F'6 TAS Project

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F.6 TAS Project

• The features of Sulphur Dioxide (SO2) in white
  wine

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Contents

• Definition of white wine
• Why should we add SO2 in brewage?
• The uses of SO2 in brewage
• How do we add SO2 in brewage?
• How do we find the amount of SO2 in wine?
• How much SO2 in white wine?
• What is the result of adding excess SO2?
• How many SO2 should we add to white wine?

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1. Definition of white wine

• White wine is made of grape, consisting of yellow
  colour , flavours and fruity aromas. The body
  isnt colourless because of white body is only
  given out at one end of the spectrum. The
  intensity of yellow colour depends on different
  concentration which lower concentration gives
  pale yellow body.
• White wine is different to Chinese white wine
  which is made of rice, wheat, sorghum and corn.
  Besides, it is colourless and contains vegetal
  aromas. Colourless body exists because it must
  pass through distillation.

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2. Why should we add SO2 in brewage?

• There is brown corruption happened in the wine
  and the wine only temporarily stores.
• The reason of occurring brown corruption is due
  to the oxidation of yeast happening and leak of
  SO2 in the wine.
• When the mold is growing, they emit an enzyme
  which can react with air to form insoluble phenol
  chemicals, the muddy precipitants and changing
  the wine colour happen then to be brown. Besides,
  there is peroxide smell and boiled smell.

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• In general, brown corruption happens in the wine
  which is a leak of SO2 nuked outdoor in
  displace the bucket. So, not only choosing good
  quality fruit, but also adding SO2 to
  fermentation is effective precaution. SO2 is an
  anti-oxidant which can prevent oxidation
  happening. Moreover, it can act as an catalyst to
  dissolve ingredients. Some ingredients are useful
  for preventing the corruption happening, like
  Vitamin C which can reduce the insoluble phenol
  to be soluble.

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3. The uses of SO2 in brewage

• SO2 is a good sterilizing agent
• SO2 also has a clarification function in wine
• SO2 can prevent the oxidation of wine and mash
• SO2 has another function for dissolving the
  advantageous ingredients

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1) SO2 is a good sterilizing agent

• SO2 can kill and suppress the microorganisms.
  When SO2 is added to wine in special
  concentration, the other microorganisms cant be
  active but the yeasts in wine can still reproduce
  them so quickly, the selective effect of SO2 is
  shown, it maintains the fermentation of wine in
  order to make it in a good smell and tastes.

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2) SO2 also has a clarification function in wine

• When SO2 is put in the wine, the microorganisms
  cant work probably and be killed. However, the
  fermentation of it reaches the highest point
  which more yeasts carry out anaerobic
  respiration. As a result, the time of the
  sterilization process and the clear process
  increase so that the effect of them is better.
  This condition also has a benefit for making
  white wine.

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3) SO2 can prevent the oxidation of wine and mash

• When enough SO2 is contained in mash, the oxygen
  (O2) in it reacts with SO2 at once in order to
  stop the reaction of enzymes in wine. Moreover,
  SO2 can prevent the corruption happening in
  fruit, decolorizing the wine and the turbidity of
  the products. It can maintain the function of
  Vitamin C and enhance the stability of the wine.

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4) SO2 has another function for dissolving the
advantageous ingredients

• When SO2 is added to the wine, it reacts with
  hydrogen ions (H) contained in the wine to form
  sulphuric (IV) acid (H2SO3), which makes the
  advantageous ingredients on fruit coats such as
  colorant and salt dissolved. This can increase
  the quality of nonvolatile substances in wine in
  order to make the bright color of wine.

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The procedure of White Wine
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4. How do we add SO2 in brewage?

• Burning and fumigation of the sulphur
• Adding sulphur dioxide gas in wine directly
• Adding the liquefied sulphurous acid agent into
  wine directly
• Add Potassium Metasulphite (K2S2O5) into wine

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1) Burning and fumigation of the sulphur

• It is a traditional method to get sulphur
  dioxide, the sulphur lines, sulphur papers or
  sulphur is burnt in tightly shut space. The room
  or container should fill with sulphur dioxide
  swiftly. After a few minutes, tightly shut space,
  there are some equipment which would process
  sterilization. Since this method is primitive and
  less effect, it hasn't been used nowadays.

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2) Adding sulphur dioxide gas in wine directly

• The bottle of sulphur dioxide gas contains in a
  steel bottle, putting on a balance can measure
  the amount of the gas. It can pass through the
  pipe to the wine to react then become free in the
  wine.

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3) Adding the liquefied sulphite reagent into
wine directly

• In general, we should choose the concentration of
  sulphite reagent in 5 to 6. The reagent is
  convenient and control the volume used easily. If
  saturated liquefied sulphur dioxide is used, the
  temperature and the volume of sulphur dioxide
  used has to respect which can be calculated.
  However, when the reagent is added, complete
  stirring is necessary.

