Author Topic: Washed Rind Culture Primer  (Read 1502 times)

Offline fattyacid

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Washed Rind Culture Primer
« on: February 25, 2011, 06:11:12 PM »
Hello folks,

Here are some nuggets of info on washed rind cultures from a lecture at the Institut de Technologie Agricole (ITA) of St-Hyacinthe, QC., Canada.

Four different families of microorganism are involved in the ripening of washed rind cheeses:

1.Yeasts
2.Micrococci
3.Corynebacterias
4.Geotrichum

YEASTS

Main used species are:

• Debariomyces (CH/DH)
• Kluyveromyces (KL71)

Characteristics

• Mesophile (opt. 20-30oC)
• Are digesting lactic acid, therefore increasing pH (mainly CH/DH)
               >CO2 is produced from lactic acid
• Are digesting residual lactose to produce CO2, therefore prevents post acidification    (mainly KL71)
• Ammonia (NH3) is produced from proteins
• Fruity aromas are produced from lipids(mainly KL71)
• Are not sensitive to low pH, will grow up to neutral pH.
• Are not sensitive to temperature between 2-35oC
• Are not sensitive to aeration. Will grow with or without O2. But will produce more  alcohol in low O2 >change the taste.
• CH/DH is more salt resistant than KL71, therefore more active than KL71 in early ripening NB In brine, yeast will remain dormant.
• Are not visible, but will produce fruity and bread aroma

Conclusion

• Debariomyces is a greater pH neutralizer than Kluyveromyces
• Kluyveromyces produces more aroma than Debariomyces (fruity aroma)



MICROCOCCI

Main species used

• Staphylococcus xylosis (MVA)

Characteristics

• Mesophile (opt. 30-35oC)
• Resist pasteurization
• Will start to grow at pH 5,2, but is not digesting lactic acid
• Predigest protein for B.linens (1st cut of the protein chain)
• Grow faster than B.linens, protects the cheese against contaminants
• Are not sensitive to temperature between 4-45oC
• Are not sensitive to aeration. Will grow with or without O2.
• Coloring & Sticky rind
• Bring lots of aroma

Conclusion

• Micrococci do not increase pH.
• They help b.linens to establish by predigesting protein and by protecting the rind against
contaminants.


CORYNEBACTERIA

Main species used are:

• Brevibacterium (LB, SR3)
• Arthrobacter (MGE)
• Corynebacterium (SR2)

Characteristics

• Mesophile (opt. 25-30oC, min 10-15oC)
• Brevibacterium digest only protein
• Will grow at pH 5,5-6,5
Can not grow without 02. Good aeration is a key for success!
• Requires a minimum of 4% salt, salt tolerant up to 12%.
Eg. B.linens will be active at 30% of its full capacity with salt at 10%
B.linens will be active at 67% of its full capacity with salt at 5%

Conclusion

• pH of 5,5-6,5 is a must
• Aeration is a must
• Will not grow at lower temperature than 10oC.


GEOTRICHUM CANDIDUM

Characteristics

• Mesophile (opt. 25oC, min 4oC)
• pH 4,6-7
• Not very tolerant to salt. Will accept 4% but not 10%
• Help prevents contamination

Conclusion

• Geotrichum will not grow in the first day of ripening because of the high level of salt on the cheese surface.
• It will grow after the yeast and the micrococci, but will still bring some benefit to the B.linens establishment.
• Geotrichum will help at the end of the ripening, when the mould type (Geo17) is used, to
produce a powdery growth on the cheese surface. That will help to dry the cheese surface.

RIPENING EVOLUTION

1. After salting, cheeses are an acid environment and have a high salt concentration on the rind.
2. Yeasts are digesting lactic acid to produce CO2, and digesting protein to produce small amount of ammonia.
3. pH is rising
4. Yeasts are also producing some by-product required by B. linens
5. Yeasts are slowly digesting Lipids to produce fruity aromas
6. Micrococci will start to grow when pH reach 5,2.
7. Micrococci will start digest protein, which help B.linens
8. Micrococci produces color, aroma, and sticky rind
9. As salt concentration gets lowered on rind surface, Geo will start to grow
10. Geo is helping to reduce acidity and also reduces the stickiness by growing a mycelia.
11. B.linens starts to grow (within 7-14 days of production)
12. Geo produces its white powdery growth

WASHING PROCEDURES

NB. Yeasts, Micrococci, Geotrichum (mould type) and B.linens should all be added to the milk to accelerate
their growth.

