Processing technology of pitaya wine

Abstract

The invention provides a pitaya wine processing technology. The pitaya wine processing technology is optimized aiming at the problems that pigments are easy to degrade, the fermentation efficiency is low, and the flavor is single in a traditional technology. According to the raw material pretreatment, ultrasonic cleaning (0.05% sodium hexametaphosphate solution) is combined with metal ion control (Fe2 / Cu2 is less than or equal to 0.1 mg / L), and the juice yield is increased through composite enzymolysis (pectinase and cellulase). In the low-temperature fermentation stage, the period is shortened to 10 hours by utilizing fed-batch strain activation, and the retention rate of characteristic aroma is remarkably improved by combining pulse ultrasound and nitrogen protection (the oxygen content is less than or equal to 0.5 ppm); and through infrared monitoring and gradient cooling, accurate control of the alcoholic strength being 12% vol and the residual sugar being less than or equal to 4g / L is realized. In the aging stage, nitrogen is adopted to isolate oxygen (high-purity nitrogen is greater than or equal to 99.99%) and a KPA stabilizer, so that the degradation rate of betacyanin is less than or equal to 10%. Finally, the stability is improved through ceramic membrane filtration, cold stabilization and pasteurization, and the product is purplish red in color and luster and complex in flavor and has industrial application potential.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wine processing, in particular to a pitaya wine processing technology. BACKGROUND

[0002] The pitaya wine is a characteristic fruit wine prepared from fresh pitaya, which has a fascinating purple red color, is crystal clear, has a rich fruity aroma, has a complex aroma of rose and honey produced by fermentation, has a smooth and mellow taste, has a balanced sweetness and sourness, has a slight tea polyphenol aftertaste and flavor level, and is a low-alcohol fruit wine product with visual beauty and unique flavor.

[0003] The traditional pitaya wine processing has the following problems:

[0004] 1. Pigment degradation: the pitaya red pigment (betacyanin, anthocyanin) is easily catalyzed and oxidized by metal ions (Fe 2 , Cu 2 ), resulting in a color fading rate of 30%-50%;

[0005] 2. Low fermentation efficiency: the free cell fermentation period is as long as 15-20 days, and the low-temperature control precision is insufficient;

[0006] 3. Flavor homogenization: the characteristic aroma (such as 2-phenylethanol and beta-damascone) is not retained enough, and the content of higher alcohols (isopentanol) is too high. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a pitaya wine processing technology.

[0008] The technical problem to be solved by the present application is solved by the following technical solution:

[0009] Step 1: Pretreatment of raw materials

[0010] 1.1 Ultrasonic cleaning

[0011] Select red pitaya with maturity ≥ 90%, and place it in an ultrasonic cleaning machine, and clean it with 0.05% sodium hexametaphosphate solution (pH 3.5) for 10 min, with an ultrasonic frequency of 28 kHz, a power of 200 W, and a water temperature of 15℃.

[0012] After cleaning, detect the Fe 2 / Cu 2 content in the cleaning solution by atomic absorption spectrometry to ensure that the residual amount is ≤ 0.1 mg / L.

[0013] 1.2 Crushing and color protection

[0014] The pulp is broken into 2-4 mm in size, 0.3 g / kg of D-erythorbic acid, 0.2 g / kg of EDTA-Na, 0.1% of phytic acid and 0.05% of tea polyphenol are added, the pH is adjusted to 3.8-4.0, the stirring speed is 200 rpm and the stirring time is 15 min.

[0015] The color protection agent is added in the following order: first, EDTA-Na is added and stirred for 5 min, then D-erythorbic acid is added, and finally the pH is adjusted; the breaking equipment is a spiral juicer with a screen hole diameter of 4 mm.

[0016] 1.3 Enzymolysis

[0017] A compound enzyme preparation (pectinase 0.05% + cellulase 0.02%) (enzyme activity ≥ 10 U / g) is added, and the enzymolysis is carried out at 45°C for 2 h, the stirring speed is 150 rpm, and after the enzymolysis, the temperature is cooled to 4°C and centrifugal filtration is carried out (3000 rpm x 10 min).

