3. Quality assurance (QA) and quality control (QC). Flashcards
What are the components of wine?
- Alcohol.
- Acids.
- Esters.
- Residual sugars.
- Glycerol.
- Aldehydes/ketones.
- Phenolic compounds
Why are aromas hard to fully detect in wine.
- People sensitivity - there are 1000 volatile compounds/molecules, only a few have a threshold of perception, and people will have different threshold for each molecules.
- Aromas are not additive, but a sum of different chemicals interactions like:
A. Masking interaction - one compound masks another.
B. Synergistic interaction - combination of multiple compounds to form an aroma.
What are the compounds that are forming aromas?
- Wine aroma - 20 main different aromatic chemicals, the only one present in grapes is b-damascenone, the rest is all produced by yeast’s metabolism working on precursors in grape juice.
- Contributory compounds - low perception threshold compounds with high synergistic interactions.
- Impact compounds - low concentration but they contribute to varietal character, many wines lack these compounds.
- Nonvolatile wine matrix - wine constituents with no aromatic characteristics influence aromatic molecules perception.
Main wine aromas are coming from?
- Higher alcohols (e.g. butyric, isoamylic, hexylic, phenylethylic).
- Acids (acetic, butyric, hexanoic, octanoic, isovaerianic).
- Ethyl esters from fatty acids.
- Acetates and compounds (e.g. diacetyl).
- Ethanol.
Most common contributory compounds.
- Volatile phenols (e.g. guiaicol, eugenol, isoeutigenol, 2,6dimethoxyphenol, allyl-2,6-dimethoxyphenol).
- Ethyl esters.
- Fatty acids.
- Acetates of higher alcohols.
- Ethyl esters of branched fatty acids.
- Aliphatic aldehydes with 8 to 10 carbon atoms.
- Branched aldehydes (e.g. 2-methylpropanol, ketons)
- Vanillin and its derivatives.
Famous impact compounds.
- Methoxypyrazine - green, grassy aromas, is formed in grapes and is highly stable during fermentation/ageing.
- Monoterpenes - eg. linalool the floral compound of Muscat and rose-cis oxide, the rose of Gewurztraminer.
- Rotundone - pepper in Syrah.
- Polyfunctional thiols (mercaptans) - tropical fruit scent in Sauvignon Blanc (called 4MMP, 3MHA, 3MH).
Most famous volatile compounds for wine aromas.
- Esters - reaction of organic acids with alcohols during fermentation and ageing. (e.g. ethyl acetate = acetic acid + ethanol), mostly are fruity aromas also oily, herbaceous, buttery, nutty.
- Aldehydes - minor but important in Sherry for acetaldehyde.
- Vanillin - from oak barrels.
- Ketons - mainly diacetyl, buttery aromas (also from acetoin) or roses/floral in Chardonnay or bouquet in Riesling (b-damascenone) at low level, bad at high levels like bitter taint of benzoic (usually comes from bad application of epoxy resin in vat lining).
- Higher alcohols/fused oils - amyl alcohols pungent aromas that can be pleasurable in contained quantities (e.g. hexanol grassy aromas).
- Lactones - sweet spicy coconut in oak, or botrytised and oxidated wines for aromas of sweet spicy toast and nuts.
- Acetic acid (acetobacter) - sour and vinegar aromas.
- Volatile phenols - brettanomyces forms 4-ethylphenol and 4-ethylguaiacol has aromas of spiicy, gamey. animal.
- Terpenes - floral, grapey, linalool, geranium character in Muscat, Gewurz, Pinot Gris. There are around 40 different types in the grapes but only 24 can really pass the threshold.
- Methoxypyrazines - metabolism of amino acids, heterocyclic compounds that contain nitrogen, herbeceous aromas in Cab Franc, Sauv, and Sauvvy B.
- Volatile sulfut compounds - mercaptans (thiols) in controlled quantities are good, if too high is a fault.
What gives green aromas to wine?
- Compound group called alkyl-methoxypyrazines - present in green tissue of plants (e.g. green bell pepper). Most famous type is isobutyl (high threshold), also isopropyl and sec-butyl in low levels.
Methoxy can also be influence by other things:
A. Insect taint - e.g. ladybug has insane levels of methoxypyrazine and can taint a wine if found in the middle of the bunches, or falls into the vat.
B. Viruses - leafroll virus delays berry maturation so more methoxypyrazine are retained.
- Green leaf volatiles - oxyplin pathway chemical reaction, typical from plant defence.
- Eucalyptus taint - molecules are transferring from eucalyptus and pine trees.
How methoxypyrazine grows inside a grape and why?
Together with tannins they work as antifeedand for the birds - to keep them away to eat grapes when unripe.
They grow reaching a high level just before veraison, then they decrease with ripeness.
How can a winemaker lower the levels of methoxypyrazines?
