| Epidemiological studies have attested the health benefits of wine. Consequently, due to the desire of customers to consume sulfite-free wine with elegant flavor and health-related attributes, the improvement of winemaking process has become a challenge in enology. Therefore, the use of non-thermal processing technologies have been explored in vinification process to replace sulfur dioxide due to its possible health hazards and sensory defects in wine. Hence, this research was undertaken to investigate the effects of high pressure and ultrasound on the phytochemical and volatile compounds of a sulfur dioxide-free wine. Besides, this study intend to produce a phytochemical-rich wine with excellent organoleptic features and antioxidant properties utilizing mulberry (Morus nigra) as a substrate. Therefore, a methodical approach by means of multivariate analysis in addition to response surface methodology was employed to investigate and improve the main steps of winemaking process. In order to achieve these objectives, the following methods: spectrophotometric, hunterlab, high performance liquid chromatography diode array detector and headspace solid phase micro extraction gas chromatography-mass spectrometer coupled with a flame ionization detector were employed to analyze the effects of enzymes, fermentative parameters, ultrasonication, pressurization as well as their interactive effect on the polyphenol compounds, chromatic properties, volatile components and antiradical powers at different stages of the vinification, chiefly maceration, fermentation and aging processes. The outcomes and main contents are listed as follows:(1) Maceration processThe enzymatic treatment was noted to have a detrimental impact on the volatile profile of the mulberry must. Besides, the phytochemical compounds and color properties were observed to be altered in different ways in relation to the seven enzymes applied. Due to its less adverse effect on the volatile profile, in addition to its relative positive effect on the color properties and phytochemical compounds, Pectinex UF (PUF) was considered to be the most appropriate enzyme for mulberry must maceration. Hence, the must macerated at 20 ℃ for 1 h with PUF (15 ml/100 kg) was typified by the total phenolic content (TPC) of 276.79 mg/100 ml GAE, total flavonoid content (TFC) of 358.74 mg/100 ml RE, total anthocyanin content (TAC) of 49.71 mg/100 ml C3GE, lightness (L*) of 2.65, redness (a*) of 17.61, yellowness (b*) of 3.82, chroma (C*) of 18.02, hue (H°) of 12.25, browning index (BI) of 1.48 and total volatile compound of 620.86μg/l.The sonication frequency (Fs), enzyme concentration (CE) and maceration time (TM) as well as their synergetic effects were demonstrated to significantly impact on the phytochemical compounds and chromatic properties of the mulberry must. In respect to these parameters, the optimal operating condition of the Ultrasound-Assisted Enzymatic Extraction (UAEE) treatment was established to be Fs of 34 KHz, CE of 0.010% v/w and Tm of 12.00 min with pulse duration of 10 s on and 5 off, fixed power of 60 W at 20 ℃ . At this condition, the UAEE must was demonstrated to have the highest TPC (299.27 mg/100ml GAE), TFC (378.02 mg/100 ml RE), TAC (55.32 mg/100 ml C3GE) and L* (3.50) with the lowest BI (1.20) as compared to the musts obtained at the optimal conditions of ultrasonic (36 KHz for 18 min at 35 ℃ ), enzymatic (0.012%v/w for 45 min at 18 ℃ ) and conventional (60 min at 20 ℃ ) treatments.(2) Fermentation processThe fermentation temperature (TF), pH, inoculum size (Is) of the yeast Actiflore F33 and °rix (°x) as well as their interactive effects were revealed to significantly affect the phytochemical compounds, ethanol concentration (ETHC), total higher alcohol concentration (THAC) and total ester concentration (TESC) of the mulberry fruit wine. With regards to these parameters, the optimum operating fermentation condition was established to be Tf of 25 ℃ , pH of 4.00, Is of 10% v/v and °x of 26. Under this condition, the resulting wine was found to have a TPC of 601.40 mg/100 ml GAE, TFC of 479.13 mg/100 ml RE, TAC of 148.07 mg/100 ml C3GE, ETCH of 82.85 g/1, THAC of 249.91 mg/1 and TESC of 52.55 mg/1. Hence, the wine obtained under the optimal condition was considered as a phytochemical-rich mulberry fruit wine (PRMW) on the basis of its higher content in phytochemicals compared to the conventional mulberry fruit wine (CMW) produced at Tf of 24 ℃ , pH of 3.50, Is of 12% v/v and ℃°x of 24. Moreover, the PRMW was typified by its higher antioxidant capacities of 1,1-Diphenyl- 2-picrylhydrazyl (91.31%) and 2,2’-azino-bis(3-ethylbenzothiazolin-6-sulfonic acid) (74.23%). With respect to the Hedonic test, the PRMW was noted to have a better organoleptic features (color of 7.97, taste of 7.68, aroma of 8.29, flavor of 8.55 and body of 7.04) with an overall acceptance of 8.51 than that of the CMW.