[0018] Centrifugal filtration is used to remove the pulp residue and dissolved metal ion complexes.

[0019] Step 2: Low-temperature fermentation

[0020] 2.1 Strain activation

[0021] Saccharomyces cerevisiae Y2 is inoculated into a wort medium (20°Brix of sugar, containing 0.5 g / L of yeast extract and 0.2 g / L of MgSO), and is cultured at 28°C for 10 h (originally 12 h) with a shaking speed of 180 rpm, until the cell concentration is ≥ 2 x 10 CFU / mL.

[0022] A flow-inoculation method is used, and 0.05 g / L of active dry yeast is added at the beginning of the fermentation.

[0023] 2.2 Inoculation and fermentation

[0024] The fruit pulp is inoculated at a dosage of 0.19 g / L, and SO39 mg / L is added, and the fermentation is carried out at 18-22°C, the fermentation tank is protected by nitrogen (oxygen content ≤ 0.5 ppm), and the sugar content and alcohol content are monitored daily; pulse ultrasonic treatment is carried out at the 3rd-7th day of fermentation (working for 2 min / stop for 3 min, power 250 W, total treatment time 30 min / day), and nitrogen is filled after ultrasonic treatment (flow rate 1 L / min).

[0025] An infrared spectrum sensor is installed to monitor the glucose and ethanol concentrations in real time, with an error of ≤ 2%; when the residual sugar decreases to 5 g / L, gradient cooling is started (decreasing by 1°C per day to 15°C), and the fermentation period is extended to 9-12 days.

[0026] 2.3 Judgment of fermentation end point

[0027] The fermentation is ended when the residual sugar is reduced to 4 g / L or less and the alcohol content reaches 12% vol, and the total cycle is 7-10 days.

[0028] Step 3: Aging under nitrogen protection

[0029] 3.1 Aging conditions

[0030] The fermentation liquid is transferred to a 316L stainless steel food-grade ceramic tank (the inner wall is coated with polytetrafluoroethylene), and is aged in the dark at 10-15°C for 3 months, with nitrogen being continuously introduced (flow rate 0.5 L / min, purity ≥ 99.99%) to maintain the oxygen content in the tank at ≤ 0.5 ppm.

[0031] During the aging period, samples are taken every week, and the betalain content is detected by HPLC to ensure that the degradation rate is ≤ 10%.

[0032] 3.2 Addition of stabilizers

[0033] KPA is added at 150 mg / L at the beginning of the aging period, and the tartaric acid content is detected every week to ensure that the concentration is ≤ 0.5 g / L; KPA is supplemented according to the detection results to a total amount of 150 mg / L.

[0034] Step 4: Stabilization treatment and filling

[0035] 4.1 Filtration

[0036] A 0.2 μm ceramic membrane filtration system (membrane flux 180-220 L / (m 2 ·h), transmembrane pressure difference ≤ 0.12 MPa) is used, and after filtration, cold stabilization treatment is performed (-4°C for 72 h), and tartarate crystals are filtered out.

[0037] 4.2 Sterilization

[0038] 65°C pasteurization for 30 min, and rapid cooling to 20°C.

[0039] 4.3 Filling

[0040] Brown glass bottles (inner wall coated with food-grade polymer coating) are used for filling, and the bottle opening is flushed with nitrogen 3 times before filling, the filling temperature is 20°C, and the oxygen content in the headspace of the bottle is ≤ 0.3%; the bottle stopper is a synthetic polymer stopper (gas permeability ≤ 0.1 cm 3 / (day·atm)).

[0041] Advantages of the present application:

[0042] 1. The pigment stability is significantly improved, and the color retention rate is increased by more than 30%

[0043] By composite color protection system (D-erythorbic acid + EDTA-Na + phytic acid + tea polyphenol) and metal ion control technology (atomic absorption spectrometry detection residual amount ≤0.1 mg / L, centrifugal filtration to remove metal complex), combined with low temperature aging (4℃ enzyme after centrifugation, 15℃ nitrogen protection aging), betalain 535 nm absorbance value change ≤15%, the fading rate from traditional 30%-50% to 12%-18%, realize the long-term stability of pitaya wine color.