Methoxypyrazine are a stable compound (also during and after fermentation) and don’t go away with simply more hang time.
- Expose grapes to the sun with leaf removal (reduce accumulation rather than increase degradation, so impact is minor).
- Slowing growth just before accumulation phase.
- Winemaking techniques such as oak ageing, gentle pressing, must clarification in must, thermovinification. Low level of impact. Most of the work needs to be done in the vineyard.
How alcohol impacts wine aromas?
- Alcohol and natural acids, coming in contact, form esters.
Usually esters are split apart again by water (hydrolysed) into acids and alcohol and then recombined in different ways creating more aromas.
Higher-alcohol wines have more fruity aromas (e.g. pineapple, bananas, strawberry, raspberry and others).
- Alcohol can also masks aromas as it modify solubility of aroma compounds and it doesn’t leave the solution making the wine less aromatic.
- Alcohol has a sweet tasting component to it. Infact low alcohol wines are drier. The problem if that when it’s too high it does have an effect of making the wine hot, astringent and bitter.
How alcohol is chemically formed?
Carbon chain (carbon C groups with hydrogen H) + OH (group that gives alcohol its characteristics)
The number of carbon chains present forms different types of alcohol.
Is ethanol the only form of alcohol produced during fermentation?
No, is just the dominant.
All the small quantities of other alcohol are playing a part in bouquet and flavour.
How can we divide types of alcohol in wine?
By relating them to ethanol in carbon chains.
- Less carbon chains than ethanol.
Methanol (CH3OH) - unpleasant and highly toxic (in high quantities can bring blind, madness and death). In wine has low quantities, while in spirit it is discarded as head (boils at low temperature).
- Ethanol (CH3CH2OH).
- Higher alcohols/fused oils - bigger carbon chains than ethanol.
Propanol (CH3CH2CH2OH) and Butanol (CH3CH2CH2CH2OH).
Less toxic but unpleasant (nausea, headaches). They are discarded in spirits as tails boiling at high temperatures.
How can you calculate alcohol by volume rather than weight?
17 grams of sugar = 1% alcohol volume.
In this way you can calculate alcohol and volume of enrichment.
E.g. if a must has 170 g/L it will be equal to 10% so if 2% more is required you will need 34 g/L.
To understand the total you can then multiply 34 for the mass of must e.g. 4000 litles X 34 = 136 kg.
It is a simplification, as fermentation is more complex than this but it is helpful.
What happens to alcohol when it oxidises? What it produces?
(all VA questions can be used into Va section later in this chapter)
- Acetic acid (the acid of vinegar) is produced through the influence of acetic bacteria (acetobacter). It is also called volatile acidity.
Ethanol (CH3CH2OH) + oxygen (O2) = acetic acid (CH3COOH) + water (H2O).
It is an aerobic process, VA needs oxygen to form.
- Aldehyde - ethanol oxidation specifically produces acetaldehyde (ethanal) which is the most important aldehyde (90% in wine).
Where are the bacteria for VA present?
In the skins of the grapes.
For this reason it is hard to find rose and white wines with high VA.
Is volatile acidity good for the wine? When it become noticeable? What does is smell of?
Every wine has a particular amount of it, it add complexity to the wine but needs to be kept in check as if high can become a fault.
Becomes noticeable at 0.8g/L. Limits on VA in EU is 1.2g/L for reds and 1.08g/L for whites and roses.
If too high it will smell like nail varnish removal or cellulose thinners.
Can you name two examples of rising VA and the causes?
- VA raises with time. Older wines will have a stronger VA.
- Esterification - similar to bottle maturing process. The acetic acid (CH3COOH) reacts with ethanol (HOCH2CH3) and produces (=) the ester ethyl acetate (CH3COOCH2CH3) and water (H2O) augmenting VA aromas.
- Hot climates and warm temperature fermentation will increase the rate of activity of the bacteria.
How can a winemaker get rid of VA?
- Filter the bacteria out.
- Gas blanket the vat (nitrogen, CO2 or a mixture of both).
- SO2 calm the bacteria.
What are the problems of acetaldehyde?
- Unpleasant flavours - yeasty, green apple (good in fino sherry though).
- Binds with sulphur dioxide producing bisulfite components and lowering SO2 protection.
These problems are rare thanks to modern equipment in the winery.
- Can cause headaches in certain people.
What is the third most abundant component of wine after alcohol and water?
Glycerol (4g/L to 10g/L).
Colourless liquid with a sweet taste - improves mouthfeel giving weight and smoothness to the wine.
You can see it as the legs in the wine glass are formed by the combination of alcohol and glycerol due to a surface tension effect.
How glycerol is formed?
- From the sugar of the grapes, during fermentation (the higher the sugars, the higher the glycerol levels).
- Yeast strain can affect levels.
- In botrytis cinerea wines glycerol is naturally formed by noble rot’s metabolism reaching up to 30g/L giving lush, smooth viscosity.