(3) Aging processAt optimal conditions, the ultrasonication (frequency of 26 KHz, pulsating time of 10s on and 5 s off, fixed power of 60 W, temperature of 10 ℃ and processing time of 30 min), the pressurization (pressure level of 300 MPa, temperature of 10 ℃ and processing time of 20 min) and the manosonication (pressure level of 200 MPa, frequency of 24 KHz, pulsating time of 10s on and 5 s off, fixed power of 60 W, temperature of 10 ℃ and processing time of 15 min) techniques were demonstrated to alter the phytochemical families associated with the chromatic characteristics of the sulfur dioxide-free mulberry fruit wine aged in a stable dark atmosphere at 15 ℃ for 2 months. Hence, the ultrasonicated aged wine (USW) was noted to have the highest value in total flavonol index (285.07 mg/100ml RE), total anthocyanin index (111.35 mg/100ml C3GE), condensed tannin index (615.69 mg/100ml CE), monomeric anthocyanin (14.53), wine color (15.99), color density (24.47), color intensity (35.59), percent of pure red (68.13), percent of red (61.07), a* (58.59), C* (59.30) and saturation (4.62). While, the pressurized aged wine (HPW) was characterized by having the utmost value in polymeric anthocyanin (4.73), copigmented anthocyanin (0.05), total color of pigments (4.49), color stability (4.77), polymeric color (11.75), percent polymeric color (67.79), color tonality (0.92), percent of yellow (43.34), L* (15.52), b* (12.83) and H° (13.11). Whereas, the manosonicated wine (MSW) was typified by its lowest value in percent of blue (9.30), total color difference (1.89) and the uppermost value in total phenolic index (427.99 mg/100ml RE).Moreover, at the conditions abovementioned, the non-thermal processes (NTP) were proven to affect the volatile compounds fingerprint of the sulfur dioxide-free aged mulberry fruit wine (AMW). Hence, pressurization was found to have an adverse impact on the acid family inversely to that of sonication. However, the other chemical families (ester, volatile phenol, aldehyde, ketone, terpene, lactone and furan), except the alcohol family were noted to be positively affected by the NTP. In view of their odor activity values,75 compounds were identified to contribute markedly to the aromatic profile of the AMW. Indeed, the NTP was demonstrated to enhance the aroma series (nutty, caramel, woody, chemical, vegetative, floral and fruity) of the AMW, except the microbiological series which was reduced by pressurization and manosonication. Therefore, with respect to the quantitative descriptive analysis (visual, olfactory and gustatory attributes) assessed using the geometric mean, the USW was typified by having the highest depth color (38.01), red brown color (79.81), cherry note (67.22), caramel note (50.91), lilac note (28.53), fatty note (34.42), bitterness (50.67) and the lowest violet note (16.02). While, the HPW was distinguished by having the utmost bilberry note (34.37) and the lowermost blackberry note (21.91), vegetal note (10.54), body (33.31). Whereas, the MSW was characterized by having the uppermost blackcurrant note (80.51), chamomile note (64.98), rose note (76.01), lactic note (38.48), stone fruit note (70.18), bouquet (56.11) and the lowest herbaceous note (10.54), aroma intensity (21.91), astringency (28.26), balance (54.43), persistence (40.36). Therefore, the mathematical model of the overall quality of the AMW was as follows:Y= 68.8763+1.4424 olfactory+1.7379 gustatory+1.5218 visual(4) Antioxidant propertiesThe AMW was demonstrated to exhibit 13 antioxidant properties such as total antioxidant capacity (TA-CA), ferric reducing antioxidant power capacity (FRAP-CA), reducing power capacity (RP-CA), cupric ion reducing capacity (CUPRA-CA), metal chelating capacity (MC-CA), lipid peroxidation capacity (LP-CA),1,1-Diphenyl-2-picrylhydrazyl radical scavenging activity (DPPH·-SA),2,2’-azino-bis(3-ethylbenzothiazolin-6-sulfonic acid) radical scavenging activity (ABTS’-SA), N,N-dimethyl-p-phenylendiamine radical scavenging activity (DMPD·-SA), superoxide anion radical scavenging activity (O·2--SA), nitric oxide radical scavenging activity (NO’-SA), hydroxyl radical scavenging activity (HO’-SA) and hydrogen peroxide scavenging activity (H2O2-SA). These antioxidant properties were revealed to be attributed to 18 polyphenolic compounds made up of 10 phenolic acids,6 flavonols and 2 anthocyanins. Therefore, in view of the NTP effect on the antioxidant compounds of the AMW, the USW was characterized by having the uppermost content of TFC (507.01 mg/100ml RE), quercitrin (18.22 μg/ml), morin (321.21 μg/ml), rutin (142.85 μg/ml), quercetin (245.12 μg/ml), myricetin (2.03 μg/ml), kaempferol (3.48 μg/ml), cyanidin 3-O- rutinoside (111.37 μg/ml), RP-CA (50.52 mM AAE) and LP-CA (56.16%). While, the HPW was typified by having the lowermost content of TAC (131.25 C3GE), cyanidin-3-O-glucoside (122.68 μg/ml), TA-CA (413.26 mM AAE), FRAP-CA (171.72 mM FeSO4E), CUPRA-CA (122.88 mM TE), ABTS-SA (61.45 mM TE), MC-CA (50.43%), O2—--SA (75.62%), NO’-SA (78.98%) and HO’-SA (74.69%). Whereas, the MSW was typified by having the maximum content of TPC (658.00 mg/100ml GAE), gallic acid (3.29 μg/ml), protocatechuic acid (185.73 μg/ml), gentisic acid (1.66 μg/ml), p-hydroxybenzoic acid (18.18 μg/ml), vanillic acid (0.99 μg/ml), syringic acid (2.08μg/ml), chlorogenic acid (55.96 μg/ml), caffeic acid (89.30 μg/ml), p-coumaric acid (5.14μg/ml), ferulic acid (59.68 μg/ml), DPPH-SA (312.07 mM TE), DMPD’-SA (164.41 mM TE) and H2O2-SA (89.73%).The study provides a valuable insight of the application of ultrasound, high pressure and manosonication techniques in winemaking for the improvement of mulberry fruit wine quality. The outcomes of this research would be beneficial for oenologist for the production of aromatic mulberry fruit wine with health-related benefits. |
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