Ph Question

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Loco
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Ph Question

Post by Loco » Sun Jan 24, 2021 20:05

I was just wondering about the ph level, if you leave sausage in fermenting chamber will the ph just continue to drop for as long as itl is is thereor does it stop at some point? how low could it go if lets just say you had 1% dextrose in the mince?
just something i was thinking about, figure someone here would know the answer.
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christofaun
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Re: Ph Question

Post by christofaun » Mon Jan 25, 2021 12:36

Perhaps someone with slightly more experience could weigh in on this, but my understanding is that pH drop is relatively proportionate to the amount of dextrose as metabolized by starter cultures. About 1 g (0.1%) of dextrose per 1 kg of meat lowers pH of meat by 0.1 pH. This means that 10 g of dextrose added to meat with initial pH value of 5.9 will lower pH by one full unit to 4.9. Sugar levels of 0.5% - 0.7% are usually added for reducing pH levels to just under 5.0.

There isn't anything particularly wrong with adding up to 1% dextrose, though at some point you risk your product becoming unpalatably sour, though, I suppose that's a personal line worth investigating.
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StefanS
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Re: Ph Question

Post by StefanS » Mon Jan 25, 2021 15:21

christofaun wrote:
Mon Jan 25, 2021 12:36
About 1 g (0.1%) of dextrose per 1 kg of meat lowers pH of meat by 0.1 pH. This means that 10 g of dextrose added to meat with initial pH value of 5.9 will lower pH by one full unit to 4.9. Sugar levels of 0.5% - 0.7% are usually added for reducing pH levels to just under 5.0.
theoretically - yes, practically - not exactly.
1. pH as units means (petentia of Hydrogen) and is logarithmic not linear,
2. addition of sugars are very important but also should be taken under consideration glycogen in meat as other additions like spices (ex. red pepper containing 10-15 % of sugars).
3. temperature, time and starter also important
Addition of 2 g/kg to pork (0.2% of dextrose will lower pH to 5.2 - 5.3 level). Same addition ( 0.2% ) to beef or deer will lower pH to 4.9-5.0. Horse meat will go to below 4.8. Addition of 1 % (10 g/kg) of dextrose will lower pH to around pH 4.4-4.5 (level when LAB stop working and some of them will die). During maturing time enzymatic reactions of proteolyze and lipolyze with help of molds will change acidity level towards neutral zone. In many cases pH on end of maturing will return to level around pH 6.0.
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christofaun
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Re: Ph Question

Post by christofaun » Mon Jan 25, 2021 18:56

Whoa, I knew that the acidity stabilized somewhat but I didn't realize that it bounced back completely like that. It's specifically the enzymatic action during maturing that breaks down and neutralizes lactic (and other?) acids? I definitely want to look into this further. Especially curious what those break down into.
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Re: Ph Question

Post by redzed » Tue Jan 26, 2021 18:53

To add to Stefan's point No. 1 regarding how pH is measured. This is one of the most mistunderstood areas by not only amateur salami makers but also by many authors of the books on the subject. They all call for way too much carbohydrate when fermenting with starter cultures. Some time ago I added the following reply to a question on this forum and am repeating it below:

As I wrote in my above post .5% is usually too much sugar if you want a milder, but more complex and flavourful salami The problem here is that many recipes, especially in earlier publications specified that exact amount. It was based on information that stated that 10g of dextrose will lower the pH of meat by 1 full pH point. That is totally true and does work if you are making a Scandination salami or a summer sausage. But there is the total erroneous assumption that if you measure the meat and the pH is 5.8 then you add 5 grams to bring it down to 5.3. Why is that wrong? Well, pH is measured on a logarithmic scale, rather than a linear scale. So, let`s review a number of sources, that are considered credible, as to how much sugar we need to add to a meat batter to reach the desired pH.

Let`s start with Stan Marianski, who writes “About 1 g (0.1%) of dextrose per 1 kg of meat lowers pH of meat by 0.1 pH. This means that 10 g of dextrose added to meat with initial pH value of 5.9 will lower pH by one full unit to 4.9. Sugar levels of 0.5% - 0.7% are usually added for reducing pH levels to just under 5.0.”
Marianski lifted that from the eminent meat scientist Fidel Toldra who described it this way in Dry-Cured Meat Products: “The type of carbohydrate must be carefully chosen since it affects the rate of pH drop. It must be chosen based on the temperature of fermentation, the ability of the strain to ferment it (Table 5.1) and the totaltime of processing. The amount of carbohydrate added will affect the extent of pH drop. Approximately 1% sugar will yield a reduction of about 1 pH unit during fermentation.(p.93) In general, the amount of sugar may vary between 0.5 and 1 % but may reach 2% in some semi-dry fermented sausages. Glucose and saccharose are metabolized quickly and ensure a rapid acidification. Lactose follows at a slower rate than glucose. Dextrines or starch are metabolized slowly and their use is recommended for long ripening sausages. (p.6)”