Can a winemaker influence esters formation?
Yes.
- Use specific commercial yeasts.
- Add specific malolactic bacteria.
- Lower temperatures (to retain aromas, high will destroy them).
- Acidification to increase esters formation.
What makes a wine sweet?
- Sugar/residual sugar.
- “Sweet aromas” (fruit) - some aromas affect perception, sometimes fruit aromas can change perception (e.g. an old sweet wine smells drier because has lost all fruit aromas).
- Alcohol - tastes sweet.
What type of sugar remains as residual sugar in the final wine?
Mainly fructose.
Glucose is the one the ferments the most as yeast membranes are more permeable to glucose.
Sucrose is mainly a sweetener that is added - it tends to go through a process called inversion where the acids will transform it into glucose and fructose.
EU wine sweetness regulating terms and residual sugars.
- Dry - up to 4g/L.
- Medium dry - up to 12g/L.
- Medium/medium sweet - between 12g/L and 45g/L.
- Sweet - not less than 45g/L.
What are the most important phenolic compound in wine?
Phenolic compound are divided into two groups.
A) Non-flavonoid - little or no importance.
- Acid phenols - cause browning in white wine,
- Gallic acids - presents during oak contact.
B) Flavonoid
- Tannins - extracted by alcohol, usually extraction is higher at the end of fermentation when alcohol is higher and in post maceration.
- Anthocyanins - responsible for wine colour, infused from broken skin cells into the liquid (or by heat and pressure) similar to tea leaves in hot water).
What is the difference between quality control (QC) and quality assurance (QA)?
Quality control is the process of monitoring and controlling parameters - from planting the vineyards to storing bottles. Includes lab analysis on wines.
Quality assurance is the totality of all the management actions to achieve high standards. It is a management concept,
How many times wines is analysed and how do you keep a record of it?
Depends on the producer’s Quality Plan. The more analysis the better, from before picking to after bottling, as it will provide more data.
Traceability is required in the EU by law on each batch. A winemaker should be able to track every single bottle he produces. Can go from simple paper filing to complex computer programs for big wineries that blend wines from all over the country.
Where is wine analysed?
- In-house lab - very costly, mainly for big wineries that work on blends.
- Accredited specialist wine laboratories.
What specifics are analysed in wine?
- Density.
- Alcohol.
- Total dry extract.
- TA (Total acidity).
- pH.
- Volatile acidity.
- Residual sugars.
- Tartrate stability.
- Protein stability.
- Additives (SO2 + others).
- Dissolved oxigen.
- Iron and copper.
- Sodium and potassium.
- Clarity and filterability.
How density is measured?
- Hydrometer - a glass float with a graduated scale stem, the more it sinks the lower the density.
- Densimeter - liquid is injected into a small glass tube, the denser the liquid and the slower the vibrational period of the tube (expensive but fast).
How is density expressed?
A) Density (mass of a given volume of liquid at a given temperature).
- g/L at 20C (EU) - preferred
B) Specific Gravity (SG) - comparison of the mass of a given volume of liquid with the mass of the same volume of water.
- Baume (Be) - SG x 1000 (France)
- Oechsle (Oe) - Be - 1000 (Germany)
C) Brix - density of a solution of sucrose expressed as a percentage by weight (pocket refractometers are calibrated like this).
- Brix.
- Babo (Italy).
- KMW (Klosterneuburger Mostwaage, Austria).
- Hungarian must weight.
Main problem of calculating density.
Dissolved sugars increase density. Alcohol decreases it.
How alcohol is expressed on the label?
By percentage of volume (%).
It was before in proof - a small heap of gunpowder was wetted with the spirit and then matched on fire, 100 proof was 57%. American proof was double the percentage by volume and that created confusion with consumers.
Why analysing alcohol is difficult?
Because ethanol is not very reactive. Most methods depend on physical characteristics (density, infrared radiation).
How alcohol is calculated?
- Distillation - a sample of wine is boiled, and alcohol vapours into a condenser where a liquid is formed. The density of the distillate is then measured.
- Near infrared region (NIR) - a beam of light of NIR pass trough the wine and with a button press the answer is printed out (useful in labs where hundreds of samples are analysed every day).
- Gas chromatography - a small sample is into a long column with an absorbent, inert gas pass through and the column is heated up in an oven that vaporise the alcohol, individual alcohols can be analysed as their speed is different going up the column
What is total alcohol?
It depends on how much residual sugar is left in the wine.
- Actual alcohol - how much alcohol there is in wine.
- Potential alcohol - the amount of alcohol in the wine’s residual sugar component.
The sum of the two is total alcohol.
What is total dry extract (TDE)?
It is the amount of non volatile substances remaining after evaporation of the wine to dryness at 100C atmospheric pressure.
Water and alcohol evaporate leaving sugars, glycerol, non volatile acids, mineral salts, polyphenols and minor constituents.
