Structural, functional, and biological properties of potato peel oligosaccharides

Accepted Manuscript Structural, functional, and biological properties of potato peel oligosaccharides

Khawla Ben Jeddou, Fatma Bouaziz, Claire Boisset Helbert, Oumèma Nouri-Ellouz, Sameh Maktouf, Semia EllouzChaabouni, Raoudha Ellouz-Ghorbel PII: DOI: Reference:

S0141-8130(17)34542-7 https://doi.org/10.1016/j.ijbiomac.2018.02.004 BIOMAC 9054

To appear in: Received date: Revised date: Accepted date:

17 November 2017 18 January 2018 1 February 2018

Please cite this article as: Khawla Ben Jeddou, Fatma Bouaziz, Claire Boisset Helbert, Oumèma Nouri-Ellouz, Sameh Maktouf, Semia Ellouz-Chaabouni, Raoudha EllouzGhorbel , Structural, functional, and biological properties of potato peel oligosaccharides. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Biomac(2017), https://doi.org/10.1016/j.ijbiomac.2018.02.004

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ACCEPTED MANUSCRIPT Structural, functional, and biological properties of potato peel oligosaccharides

Khawla Ben Jeddou1,7, FatmaBouaziz2, Claire Boisset Helbert3,Oumèma Nouri-Ellouz1,4,

Ecole Nationale d'Ingénieurs de Sfax, Laboratoire d'amélioration des plantes et valorisation

des agro-ressources, BP 1173, 3038 Sfax, Tunisia.

Ecole Nationale d'Ingénieurs de Sfax, Unité enzymes et Bioconversion, BP 1173, 3038 Sfax,

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Tunisia. 3

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Sameh Maktouf5,Semia Ellouz-Chaabouni1,2,6and Raoudha Ellouz-Ghorbel2,6

Service de Chromatographie, Purification et analyse de polysaccharides CERMAV-CNRS,

Institut Préparatoire aux Etudes d'Ingénieurs de Sfax, Département de Biologie et Géologie,

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601 rue de la Chimie,38041 Grenoble cedex 9, France

BP 1172, 3018 Sfax, Tunisia.

Institue de l’olivier, Laboratoire d’amélioration de la productivité de l’olivier et la qualité du

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produit.

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Université de Sfax, ENIS, Unité de Service Bioréacteur couplé à un ultrafiltre, Route de

Soukra km 4, BP 1173, 3038 Sfax, Tunisia. 7

Corresponding Author: Khawla Ben Jeddou

Tel: +216 96961537 E-mail:[email protected]

ACCEPTED MANUSCRIPT Abstract: Enzymatic hydrolysis of water-soluble polysaccharides from potato peel waste (PPPW) generates low molecular weight oligosaccharideswith a yieldof 63%. The oligosaccharides generatedfrom potato peel polysaccharides (OPPP)were purified bySuperdex-30column. The results showedthe presence of 8 peaks(OPPP1-OPPP8).The identification of all thefractions

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by chromatography analysis(GC-FID) illustrated that the most prominent residues were

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glucose with traces of galactose, arabinose and rhamnose. Finally, mass spectrometry

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(MALDI-ToF-ToF) analysis showed that the generated oligosaccharides were heterogeneous and contained different degree of polymerization (DP). Indeed, the obtained oligosaccharides

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fractions OPPP3, OPPP4, OPPP5, OPPP6 and OPPP7 were compose of the following degree of polymerization DP5; DP4; DP2;DP1 and DP1, respectively. Potato peel oligosaccharides

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(OPPP) efficiency were tested using different concentrations in functional properties. The results showed good foaming and emulsion properties. This study also aimed to investigate

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the antioxidant activity of OPPP. The items explored included the DPPH radical-scavenging

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capacity (IC50 OPPP= 2.5 mg/mL), reducing power (OD: 0.622±0.032 at a concentration of 20 mg/mL), β-carotene bleaching inhibition activity (45.335±3.653%), and also the ABTS

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radical scavenging activity (14.835±0.1%).These findings indicate that potato peel oligosaccharides have potent antioxidant activities. Hence, one can suggest that these

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oligosaccharides might contribute as additives in food, pharmaceutical and cosmetic preparations. Keywords:

water-soluble

polysaccharides;

enzymatic

hydrolysis;

purification; identification; functional properties; antioxidant activity

oligosaccharides;

ACCEPTED MANUSCRIPT 1. Introduction Food quality is defined in terms of consumer acceptability: flavor, color, texture characteristics and nutritional value.Several attempts have been made to control food instability problems at different stages of manufacture and during storage. Synthetic antioxidants such as butylatedhydroxyanisole (BHA),butylatedhydroxytoluene (BHT)and tert-

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butyl hydroquinone (TBHQ) have been used as food preservatives[1].

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Regarding the health hazard and the toxic effects associated with these synthetic antioxidant molecules as well as their restriction in some countries[2,3],their replacement by natural

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molecules has been widely investigated.Polysaccharides have long been used in the food and

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medical industries. They are non toxic and biocompatible polymers that play important roles as dietary free radical scavengers for the prevention of oxidative damage. In general, many

novel promising antioxidants[4,5].

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plant polysaccharides have exhibited strong antioxidant properties and can be explored as

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However, regarding the critical uses of these complex polymersand due to the complexity oftheir structure, the therapeutic fields gave increasing importance to oligosaccharides to replace polymeric structures[6].

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Oligosaccharides can improve quality and enhance nutritional value of final food products

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due to their technological and nutritional features ranging from their capacity to improve texture to their effect as dietary fibers. For this reason, they are among the most studied ingredients in the food industry. The use of natural oligosaccharides as food additives has been a reality since the food industry understood their potential technological and nutritional applications. Currently, the replacement of traditional ingredients and/or the synergy between traditional ingredients and oligosaccharides are perceived as promising approaches by the food industry[4].

ACCEPTED MANUSCRIPT The entrance of this new generation of food additives in the market, often claiming health and nutritional benefits, imposes an impartial analysis by the legal authorities regarding the accomplishment of requirements that have been established to introduce novel ingredients/food, including new oligosaccharides. It was previously reported that oligosaccharides generated by enzymatic or chemical

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hydrolysis of the monostromanitidum polysaccharide exhibit potent biological activities such

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as glucose oligomers acting as anticancer drugs[7].