NBB. It is very important to get each different microorganism established at the right moment.

NBB For that, regular washing, proper aeration and appropriate ripening temp. should be provided.


*Washing of the cheese should start 2 days after production day
*For the first 2 weeks, cheeses should be washed every 2 days
*For the first wash, we only need yeast in the washing solution
*On the2nd wash, micrococci and yeast should be used
*On the 3rd wash, B.linens, micrococci and yeast should be used
*On the 4th wash, we need only B.linens
*As we start to observe the pigmentation of B.linens, we can slowly spread out the washes to 2 x /week and then once a week. However, more frequent turning of the cheese might be required during the complete ripening.
*Towards the end of the ripening, when B.linens is well established on the rind, we can start to introduce Geo in the washing solution along with B.linens.
*When rind reaches a desirable state, cheese can be wrapped in permeable paper (B.linens needs O2!) and cheeses can be moved to a cooler environment (8-10oC). It will slow down ripening but will allow for more flavor development since enzymes will work slower.


> In early ripening, soft brushes or cloth with plenty of washing solution should be used to wash the rind since it is still very fragile. Later on, when rind is more firm, firmer brushes and little washing solution can be used.

>The intensity of the coloration resulting from B.linens is based on strain selection and combination of salt and pH at cheese surface. The best combination is salt at 4% and pH at 7.

>Sometimes, when B.linens is well established but becomes too aggressive, we can slow it down by using vinegar in the washing solution. This will decrease pH of the rind


OTHER NOTES



*  % moisture: HRED (Humidité relative sur extrait sec dégraissé)

HRED = % Water/ 100-%MF

*Salt requirement

Linked with % moisture in cheese. Salt requirement increases as % moisture in cheese increases since salt gets dissolved in water, not in fat.

*Buffering Capacity

The milk buffering capacity is its ability to minimize a decrease in pH Value while lactic acid is added.

Milk with weak buffering capacity will show rapid decrease of pH value when lactic acid is produced by lactic starters.

Milk with strong buffering capacity will show slow decrease in pH value when lactic acid is produced by lactic starters.

The buffering capacity of milk depends on its composition.

>Casein contributes to 35% of milk buffering capacity

>Serique proteins contributes to 5% of milk buffering capacity
* Serique proteins are the soluble proteins. They are lost in the whey.

>Minerals (mainly Phosphorus and Calcium) contributes to 60% of milk buffering capacity. When milk is acidified, Calcium phosphatase becomes soluble, and therefore neutralize H+ ions.

*Ammonia (NH43H)

Ammonia is a base. Therefore it can be used in the atmosphere to help increase pH of cheese rind. It’s also been used in the washing solution for the same purpose!

*Colliforms:

In theory, are not supposed to survive in saturated brine. They explode! In practice, some areas in brine have a lower salt content (around particles) that allows the colliforms to survive.

*Pink/burgundy color default

Can be created by an excess of wild Arthrobacter sp.

Fat degradation

Triglycerides..................>Free fatty acids................>Aromatic molecules
                                         Lipase (1)                          Esterase (2)


Residual rennet: No fat degradation
Yeast: no fat degradation
Micrococci: Some fat degradation at 1 &2
Geotrichum: some fat degradation at 1
B.linens: Some fat degradation at 1 &2

NB. In a wash rind technology, fat is not degraded as much as in a bloomy rind technology since the organisms involved in the ripening are not strong lipid digesters. Most of the aroma development comes from the degradation of proteins


*Protein degradation

Protein...........> Peptide (some bitter..)...........>Amino Acids...........>Aromatic molecules
                              1                                             2                                3,4,5

1: Proteinase or endopeptidase
2: Peptidase or exopeptidase
3: Desominase
4: Decarboxylase
5: Lyase à production of phenols (garlic, onion & cabbage taste)

Residual rennet is active at: 1
Yeasts are active at: 1 & 2
Micrococci are active at: 1, 2, 3 & 4 à Aroma development
Geotrichum is active at: 1, 2 & 3 à Aroma development
B.linens is active at: 1,2, 3 & 4 à Aroma development
Pseudomonas is active at 1 & 5

*Bitterness

If cheese pH stays around 5.5, bitterness has more chance to be present, since at that pH, residual rennet is very active. Residual rennet will degrade proteins into peptides, but will not further degrade them into amino acids. The resulting peptides can be bitter peptides.