Why do you calculate total dry extract?
In dry wines - it indicates if the wine has been subjected to falsification (e.g. add water). 16 to 20g/L TDE, the bigger the wine the bigger the figure.
In residual sugar wines - indicates the amount of residual sugar (e.g. 12g/L of sugar = 28/32g/L TDE).
What is TA?
Stands for both total acidity and titratable acidity.
- Total acidity is the measure of all the organic acids in the wine (including VA).
To avoid complications it is express as if there is only one acid in wine.
In the EU is calculated on tartaric - with a limit on table wines of 4.5g/L.
In France is sulphuric - more complicated and nonsense.
- Titratable acidity looks at the ability of the acid in the wine to neutralise a base (alkaline substance, usually sodium hydroxide).
In most cases total acidity is too hard to calculate so assume that titratable is the one on the analysis - the unit will always be slightly lower than the real TA.
How VA is calculated?
- Wine is taken through a pipette and transferred into a flask.
- An alkaline solution, inside a burette, gets into the wine, until the liquid becomes neutral.
- Endpoint - an indicator (substance), or a pH meter (useful in red wines as colour change is harder to detect) change the colour of the wine when neutrality is reached. The amount of alkaline solution used is then proportional to the TA in the wine.
Why TA is measured?
- To correct the wine prior to fermentation - in rare cases after.
- Bottling companies use it to check if wine has been watered (TA should be the same as the analysed wine and the bottled one) so to check scams.
What is pH?
Concentration of hydrogen ions in a solution.
Affects colour, taste, keeping qualities.
It is a number that calculates all acidity and includes the buffer effect of natural salts in wine - they can change TA but not pH levels.
What is the formula of pH?
-log10[H+]
pouvoir hydrogene (hydrogen power).
It is in a negative logarithmic scale:
- The lower the number the higher the acidity.
- pH 3 is ten times more acidic than pH 4.
How does pH works?
The acidity of an acid depends on its dissociation constant (pK3).
Dissociation is the release of protons into a solution.
The lower the number the more dissociated the acid is.
Sulfuric acid - pK3 1 (strong and completely dissociated).
Tartaric - pK3 3,01
Malic - pK3 3,46
Lactic - pK3 3,81
Carbonic - pK3 6,52 (weak acid)
E.g. during MLF malic acid turn into lactic - from two protons moves into one proton only lowering dissociation and shifting pH.
What is the pH scale?
0 (acidic e.g sulfuric acid) to 14 (alkaline - e.g. caustic soda).
7 is neutral (water).
Wine stands between 2.8 and 4. Even small changes of 0.2 are massive in the wine.
White wine = 3 - 3.3
Red wine = 3.3 - 3.7
How pH is measured?
- A pH meter is inserted into the sample and the reading is given. Needs to be calibrated for every use as the electrode might change.
- Tables to dissolve in liquids that yield a solution of accurately know pH.
Usually is measured in wine as in must pH could change because of acidification or MLF.
Is it preferrable to have high or low pH?
There are no links to pH and quality. Winemakers prefer low pH levels because:
- Less risk of oxidation.
- Less risk of microbial spoilage (e.g. brett).
- Affects amount of SO2 present in active molecular form - the lower the pH the more SO2 is present requiring less additions.
Is TA more important than pH?
Generally gives a better reading of acidity.
The problem is that you can have high pH wines with high TA - that’s because different acids gives different “flavours”.
What is VA (volatile acidity) and how it is expressed?
It is the measure of the components of total acidity that can be separated by boiling the wine.
Expressed in acetic acid, its major constituent, which is the product of alcohol’s oxidation and the acid of vinegar.
In France someone uses sulphuric acid (multiply acetic by 1.225).
How VA is calculated? What are the main problems.
Volatile acids are boiled off and distilled.
- Condition of distillation needs to be the same as volatile acidity have various acids that boils at different temperatures.
- Esters might form - they are neutral not acetic. VA numbers might then change.
What is Fehling’s titration? What does it measure? Why it is used?
A titration which involves a reaction with copper salts.
Determines residual sugar (RS).
Hard to use density (alcohol is less dense than water so interferes with values) or RIR (refractive index of alcohol is different from water).
How do you check tartrate stability before bottling?
- Standard test - a sample is refrigerated at -4C for 3 days and then checked for crystal presence.
- Measure of concentration of tartaric, potassium, calcium, alcohol, and pH - then a formula established stability.
- Conductivity test - wine stirred at zero degrees (divides potassium bitartrate crystals from the solution), then change in electrical conductivity is measured, if rises it means that crystals are dissolving (stable).
Main problems of tartrate stability checks.
- Colloids might prevent at the time of the test the formation of crystals.
- In conductivity tests is best if who does the test is someone who knows well the wines as every wine will react differently.
