The taste of grain mash. If the mash is sour, what to do, how to correct the situation

Of all possible problems with mash, souring is the most common among moonshiners. The wort appears sharp and bad smell vinegar, hydrogen sulfide and rotten eggs. Many try to revive the mash using soda and chalk, but we are definitely convinced that It’s easier to just pour it out and not risk your health. The raw materials are not worth the risks you are taking.

However, we would like to consider reasons for increased acidity, preventive measures , and instructions for restoring mash after souring. If the mash has bad taste, then moonshine will share its organoleptic properties with it. There are some methods that will improve taste qualities drink, but the quality will still leave much to be desired.

Grain and malt mash are most susceptible to souring, since it is very easy to spoil it without observing the temperature regime

Souring occurs as a result of contact of acetic bacteria and oxygen with alcohol. As a result of a chemical reaction, alcohol decomposes into water and acetic acid, which has such an unpleasant smell.

The store sells special plastic fermentation barrels with a water seal already installed

Oxygen entering the mash (lack of a water seal). If your fermentation occurs with the lid open and without a water seal, then the likelihood of increased acidity and the appearance of mold increases tenfold. This is the most popular reason why moonshiners lose tons of mash.
Dirty fermentation tank and contaminated raw materials. Unwashed containers, a rotten area on the fruit, or malt with bacteria can also lead to sourness. This happens quite rarely, but it is possible.
Increasing temperature and leaving the mash in the sun. The wort should be stored in a dark place. It has extremely negative contact with sunlight, so try not to remove this liquid from its storage location before distillation.

As a preventive measure, it is necessary to follow the basic rules of fermentation: install a water seal, maintain maximum equipment hygiene, use high-quality raw materials and store the fermentation container in the dark.

This is enough to virtually eliminate any possibility of abnormal chemical processes occurring in fermentation.

What can you do with sour mash?

The most correct and reliable solution would be pour out the mash and put in a new one. An overpayment of several hundred or thousand rubles is nothing compared to the harm it can cause.

If you are willing to take risks, then you can try to clear the wort of acetic acid and make moonshine of acceptable quality from it:

Don't be greedy and take away all the harmful fractions of your product

Distill the sour mash without dividing into fractions. When the strength in the stream drops to 30 degrees, stop distilling.
Dilute the resulting distillate with clean water to 20 degrees.
Add baking soda in proportions of 25 grams per 1 liter of pure alcohol.
Stir vigorously, seal tightly and let the mixture brew for 3-4 hours.
Carry out the second distillation, dividing the moonshine into fractions. Don’t spare the “heads”, select more and be honest.
If after these procedures the moonshine still has some smell, then run it through a water filter. The technology is presented here -.
If after this you still have any problems, then simply pour your product down the drain and forget about it.

In any case, sour mash is a wonderful experience that suggests mistakes that need to be corrected. The decisions you make can improve the quality of the product and give a higher “yield” of alcohol per kilogram of raw materials.

The problem described above is perfectly described in a popular video from Alexander Kuleshov on his Youtube channel Distillarus.

The author shares experience that is applicable to our situation with sour wort and further actions to eliminate it. We recommend viewing to anyone who has encountered or is afraid of encountering similar difficulties.

Beginning moonshiners face one problem: their alcohol-containing mixture spoils. Moreover, it disappears because the acidity of the mash changes. But what kind of indicator is this anyway?

Let's look at it, as well as the factors on which it depends, and actions to save the wort. Knowing what to do, you can prepare high-quality alcohol and protect the drink at the infusion stage.

This is the pH level of the alcohol-containing mass, that is, a measure of the activity of hydrogen ions in it. Simply put, this is the degree of acid concentration in the raw material. And this indicator can increase or decrease depending on internal or external indicators (we will consider which ones below).

It is known from chemistry: if the pH level is below 6.0, the environment is considered acidic, if above 8.0 - alkaline. But what about the indicators for wort?

The optimal acidity of rejects before distillation is from 3.5 to 4.2 pH. If it is less than the specified level, the yeast will slow down its activity or even “fall asleep”; if it is more, lactic and vinegar bacteria will be activated, which spoil the raw materials.