Ockerman and Basu explain it this way: “Simple sugars such as glucose (dextrose, 0.5 to 1%, a minimum of 0.75% is often recommended) which is the fermentation substrate can be readily used by all lactic acid bacteria. The quantity of sugar influences the rate and extent of acidulation, and also contributes favorably to flavour, texture, and yield properties. The amount of dextrose added, up to ~ 0.7%, will directly influence the final product pH and additional sugar will not decrease pH further since bacterial cultures can not grow in excess acid. (p.120)”

Gerhard Feiner also uses the 10g equals 1 point pH drop correlation: “Generally, 1 g (or 0.1%) of dextrose added per 1 kg of salami lowers the pH by 0.1 pH unit, which is equal to reducing the pH by 1 unit when adding 1%, or 10 g, of dextrose per 1 kg of salami. Therefore, 8-10 g of dextrose reduces the pH in salami from around 5.7 to around 4.6-4.8, which is frequently the final pH desired. Similar declines in pH value can be achieved by adding 7 g of dextrose or 2-4 g of lactose. (p.125)”

So the common thread in all of the above is 10g of dextrose will lower the pH by one point. But all refer to lowering the pH to 4.6 - 4.8, and not from 5.7 - 5.8 to 5.2 - 5.3. The reason for that is that we don`t need as much sugar to lower the pH from those higher levels. 1 gram of dextrose will not lower the pH by .1 and 2 grams will not lower it by .2. Being a logarithmic measurement, pH is not linear and is not directly proportional to the acid concentration.. This means that for each one-digit change in pH, the acidity (H+ concentration) changes by 10 times. For example, a salami batter with a pH of 5 has 10 times more H+ than a batter with a pH of 6. This video explains the difference between linear and logarithmic scale. https://www.youtube.com/watch?v=xgYalAy8oeg

So now we know that we can add 7-10g of dextrose when we want a to make a Scandinavian style salami or an American summer sausage. But when making a mild flavoured Mediterranean style sausage 3g usually enough with slow fermentation. And even then it sometimes can be too much as many of us have discovered with B-LC-007. While the amount of sugar will ultimately determine the acidity of the salami, there are other factors to consider. One important one is fat content. Lactic acid will not metabolize fat so salami with a high red meat content will require more sugar and less when there is a high proportion of fat. Furthermore, using the same amount of fermentable sugar, pH will drop to a lower value in a fast fermentation than in a slow fermentation using the same strain. Better control of the fermentation process and better results can be achieved by using a combination of sugars which will slow the fermentation and still lower the pH to the desired level. Gerhard Feiner explains it this way:

The decline in pH value in the product depends largely on the type and amount of sugar introduced into salami in first place. Elevated levels of sugar leads generally to a stronger acidification and therefore lower pH values. To be fermented into lactic acid, sugars such as sucrose, lactose, and maltose must be broken down first into monosaccharide. Glucose, on the other hand, can be fermented directly into lactic acid and is therefore by far the most often applied form of sugar in fermented salami. The production and ratio of d- and l-lactic acid in the salami depends on the species of lactic acid chosen as being the starter culture. Sucrose is the second fastest fermentable sugar. Maltose and lactose require a considerably longer period of time for the glycosidic bonds in their molecules to be broken until fermentable monosaccharide are produced. In essence, all lactic acid bacteria (LAB) can ferment glucose into lactic acid. Sucrose can be fermented by around 85% of LAB, maltose by around 70% of LAB and lactose by only around 55%. Only around 30% of lactic acid bacteria ferment galactose into lactic acid. (pp125-126)

Lastly, let's take a look at Marianski`s salami recipes. They all call for 2-4 grams of sugar in traditional Southern European products. Toldra also points out that even naturally present Lactobacillus spp. ferment added sugars, generally between 2 and 4 g/kg of sausage mass, and in case the pH value tends to drop to levels below 5.3-5.2.

I hope this will help everyone to get a better grasp on the fermentation process and encourage more study and experimentation.
For those that don't want to dwell on the detail, there are three points in there that form the basis of the above:
1. ph is measured on a logarithmic scale and not on a linear scale.
2. The common guideline of using 1gram of dextrose to lower the pH by .1 applies only when you are adding 10g to the salami. You need considerably less when you want to lower the pH to 5.3 - 5.2.
3. It is good practice to use more than type of sugar when fermenting Southern European style sausages.
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Re: Ph Question

Post by StefanS » Tue Jan 26, 2021 20:41

redzed wrote:
Tue Jan 26, 2021 18:53
3. It is good practice to use more than type of sugar when fermenting Southern European style sausages.
missed word - ONE ....in words - "more than one type of sugar" :wink:
Great explanation .
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Re: Ph Question

Post by Indaswamp » Wed Jan 27, 2021 01:23

Very good info! Thanks for posting!

So if I wanted to make a Southern European Slow fermented salami, what combination of sugars would you recommend? And percentage of each? Dextrose and maltoderxtrin?
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