The best solution might be teaching consumers about the zero risks of tartrate (apart from BIB if blocks the tap).
What are the main problems of unstable proteins?
- Haze, cloudiness.
- Deposit.
What are the methods to check protein stability?
- A small sample is heated to 80C and then brought to room temperature. If then the wine is hazy needs fining.
- Add phosphomolybdic acid (Bentotest reagent). Produces a coagulation of the proteins resulting in haze.
As with tartrate stability test, better if the winemaker knows the wines.
Why is important to check permitted additives?
- To ensure correct level has been added.
- To help operators keep track and make sure that no one under or overdoses the wine.
How can you measure SO2 in wine?
- Titration with potassium iodate, which oxidises the SO2.
- 2nd Blank titration - acetaldehyde is added to wine to bind SO2. Iodine will then oxidise other substances. Then the blank titration is subtracted from titration numbers to get a correct reading.
- EU reference/peroxide method - a current of air is bubbled into wine trapping SO2, pass through a solution of hydrogen peroxide wich oxidised the SO2 to sulfuric acid. Sulfuric acid then goes through a titration. This gives the correct reading of SO2.
- Total Sulphur Dioxide - Peroxide method with alkaline solution into the wine sample. It will bind SO2 converting it to free.
What other additives needs to be checked?
- Ascorbic acid.
- Sorbic acid.
- Metatartaric acid.
- Citric acid.
They all have legal limits that needs to be respected.
Why you need to calculate DO (dissolved oxygen)?
Because it can saturate the wine and destroy it.
20C - 1 lt of wine can absorb 8mg/L.
-5C - twice as fast (more dangerous).
How do you calculate DO? What are the main problems?
With a meter. Modern ones are called “Nomasense”.
- Electrode can go out of calibration.
- The atmosphere is 20% oxygen - can give high results that are inaccurate.
What is the effect of iron and copper in wine? How do they get into wine?
Iron - limit at 10mg/L, increases because of old galvanised buckets or ancient presses.
Copper - 0.2 mg/L, actually hepful because removes hydrogen sulfide (rotten egg reduction aroma) and it is sometimes added by winemakers, increases because of bronze fittings/pumps and late spraying in vineyards.
How do you calculate iron and copper?
With AA (atomic absorption spectrometer).
A light beam from a special electrode lamp with iron or copper pass through a gas flame.
Wine is sprayed through the gas flame. Intensity of the beam is measured.
Why sodium and potassium needs to be checked.
They have normal levels:
Potassium - 1000 mg/L
Sodium - 20 mg/L
Ion exchange alters it, concentrating the sodium by a factor of 10.
How can you calculate sodium and potassium?
Flame photometer.
Measures the emission of light at the characteristics sodium waveleght (street lights).
How can you check if your wine needs clarification and filtering?
- Nephelometer (for turbidity) - measures the loss of direct light by scattering particles in suspension in an opaque liquid, measured in “ntu” (reds below 1 ntu, whites 2000 mtu).
- Filtration tests - lab bench top filtration to measure the time it takes to filter a sample on a reference membrane at a given temperature.
How can you control yeast and bacteria levels pre bottling?
- A funnel is sterilised and a small membrane inserted.
- The funnel is then inserted into a flask and the wine sample is then inserted into the funnel.
- A vacuum pump sucks the wine through the membrane where microorganisms are stuck.
- The membrane is removed and placed on the surface of a nutrient medium that nourishes the organisms to reproduce rapidly.
- After 3 days the membrane is examined as yeast/bacteria colonies are visible by naked eye. If the filter looks like before this procedure the bottle is clean.
Mostly done to check problems of 2nd fermentation in bottle.
Three main advanced method of analysis.
- Chromatography - separates components of a mixture, as they pass at different speed, through a tube containing an absorbent material.
- Enzymatic testing - enzymatic kid and spectrophotometer as enzyme catalyse with specific compounds, then compared with a reference curve (acetic, malic, lactic, glucose, fructose, ammonia, nitrogen)
- DNA - can tell origin and vintage of wine, great for fraud detection.
Three main types of chromatography.
- Gas.
- Liquid (HPLC)
- Mass.
Main models to ensure quality (quality management systems for quality assurance).
- HACCP (Hazard Analysis and Critical Control Points) required by law in the EU, controls hazards significant for food safety.
- ISO 9000 family (9000, 9001, 9004).
- ISO 22000 - food safety management.
- TQM (Total Quality Management) - everyone is both supplier and customer (customer satisfaction comes from within the business and not external).
- Kaizen - continuous improvement in small steps (Japanese concept).
HACCP 7 principles.
- Conduct a hazard analysis.
- Determine Critical Control Points (CCP).
- Establish critical limits.
- Establish a system to monitor the control of the CCP.
- Establish the necessary corrective action.
- Establish procedures to verify that the system is working.
- Establish documentation and recording.
