Industrial Lecture 4

8/4/2019 Industrial Lecture 4

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BIO 425Industrial Microbiology

Seyhun YURDUGLLecture 4

Distilled alcoholic beverages&

Cheese making


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Content Outline Distilled alcoholic beverages and examples

Flavored spirits Cheese making


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Distilled alcoholic beverages Distilled products (Spirits):

represent a substantial proportion of themarket for alcoholic beverages.

The general scheme in the production lineinvolves five major steps.


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Major steps in production

Selection of the raw material

Processing of the raw material to give a

fermentable extract Alcoholic fermentation by yeast

(S.cerevisiae)

Distillation of the fermented material togive the distillate product

Post-distillation processing


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An important advantage Because of distillation;

[Ethanol] increases so:

No contamination problem is observed indistilled products.


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E. g. Whisky Prepared from fermented cereal extracts,

aged in oak barrels before bottling.

produced principally in Scotland, Ireland,North America & Japan.

raw material: Mainly maize, wheat, barley,rye, oats and rice.


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Production of whisky

Raw material is mixed with appropriate water

Milling

Processed to extract(e.g. starch conversion to maltose, amylose etc.)

Mashing process (120-150 C for gelatinization)

Cooling of mash to 60-65 C-(malted barley & bacterial enzymes are added.)

Formation of cereal slurry, cooled, inoculated with yeastat 20-30 C for 2-3 days, to give a final ethanol conc. of 6-9%

Mash is distilled after fermentation and final product is obtained


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Rum

A key product of West Indies.

Distilled fermented sugar cane juice-containmolasses.

A waste by-product of cane sugar refining.


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Production of rum

Cane sugar

Heat until pasteurization, adjust pH to 4.0

Dilution to give 12-20% concentration of fermentable sugars.

Add S.cerevisiae to conduct fermentation 20-30 C for about 2 days forlight flavored rum.

Long time (12 days) for heavy flavored rum


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Brandies and wine spirits Distillates of fermented fruit juices

e.g. Cognac, Armanac-in French winegrowing regions.

Yeasts are responsible for alcoholicfermentation of fruits.


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Flavored spirits

Neutral alcohol: Basis for production.

greater than 96 % alcohol, provided by very little flavor contribution

from congeners (essences).

e.g. Gin: addition of an extract of Juniperplant.


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Low alcohol and alcohol free

beverages Both social, cultural, religious and health

issues promote their production.

now applicable to beer, wine and cider

A decreased concentration of ethanol (lessthan 2.5 % v/v)


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Two approaches for production of

low alcohol and alcohol freebeverages

A) Physical methodology- removal of ethanol from the fully fermentedproduct:

evaporation, distillation, dialysis, reverseosmosis, adsorption, freezing and extractionwith supercritical carbondioxide


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Two approaches for production of

low alcohol and alcohol freebeverages

B) Manipulation of fermentation - managedto yield low amounts of ethanol

e.g. Incorporation of less sugar content,

or novel species of yeasts are used thatferment sugars;

to relevant flavor volatiles, with decreasedethanol production.


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Cheese-making If milk is quickly infected by bacteria,

gives sourness by converting the sugar(lactose):

by the operative activity of lactic acidbacteria,

it is likely to say that cheese is producedby this sourness.


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Technological aspects of cheese-making

Directly produced from the milk proteinCasein

Casein curdled by the acid produced by Streptococci

Rennin addition-obtained from stomach lining of the calf

Separation of acid curd from the whey

Whey: used to make whey solids from whichprocessed cheese is prepared.


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Some words to define cheese A form of food preservation,

in which milk protein and fat areconcentrated approximately ten- fold andthe milk sugar (lactose) is fermented intolactic acid;

by lactic acid bacteria.


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The preservative property Arises from combined effect of:

acidification,

dehydration,

salt addition.


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The conversion of milk to cheese

involves: Coagulation,

acidification,

water removal (syneresis, curd draining andpressing),

salt addition,

cheese ripening.


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The world cheese consumption:

Annually 14000000 tonnes- world basis,

40% produced in EU,

within the world 900 types exist.


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Starter cultures: Required to start cheese making and other

fermented food,

Inoculation of a known culture of m/o,

Relies on to produce the desiredfermentation,

thus assuring a uniformly qualified product.


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Types of lactic acid bacteria:

Mesophiles (Optimum T= 30-33C),

used in fermentation technologies where 20-40C is the predominating T).

Thermophiles (Optimum T= 40-45C) used

in fermentation technologies where 30-50Cis the predominating T).


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Most important starters:

Streptococcus salivariussubsp.thermophilus (S.thermophilus).

Lactobacillus bulgaricus.


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Other species: Mesophilics,

E.g.Lactococcus spp,Leuconostoc spp.

Non-starter lactic acid bacteria in cheesevarieties like for e.g.

Lactobacillus casei, Lactobacillusplantarum

Pediococci spp, Micrococci spp.


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Secondary flora Molds,

E.g.Penicillum camemberti.

This is the main species used for mold-ripenedcheeses (Camembert cheese).

Geotrichium candidum - Mold ripened cheese,

combinational use withPenicillum camemberti Penicillum roquefortii-Blue cheese, Danish Blue,Roquefort cheese.


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Yeasts Kluvyeromyces lactis

S.cerevisiae

In Blue, soft, mould ripened cheese.

Candida utilis

In Red smear-ripened (surface ripenedcheese).


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Other bacteria Corynebacteria spp.(Red bacteria)

E.g.Brevibacterium linens: importantspecies.

Provides red / orange color and acharacteristic odor,

originating from sulfur containingaminoacids, salt tolerant, G(+) aerobic.

Propionibacteria spp.


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Propionibacteria spp. PrincipallyPropionibacterium freudenreichii,

Used in Swiss cheese technology: (Emmenthal,Gruyre, Appenzell)

3 CH3CHOHCOO- 2 CH3 CH2 C00

-+CH3C00-

+ H2O + CO2

propionate acetatelactate


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Components:

Carbondioxide: responsible for eye

formation, Propionate and acetate: flavor components.


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LITERATURE CITED Forsythe, S.J. The Microbiology of Safe

Food, Blackwell Science, Cambridge, 2000.

Wood, B. J. B., Microbiology of FermentedFoods, Vol.1 and 2, Blackie Academic andProfessional, London, Second edition, 1998.

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Industrial Lecture 4