[0044] 2. Fermentation efficiency is improved by 40%, and the period is shortened to 9-12 days

[0045] By using flow feeding inoculation (initial yeast concentration ≥2×10 CFU / mL + additional 0.05 g / L active dry yeast) and pulse ultrasonic treatment (250W, intermittently 2min / 3min), combined with infrared spectrum online monitoring (glucose and ethanol concentration error ≤2%) and gradient cooling (1℃ per day to 15℃), the fermentation period is shortened by 40% compared with traditional 15-20 days, while the isopentanol content is reduced by 30% (verified by GC-MS), and the inhibition effect of higher alcohols is significant.

[0046] 3. Characteristic aroma retention rate is increased by 25%-40%, and flavor uniqueness is enhanced

[0047] By ultrasonic enhanced metabolism (promoting 2-phenylethanol and β-damascenone synthesis), cold stable treatment (-4℃ / 72h precipitating tartrate) and low oxygen filling (headspace oxygen ≤0.3%), SPME-GC-MS detection shows that the content of characteristic aroma components is increased by 25%-40%, and the synthetic polymer plug (gas permeability rate ≤0.1 cm 3 / (day·atm)) effectively reduces the escape of aroma, and the complexity and recognition of product flavor are significantly improved.

[0048] 4. Wine body stability meets commercial standards

[0049] Full nitrogen protection (oxygen content ≤0.5ppm) and multi-layer barrier design (brown bottle + high molecular coating + nitrogen flushing) reduce the risk of oxidation by more than 50% during the shelf life, and the wine body stability meets the commercial standards (tartaric acid ≤0.5g / L), meeting the needs of industrial production. DETAILED DESCRIPTION

[0050] In order to make the technical means, creative features, purposes and effects realized by the present application easy to understand, the following specific examples and comparative examples are combined to further illustrate the present application.

[0051] Example 1 (process of the present technical solution)

[0052] Step 1.2 Color protection agent: D-erythorbic acid 0.3 g / kg + EDTA-Na 0.2 g / kg + phytic acid 0.1% + tea polyphenols 0.05%

[0053] Step 2.2 Fermentation parameters: pulsed ultrasound (250 W, intermittent 2 min / 3 min), flow inoculation (supplement 0.05 g / L active dry yeast), gradient cooling to 15°C

[0054] Step 3.1 Aging: nitrogen flow 0.5 L / min, oxygen content ≤0.5 ppm

[0055] Step 4.1 Filtration: 0.2 pm ceramic membrane (membrane flux 200 L / (m 2 ·h)), cold stabilization treatment -4°C / 72 h

[0056] Example 2 (color protection agent optimization)

[0057] Step 1.2 Color protection agent: D-erythorbic acid 0.4 g / kg + EDTA-Na 0.3 g / kg + phytic acid 0.15% + tea polyphenols 0.1%

[0058] Other steps same as Example 1

[0059] Example 3 (ultrasound parameter adjustment)

[0060] Step 2.2 Fermentation parameters: pulsed ultrasound (300 W, intermittent 1 min / 2 min), flow inoculation (supplement 0.1 g / L active dry yeast), gradient cooling to 14°C

[0061] Other steps same as Example 1

[0062] Comparative Example 1 (without composite color protection agent)

[0063] Step 1.2 Color protection agent: only D-erythorbic acid 0.3 g / kg + EDTA-Na 0.2 g / kg (omit phytic acid, tea polyphenols)

[0064] Other steps same as Example 1

[0065] Comparative Example 2 (without pulsed ultrasound)

[0066] Step 2.2 Fermentation parameters: no ultrasound treatment, normal temperature fermentation (18-22°C), no supplement of active dry yeast

[0067] Other steps same as Example 1

[0068] Comparative Example 3 (without nitrogen protection)

[0069] Step 3.1 Aging: air exposure aging (oxygen content ≥5 ppm)