HACCP full process.
- Assemble HACCP tram. All representatives from all part of the production process needs to be present (e.g. viticulturalist, oenologist, winery manager, bottling supervisor, etc).
- Set scope of the investigation and describe product - set production in macro parts e.g. vineyard management, winery, bottling line.
- Identify use of product - sale in bulk, export bottling, home sales, etc.
- Flow diagram of the process. In this way every step can be controlled.
- Site visit to confirm.
- List of hazard for each step of the process - major part of HACCP.
- Define CCP - assess by probability of happening (is it frequent, sometimes, or rare?)
- Critical limits are set - e.g. controls pH, SO2, temp, etc.
- Monitoring system setup.
- Corrective action to observe CCP.
- Verification system setup - CCP needs to be under control.
- Documentation and records setup.
While assessing CCP what questions are asked?
- Do preventative control measures exist?
- Are these control measures necessary at this step?
- Will these control measures eliminate or reduce the hazard to an acceptable level?
- Could contamination occur to unacceptable levels?
- Will a subsequent step eliminate this danger?
HACCP in wine: why it is used?
pH and alcohol kills most bacteria.
- Illegal spray in vineyards (excessive chemicals).
- Metal contamination.
- Excessive SO2.
- Foreign bodies in wine during bottling.
Main CCP in wine examined in the flow chart with examples.
- Grape growing - illegal spraying, chemical residues.
- Cold stabilisation - coolant contamination.
- Additions - excessive SO2.
- Analysis - incorrect results.
- Line sterilisation - machine not sterilised.
- Membrane filtration - fermentation in bottle.
- Bottle rinsing - foreign bodies not eliminated.
- Bottling - broken glass.
- Corking/capping - foreign bodies, glass or cork.
- Final checks - nonconformance.
How can you be sure of HACCP results?
Simply, you cannot.
How can you correctly check that there are no foreign bodies in the bottle or chemicals use in the vineyard?
There are many interpretations of HACCP. The main goal is to focus attention on potential dangers.
ISO 9000 is based on what? What are its three main parts?
- Total documentation of business procedures.
- Tight internal control.
- On-going assessment by an accredited body.
- ISO 9000:2015 - quality management system fundamental.
- ISO 9001:2015 - quality management system standard.
- ISO 9004:2018 - quality management of organisations.
5 main headings of ISO 9000.
- Quality management system.
- Management responsibility.
- People
- Product realisation.
- Measurement, analysis and improvement.
Advantages and disadvantages of ISO 9000.
Advantages.
- Focus on people being trained for the jobs rather than written procedures.
- Based on continuous improvement and focus on customers.
- Gives insight on system reviews and gives bigger focus on people about responsibilities and duties.
Disadvantages.
- Bureaucratic - workload is high.
- Cost.
How ISO 14000 and ISO 22000 differs from ISO 9000?
ISO 14000 adds the environmental impact and performance of the system.
ISO 22000 is appropriate for the wine industry and incorporates hygiene measures.
What is the concept of “due diligence”?
You need to be able to prove and demonstrate that you took all the precautions to ensure that the foodstuff you are selling is safe.
How do you check due diligence. What’s the main problem?
Visit all suppliers of any finished product and carry an audit.
- Many audits have no bearing on product quality - only compliance with set procedures.
- Each retailer insists on carrying their own audits - many annual audits.
- Many audits are made by people who have less knowledge than the supplier that has been checked.
What is the BRC Global Food Standard?
Covers all foodstuff - sets the benchmark for food safety management system in the UK.
Main problem of BRC and wineries.
Many auditors were not experts. They imposed conditions to wineries that were unnecessary amplifying cost.
What are the major quality management awards?
- Deming Award (Japan) - transnational.
- Malcolm Baldridge National Quality Award (USA).
- European Foundation for Quality Management (EU) - mainly based on recognition for years of dedication to quality management.
9 aspects that are scrutinised by the EFQM to give the award.
- Leadership.
- People management.
- Strategy and planning.
- Resource management.
- Quality system and processes.
- People satisfaction.
- Customer satisfaction.
- Impact on society.
- Business results.
What is the difference between a fault and a taint?
- Fault - developing during winemaking (mouse, oxidation, reduction, VA).
- Taint - from outside (cork, smoke).
Are all wine faults real faults?
Yes and no.
There are some context dependant faults like reduction and brett.
Why improvement in wine fault is slower compared to other technologies?
Even if retailers are happy to reimburse or restaurants to change the bottle, the specific fault in the wine is rarely recorded giving bad data.
How oxidation happens?
Oxygen from the atmosphere gets into the package because of a poor closure or through the material of the package.
How can you recognise an oxidised wine?
- Loss of colour (brown in white, brown orange pink in rose, garnet in red).
- Bouquet will lose freshness, aromas of caramel and meat.
Are wines made for early consumption going bad because of faster oxidation?
