الفهرس 
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Abstract
Natural phenolic antioxidants were extracted from Jojoba seed waste in the current research. Defatted jojoba seed meal (JSM), detoxified meal residue (DMR), and jojoba seed shell (JSH) samples were collected using different solvents, including 70/30 (vol/vol) ethanol/water, 70/30 (vol/vol) methanol/water, and 60/40 (vol/vol) acetone/water.
The Folin-Ciocalteu system is used to assess total phenolic content (TPC). In addition, the DPPH radical scavenging and β-carotene linoleic acid bleaching methods were used to assess the antioxidant activity (AA) of solvent extracts in vitro. The oxidative stability of super palm olein (SPO) supplemented with 200ppm JSM and JSH on rancimat at 110°C was assessed by comparing the induction time of SPO supplemented with 200ppm BHT and SPO without antioxidant.
DMR, on the other hand, was measured in the 200-1000ppm range. Furthermore, due to the harmful effects of synthetic antioxidants (by determining the peroxide value, thiobarbitoric acid, and acid value during 28 days of storage at room temperature) and antimicrobial activity (by determining the counts of total bacteria), DMR and JSH were evaluated for their efficiency as antioxidant and antimicrobial agents and use in cake preservation as a natural plant preservative. The effects of DMR400ppm, DMR800ppm, DMR1200ppm, and JSH200ppm on the appearance, colour, odour, taste, texture, and overall acceptability of the cake samples were also assessed and compared to BHT and the control sample.
The obtained results indicate that:-
1) The highest amount of extraction yield is observed with 60% acetone extract of JSM (22.61±0.57%). In addition, the highest total phenolic compounds (TPC) is observed with 60% acetone extract of JSH (163.81±6.88 mg GAE g -1 extract DW).
2) As the concentration increased, DPPH radical scavenging activity (RSA) increased, which is known as antioxidant activity (AA).
3) The radical scavenging activity of BHT was significantly (p<0.05) higher than that of the experimental samples at all concentrations. BHT> JSH> JSM> DMR had the highest RSA (%) of methanolic extract.
4) Results demonstrated also that 70% methanolic and 70% ethanolic extracts of JSH had the best DPPH RSA 81.00% and 80.41%, respectively. On the other hand, 60% acetone extract of DMR had the lowest DPPH free radical scavenging activity 51.30±0.71.
5) Moreover, the presence of phenolic antioxidants in these extracts significantly (P<0.05) decreased the oxidation of β-carotene. The percentage of inhibition of bleaching of β-carotene was significantly (P<0.05) varied from 85.04 to 93.88 for JSM, 61.02 to 67.96 for DMR and 88.92 to 95.78 for JSH. However, the ethanolic extract of JSH showed significantly (P<0.05) the highest inhibition of bleaching of β-carotene followed by the ethanolic extract of JSM (95.78±1.03 and 93.88±0.13 %), respectively. These extracts were more effective than BHT at reducing the oxidation of β-carotene.
6) The 70 %ethanol extract was chosen as the most suitable solvent for the extraction of phenolic compound for the protective β-carotene/linoleic model system oxidation based on the test results of the AA of each extract.
7) In terms of the effect of these extracts on super palm olein stabilisation, the added extract increased the rancimat induction time (IT) of oxidation and the protection factors (PF) of super palm olein at all concentrations (SPO). SPO + JSM200ppm (IT = 21.77 h; PF = 1.20), SPO + JSH 200ppm (IT = 22.43 h; PF =1.24), SPO+ DMR 200ppm (IT = 19.38 h; PF= 1.07), SPO+ DMR600ppm (IT= 21.82 h; PF= 1.21),SPO+ DMR1000ppm (IT= 23.29 h; PF= 1.29), compared to control (IT = 18.06 h; PF = 1.0), and SPO + BHT 200ppm (IT = 20.94 h; PF= 1.16).
8) As a result, at a concentration of 200ppm, the ethanolic extract of JSM and JSH will stabilise SPO. In the rancimat test, they were more successful than BHT. When compared to JSM and JSH, detoxified meal prepared for animal feed (DMR) had lower TPC residue with moderate (% of inhibition activity AA).
9) Furthermore, when compared to the synthetic antioxidant BHT200ppm during 28 days of storage, DMR800ppm, DMR1200ppm, and JSH200ppm showed high antioxidant activity and successful antimicrobial properties for butter cake.
It can be concluded from this study that jojoba seed byproducts are a very promising source of bioactive compounds with antioxidant and antimicrobial. This neglected waste product from an industrial oilseed crop should be given more attention to get optimum benefits for the pharmaceutical (nutraceutical) industry. It’s possible that these extracts may be a good substitute for synthetic antioxidants in protecting vegetable oils like SPO, which contain varying amounts of unsaturated fatty acids. Furthermore, they can be used as a natural antioxidant and antimicrobial in bakery products and other foods, especially those that contain lipid, extending the shelf life of those foods.