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Glucans are a large group of homopolysaccharides, distributed widely in nature. Glucans such as a linear β1–4 glucan (cellulose) and α glucan (starch, glucogen)are the most important

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energy storage substances for both animals and plants. Conversely, β-glucans cannot be universally used as energy source because only herbivores can digest them. However, β-

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glucans appear to be recognized as non-self molecules by the innate and adaptive immune systems [8] and may, therefore, be effective in the treatment of cancer, including human

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leukemia [9], microbial infections, hypercholesterolemia, and diabetes [10,11, 12]; therefore,

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β-glucanshave the potential to serve as medicinal supplements. Potato peels are rich in substances with high added value,especially polysaccharides [13].

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Hence, in the present study and for the first time, oligosaccharides from polysaccharide potato

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peels (OPPPs) were first prepared enzymatically from potato peel polysaccharides, then their monosaccharide compositions were determined using a gas chromatography–flame ionization detector, and their chemical structures were determined using mass spectrometry. Afterwards, the antioxidant activities of the OPPPs were assessed. Finally, their functional properties were demonstrated.

2. Materials and methods 2.1. Plant material and chemicals

ACCEPTED MANUSCRIPT Fresh potato peel waste (PPW) were obtained from the variety Spunta. They were washed, dried at 50◦C for 48 h, ground and sieved to obtain particles between 500 and 1000 µmin size. They were then stored at room temperature (25 ± 5◦C) until used. Oligosaccharides were generated enzymatically from the polysaccharides extracted from potato peel powder. DNS (3,5-dinitro salicylic acid), DPPH (1,1-diphenyl-2-pycrilhydrazil), BHA, β-carotene, L-

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ascorbic acid, phosphomolybdate and ABTS were purchased from Sigma Chemical Co. (St

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Louis, MO). All other chemicals (potassium ferricyanide, trichloroacetic acid (TCA), ferric-

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chloride, sodium hydroxide, FeCl3, and other solvents) were of analytical grade.

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2.2. Microorganism

The microorganism Bacillus sp. UEB-S (accession number HM10077) is an amylase-

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producing bacterium isolated from theBen Garden region, a Tunisian southern area [14].

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2.3. UEB-S enzyme production at shake flask scale

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Inoculation was performed as follows: One isolated colonywas dispersed in a 250 mL erlenmeyer flask containing 50 mL LB medium and incubated for 14 h at 37◦C in a rotary

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shaker set at 200 rpm. Amylase production by the Bacillus sp. UEB-S strain cultures was

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conducted at 37◦C in 250 mL flasks containing 50 mL of optimized culture medium[15]. 2.4. Extraction of oligosaccharides from potato peel (OPPP) Polysaccharides extracted from potato peel waste (PPPW) [13](1–4%) were mixed with buffer at different pH values(3; 4; 5.5; 6; 7 and 8) and treated with UEB-S enzyme (1001300U) at different temperatures (40, 50, 60, 70 and 80°C). Samples were with drawn from the reaction at different time intervals (1h-24h). These samples were cooled and then centrifuged for 10 min at 8000 rpm. The supernatants were assayed for reducing sugar by the 3,5-dinitrosalicylic acid (DNS) method. After enzymatic hydrolysis of PPPW, the proteins

ACCEPTED MANUSCRIPT were removed from the supernatant. The resulting solution was centrifuged at 7000 rpm for 10 min. To remove the insoluble fraction containing undigested polysaccharides, the supernatant was precipitated with 2 volumes of ethanol (91%) for 24 h at room temperature. The oligosaccharide fraction dissolved in the supernatant was concentrated in a rotary

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evaporator at 40°C. The remaining solution was freeze-dried overnight and stored at -20°C. 2.5. Thin-layer chromatography (TLC) of hydrolysates

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The enzymatic hydrolysates were analyzed by thin-layer chromatography (TLC). Sugar

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solution was applied to a percolated silica gel plate (Merck). The chromatoplate was placed in

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a TLC chamber containing the developing solvent: chloroform/acetic acid/water (6:7:1 byvolume). It was dried under warm air then sprayed with a mixture of ethanol (95%) and

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H2SO4(5%) and finally heated for 10 min at105◦C to visualize the colored spots.

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2.6. OPPP purification

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The purification of OPPPs was performed using a KNAVER low pressure pump, differential refractometer IOTA. Molecule separation was performed on a Superdex TM peptide10/300 GL (Superdex-30) with optimum ranks of separation between 100-7000 Da. 167 mg/mL of

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oligosaccharides were prepared and filtered over 0.2 µm before injection. The content of each

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sample was then separated according to size. Oligosaccharides were eluted using ammonium carbonate (0.1M) at 1.2 mL/min. All fractions were collected and freeze-dried overnight. 2.7. Monosaccharide analysis by GC-FID The elemental monosaccharide composition (molar ratios) of the purified oligosaccharides was determined using a modified method of Kamerling et al. [16]. 50 µg myo-inositol, used as internal standard, was added to 1 mg lyophilized oligosaccharide fractions (OPPP1 to OPPP2). The mixture was hydrolyzed for 4 h at 100◦C, in a screw glass tube, using 500 µL methanolic HCl (3 N). After cooling to room temperature, all fractions were neutralized with

ACCEPTED MANUSCRIPT 10 mg silver carbonate. The methyl glycosides generated were then converted to their corresponding volatile trimethylsilyl derivatives: the reaction took place by adding 100µL pyridine and 100 µL derivatization reagent, bis (tri-methylsilyl) trifluoroacetamide (BSTFA) + 1% trimethylchlorosilane (TMCS) (Supelco), and incubated at room temperature overnight. After solvent evaporation under nitrogen flow, the per-O-trimethylsilylmethyl glycosides

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generated were resuspended in 500 µL dichloromethane,and analyzed using a gas

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chromatography-flame ionization detector (GC-FID). An Agilent GC 6850A instrument equipped with an HP-5MS capillary column (30 m length, 0.25 mm diameter and 0.25 µm

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film thickness) was used. The GC oven temperature was set at 120◦C,increased first to 180◦C

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at 3◦C/min, then increased to 200◦C at 2◦C/min and held for 5 min. The helium carrier gas

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flow was set at 1.5 mL/min and the injection volume was 0.1µL. 2.8. Mass spectrometry of oligosaccharide fractions

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Mass spectra were performed in the mass spectrometry service of the Molecular Chemistry

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Institute of Grenoble (ICMG). The spectrometer ESQUIRE 3000+(Bruker Daltonics) was used for the electrospray ionization method kind (ESI) and the equipment Bruker MALDI-

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ToF-ToF Speed (BrukerDaltonics) was used for the MALDI-TOF technique. Lyophilized samples were diluted in water and deposited on a matrix DHB (2,5-dihydroxybenzoic acid

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(2,5-DHB)).