Understand that the acidity has changed during the infusion process, possible based on the following criteria:

fermentation has slowed down significantly or stopped completely, quickly or even suddenly;
the alcohol-containing mass began to smell unpleasant - sharply, with a noticeable aroma of vinegar;
the mash began to taste sour (although it was bitter) - so much so that it made your cheekbones ache.

As soon as one of these signs appears, it’s time to sound the alarm and try to save the raw materials. Although ideally, of course, it is necessary not to lead to such situations, and for this it is necessary to understand when risks arise and develop.

What does acidity depend on?

Key negative factors that can increase or decrease the pH level of an alcohol-containing mass are the following:

Excess oxygen, which in the vast majority of cases is formed due to too frequent opening of the container for infusion and stirring of the wort. Consequences: oxidation, death of yeast, appearance of acetic bacteria, decrease in ethanol concentration along with a simultaneous increase in acidity.
Abrupt change temperature regime insistence. It is simply unacceptable to keep a container with “playing” raw materials in a drafty room or in close proximity to a heater or radiator. Rapid and significant warming will lead to the death of the yeast, and cooling will lead to the hibernation of the strain, the cessation of carbon dioxide production, and a drop in the pH level below the optimal level.
Activation of lactic acid bacteria that enter the container as a result of insufficiently good disinfection of either the walls of the container itself or those in contact with the mass of instruments. These microorganisms begin to take food from the yeast, produce vinegar and thus increase acidity.
Absence or malfunction of the water seal. This device (an alternative is a stretched medical glove with several punctures) prevents oxygen from entering the fermentation container and also removes carbon dioxide, that is, it ensures the normal course of the “game” process.

Important! The listed reasons are typical for any alcohol-containing mass, even if yours is based on tomato paste or another equally original ingredient. Failure to comply with the infusion technology inevitably entails a change in the pH level.

What to do if the mash is sour

Naturally, we need to try to save it, without pouring out a couple of tens of liters of raw materials. Although a lot depends on when exactly you noticed the disappearance and to what stage it reached. The souring process can take from 4-5 days to 2-3 weeks. Therefore, it is important to periodically check the wort (not allowing it to come into free contact with air), smell and taste it.

The mass will finally and irrevocably deteriorate when the concentration of vinegar in it reaches 7-10%. By this point, its aroma and taste will become distinctly sharp and unpleasant, and then it will really have to be thrown out. But you will notice something is wrong in time if you regularly use a pH meter or at least a litmus test.

Okay, let’s say that you didn’t keep track, and your mash is a little sour – let’s look at what to do in such a situation. It’s simple: you need to compensate, that is, add a neutralizing substance to the container. There are two options - alkali or sugar, and each of the components is capable of effectively normalizing the pH level, and therefore deserves detailed consideration.

Reducing the acidity of mash with baking soda

The convenience of the method is that one of the most accessible and even cheap alkalis is used. The method is extremely easy to implement - all you need to do is:

add (attention, before distillation!) baking soda to the “playing” wort - in a proportion of 20 mg/l;
distill, carefully draining the heads and finishing picking up the body as soon as the strength of the stream drops to 45 degrees;
dilute to 25% and repeat the previous step 2 more times.

The output, after such triple distillation, will be relatively little of the finished product, but still more than nothing. But when adding soda, even slightly “sweetened” soda can be effectively used, in which the sourness is felt immediately and quite strongly. Plus, the distillate will be quite strong (closer to 70 degrees), so it can be generously diluted.

Restore the acidity of the mash with sugar

This method is applicable when the fermentation process has stopped. Putting it into practice is also extremely simple - you just need to:

pour sugar into the alcohol-containing mass at the rate of 2 tbsp. l. /1 l;
wait a couple of hours and check the wort for yeast activation;
if fermentation has not resumed, add raw rice to the container in the proportion of 0.5 cups / 10 l;
wait 3-4 days - during this time the pH level of the future alcohol should normalize.

A complete alternative would be berry, fruit or even grain sourdough. It is especially good if you have it infused or made from jam. Take it in the same proportions as sugar, and if the reduction is successful, it will not change the organoleptic properties of the distillate in any way.

How to fix sour moonshine

Rarely, but it happens that the raw materials are almost normal in taste and aroma, and finished product It’s impossible to drink from it, your cheekbones are so cramped. Why does this happen, where does such a powerful acidic taste come from? There are only two possible reasons:

During distillation, the “tails” were taken for too long, until the stream ceased to be strong (“to water” in the jargon). As a result, the product was oversaturated with organic acids.
The still is made from a material that has come into contact with the raw material during the heating process. Physicochemical reactions lead to the formation of undesirable compounds that change the organoleptic properties of alcohol.

