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Study on the development of pumpkin wine

Using pumpkin as raw material, the alcohol fermentation technology was studied. The optimum technological conditions of alcohol fermentation in pumpkin juice were determined by single factor experiment and orthogonal experiment, namely, the sugar content in pumpkin juice was 22%, the inoculation amount of dry yeast was 5.0%, the pH value was 4.0, the temperature was 24℃, the fermentation time was 3 days, and the alcohol content could reach13.8% vol.

Pumpkins have a long history of cultivation. As a vegetable, fruit not only has high edible value, but also has a dietotherapy function that can not be ignored. It contains starch, protein, carotene, vitamin B, vitamin C, calcium, phosphorus and other ingredients, and has attracted people's attention because of its rich nutrition and high health care function.

Deep processing of pumpkin can not only retain the effective nutrition and health care components of pumpkin, but also break through the seasonal restrictions of pumpkin.

However, at present, there are few manufacturers of pumpkin deep-processed products in China, and few pumpkin wine drinks are sold.

In this experiment, pumpkin was used as raw material, and the effects of nitrogen source, temperature, sugar content, pH and inoculation amount on the product were comprehensively considered, which provided some reference for the further development of pumpkin wine.

1 materials and methods

1. 1 experimental materials and reagents

Commercially available pumpkin, pectinase (30000 u/ml), Angel high-activity dry yeast, white sugar, yeast extract, ammonium chloride and citric acid.

1.2 equipment and instruments

JA 1203 electronic balance; Beat the juicer; HH-4 digital constant temperature water bath pot; HC TP 1 1B 5 tray drug balance; GMSX—280 portable pressure steam sterilizer; Kxh 10 1-2A constant temperature drying oven; KXB- 1 1H constant temperature incubator; PHS-3C type acidity meter; Alcohol measuring instrument; Alcohol distillation unit; Thermometer; Philips juice residue separation juicer; BC-50E volumetric refrigerator; Refractometer; Distillation device; Common glassware.

1.3 experimental method

1.3. 1 Preparation of pumpkin juice

Pumpkin → selecting, cleaning → peeling → pulp → slicing → beating → adding pectinase → enzymolysis → inactivation and passivation → filtering, and calculating the juice yield according to the source of Huaxia wine.

In this experiment, pectinase was used for enzymolysis, the enzymolysis time was 4.0h, the enzymolysis temperature was 45℃, the addition of pectinase was 0.08%, and the juice yield of pumpkin reached 76.8%.

1.3.2 Optimization of ethanol fermentation conditions of pumpkin wine

The effects of nitrogen source, sugar content, inoculation amount, temperature and pH on the alcohol fermentation process of lemon fruit vinegar were studied by single factor experiment.

1.3.2. 1 nitrogen source

Yeast extract 1% and 2g/ 100mL ammonium chloride were added to do blank test.

The fermentation temperature was controlled at 28℃, the pH of the fermentation broth was adjusted to 4.0 with citric acid, the sugar content was 65438 04%, the inoculation amount of solid dry yeast was 5%, and the fermentation time was 3 days. The sugar content was measured every day, and the alcohol content was determined after fermentation.

1.3.2.2 sugar content

Five sugar levels were designed, which were 14%, 18%, 22%, 26% and 30% respectively. The fermentation temperature was controlled at 28℃, and the pH value was adjusted to 4.0 with citric acid.

The inoculation amount of solid dry yeast is 5%, and the sugar content is measured every day, and the alcohol content is measured after fermentation.

1.3.2.3 Inoculation amount

Five levels of yeast inoculation were designed, in which the addition of solid dry yeast was 2%, 3%, 4%, 5% and 6% respectively, the fermentation temperature was controlled at 28℃, the pH was adjusted to 4.0 with citric acid, the addition of sodium sulfite was 65,438+000 mg/L, and the addition of sucrose was 65,438+04%. Measure sugar content every day and alcohol content after fermentation.