2.9. Functional properties 2.9.1. Foaming properties Foam capacity (FC) and foam stability (FS) of OPPP were determined according to the method of Shahidi et al.[17]. Twenty milliliters of OPPP solution at different concentrations (0.5, 1, 2, 4 and 6%; w/v) were homogenized using a Moulinex R62 homoge-nizer (Organotechnie, Courneuve, France) to incorporate the air for 1 min at room temperature (20

ACCEPTED MANUSCRIPT ± 1◦C). Whipped samples were then immediately transferred into a graduated cylinder, and the total volume was measured immediately and at 30 min after whipping. Foam expansion was expressed as percentage of volume increase after homogenization at 0 min. 2.9.2. Emulsion properties

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The emulsion capacity (EC) and emulsion stability (ES) of the oligosaccharide fractions were investigated according to the method of Yasumatsu et al.[18] with some modifications. OPPP

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suspensions (10 mL) at different concentrations (1, 2, 4 and 6%) were mixed with 3 mL of

min and then centrifuged for 10 min at 8000 × g.

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soybean oil using a Moulinex R62 homogenizer (Organotechnie, Courneuve, France) for 1

ℎ𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑒𝑚𝑢𝑙𝑠𝑖𝑜𝑛 𝑙𝑎𝑦𝑒𝑟 𝑡𝑜𝑡𝑎𝑙 ℎ𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑

) ∗ 100

Eq.(1)

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𝐸𝐶, % = (

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The emulsion capacity (EC) was calculated according to equation (1).

The ES was determined by heating the emulsion at 80°C for 30 min, cooling with tap water

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for 15 min, and centrifuging at 8000 g for 5 min.

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ES was calculated according to equation (2). 𝐻𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑟𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔 𝑒𝑚𝑢𝑙𝑠𝑖𝑜𝑛 𝑙𝑎𝑦𝑒𝑟

𝐸𝑆, % = (

𝑡𝑜𝑡𝑎𝑙 ℎ𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑

) ∗ 100

Eq.(2)

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2.10.Antioxidant activity

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2.10.1.Total antioxidant activity The total antioxidant activity of the OPPP fractions was measured by the phosphate molybdate test according to the method of Prieto et al.[19]. The assay is based on the reduction of Mo (VI) to Mo (V) by the extract and subsequent formation of a green phosphate/Mo (V) complex at acidic pH. The reaction consisted of mixing 0.1 mL of oligosaccharide solutions prepared at different concentrations (0.5 to 10 mg/mL) with 1 mL of reagent solution (0.6 M sulfuric acid, 28 mM sodium phosphate and 4 mM ammonium molybdate). The reactions took place at 95◦C for 90 min. After cooling to room temperature,

ACCEPTED MANUSCRIPT the absorbance was measured at 695 nm against a blank containing 1 mL reagent solution and 0.1 mL water, incubated under the same conditions as the samples. The antioxidant activity was expressed as ascorbic acid equivalent using a standard curve. 2.10.2. DPPH radical scavenging activity

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The DPPH radical-scavenging capacities of OPPP was determined as described by Saleh et al. [20]. A volume of 500 µL of each sample at different concentrations (1 to 5 mg mL−1) was

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added to 375 µL of 99% ethanol and 125 µL of DPPH solution (0.02% in ethanol) as free

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radical source. The mixtures were shaken and then incubated for 60 min in a dark room at room temperature. Scavenging capacity was measured spectrophotometrically (UV mini

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1240, UV/vis spectrophotometer, SHIMDZU, China) by monitoring the decrease in

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absorbance at 517 nm. In its radical form, DPPH has an absorption band at 517 nm which disappears upon reduction by an antiradical compound. Lower absorbance of the reaction mixture indicated higher DPPH free radical-scavenging activity. BHA was used as positive

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control. The anti-radical activity is determined using the formula: DPPH scavenging activity (% )= ((Acontrol- Asample) / Acontrol) *100

Eq.(3)

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where Acontrol and Asample represent the absorbance of the control and the sample, respectively. 2.10.3. Measurement of reducing power

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Reducing capacity was measured as described by Yildirim et al. [21]. Briefly, 0.5 mL oligosaccharide solution, 1.25 mL phosphate buffer (0.2 M, pH 6.6), and 1.25 mL potassium ferricyanide (1%, w/v) were mixed and incubated at 50◦C for 30 min. After cooling to room temperature, 1.25 mL trichloroacetic acid (10%, w/v) was added to the reaction mixture and centrifuged. Then, 1.25 mL supernatant solution was mixed with 1.25 mL distilled water and 0.25 mL fresh ferric trichloride (FeCl3, 0.1%, w/v). Finally, the reaction mixture was shaken and its absorbance was detected at 700 nm against a blank (water was used instead of

ACCEPTED MANUSCRIPT oligosaccharide solution). The absorbance of the reaction mixture indicates the reduction capacity of the sample. BHA was used as the reference antioxidant. 2.10.4. β-Carotene-linoleic acid assay Antioxidant activity was assayed using the β-carotene bleaching method described by Koleva et al.[22].A stock solution of β-carotene/linoleic acid mixture was prepared by dissolving 0.5

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mg of β-carotene, 25µL of linoleic acid and 200µL of Tween 40 in 1 mL of chloroform. The

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chloroform was evaporated under vacuum at 45◦C; 100 mL distilled water were then added,

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and the resulting mixture was vigorously stirred. The emulsion obtained was freshly prepared before each experiment. An aliquot (2.5 mL) of the β-carotene-linoleic acid emulsion was

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transferred to tubes containing 0.5 mL oligosaccharide fractions (10 to 50 mg/mL). Following

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incubation for 2 h at 50◦C, the absorbance of each sample was measured at 470 nm (UV mini 1240, UV/vis spectrophotometer, SHIMDZU,China). BHA was used as positive standard. A control consisted of 0.5 mL distilled water instead of the sample solution. BHA was used as

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positive standard.The antioxidant activities of OPPP were evaluated in terms of bleaching of

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β-carotene using the following formula:

𝑨

−𝑨

𝑨𝒏𝒕𝒊𝒐𝒙𝒊𝒅𝒂𝒏𝒕 𝒂𝒄𝒕𝒊𝒗𝒊𝒕𝒚 (%) = (𝟏 − [𝑨𝒔𝒂𝒎𝒑𝒍𝒆(𝟎𝒉)−𝑨𝒔𝒂𝒎𝒑𝒍𝒆(𝟐𝒉) ]) ∗ 𝟏𝟎𝟎 Eq(4) 𝒄𝒐𝒏𝒕𝒓𝒐𝒍(𝟐𝒉)