No, because of natural decomposition (the fruit compounds will natural break down) - they are lacking structure to age. Can happen in complete lack of oxygen.
What are the main causes of oxidation in wine that reacts with oxygen?
- Phenols (both in skins and seeds).
- Transition metal ions (copper, iron).
How can you protect the wine from oxidation?
- Gentle pressing to protect from oxygen - low phenols are extracted.
- Hyperoxidation.
- SO2.
Is there any specific law to understand when a wine should be consumed?
Some bottles might tell you that they are for early consumption but wine is not under this EU law because, by mistake, there’s an assumption that every wine will last more than 72 weeks.
What is reduction? How can you recognise it?
Reduction by sulphur dioxide to hydrogen sulphide.
Creates VSC (volatile sulfur compounds).
Residual sulphur might come from:
- Vineyard treatments.
- Stressed fermentation.
- Lees ageing in no oxygen ambient.
Why reduction has aromas of matchstick, flint and gooseberry?
Volatile sulfur compounds attach themselves to mercaptans such as thiols or methional.
How can you remove reduction?
- Change packaging or closure.
- Use less or no SO2 at bottling.
- Add copper sulfate - copper ion dissolves and make sulphide ion precipitate.
- Racking.
Certain volatile compounds associated with reduction cannot be removed (such as disulfides the ones that give the wine aromas.of rotten eggs, garlic and onion).
What are the two main problems of light damage for bottled wine? How can you solve it?
UV - destroy sulphides making the wine prone to oxidation.
Yellow wavelength - create foul smelling sulphides (light struck aromas).
They are both present in the fluorescent light tubes present in shops. You need coloured glass to stop them.
What heat does to the wine?
- Accelerate chemical reactions, ages the wine quickly.
- Cook fruit aromas (figs, prune).
- Increase pressure of the packaging - cork might be push out, leaving oxygen to get in.
Are tartrate crystal a wine fault? What is the main problem?
Not really.
Consumers don’t like them. They are harmuful, even if eaten. They think is added sugar or broken glass.
They are not tartaric but calcium tartrate or potassium bitartrate.
How can we get rid of tartrate crystals?
- Do everything before bottling - fining, testing colloids presence, stabilisation and tartrate stability checks before bottling.
- Decant the wine.
- Educate the consumer about it.
- After bottling - get the whole bottled wine production affected, empty it in a vat, stabilise it and rebottle.
What foreign bodies you can find in wine?
- Broken glass.
- Insects.
- Human hair.
- Pieces of cork.
- Parts of filling machine.
HACCP guidelines make sure that it doesn’t happen.
How can pieces of glass get into the bottle?
Small pieces of glass gets chipped off the rim of the bottle because of badly formed bottle necks, or poor maintenance of the filling machine.
Why cork taint is a common problem?
In the 1990s request was high and that brought to low quality.
Back in the day the problems was up to 10% now is just 3% (which is still quite high).
What forms cork taint.
TCA (2, 4, 6 trichloroanisole)
- Phenols - from wood preservatives (includes wooden pallets or beans).
- Chlorine (hypochlorite sterilants) - mostly banned, also water from the city is dechlorinated before entering the winery (alternatives are peracetic acid and ozone).
The wood has pores running through the tree bark that can host microbes.
How can you analyse TCA in wine?
Through a gas chromatography-mass spectrometry (GC-MS).
Can you use a corked wine to cook?
Yes, TCA is steam volatile, it goes away while boiled.
How volatile acidity forms?
Bacteria (coming from a lack of SO2 and high DO levels) convert alcohol to acetic acid, which reacts with remaining alcohol former the ester of ethyl acetate (nail varnish).
How can you avoid VA?
You cannot save a wine with high VA.
- QA is fundamental.
- Control oxygen exposure (blanketing the wine, use proper filtration, SO2 use).
- Healthy grapes.
What happens when a wine referment in bottle?
Residual sugar gets fermented by stray yeasts.
- Wine gets cloudy.
- CO2 pressures the cork out.
- In BIB can blow up by bursting - if in pallets the damage can be even stronger.
Usually is because of bad hygiene or ignored procedures. It is rare today.
How can you treat a bottle with a high risk of refermentation in bottle?
- Disgorge the bottle/BIB and filter the yeasts out.
- Wine needs an extra check to see if there has been any alteration.
- SO2 correction is important as refermentation will probably destroy most of the SO2 present in the wine.
What casse means in French?
Precipitation.
What is an iron casse and how can be prevented?
Harmless white deposit coming from a reaction between iron and phosphate.
Can be prevented in two ways:
1. Blue fining to reduce iron levels.
2. Add citric acid to prevent deposit formation.
Why copper casse is a problem for wine?
- Gives a brown haze to the wine.
- Copper is toxic so levels need to be controlled.
Is the haze in copper casse temporarily?
Yes. It goes away.