Important! To avoid such problems, you just need not to be greedy when distilling and finish collecting the “body” on time, and also use a high-quality apparatus made of stainless steel, copper, glass and other materials that are inert to alcohol.

If the mash is too old, is it possible to distill moonshine from it? Theoretically, yes, but if the concentration of vinegar in it is higher than 10%, from a practical point of view, such an activity is pointless, since the finished product will turn out tasteless, and this cannot be corrected. When you want to do it for real good alcohol, do not use raw materials that have a strong smell, because the unpleasant aroma will not disappear.

But just slightly sour moonshine You can still fix it - using alkali. We have already considered the option with soda, therefore, to broaden our horizons, we will turn our attention to another one - with the addition of chalk.

The acidity compensation method boils down to the following steps:

send the moonshine for re-distillation and finish sampling the “body” immediately when the stream weakens to 45 degrees;
dilute the resulting distillate to a strength of 20° and pour chalk into it - in a proportion of 25 mg/l;
mix, carefully and carefully, seal hermetically, let it brew for 3-4 hours;
perform another distillation (the third in total). In this case, you select the heads with particular pickiness, in an amount of 15% of the total volume of the product, and start draining the “tails” as soon as the yield strength becomes weaker than 45 degrees;
dilute again until ready for consumption, seal hermetically and let stand for another 3-4 days so that the taste stabilizes.

Prevention is indispensable

It is important not only to know why moonshine turns out sour, but also to prevent risks. For this purpose, you need to install a water seal on the neck of the infusion container or, in as a last resort, put on a glove.

It is also necessary to maintain a constant temperature in the room in which the reservoir with the “playing” mass is located, at around 25-28 ° C. And finally, it is worth performing the distillation immediately after the fermentation process is completed. Do not delay, this will help reduce the likelihood of raw materials coming into contact with oxygen.

Maintain technology, pay attention to prevention, promptly correct changes in acidity, and cereal or - fruit mash— will fully reveal its original properties in moonshine. Just remember that even the purest and smoothest drink is still strong alcohol, and don’t get carried away with excessive consumption.

Even distillers with sufficient production experience strong alcohol They can’t always say how much is fermenting and what influences it. It is still impossible to determine this with an accuracy of one day, since The fermentation process depends on many factors:

raw materials used for wort;
maintaining proportions when adding ingredients;
room temperature and humidity;
compliance with brewing technology;
Not the least of the reasons is water. Eg, boiled, deprived of oxygen, slows down this process.

In order to determine the fermentation time with the greatest probability (if all the above influence factors are correctly observed), first of all need to rely on the raw materials used.

The most popular - if the manufacturing technology is followed, the wort becomes ready for distillation in a time from 5 to 14 days. It is after five days that you need to look at it and check for readiness. Although, as a rule, the most optimal period is 7 – 10 days.
The mash, the basis for which is starch (its sources are grain, potatoes, ready-made starch), ferments much less - already from 3 – 5 days she is ready to be driven.
For fruit and grape mashes using yeast, it is required about two or even three weeks for maturation.
If yeast is not added specifically, but only wild yeast found on fruits (berries) is used, then fermentation may take longer up to 45 days. It's very It is important to use a water seal oh, otherwise the food may turn sour and you will end up with vinegar, which is also not bad, but our goal is completely different!

Peculiarities. The indicated time is relative, since much also depends on the temperature.

The process works best if the room temperature is between 20 – 22°C. It is acceptable from 18 to 28°C, but it is not advisable to go beyond these limits.

How long can you steep the mash?

A situation is possible when fermentation is already completed, and you do not have the opportunity in the coming days.

First of all, make sure that you have a truly finished product.

Fully ripened mash has strong alcohol smell, there is no release of carbon dioxide (no bubbles or hissing).

This can be checked with a lit match: if you bring it to the surface of the mash and it continues to burn, it means that carbon dioxide is not released and there is no fermentation.

And most importantly - the mash tastes bitter, without the slightest sweetness.