1.3.2.4 temperature

Five temperature levels were designed, which were 22℃, 24℃, 26℃, 28℃ and 30℃. Adjust the pH to 4.0 with citric acid, the inoculation amount of solid dry yeast is 5%, and the addition amount of sucrose is 14%. The sugar content was determined every day, and the alcohol content was determined after fermentation.

1.3.2.5 pH value

Five pH levels were designed in this experiment, which were 3.0, 3.5, 4.0, 4.5 and 5.0 respectively. The pH was adjusted with citric acid, the fermentation temperature was controlled at 28℃, the inoculation amount of solid dry yeast was 5%, and the addition amount of sucrose was 65,438 04%. The sugar content was determined every day, and the alcohol content was determined after fermentation.

1.4 orthogonal experimental design for ethanol fermentation of pumpkin

According to the results of single factor experiment, the optimum range of inoculation amount, sugar content, temperature and pH value was determined. Four factors of optimizing orthogonal test table. Taking inoculation amount (%), sugar content (%), temperature (℃) and pH as four factors, an orthogonal experiment with four factors and three levels was carried out.

Choose an appropriate range for each factor. See table 1 for the orthogonal test design table.

1.5 Analysis of main components of raw materials

Determination of pH value: pH meter method.

Determination of soluble solids: refraction method.

Determination of alcohol content: alcohol distillation method.

2 Results and analysis

2. 1 nitrogen source

Nitrogen source is an important nutrient element for microbial growth and metabolism, which can shorten the fermentation cycle of microorganisms, enhance the flavor of products and improve production efficiency. Therefore, yeast extract and ammonium chloride were used to study the effect of nitrogen source on alcohol fermentation process, and the results are shown in Table 2.

As can be seen from Table 2, the blank experiment without nitrogen source has higher alcohol content, which may be because the nitrogen source contained in pumpkin juice can completely meet the growth of yeast.

However, the addition of nitrogen source will make the fermentation broth too rich in nutrition and provide good external conditions for the growth and reproduction of yeast cells. Yeast uses carbon source for its own growth, which reduces the substrate sugar converted into alcohol during alcohol fermentation, which eventually leads to the extension of fermentation cycle and the decrease of alcohol content.

Therefore, nitrogen sources should not be added in pumpkin juice alcohol fermentation.

2.2 Sugar content

The experiment was carried out according to the conditions described in 1.3.2.2, and the results are shown in Table 3 and Figure 1 and Figure 2.

From the results in Table 3, by comparing the magnitude of amplitude R of A, B, C and D, it can be seen that the primary and secondary relationship of the four factors is: B (sugar content) >; A (inoculation amount) > D(PH)>c (temperature). The amount of sugar added has a significant effect on alcohol fermentation, but the effect of inoculation amount is relatively small. The best combination among 9 experiments was No.6, A2B3C 1D2, that is, sugar content was 22%, inoculation amount was 5.0%, pH value was 4.0, and temperature was 24℃. Under these conditions, the alcohol content can reach13.8% vol.

3 Conclusion

3. 1 The ethanol fermentation technology of pumpkin was determined by single factor experiment.

There is no need to add nitrogen source, the sugar content of alcohol fermentation 14%-22%, the suitable inoculation amount range is 4.5%-5.5%, the optimum temperature range is 24℃-28℃, and the optimum pH range is 3.5-4.5.

3.2 The orthogonal design was used to study the ethanol fermentation technology of pumpkin.

By investigating the influence of various factors on the product during pumpkin alcohol fermentation, the optimum technological parameters of pumpkin alcohol fermentation were determined as follows: sugar content 22%, inoculation amount 5.0%, pH value 4.0 and temperature 24℃. Under these conditions, the alcohol content can reach 65438 03.8%.

To sum up, the primary and secondary relations of the four factors are: sugar content >; Inoculation amount > PH value > temperature.