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𝒄𝒐𝒏𝒕𝒓𝒐𝒍(𝟎𝒉)

Where Asample (0h): absorbance of the sample at t = 0,A sample (2h): absorbance of the sample at t

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= 2 h, A control (0h): absorbance of control at t = 0, A control (2h): absorbance of control at t = 2 h. 2.10.5. Free radical-scavenging ability usinga stable ABTS radical cation (TEAC) ABTS radical assay was used to evaluate the ability to scavenge free ABTS radicals, based on the protocol of Re et al. [23] with some modifications. ABTS radical cations (ABTS.+) were prepared by reacting a 7.4 mM ABTS stock solution with 2.45 mM potassium persulphate (1:1, v/v), after which the mixture was kept overnight (12-16 h) in the dark at room temperature. The ABTS radical solution was diluted with distilled water to an absorbance of

ACCEPTED MANUSCRIPT of 0.700 (± 0.02) at 734 nm and equilibrated at 30°C. A reagent blank reading was taken (A0). A 3 mL aliquot of the diluted sample was added to 20 µl of each of the above-prepared radical solutions and protected from light for 6 min. The ABTS.+ scavenging activity (in %) was given by (1 − A/A0) × 100%, where A and A0 represent the absorbance values of ABTS + solution with and without the test samples. All determinations were performed in duplicate.

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Trolox ((6-hydroxy-2,5,7,8- tetramethylchroman-2-carboxylic acid), a water-soluble analog of

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vitamin E) was used as standard.

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2.11. Statistical analysis

All experiments were carried out in triplicate, and average values with standard deviation

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errors are reported. They were statistically analyzed using the SPSS software (version 17.0;

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SPSS Inc., Chicago, IL, USA) using the Duncan test performed after analysis of variance (ANOVA).

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3. Results:

3.1. Hydrolysis of potato peel polysaccharides It is well known that biological properties of oligosaccharides are influenced by their

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monosaccharide composition and length[24,6].

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Potato peel polysaccharide hydrolysis measured in terms of degree of hydrolysis, is an important process to obtain oligosaccharides with interesting biological activities. Different parameters were optimized such as enzyme content, temperature, pH, polysaccharide concentration and extraction time. 3.1.1. Effect of enzyme content The selection of the specific activity of enzyme extract is a first crucial step for parameter optimization. Fig. 1A shows that the hydrolysis yield of PPPWs increases with increasing enzyme content. Indeed, ahydrolysis yield of 43.6±0.566% was obtained using 1000 U/mL of

ACCEPTED MANUSCRIPT amylase activity. Beyond that, the concentration of the extracted oligosaccharides was almost constant. 3.1.2. Effect of temperature Temperature is the most important factor in the extraction of heat-sensitive compounds. Along with the increase in temperature, the rate of solvent diffusion and the intensification of

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mass transfer result in dissolution of thecomponents. The hydrolysis yield of extracted

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oligosaccharides increased from 44.1±0.042 to 62.08±0.29% when the temperature of

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hydrolysis was increased from 40 to 50°C as reflected in Fig. 1B. After that, the concentration of the extracted oligosaccharides decreased. Indeed, increasing the temperature beyond

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certain values might promote possible concurrent decomposition of oligosaccharides [25]. 3.1.3. Effect of pH

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The pH profile of the oligosaccharide hydrolysis is presented in Fig. 1C. The results show that the hydrolysis yield increases with increasing pH value. An optimum extraction yield was

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observed at pH = 5.5.

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3.1.4. Effect of polysaccharide concentration As shown in Fig.1D, the use of 1% potato peel polysaccharides leads to a maximum

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hydrolysis yield of 63.6±3.96%. 3.1.5. Effect of extraction time

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The range of extraction time was designed based on the practical and economical aspects. The effect of time on the release of oligosaccharides extracted is shown in Fig. 1E. The hydrolysis yield of oligosaccharides increased with time and reached 62.93% after 8 h of hydrolysis. Beyond that, the concentration of extracted oligosaccharides was almost constant. The analysis of the enzymatic hydrolysate by TLC at different time intervals (1h-24h)(Fig. 1F) revealed that potato peel oligosaccharide hydrolysates contain glucose(G1), maltose (G2), maltotriose (G3), maltotetraose (G4) and maltopentose (G5).Fig. 1A also shows that the same

ACCEPTED MANUSCRIPT hydrolysis products were obtained after 1 h of hydrolysis. Hence,the extraction time was fixed at 1 h. The optimum conditions for hydrolysis of potato peel polysaccharides were therefore established to be specific enzyme activity of 1000 U/ mL, temperature of 50°C, pH value of 5.5, substrate concentration of 1% and extraction time of 1 h. Bouaziz et al.[4] reported that

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the optimum conditions for the hydrolysis of almond gum polysaccharides are: almond gum

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polysaccharide concentration at 1%, specific activity of enzymatic extract of 3.83 unit/mg and

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hydrolysis time of 90 min of incubation.

The optimum potato peel oligosaccharide extraction yield was 50%. This yield was higher

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than that of oligosaccharides generated from almond gum polysaccharides (33.5%) [4]. However this extraction yield was lower than that of the rhamnogalacturo-oligosaccharides

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obtained from potato pectic polysaccharides using multi-enzymatic preparationswith yields of 93.9% [26].

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3.2.OPPP purification

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The oligosaccharides generated by enzymatic hydrolysis of potato peel polysaccharides were purified. Fig. 2 shows the presence of 8 peaks (OPPP1-OPPP8). For each peak, the

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corresponding fractions were collected from the gel filtration Superdex-30,lyophilized, and their monosaccharide composition and structure assessed.

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3.3.Monosaccharides of OPPP analysis by GC-FID Different fractions eluted from the gel filtration Superdex-30 were analyzed by gas chromatography analysis (GC-FID) of trimethylsilyl derivatives after methanolysis of the OPPP

fractions,

to

determine

their

monosaccharide

compositions.