So as not to lose valuable product, and fermented and sour mash will produce moonshine with an unpleasant odor and taste, you need to take the container to the basement or just a cold room with a temperature of 10 to 0°C. This will prevent souring of the mash and besides, it takes 5 – 7 days. All that remains is to drain the sediment and distill. Most types of ready-made mash can be infused in “basement” conditions for up to a month or even more without loss of quality.

Attention! You cannot steep grain mash for a long time, even in the cold.

Acid inevitably accumulates in it (acetic acid fermentation begins) and as a result, instead of moonshine with a pleasant grainy taste, you get sour booze.

How to stop fermentation of mash?

It is possible that you will someday need to stop fermentation, because moonshine is needed urgently, and you see that the process is still ongoing. Can artificially stimulate its cessation.

Please note: if fermentation has not finished, you will get less during distillation strong moonshine, than expected, because the yeast did not have time to convert sugar into alcohol.

The most suitable additive for stopping fermentation is leftover from previous distillations “tails” with a strength of about 25°. They will add alcohol to the wort and the yeast will die. In addition, this way you use the “waste” product to your advantage and will not lose in the amount of alcohol produced.

How to speed up fermentation?

But knowing in advance that you need fast-ripening sugar mash, resort to one of the suggested tricks (or even several at once).

So that if possible accelerate ripening, use these methods:

using only the freshest yeast. Under suitable conditions, they will act more actively and quickly complete their task of converting sugar into alcohol;
adding bread crusts to the wort accelerates ripening. You probably observed this yourself during cooking;
pre-diluted and added tomato paste: up to 100 g per 10 liters of wort;
peas or corn in the amount of 300 - 400 g per 10 l;

Please note. Peas, added after the fermentation process has begun, can produce a lot of foam, which is quite easily extinguished by the crumbled biscuits.

increasing the amount of water or decreasing the amount of sugar compared to what is specified in the recipe (no more than 20%) also speeds up ripening. But be prepared for the fact that you will get less strong alcohol during distillation;
adding unwashed raisins will speed up the process due to wild yeast on its surface;
stirring the wort daily (several times possible). When stirring, gas bubbles are intensely released, which also speeds up ripening.

A few questions about fermenting mash

Many (especially beginners) moonshiners have accumulated questions, which we will try to answer below.

Braga has not fermented, is it possible to drive it away?

Of course, it is not advisable to do this, but in case of emergency, it is possible. Take advantage tips for stopping fermentation. But a shortage of alcohol is almost certainly guaranteed. Incomplete fermentation means that the sugar has not yet been converted into alcohol.

Carefully. During distillation, foam may be released, which will affect the quality of the product. In this case, secondary distillation helps.

Why does mash ferment for a long time?

As already noted, there are many factors that influence the duration of ripening. In addition to the quality of the ingredients, it is imperative pay attention to the room temperature. If it is below 18°C, then the vital activity of the yeast is very weak, so the process is sluggish. Above 30°C, their vital energy also decreases, and at around 40°C they die completely.

In addition, the fermentation tank should not be placed on a cold floor (tile, porcelain tile, stone). There should be a warm base underneath. Otherwise, even if the room is 22°C, the mash may be 16 degrees, which is unacceptable.

What to do if the mash runs away?

The most common causes of increased foaming:

using baker's yeast instead of alcoholic yeast or accidentally exceeding its quantity;
adding honey to the wort instead of sugar;
malt and grain raw materials at the first stage of fermentation can also produce too much foam;
exceeding the permissible volume for wort.

note: should be filled with mash to a maximum of 2/3 of the volume. And when using products that can potentially produce a lot of foam - only half.

Exceeding it risks the fact that you will have to collect the wort on the floor, wash the containers, and in this case you will also lose some of the alcohol.

But it happens to many people that the wort foams, and something urgently needs to be done about it. Therefore, we offer several options:

The best way if foam suddenly appears is move the container to a colder room for a couple of days, and then return to comfortable conditions for mash. But do not overdo it, it is advisable that the temperature is not lower than 15°C.
There is no such possibility then divide the wort into two containers. After a couple of days, when the violent foaming stops, drain together again.
Crumble over the wort 1-2 cookies.
Pour into container vegetable oil , which also extinguishes foam quite well. A couple of tablespoons is enough.
Add some ice. This will help reduce the amount of foam, but will slow down the fermentation.