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4) Add Potassium Metasulphite (K2S2O5) into
wine

• K2S2O5 is a white crystal, it contains 57.6
  sulphur dioxide. This reagent must preserve in
  dry and airtight container to prevent K2S2O5
  oxidizes to potassium sulphate and lose
  disinfection. K2S2O5 dissolves into water and
  makes the solution in 10 concentration, it
  includes 5 sulphur dioxide. When the K2S2O5 is
  dissolved in water and is muddled completely, the
  efficiency of sulphur dioxide may be more.

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5. How do we find the amount of SO2 (aq) in white
wine?

• We can process titration to find out SO2 by
  iodine solution.
• 25.0 cm3 of a sample was transferred to a conical
  flask.
• Adding about 15cm3 1M aqueous sodium hydroxide
  to wine which provides OH- to let SO2 convert to
  SO32-. It can prevent evaporation happened
  because SO2 is volatile. And then, let the wine
  stay for 15 minutes to reach complete conversion.
• 15 cm3 of 2M sulphuric (VI) acid was added to the
  mixture to reduce SO32- to SO2.

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• The steps of b) c) can be shown as following
  equation
• 2SO2 (aq) 2OH- (aq) ? 2SO32- (aq) H2 (g)
• SO32- (aq) 2H (aq) ? SO2(aq) H2O (l)
• Adding starch indicator solution to the resulting
  solution and then quickly titrated with 0.0050M
  potassium iodide solution consisting of I2 (aq)
  which is volatile.
• The result is the colour of wine changed from
  colourless to dark blue then the end point and
  the reading of volume of used KI (aq) existed.
• The following equation can display the
  titration
• I2 SO2 2H2O ? 2I- SO42- 4H

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6. How much SO2 in white wine?

• We have titrated with 3 types of wines
• Chinese white wine Rice wine 30 alcohol
• Spark wine ---- Vodka carbonated water which
  Vodka is high concentration of alcohol is
  distilled wine Sub-Zero 5 alcohol
• White wine Marzo white wine 12 alcohol
• According to Hong Kong Preservation in Food
  Regulations, the limit of SO2 in wine is
  450mgdm-3.

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• The total volume of used KI (aq) (1.21.70.8)/3
  cm3 1.23 cm3
• So, the concentration of SO2 in the Chinese white
  wine
• molarity of KI (aq) volume of used KI (aq) /
  volume of the sample
• 0.0050 M (0.00123 / 0.025) dm3 0.24610-3
  M
• 0.24610-3 (32.06 16 2) 15.76 mgdm-3

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• The total volume of used KI (aq) (3.14.62.1)/3
  cm3 3.27 cm3
• So, the concentration of SO2 in the spark wine
• molarity of KI (aq) volume of used KI (aq) /
  volume of the sample
• 0.0050 M (0.00327 / 0.025) dm3 0.65310-3
  M
• 0.65310-3 (32.06 16 2) 41.85 mgdm-3

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• The total volume of used KI (aq) (8.99.19.2)/3
  cm3 9.07 cm3
• So, the concentration of SO2 in the white wine
• molarity of KI (aq) volume of used KI (aq) /
  volume of the sample
• 0.0050 M (0.00907 / 0.025) dm3 1.81410-3
  M
• 1.81410-3 (32.06 16 2) 116.20 mgdm-3

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7. What is the result of adding excess SO2 ?

• Copper and white wine's corruption
• Awful smell due to H2S
• Headaches for asthma

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The source and amount of copper in the white wine

• The source of copper in the wine are the
  facilities in the brewery and antideteriorant. In
  the fermentation, a great majority copper are
  reduced to copper (II) sulphate then
  precipitation. After the process, the amount of
  copper only shares 0.2 - 0.3mg.
• In the bottling, there is turbidity happened
  which brick-red precipitate is formed in the
  containing SO2(aq) wine. But, the turbidity and
  precipitate disappear when the wine is nuked
  outdoor. Besides, high temperature, sharking and
  sunlight can speed up the rate of corruption.
  According to the research, if the wine contains
  0.5mg of copper, the corruption can occur.

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The change of the copper in wine and its
corruption (Cu2SO3)

• The corruption is due to the reduction between
  copper and copper (I) ion , so the factor of the
  reaction are enough amount of copper and SO2.
• There are few reactions to explain the reason of
  corruption
• Cu2 RH ? Cu R H where RH represents
  reducing substance
• 6Cu 6H SO2 ? 6Cu2 H2S H2O
• Cu2 H2S ? CuS 2H where CuS can form
  colloidal solution happens turbidity and
  precipitate
• So, we can say that the corruption is due to
  forming colloidal solution of CuS and copper.