Trimethylsilyl

monosaccharide derivatives were used as reference.In particular, Fig.3 and Supplementary material 1 show that all fractions were composed of especially glucose at a molar ratio of 1. Galactose was also present in the OPPP fractions in lower amounts. An exception was noted

ACCEPTED MANUSCRIPT in fraction 7. Indeed, its molar ratio of galactose was 0.33. The OPPP fractions contained traces of rhamnose and arabinose. The results obtained also illustrate that fraction 8 was composed only of glucose.Therefore, we can conclude that glucose was present in the backbone and thatsome residues of galactose, rhamnose and arabinose may be in the position of the branched structure of OPPPs. It was previously reported that the galactose (58.9–

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91.2%, w/w) was the main monosaccharide of galactose-rich oligosaccharides generated from

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potato rhamnogalacturonan I pectic polysaccharides by enzymatichydrolysis while arabinose

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represented 12–15% [26]. Bouaziz et al.[4] reported that oligosaccharides of almond gum (OAG) are mainly composed of galactose and arabinose with traces of xylose, rhamnose,

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glucose and mannose. Our results are in disagreement with those obtained by [27]. Indeed, these authors reported that the polysaccharides in potato pulp are composed mainly of

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arabinogalactan-rich rhamnogalacturonan-I (RG-I), homogalacturonan (HG), cellulose and hemicellulosicfractions. Ben Jeddou et al.[13] demonstrated that the extracted polysaccharides

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from hetero-β glucan.

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(PPPWs) contain only 10.8 ± 0.02% starch. In conclusion,our oligosaccharides were obtained

3.4.Mass spectrometry of oligosaccharide fractions

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After the purification and the identification of monosaccharide compositions, the potato peel oligosaccharide fractions (OPPP3, OPPP4, OPPP5, and OPPP6) were subjected to mass

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spectrometry (MS) analyses. The results of these analyses are presented in Fig.4 and show that the unpurified oligosaccharides (OPPPs) contain heterogeneous oligomers of DP≤ 20 (Fig.4A). After purification, the concentration of low DP oligomers increased substantially, confirming the presence of larger oligomers in the original samples. The result obtained presented in the Fig.4B shows that the potato peel oligosaccharide fraction OPPP3 was composed of two oligosaccharides with the following molecular weights 828 Da and 504 Da which correspond to oligomers with the polymerization degree of DP5 and DP3, respectively.

ACCEPTED MANUSCRIPT In addition, Fig.4C, shows that the oligosaccharide fraction OPPP4 has a molecular weight of 666 Da which indicates that this oligosaccharide has a degree of polymerization of 4 (DP4). Besides, Fig.4D and 4E showed that the potato peel oligosaccharide fractions OPPP5 and OPPP6 present the lowest molecular weights of 342 Da and 180 Da, respectively. Consequently, the oligosaccharide OPPP5 has a degree of polymerization of 2 (DP2) and the

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oligosaccharide OPPP6 has a degree of polymerization of 1 (DP1).

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These data are in good agreement with the resultsof Gómez et al.[28] who extracted pectins

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and pectic oligosaccharides derived from lemon peel wastes (LPW). In fact, they reported that after enzymatic processing of LPW, the concentration of low DP oligomers increased,

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confirming the presence of larger OGalA (oligogalacturonides) in the original samples. Based on the high content of the four oligosaccharide fractions (OPPP3, OPPP4, OPPP5 and

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OPPP6) in the crude oligosaccharides these fractions were mixed and their functional properties and also their antioxidant activity were investigated.

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3.5.1. Foaming properties

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3.5.Functional properties

The property of food macromolecules such as proteins and polysaccharides to form stable

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foams is important in the production of a variety of foods [29]. Foam can be defined as a twophase system consisting of air cells separated by a thin continuous liquid layer called the

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lamellar phase. The distribution of the size of air bubbles in foam influences the foam product’s appearance and textural properties; foams with a uniform distribution of small air bubbles impart body, smoothness, and lightness to the food. Food macromolecules in foams contribute to the uniform distribution of fine air cells in the structure of foods [30]. Due to their predominantly hydrophilic characteristics, polysaccharides generally remain in the aqueous subphase, acting as thickeners and stabilizers [31].

ACCEPTED MANUSCRIPT The foam capacity (FC) and foam stability (FS) of OPPPs at various concentrations (0.5, 1, 2, 4 and 6%; w/v)are shown in Fig. 5 A and B. The increase of OPPP concentration resulted in an increase in foam capacity, which was more pronounced at high concentrations. Indeed, at a concentration of 6%, the foam capacity of OPPPs was 55%. These results are in line with whose obtained by Ben Jeddou et al. [13]. In

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fact, at 6%, the FC of PPPWs was more than 50%.

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The foaming properties were better when the oligosaccharide concentration increased, which

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could be attributed to the fact that oligosaccharides can increase the viscosity of the aqueous phase and create a network that stabilizes the interfacial film (air–water) [32].The results also

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indicate that FS increased with increase in the OPPP concentration at 1 min. FS decreased significantly with time at all concentrations. At 1%, 4% and 6%, the OPPP foam was totally

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unstable at 15 min (FS = 0%). Ben Jeddou et al.[13] reported that the FS of polysaccharides formed at a concentration of 4 and 6% decreased with time but after 5 min the FS value was

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stable.

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An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unbendable). The term emulsion should be used when both phases are liquids. In an emulsion,

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one liquid is dispersed in the other. Surface-active oligosaccharidescan, therefore, act both as emulsifiers and stabilizers.

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The emulsion properties of OPPPs at different concentrations (0.5, 1, 2, 4 and 6%) are expressed by two parameters, their emulsion capacity (EC) and their emulsion stability (ES). The EC and ES values remained constant with increasing OPPP concentrations. The oligosaccharides isolated from potato peel by-products attained an exceptional EC and ES of more than 80% at all concentrations. The emulsion capacity and stability of OPPPs were not significantly different from those of water-soluble polysaccharides from potato peels [13]. Moreover, Mokni et al. [32], showed a

ACCEPTED MANUSCRIPT low EC and ES of water-soluble polysaccharides from chickpea flour at all the tested concentrations compared with those of oligosaccharides from potato peels. 3.6.Antioxidant activity In vitro antioxidant tests are very useful, time saving and an economic activity to investigate the antioxidant potentialof pure compounds before commencing the compound to the in vivo

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model for the antioxidant potential against free radicals.

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The antioxidant activities have been attributed to various mechanisms, among which are

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prevention of chain initiation, binding of transition metal ion catalysts, decomposition of peroxides, prevention of continued hydrogen abstraction, and radical scavenging [33].

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Different methods have been adopted to assess the antioxidant activities of the mixture of potato peel oligosaccharides (OPPP3, OPPP4, OPPP5, OPPP6). All the tests were performed

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in triplicates and at least one synthetic antioxidant was used as a standard reference in each test.