- Copper casse is a mix of cuprous ions and proteins that forms in anaerobic conditions.
- As the bottle is open the cuprous ions oxidise (to cupric ions) breaking the complex - haze disappears.
How can you solve copper casse?
- Prevent by constant analysis.
- Blue fining.
How mouse taint is formed and where?
From 3 tetrahydropyridines compounds:
1. 2-ethyltetrahydropyridine (ETHP).
2. 2-acetyltetrahydropyridine (ATHP).
3. 2-acetylpyrroline (APY).
Forms because of:
- Certain Brett yeast strains.
- LAB (lactic acetic bacteria).
- Acetaldehyde.
How the aromas of mouse comes into the wine?
They are not in the wine at first.
Tetrahydropyridines move from volatile to non volatile.
In white wines with low pH you cannot sense it (because of the pH).
When the wine mixes with saliva (as it has a neutral 7 pH) the wine raises the ph making the tetrahydropyridines volatile showing the aromas of mouse cage,, popcorn, sweet corn, ricecakes, crackers, salami, dirty sock.
What wines are at risk of mouse taint?
- No SO2.
- No fining/filtering.
- High pH.
- Wild ferment.
- Whole bunch with carbonic.
- Poor hygiene cellar.
What is the main problem of brett?
Is that certain wines that has it are regarded as high quality.
How aromas of brett are formed?
This is because of three compounds present in the yeast:
- 4-ethylphenol - farmyard, antiseptic plasters (unpleasant).
- 4-ethylguaiacol - bacon, spice, cloves, smoky (attractive).
- isovaleric acid - cheese, rancid, sweaty saddle (unpleasant).
The strength will depend on the specific strain.
These compounds will strip unfermentable residual sugars changing their texture (dryness) plus giving aromas of animal shed, horse saddle, medicinal (plaster), savoury and spicy.
Why brett occurs and how can you stop it?
Appears because of
- Poor hygiene.
- Low sulphite levels.
- High cellar temperatures.
- High pH (white wines are less subject to it).
- High residual sugar.
- High leftover nutrients.
You can stop it by adding a lot of SO2.
Why a powerful smell of geranium appears on the wines?
A certain strain of lactic acid bacteria infects a wine containing sorbic acid - the metabolisation produces a substance known as 2-ethoxyhena-3,5-diene (which is the aroma of geranium also called pelargoniums).
How can you avoid geranium taint?
You can only prevent it. Caused by poor hygiene.
No use of sorbic acid as an additive. Filtration and sterile techniques can be used instead.
How can rot influence negatively the wine? Can you solve the problem?
By producing mouldy taste in the final wine (dank aromatics).
- Clean and dry vessels (mould can be in vats as well).
- Blending.
- Carbon fining.
How smoke taint works?
Wild bush fires, happening between veraison and harvest, produce molecules from burnt lignin (guaiacol, 4-methylguaiacol) that are getting within grape skins.
The two compounds are the same happening during oak toasting in barrels but quantities are incredibly high and dangerous to wine.
As the toxic compounds enter the grape skin, the cells start a detoxification process called glycosylation where they bind to these one molecule of sugar that makes the compound water soluble.
What is the main problem of smoke taint? How can you solve it?
You cannot eradicate it.
As glycosylation makes the compound water soluble, you cannot smell it until after fermentation bring the compounds back thanks to hydrolysis.
The only option to check before fermentation is to test for smoke related compounds in order to understand the levels of guaiacol and 4-methylguaiacol.
Can you minimise the danger of smoke taint?
The main goal is to minimise transfer of smoke taint from the skins to the must:
- Hand harvesting.
- No leaves in harvest baskets (they might have smoke taint too).
- Cool temperature (less extraction).
- Separate free run from press wine.
- Shorter extraction time with limited or no skin maceration.
Other techniques can remove smoke taint but with the problem of taking away also aromas such as:
- Activated carbon.
- Reverse osmosis.
What causes eucalyptus taint?
Cause by eucalyptus trees.
You need to plant the vines away from the trees.
What insect can cause taint in the grapes?
Asian lady beetle (Ladybug).
By mistake is harvested with the fruit and ends up in the press or in the maceration vessel.
Cannot cure it. Prevention is done by:
1. Cleaning the clusters before harvest.
2. Spraying insecticides.
Why do we ship in bulk?
- Lower carbon footprint.
- Retailers have more control on the bottling process.
How is wine shipped in bulk?
- Food grade tanker trucks.
- Smaller plastic tanks.
- Stainless steel ISO tanks (continual journey).
- Flexitanks for deep sea transport.
Standard quality maintenance steps for bulk shipping.
- Quality audit of the supplier.
- Agreement on specification and regime of procedure.
- Transportation contractor.
- Pre-shipping samples.
- Control points and measurement.
- Strict regime at reception point.
- Paper trail documenting control points.
