- C- تشوه) H-O وتمدد ثاني أكسيد الكربون للفينول( ، 1146 سم 1- )اهتزاز C-O-C من السليلوز والهيميسليلوز( ، 1113 -1 سم سم 1059 ، 1- -1( اهتزاز تمدد ثاني أكسيد الكربون من السليلوز وهيميسليلوز(، 885 سم سم 814 ، 1- 610 ، -1 سم -1 ، و 495 سم ، على التوالي. أظهرت المعالجة القلوية لبقايا األلياف واأللياف الطافية قمم مماثلة. تم تقييم الضرر الهيكلي للبقايا واأللياف الطافية من خالل القمم المفقودة والجديدة، وزيادة أو نقصان قيم الشدة عند قمم معينة. يشير هذا إلى أن األلياف المعالجة يمكن أن يكون لها قدرة أكبر على إنشاء روابط بينية عند استخدامها في المنتجات الغذائية والتطبيقات األخرى. لذلك أظهرت بقايا األلياف واأللياف الطافية أعلى استرطاب مقارنة بنوى التمر)05.0
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Al-Shaaibyah, Siham Nasser Khamis.
Sultan Qaboos University.
2022