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3.6.1.Total antioxidant activity

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The phosphomolybdate method is an evaluation of the antioxidant capacity by quantitative assay of ion reduction where the results are expressed in α-tocopherol (µmol/mL). Fig. 6A

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depicts the ability of OPPP to reduce Mo (VI) to Mo (V) at acidic pH and the formation of a green molybdate phosphate complex compared with that of BHA used as a positive control at

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different concentrations ranging from 0 to10 mg/mL. The antioxidant activity of the OPPP exhibited a linear relationship with the concentration of the extract. The standard antioxidant BHA possesses a higher amount of antioxidant activities than the oligosaccharides. The oligosaccharides extracted from potato peels show a high antioxidant activity compared with that of thewater-polysaccharides from potato peels. Indeed, at 10 mg/ mL, the total antioxidant activity of OPPP and PPPW were 87.66±9.38α-tocopherol (µmol/mL) and 12.65± 0.02α-tocopherol (µmol/mL) [13], respectively.

ACCEPTED MANUSCRIPT 3.6.2.1. 1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity The DPPH radical had been widely used to investigate the scavenging activities of several with absorption property. The color changes from purple to yellow after reduction, which can be quantified by its decrease of absorbance at 517 nm wavelength. Fig. 6B shows the ability of OPPPs to scavenge DPPH radicals compared with that of BHA

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natural compounds such as crude extracts of plants. DPPH possesses a proton-free radical

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used as a positive control at different concentrations ranging from 0 to10 mg/mL. The results

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revealed that antiradical DPPH activity depends on the concentration of the OPPP extract. Indeed, the antioxidant activity increases with increasing OPPP concentration. BHA used as

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standard exhibited DPPH radical scavenging activity compared to the oligosaccharides. At a concentration of 10 mg/mL, the antioxidant of OPPPs was higher than that of the PPPWs

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obtained by Ben Jeddou et al. [13]. In fact, percentage of inhibition of the two extracts were77.52±0.96% and 44.47±6.99%, respectively. The IC50value of our oligosaccharides was

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also determined (concentration inhibiting 50% of the free radical DPPH). The lower is the

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IC50, the better is the antioxidant activity. The IC50 of OPPPs was 2.50 mg/mL which was lower than that obtained by PPPWs (11.58 mg/mL) [13]. The IC50was higher than that of

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other oligosaccharides reported in previous studies. Indeed, Bouaziz et al. [4] reported that the IC50was 0.64 mg/mL for the almond gum oligosaccharides (OAG).

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3.6.3. Measurement of reducing power We investigated the Fe3+-Fe2+ transition to measure the oligosaccharide reducing capacity. The reducing capacity of a compound may serve as a significant indicator of its potential antioxidant activity [34]. The reducing properties are generally associated with the presence of reductant, which have been shown to exert antioxidant action by breaking the free radical chain by donating an hydrogen atom [35].

ACCEPTED MANUSCRIPT The reducing power of OPPP and BHA used as reference isshown in Fig. 6C: the reducing power of the samples correlated well with increasing concentrations. The BHA exhibited the highest reducing powder. Indeed, at a concentration of 20 mg/mL, the approximate absorbance value of OPPPs and the standard were 0.62±0.032 and 2.06±0.10, respectively. Ben Jeddou et al.[13] reported that the reducing power of PPPWs at this same concentration

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was 0.517±0.012. The results obtained show that OPPPs exhibit a similar reducing capacity

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(0.55±0.04) compared to peach gum oligosaccharides [36] having a reducing capacity (at 700

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nm) of 0.54 at 15 mg/mL. At the same concentration, the absorbance value of almond gum oligosaccharides (0.95) was about two times higher than that of OPPPs[4].

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These results suggest that the oligosaccharides generated by enzymatic hydrolysis of potato

peel polysaccharides. 3.6.4.β-Carotene-linoleic acid assay

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peel polysaccharides present a higher antioxidant capacity than that of the undigested potato

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The antioxidant potential of OPPPs was determined by theβ-carotene bleaching method based

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on the oxidation of linoleic acid. Linoleic acid hydroperoxides react with the β-carotene molecule resulting in rapid disappearance of the characteristic orange colour [37]. The

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presence of an antioxidant can obstruct the effect of β-carotene by acting on linoleate free radicals and other free radicals formed in the system [38].

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Different concentrations of OPPPs and BHA used as references were tested for their antioxidant activity (Fig.6D). The antioxidant activity of the OPPPs and of BHA exhibited a linear relationship with the concentration of the extract. BHA possessed a higher amount of antioxidant activities than the oligosaccharides. Indeed, at 50 mg/mL the inhibition capacity of the extracted OPPPs and BHA were 45.34± 3.65% and 90 ± 1.5%, respectively. The antioxidant activity of the water-soluble polysaccharides from potato peels (PPPWs) was lower than that of the OPPPs at the same concentration. In fact, the antioxidant value of

ACCEPTED MANUSCRIPT PPPW was 36.65± 3.95% [13]. Thus, the oligosaccharides generated by enzymatic hydrolysis of potato peel polysaccharides present a higher antioxidant capacity than that of the undigested potato peel polysaccharides. 3.6.5. Free radical-scavenging ability by the use of a stable ABTS radical cation (TEAC) ABTS radical scavenging activity of oligosaccharide extracts and TROLOX used as standard

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were evaluated using 2, 2 azobis-(3- ethylbenzothiozoline-6-sμlphonic acid).

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Fig. 6E illustrates that a high correlation was established between the OPPP concentrations

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and the antioxidant capacity. The best ABTS radical scavenging effect was shown by the standard. Indeed at a concentration of 10 mg/mL, the % inhibitionby theABTS radical cation

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of OPPPs and TROLOX were14.84±0.1 and 100±5%, respectively. Ben Jeddou et al. [13] reported that the antioxidant activity of PPPWs at 10 mg/mL was 98.6±4%. Therefore, the

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undigested potato peel polysaccharides present a higher ABTS radical scavenging effect than that of the oligosaccharides generated by enzymatic hydrolysis of this potato peel

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3. Conclusion:

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polysaccharide.

We report the purification and characterization of oligosaccharides (OPPPs) generated by

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enzymatic hydrolysis of polysaccharides from potato peels (PPPWs). The generated

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oligosaccharides were purified and the results showed the presence of 8 peaks (OPPP1OPPP8). All fractions weremainly composed of glucose with traces of galactose, arabinose and rhamnose. The analysis of fractions OPPP3, OPPP4, OPPP5 and OPPP6 by mass spectrometry (MALDI-ToF-ToF) showed the presence of the manly oligomers DP5, DP4, DP2 and DP1, respectively. The results of this study reveal that OPPPs have good foaming properties, and emulsification stability.