[0070] Step 4.3 Filling: Common glass bottle, no nitrogen flushing

[0071] Other steps are the same as Example 1

[0072] The examples and comparative examples are tested in detail, and the results are shown in Table 1 below

[0073] Table 1

[0074]

[0075] I. From the above parameters

[0076] 1. Pigment stability: Examples 1-3 chelate metal ions by composite color protection agent (phytic acid + tea polyphenol), combined with low-temperature centrifugal filtration, and the fading rate is significantly lower than that of the comparative examples (HPLC detection, n = 3, p < 0.05). The comparative example 3 has a high fading rate of 45% (a decrease of 45% in absorbance at 535 nm) due to oxidation caused by air exposure.

[0077] 2. Fermentation efficiency: Examples 1-3 use fed-batch inoculation and pulse ultrasonic (250-300W), and the fermentation period is shortened to 8-10 days, and the isopentanol content is reduced by 30%-40% (GC-MS quantitative, n = 3).

[0078] Comparative example 2 has no ultrasonic treatment, and the fermentation period is extended to 18 days, and the isopentanol content is as high as 95 mg / L (yeast metabolic disorder).

[0079] 3. Characteristic aroma retention: Examples 1-3 enhance yeast metabolism (promote the synthesis of aroma precursors) and low-oxygen filling (headspace oxygen ≤0.3%) through ultrasonic, and the contents of 2-phenylethanol and β-damascenone are increased by 25%-50% (SPME-GC-MS external standard method).

[0080] Comparative example 1 has insufficient color protection agent, and the yeast activity is inhibited, and the synthesis of characteristic aroma is reduced by more than 50%.

[0081] II. Conclusion

[0082] Examples 1-3 are significantly better than the comparative examples in pigment protection, fermentation efficiency and flavor retention, which verifies the effectiveness of the composite color protection system, pulse ultrasonic treatment and nitrogen protection process in the patent technology.

[0083] The above shows and describes the basic principles and main features of the present application and the advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application, and various changes and improvements can be made without departing from the spirit and scope of the present application. These changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A dragon fruit wine processing technology, characterized in that: The following steps are involved: (1) Raw material pretreatment: Ultrasonic cleaning: Select red dragon fruit with a maturity of ≥90%, place it in an ultrasonic cleaning machine, and clean it with 0.05% sodium hexametaphosphate solution (pH 3.5) for 10 minutes, with an ultrasonic frequency of 28kHz, a power of 200W, and a water temperature of 15°C. After cleaning, the Fe content in the cleaning solution was detected. 2 / Cu 2 Residual amount ≤ 0.1 mg / L; Crushing and color protection: crush the pulp to a particle size of 2-4 mm, add EDTA-Na 0.2 g / kg and stir for 5 minutes, D-isoascorbic acid 0.3 g / kg, phytic acid 0.1% and tea polyphenols 0.05% in sequence, adjust the pH to 3.8-4.0, stir at 200 rpm for 15 minutes; Enzymatic hydrolysis: Add a composite enzyme preparation (pectinase 0.05% + cellulase 0.02%, enzyme activity ≥ 10 U / g), enzymatic hydrolysis at 45°C for 2 h, stirring at 150 rpm, cool to 4°C after enzymatic hydrolysis and centrifuge (3000 rpm × 10 min); (2) Low temperature fermentation: Activation: Saccharomyces cerevisiae Y2 was inoculated into wort medium (20° Brix, containing 0.5 g / L yeast extract and 0.2 g / L MgSO) and cultured at 28°C with shaking for 10 h (180 rpm) to a cell concentration of ≥2 × 10 CFU / mL. The culture was then fed-batch inoculated and supplemented with 0.05 g / L active dry yeast. Inoculation and fermentation: Inoculate the pulp at an inoculum rate of 0.19 g / L, add 9 mg / L SO, and ferment at 18-22°C. The fermentor is nitrogen-filled (oxygen content ≤ 0.5 ppm). On the 3rd to 7th day of fermentation, pulsed ultrasonic treatment is performed (2 min on / 3 min off, power 250 W, total treatment time 30 min / day). After ultrasonication, nitrogen is filled (flow rate 1 L / min). The glucose and ethanol concentrations are monitored in real time (error ≤ 2%). When the residual sugar drops to 5 g / L, the temperature is gradually lowered to 15°C (1°C lower per day). The fermentation cycle is 9-12 days. Fermentation endpoint judgment: Fermentation ends when residual sugar ≤ 4g / L and alcohol content reaches 12% vol. The total cycle is 7-10 days; (3) Nitrogen-protected aging: The fermentation broth was transferred to a 316 L stainless steel ceramic tank (with polytetrafluoroethylene coating on the inner wall) and aged at 10-15 °C in the dark for 3 months. Nitrogen was introduced throughout the aging process (flow rate 0.5 L / min, purity ≥99.99%) to maintain an oxygen content of ≤0.5 ppm. KPA 150 mg / L was added at the beginning of the aging process and the tartaric acid content was tested weekly (≤0.5 g / L). (4) Stabilization and filling: Filtration: Using 0.2μm ceramic membrane filtration system (membrane flux 180-220L / (m 2 h), transmembrane pressure difference ≤ 0.12MPa), cold stabilization treatment after filtration (maintain at -4℃ for 72h); Sterilization: pasteurize at 65℃ for 30min, then quickly cool to 20℃; Filling: Use brown glass bottles (with food-grade polymer coating on the inner wall), flush the bottle mouth with nitrogen three times before filling (temperature 20℃, headspace oxygen content ≤0.3%), and use bottle stoppers with air permeability ≤0.1cm 3 / (day·atm) of synthetic polymer plugs.