*Lipases

Are more tolerant to cold than proteases. As Temp. is reduced, lipolysis is favored ( eg. Blue

• In goat cheese, lipase is responsible of the “goat” taste. This explains why, in a goat cheese, when ripening is done in cold conditions, the “goat” taste is more pronounced.

• If the ripening shelves are made of wood, they should be rough, since it will create channel for aeration under the cheese. A smooth surface will prevent a good growth of the bacteria underneath, since moisture film will be created. Suction will also be a problem and cause damage to the cheese.

• The ripening room should never be filled at more than 60% of its volume to allow good aeration.

Thank you everyone, for all your help. I have been a lurker this last year while I set up a family farm/sheep/cow creamery in Rexburg Idaho- Lark's Meadow Farms. I have not had time to contribute but I hope this makes up for a year of not sharing. Hope to share more in the future.

kendall

« Last Edit: February 25, 2011, 06:34:15 PM by fattyacid »
Whence come I and whither go I? That is the great unfathomable question, the same for every one of us. Science has no answer to it.
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Offline smilingcalico

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Re: Washed Rind Culture Primer
« Reply #1 on: February 25, 2011, 08:44:24 PM »
Great post, Kendall, I forgive you.  J/k I did the whole lurking thing too. I hope to see more posts like this from you.  And thanks.
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Offline CheeseSnipe

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Re: Washed Rind Culture Primer
« Reply #2 on: February 25, 2011, 11:15:16 PM »
Interesting info, thanks for sharing.
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Offline smilingcalico

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Re: Washed Rind Culture Primer
« Reply #3 on: February 26, 2011, 04:11:49 AM »
By the way, what do the abbreviations NB and NBB stand for?  Am I correct to assume CH/DH is what the particular strain of yeast is identified as?
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Offline george (MaryJ)

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Re: Washed Rind Culture Primer
« Reply #4 on: February 26, 2011, 04:52:08 AM »
I'm pretty sure the NB stands for "nota bene", and NBB "nota bene bene" - meaning "hey, pay attention!"   ;)  Don't know about the others.
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Online ArnaudForestier

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Re: Washed Rind Culture Primer
« Reply #5 on: February 26, 2011, 06:31:03 AM »
Nice, concise breakdown, fattyacid.  Many thanks. 
- Paul

Offline fattyacid

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Re: Washed Rind Culture Primer
« Reply #6 on: February 26, 2011, 12:34:57 PM »
By the way, what do the abbreviations NB and NBB stand for?  Am I correct to assume CH/DH is what the particular strain of yeast is identified as?

Yes, you are correct about the abbreviations. DH is Debaryomyces hansenii primarilay used for neutralization for mixed rind, washed rind and smeared cheese, also known as DHN by Danisco. CH is Candida utilis I think, but would be used  for flavor more than neutralization, especially in soft cheese.

As for NB and NBB George was spot on.
Whence come I and whither go I? That is the great unfathomable question, the same for every one of us. Science has no answer to it.
Max Planck

Offline Boofer

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Re: Washed Rind Culture Primer
« Reply #7 on: February 26, 2011, 12:43:37 PM »
Okay, fattyacid, I'll ask...what is it in your avatar?

Thanks for the culture primer.

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Offline fattyacid

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Re: Washed Rind Culture Primer
« Reply #8 on: February 26, 2011, 02:25:00 PM »
Okay, fattyacid, I'll ask...what is it in your avatar?

Thanks for the culture primer.

-Boofer-


It is a scanning electron micrograph of Lactobacillus on a piece of feta cheese. Wish I was still sharp enough to tell you the species by morphology my guess would be Lactobacillus helveticus or Lactobacillus delbrueckii

kendall
Whence come I and whither go I? That is the great unfathomable question, the same for every one of us. Science has no answer to it.
Max Planck