ACCEPTED MANUSCRIPT Finally,the potential role of oligosaccharides on the antioxidant activity compared to the synthetic compound, BHA, was confirmed. So,OPPPs could be used as additives to avoid food deterioration. Acknowledgments

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This research was financially supported by the Tunisian Ministry of Higher Education, Scientific Research and Information and Communication Technology. The authors are

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grateful to Anne-Lise Haenni of the Institute Jacques Monod (France) for reading and

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improving the English.

ACCEPTED MANUSCRIPT References [1] M. Laguerre, J. Lecomte,P. Villeneuve, Evaluation of the ability of antioxidants to counteract lipid oxidation: Existing methods, new trends and challenges,Prog. Lipid Res . 46 (2007) 244–282. [2] M. Jridi, I.Lassoued, R. Nasri, M.A. Ayadi, M. Nasri, N. Souissi, Characterization and

RI

Proteases, Biomed Res Int, Article ID 461728, 2014,14 pages.

PT

Potential Use of Cuttlefish Skin Gelatin Hydrolysates Prepared by Different Microbial

[3] C.A.Kimmel, G.L.Kimmel, V.Frankos,Interagency regulatory liaison group workshop on

SC

reproductive toxicity risk assessment,Environ Health Perspect. 66(1986) 193–221.

NU

[4] F. Bouaziz, C. Boisset-Helbert, M. Ben Romdhane, M. Koubaa, F. Bhiri, F. Kallel, F. Chaari, D. Driss, L. Buon, S.Ellouz-Chaabouni, Structural data and biological properties of almond gum oligosaccharide: Application to beef meat preservation,Int J BiolMacromol.

MA

72(2015)472–479.

[5] A. Sila, N. Bayar, I. Ghazala, A. Bougatef, R. Ellouz-Ghorbel, S. Ellouz-Chaabouni,

D

Water-soluble polysaccharides from agro-industrial by-products: Functional and biological

PT E

properties, Int J BiolMacromol. 69 (2014)236-243. [6] Y.Ikeda, S. Charef, M.O. Ouidja, V. Barbier-Chassefière, F. Sineriz, A. Duchesnay, H. Narasimprakash, I. Martelly, P. Kern, D.Barritault, E.Petit, D. Papy-Garcia, Synthesis and of

a

library

of

glycosaminoglycans

mimetic

CE

biologicalactivities

oligosaccharides,Biomaterials. 32(2011) 69-76.

AC

[7] S. Karnjanapratum, S. You, Molecular characteristics of sulfated polysaccharides from Monostromanitidum and their in vitro anticancer and immunomodulatory activities,Int J BiolMacromol. 48(31)(2011)1-8. [8]

G.D.Brown,S.Gordon,Immunerecognition

of

fungal

beta-glucans,CellMicrobiol.

7(2005)471–479. [9] N. Miyanishi, Y. Iwamoto, E. Watanabe, T.Oda, Induction of TNF-alphaproduction from human

peripheral

blood

monocyteswithbeta-1,3-glucanoligomerprepared

from

laminarinwithbeta-1,3-glucanasefrom Bacillus clausii NM-1,J BiosciBioeng.95(2003)192– 195.

ACCEPTED MANUSCRIPT [10]G.C. Chan, W.K. Chan, D.M.Sze,The effects of beta- glucan on human immune and cancer cells,J HematolOncol. 2 (2009)25. [11] J.Chen, K.Raymond, Beta-glucans in the treatment of diabetes and associated cardio vascular risks, Vasc Health Risk Manag. 4(2008)1265–1272. [12] J. Chen, R.Seviour, Medicinal importance of fungal beta-(1-3), (1-6)-glucans, Mycol Res. 111(2007)635–652. [13] K. Ben Jeddou, F. Chaari, S.Maktouf, O.Nouri-Ellouz, C.Boisset- Helbert, R.Ellouz-

PT

Ghorbel, Structural, functional, and antioxidant properties of water-solublepolysaccharides

RI

from potatoes peels,Food Chem. 205(2016) 97–105.

[14] S. Maktouf, A. Kamoun, C. Moulis, M. Remaud-Simeon, D. Ghribi, C. Ellouz,A raw

SC

starch digesting α-amylase from Bacillus sp.: production under solid state fermentation on

NU

crude millet and Biochemical characterization,J MicrobBiotechnol. 23 (4) (2013) 489–498. [15] K. Ben Jeddou, S.Maktouf, I. Ghazala, D.Frikha, D.Ghribi, R.EllouzGhorbel, O. Nouri-

MA

Ellouz, Potato Peel as feedstock for Bioethanol production: A comparison of acidic and enzymatic hydrolysis,Ind Crops Prod. 52 (2014) 144– 149.

D

[16] J.P. Kamerling, G.J. Gerwig, J.F. Vliegenthart, J.R. Clamp, Characterization by gasliquid chromatography-mass spectrometry and proton-magnetic-resonance spectroscopy of

PT E

pertrimethylsilyl methyl glycosides obtained in the methanolysis of glycoproteins and glycopeptides, J. Biochem.151(1975)491–495.

CE

[17] F. Shahidi,X.Q.Han,J.Synowiecki, Production and characteristics of protein hydrolysates from capelin (Mallotusvillosus), Food Chem. 53(1995)285-293.

AC

[18] K. Yasumatsu, K.Sawada, S. Moritaka, M.Misaki, J. Toda, T.Wada,Whipping and emulsifying properties of soybean products,J. Agric. Food Chem. 36(1972)719-727. [19] P. Prieto, M. Pineda, M.Aguilar, Spectrophotometric Quantitation of Antioxidant Capacity through the Formation of a Phosphomolybdenum Complex: Specific Application to the Determination of Vitamin E, Anal. Biochem. 269(1999)337–341. [20] M.A. Saleh, S. Clark, B. Woodard, S.A. Deolu-Sobogun, Antioxidant and free radical scavenging activities of essential oil, Ethn Dis . 20 (S1)(2010) 78–82. [21] A. Yildirim, A. Mavi, A.A. Kara, Determination of antioxidant and antimicrobial

ACCEPTED MANUSCRIPT activities of Rumexcrispus L. extracts,J. Agric. Food Chem. 49(2001) 4083–4089. [22] I. I. Koleva, T.A. Van Beek, J.P.H. Linssen, A. De Groot, L.N.Evstatieva, Screening of plant

extracts

for

antioxidant

activity:

a

comparative

study

on

three

testing

methods,Phytochem Anal.13 (1)(2002) 8–17.