Braga has stopped fermenting, but is still sweet

Here are the main reasons:

Not enough yeast. This is easy to fix: add and the process will resume.
Too much sugar (the proportion is wrong: for 1 kg - 4 liters of water). Solved by adding water and yeast.
The room is cold (hot). Bring the temperature to optimal levels for yeast activity (22 – 28°C).

Also consider the possible reasons already listed above in this article.

Is it possible to put mash in an aluminum flask?

Many generations of moonshiners have used aluminum milk flasks for mash. However, research in this area does not confirm the safety of the material. According to the recommendations of scientists and doctors, even aluminum pans are not recommended for storing acidic foods: cabbage soup, borscht, solyanka.

The brew matures from several days to several weeks and also contains a certain amount of acid. This means that aluminum oxidation products easily pass into the mash.

Conclusion. The best dishes for mash - glass, which does not interact with an acidic environment, and also – stainless steel. The main thing is that it should be exactly food grade stainless steel.

Useful videos

Fermentation process sugar mash for homemade alcoholic drinks:

What can be done to speed up the fermentation of mash, look:

Look at what to do in a situation where the mash does not ferment - the main reasons and solutions:

For the main mistakes and answers to frequently asked questions about setting up and fermenting mash, watch the video below:

Have you received comprehensive answers to your questions regarding the maturation of mash? Please note this in the comments. Share the article with your friends on social networks.

First of all, such a problem as sour mash is faced mainly by beginners who try to install mash without a water seal (by covering the container not hermetically). If you don’t wait too long and take action in time, you can save the mash. We will also look at the reasons and methods for eliminating possible souring of the mash.

The finished mash itself should be slightly sour, since during the fermentation period the yeast releases organic acids. When the mash sours, it turns into vinegar and this can be easily determined by taste and smell. Spoiled mash has a strong vinegar smell and tastes scalding and sour, like apple cider vinegar.

What can cause sour mash?

Usually the mash turns sour at the end of fermentation when the yeast eats up all the sugar and stops releasing carbon dioxide, which displaces oxygen from the jar of mash. When such mash comes into contact with oxygen, acetic bacteria wake up and convert the alcohol formed during the life of yeast into acetic acid.

Can mash turn sour due to unsterile utensils?

The answer is no, if the dishes for the mash are washed. There is no need to sterilize the mash container, just wash the bottle. Sterilization is practiced in winemaking and brewing, since these drinks are stored after fermentation in their original, low-alcohol state, and the mash is distilled. The main thing is not to wait 2-3 months to distill ready-made mash, especially if you removed the water seal (glove) after the mash had finished working.

How to avoid souring of mash?

Everything is quite simple, you need to put the mash under the water seal, fortunately nowadays there are many specialized stores for moonshine or online stores where you can buy it, in the region you can do it yourself by looking on the Internet how, now a lot has been written about it and a video has been shot. If you use a glove with a hole from a needle or a bag wrapped with tape around the throat, you need to make sure that the glove fits tightly and does not allow air to pass through. After fermentation has ended and the gloves have sagged, you need to brew moonshine in the first three days (a week maximum). If the glove fell off and you took it off, then it is better to cook it right away, otherwise even a slight sourness will be felt in the moonshine.

What to do if the mash has gone sour?

It all depends on how long it stood after fermentation ended. The more the mash was in contact with air, the more acetic bacteria consumed alcohol from the mash and the less we get when distilling such mash. If it has stood for too long, then there will be no alcohol left in it and such mash MUST be poured out.

How to cook sour mash so that the moonshine is not sour?

If, nevertheless, you decide that there is still enough alcohol in your mash not only for vinegar bacteria, but also for you, then we distill it and dilute it with water to 20%. We infuse the resulting mixture with baking soda for a couple of days, I made a tablespoon for 5 liters and distill it again. If the quality does not suit you a little, then the resulting distillate can be used for various tinctures, better citrus fruits, or let the distillate stand for another week on birch or coconut activated carbon.

Put some mash? What could be simpler! Take suitable raw materials, add water, add yeast, sugar and you’re done. All that remains is to place the container with the wort in a warm place and wait for ripening. It's like that. But why does the mash sometimes turn sour? And if the mash has turned sour, what should you do? Distill it in the hope that sour taste will it go away during the distillation process? Throw away spoiled product? Try to somehow correct the situation?