2. The dragon fruit wine processing technology according to claim 1, wherein In the crushing and color protection step, the color protection agents are added in the order of EDTA-Na, D-isoascorbic acid, phytic acid and tea polyphenols, and the addition interval between EDTA-Na and D-isoascorbic acid is 5 minutes.

3. The dragon fruit wine processing technology according to claim 1, wherein In the low-temperature fermentation step, pulsed ultrasonic treatment and nitrogen supplementation work synergistically to enhance the retention rate of characteristic aromas (2-phenylethanol and β-damascone) and reduce the isoamyl alcohol content.

4. The dragon fruit wine processing technology according to claim 1, wherein In the nitrogen protection aging step, oxygen is doubly isolated by the polytetrafluoroethylene coating and nitrogen protection, so that the degradation rate of betalain is ≤10%.

5. The dragon fruit wine processing technology according to claim 1, characterized in that: In the raw material pretreatment step, an atomic absorption spectrometer is used to detect Fe 2 / Cu 2 The residual amount ensures that the risk of metal ion catalytic oxidation is lower than that of traditional processes.

6. The dragon fruit wine processing technology according to claim 1, characterized in that: During the low-temperature fermentation step, the concentrations of glucose and ethanol are monitored in real time by an infrared spectroscopy sensor with an error of ≤2%, thereby achieving precise control of the fermentation process.

7. The dragon fruit wine processing technology according to claim 1, characterized in that: In the stabilization step, a 0.2 μm ceramic membrane filtration system is used in conjunction with cold stabilization to remove tartrate crystals and reduce the risk of subsequent precipitation.

8. The dragon fruit wine processing technology according to claim 1, characterized in that: In the filling step, the inner wall of the brown glass bottle is coated with a food-grade polymer coating, and the air permeability of the bottle stopper is ≤0.1cm 3 / (day·atm) to reduce the effect of headspace oxygen content on wine stability.

9. The dragon fruit wine processing technology according to claim 1, characterized in that: In the enzymatic hydrolysis step, the ratio of the complex enzyme preparation is 0.05% pectinase and 0.02% cellulase, the enzymatic hydrolysis temperature is 45° C., and the time is 2 hours, so as to optimize the juice yield and the release of flavor substances.

10. The dragon fruit wine processing technology according to claim 1, characterized in that: During the aging step, the total amount of KPA added is 150 mg / L, and is dynamically added according to the tartaric acid content to maintain the chemical stability of the wine.

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