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• Air can make insoluble CuS become soluble by
  oxidation, so the wine is gradually clear after
  adding air.

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The precaution of copper corruption

• There are few measure to prevent the corruption
• 1. We should stop using antideteriorant strictly
  before cropped.
• 2. The brewery facilities containing cupper
  should be tinned to prevent corruption at fixed
  period.
• If the corruption has happened, we can use sodium
  sulphide to eliminate copper. Na2S . 9H2O crystal
  can let copper to form insoluble CuS. After
  filtration, the copper can be complete
  eliminated.
• Sodium sulphide can make insoluble CuS become
  soluble in oxidation with sticking to provide
  oxygen.

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• But excess sodium sulphide forms H2S which
  remains in the containing SO2 wine, H2S may react
  with SO2 to form liquefied sulphur and
  thiosulfurous acid (H2S5O6), H2S5O6 can make the
  wine become bitter and H2S gives awful smell.
• We can use the ratio between Na2S . 9H2O and H2S
  to find out suitable amount of Na2S . 9H2O, using
  suspension method and titrating by indicator are
  the following steps.

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Awful smell substance -- H2S

• Due to preventing the mold growth, we must add
  hydrogen sulphite to the grape for pouring and
  sterilization. However, too much H2S can exist in
  the wine, the awful smell of wine is given.
• So that, we should use suitable amount of SO2. If
  the awful smell has been given form the wine, you
  can add olive oil to the wine, the amount is
  about 2 to 2.5 L per 1000L. And then, sticking 3
  to 5 times and standing for few days is needed
  for extracting H2S form the oil after the above
  steps.

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Headaches for asthma

• Person has severe asthma who is under doctors
  orders to restrict consumption of sulphites (a
  relatively small percentage of the population).
  They can experience headaches after drinking
  wine. If the person want to drink wine, they must
  choose the high dryness wine which dont taste
  very sweet. This is because SO2 is necessary for
  preservation in sweet wine.

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8. How many SO2 should we add to white wine?

• During manufacturing, the main complicated
  problem is how to control the volume of SO2. It
  is necessary to consider the relationship between
  SO2 and other variable factor. The factor of
  added volume depends on the followings
• The quality of grape fruit
• The clarification of fruit juice
• The acidity of grape must after fermentation
• The acidity of wine after the first changing
  bucket
• The acidity of wine after the second and later
  changing bucket

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1) The quality of grape fruit

• To ensure that disinfection of grape mush must
  take place, the grape fruit should be added in
  suitable volume of SO2 before squeezing to
  fermentation, in order to prevent the
  reproduction of harmful micro-organisms and the
  activity of enzyme. However, the maturity level
  of grape, freshness or organic degradation and
  the temperature are the factors of volume of SO2
  used, so the amount of SO2 used are not the same
  each times. You can refer to the table 1, 2 and
  3.

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2) The clarification of fruit juice

• In general, grape fruit juice should be taken to
  the clarification, a standard white grape wine
  could be obtained. Natural evaporated
  clarification and filtration are the clarifying
  method. But the most effective method is using
  SO2. During the clarification, it should depend
  on whether the temperature is high or low. For
  example, when the temperature is 20 degree
  Celsius, the fruit juice contain 40mg/L SO2.
  After 24 hours by natural evaporated
  clarification, it could achieve the clarification
  process.

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3) The acidity of grape must after fermentation

• After the grape must ferment and the first
  changing bucket. If the acidity of grape must is
  lower than 7.5g/L, SO2 should be added to
  regulate the acidity, allow the liquid reach
  100-150mg/L or the volume of SO2 is 20-30mg/L.

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4) The acidity of wine after the first changing
bucket

• For the grape wine which has higher acidity, if
  the temperature is suitable, the apple acid and
  lactic acid in the wine would ferment, this make
  the wine become milky, and cause the acidity
  decreases. Therefore, people should consider to
  add suitable SO2 into the wine, make the SO2
  volume in the wine become 100-150mg/L, to ensure
  the best quality of wine.

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5) The acidity of wine after the second and later
changing bucket

• As the wine is changing bucket each time, wine
  would be affected by the environment, air, etc.
  For example, if there is a temperature change or
  air pollution, the harmful micro-organisms would
  reproduce in the wine, cause the wine become bad.
  So human need to consider the volume of SO2 added
  in order to prevent the accident would not
  happen. In general, the SO2 volume in the wine
  nearly 100-150mg/L is favourable. If the volume
  of SO2 is too high, that would cause the grape
  wine produce bad smell, bad taste and the
  appearance become less attractive.