In fact, it is necessary to initially take care to prepare a high-quality product for drinking or subsequent distillation. First, select correct proportions ingredients and quality raw materials. Secondly, adhere to the order of stages technological process. Thirdly, strictly observe the fermentation conditions. And that's not it.

Why does the mash turn sour?

In addition to alcoholic fermentation, many other reactions occur in the wort, which are not always necessary for winemaking or home brewing. Millions of bacteria and a variety of microorganisms live in the raw materials, water, yeast used, air, and on the walls of the container in which the wort matures. All of them are somehow involved in chemical reactions. Sometimes, under certain conditions, the result of their presence is the appearance of an unpleasant odor, souring, turning the wort into jelly with an indigestible taste, and contamination of the mash.

What can cause an increase in wort acidity? Among the main unfavorable factors:

Excess oxygen. Fermentation is an anaerobic process. If the solution is stirred frequently, the oxygen content in the wort will increase. Oxygen does not interfere with fermentation, but at the same time it promotes the onset of other, completely unnecessary oxidation reactions. In particular, excess oxygen leads to the synthesis of acetic acid, as a result of which the mash acquires a characteristic sour taste. The concentration of ethyl alcohol automatically decreases sharply.
Lactic acid bacteria. If infection occurs, the mash will quickly turn sour and fermentation will stop. Doing anything to “reanimate” such a product is useless. The wort will have to be poured into the toilet.
Temperature violation. To prevent the mash from turning sour, it is necessary to maintain a constant temperature in the room and avoid temperature changes. Optimal conditions for normal fermentation – 25-28°C.
No water seal. A water seal (an alternative is a rubber medical glove with a hole in the finger) is necessary to allow carbon dioxide to escape. It also prevents oxygen from entering the fermentation tank. In some recipes for making mash, you need to carefully monitor the acidity of the wort.

Separately, it is necessary to say about infection with fungi and bacteria. Wild yeast is a fungus, a microorganism, one of the waste products of which is alcohol compounds. But for proper fermentation Not all types of these microorganisms are suitable for wort. If the mash is infected with pathogenic fungi such as Saccharomyces, Candida, Hansenula, Pichia, it will be impossible to obtain a high-quality distillate. The concentration of harmful compounds and unnecessary impurities in raw alcohol will be too high.

The presence of bacteria Klebsiella, Megasphaera, Obessumbacterium proteus and some others in the wort causes the formation of dimethyl sulfide. A sign of bacterial infection is the smell of boiled corn. If your mash smells like rotten eggs (sulfur compounds), there is too much hydrogen sulfide in it. In this case, the acidity of the solution can remain within acceptable limits, but it is not recommended to distill such wort, since the distillate will also smell unpleasant.

What to do if the mash is sour?

An acidic environment can be neutralized with alkali. The vinegary taste of the wort is removed by adding baking soda or chalk. This must be done before distillation. recommended at least 2-3 times. Before each subsequent distillation, sort the distillate to 25%. Select the head and tail fractions in larger quantities.

Preparation (activation) of yeast. IN warm water(30-35°C) dissolve a little sugar. Add required quantity yeast. Standard proportions: compressed yeast - 100 g per 1 kg of sugar; dry baker's yeast– 100 g per 6 kg of sugar. The yeast solution is left for 45-90 minutes in a warm place. Appearance rich foam indicates the yeast is ready to be added to the wort.
Preparation of wort. Sugar is dissolved in warm water at the rate of 1 kg of dry raw material per 4 liters of liquid.
Braga. The sugar solution is combined with activated yeast. Stir. Pour into fermentation container. Transfer for fermentation to a warm room with a constant temperature (23-30°C).

During the fermentation process, the mash heats up, so you need to carefully ensure that the total temperature in the room and in the wort does not exceed 40°C. Otherwise, the yeast will die and the mash will turn sour. If the temperature in the room is not high enough, the fermentation tank must be insulated by wrapping it in a blanket or insulating material.

Ripening time is 3–14 days, depending on the raw materials and fermentation conditions. The readiness of the product for distillation is determined by the absence of carbon dioxide emissions, appearance(transparent upper layers), smell (characteristic alcoholic), taste of the mash (sour-bitter, without sweetness). Signs of readiness must be present in the complex. Only in this case proceed to the next stage of preparing strong alcoholic drinks.