PT

[23] R. Re, N. Pellegrini, A. Proteggente, A. Pannala, M. Yang, C. Rice- Evans, Antioxidant activity applying an improved ABTS radical cationdecolorization assay, Free Radic. Biol. Med. 26(9–10)(1999) 1231–1237. [24] F. Bouaziz, M. Ben Romdhane, C. Boisset-Helbert, L. Buon, F. Bhiri, S.Bardaa, D.

RI

Driss,M. Koubaa, A. Fakhfakh, Z. Sahnoun, F. Kallel, N. Zghal, S. Ellouz-Chaabouni, Healing efficiency of oligosaccharidesgenerated from almond gum(Prunusamygdalus) on

SC

dermal wounds of adult rats, J Tissue Viability. 23(2014)98-108

[25] R. Jovanovic-Malinovska, S. Kuzmanova, E. Winkelhausen, Application of ultrasound

NU

for enhanced extraction of prebiotic oligosaccharides from selected fruits and vegetables, UltrasonSonochem. 22 (2015)446–453. N.

Khodaei,

S.Karboune,Enzymatic

MA

[26]

generation

of

galactose-rich

oligosaccharides/oligomers from potato rhamnogalacturonan I pectic polysaccharides,Food

N.

Khodaei,

S.

Karboune,

Extraction

and

structural

characterisation

of

PT E

[27]

D

Chem. 197(2016)406–414

rhamnogalacturonan I-type pectic polysaccharides from potato cell wall, Food Chem. 139 (2013) 617–623.

CE

[28] B. Gómez, B. Gullón, R.Yáñez, H. Schols , J. L. Alonso, Prebiotic potential of pectins and pecticoligosaccharides derived from lemon peel wastes and sugar beet pulp: A

AC

comparative evaluation, J Funct Foods. 20( 2 0 1 6 ) 108–121. [29] R.K.Prud'homme, S.A. Khan, (1996) (Eds.), Foams.Theory, measurements, and applications, Surfactant Science Series Marcel Dekker, New York (USA). [30] J. F. Zayas, Foaming Properties of Proteins, Functionality of proteins in foods. (1997) 260-309. [31] A.A. Perez, C. Carrera Sánchez, J.M. Rodríguez Patino, A.C.Rubiolo, L.G. Santiago, Effect of enzymatic hydrolysis and polysaccharide addition on the beta-lactoglobulin adsorption at the air-water interface, J Food Eng. 109 (2012) 712-720.

ACCEPTED MANUSCRIPT [32] A. MokniGhribi, A. Sila, I. MakloufGafsi, C. Blecker, S. Danthine, H. Attia, A. Bougatef, S.Besbes, Structural, functional, and ACE inhibitory properties of watersolublepolysaccharides from chickpea flours, Int J BiolMacromol.75(2015) 276–282. [33] A.T.Diplock, Will the ‘good fairies’ please proves to us that vitamin E lessens human degenerative of disease, FreeRadic Res. 27(1997)511-532.

PT

[34] S. Meir, J. Kanner, B. Akiri, S.P. Hadas, Determination and involvement of aqueous reducing compounds in oxidative defense systems of various senescing leaves,J. Agric. Food Chem. 43(1995)1813-1817. [35] M.H. Gordon, (1990) The mechanism of antioxidant action in vitro.In B. J. F.

RI

Hudson(Ed.), Food antioxidants (pp. 1–18). London/New York: Elsevier Applied Science.

SC

[36] X.C. Yao, Y. Cao, S.K.Pan, S.J. Wu, Preparation of peach gum polysaccharides using hydrogen peroxide, CarbohydrPolym. 94(2013) 88–90.

NU

[37] W. Binsan, S. Benjakul, W.Visessanguan, Composition, antioxidative and oxidative stability of mungoong, a shrimp extract paste, from the cephalothorax of white shrimp,J Food

MA

Lipids. 15(1) (2008)97–118.

[38] R. Balti, A. Bougatef, N. El Hadj Ali, N. Ktari, K. Jellouli, N. Nedjar-Arroume, P. Dhulster, M.Nasri, Comparative Study on Biochemical Properties and Antioxidative Activity

D

of Cuttlefish (Sepia officinalis ) Protein Hydrolysates Produced by Alcalase and Bacillus

AC

CE

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licheniformis NH1 Proteases,Amino Acids.(2011) 1- 11.

ACCEPTED MANUSCRIPT Figure captions Fig. 1: Optimization of PPPW enzymatic hydrolysis: (A) optimum enzyme unit (U/mL), (B) optimum temperature value, (C) optimum pH value, (D) optimum substrate content, (E) Enzymatic hydrolysis kinetic of PPPW, and(F) Thin layer chromatography of enzymatic

11:maltose, 12:maltotriose, 13: maltotetraose, 14:maltopentose.

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Fig.2:OPPP purification using Superdex-30 filtration gel.

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hydrolysis of PPPW:1:Glc, 2:Rham, 3:Gal, 4: AGal, 5:30min, 6:1h, 7:3h, 8:4h, 9:8h, 10:24h,

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Fig. 3: monosaccharide composition of OPPP fractions: OPPP1(A), OPPP7(B) and OPPP8

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(C) by GC-FID using trimethylsilyl monosaccharide derivatives as standards. Fig. 4:Mass spectrum of unpurified OPPP (A), OPPP3 (B), OPPP4 (C), OPPP5 (D) and

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OPPP6 (E),using ESQUIRE 3000+ (BrukerDaltonics) spectrometer andMALDI- TOF technique.

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at different concentrations.

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Fig. 5: The foaming (FC: foam capacity (A) and FS: foam stability (B)) properties of OPPPs

Fig. 6: Antioxidant activities of OPPPs at different concentrations. A: total antioxidant

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activity; B:radical scavenging activities; C: reducing power; D: β-carotene bleaching

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inhibition; E: antioxidant activities of OPPPs by scavenging ability in the TEAC assay.

ACCEPTED MANUSCRIPT Highlights Extraction and purification of polysaccharides.

oligosaccharides isolated from potato peel

Identification of potato peel oligosaccharides by chromatography methods (GC-FID and mass spectrometry MALDI-ToF-ToF).

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Determination of functional properties potato peels oligosaccharides.

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Evaluation of antioxidant activity of potato peels oligosaccharides.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6