VINEGAR AND RYE BREAD PRODUCTION

VINEGAR PRODUCTION

Vinegar

Vinegar is a preservative or a dilute solution of acetic acid containing salts and extracted matter that results from fermentation of ethanol to yield acetic acid.

Chemical formula

2CH3 CH2 OH + O2 = 2CH3 COOH + 2H2O

Vinegar Production

The production of vinegar is done in two (2) distinct steps.

Alcohol Fermentation

Acetic Fermentation (Acetification)

Vinegar Production

Fermentation is the process by which, under influence of air, warmth and moisture, sugar (or dextrose, starch converted into sugar) is changed into alcohol (C2H5 OH) and carbon dioxide (CO2). Three kinds are considered-

alcoholic acetic

Bacteria Involved in Production

The bacteria involved in Vinegar production belongs to the family Acetobacteriaceae and Gluconobacter, but most belong to the genus Acetobacter.

They are specifically designed to convert ethyl alcohol (C2H5OH) into acetic acid (CH3CO2H) by oxidation

Anaerobic Aerobic2C2H5OH 2CH3CHO 2CH3COOH + 2H2O

Bacteria Involved in Production

• These are known as acetic acid bacteria. They are:-

Gram negativeEllipsoidal to rod shaped Obligatory aerobic Nitrogen -fixing bacteriaFor Example- Acetobacter aceti

Vinegar Production

Vinegar can be produced from raw materials such as:-

WineCiderFruit mast, e.g.Grapes Berries

HoneyGrainsMalted barleyPure alcoholMolasses

Vinegar Production

Vinegar is produced via four (4) methods:

1. The Orleans process2. Natural Process3. Rapid Generator Process (Schutzenbach)4. The Submerged fermentation process

The Orleans Process

This method is a slow process that originated in France. The process involves the vinegar being processed in

large barrels with a temperature maintained at 70°F-80°F.

65-70 litres of high grade vinegar is added to the barrels as a starter material with 15 litres of wine so as to acidify the liquid to the point of optimum growth for the acetic acid bacteria.

The bacteria forms a gelatinous slime layer at the top of the surface.

The mixture is allowed to ferment with the addition of more wine for a period of one (1) to three (3) months.

The vinegar formed is then extracted from the barrels using a glass tube.

The extraction of vinegar does not stop the process, more wine is added and vinegar is continually extracted.

This is a long and slow process.

The Orleans Process (cont’d)

Barrels Uses in Orleans Process

Natural Process

This done by fermenting fresh sap in plastic or earthen jars until it sours.

The product is then placed into plastic bottles in the sun for a few days.

Sap used are from coconut or sugar palm

Sap being cured in earthen and plastic jar.

The Generator Process

This is a German method that uses a generator.The generator is an upright tank that is filled

with beechwood shavings, charcoal or coke that allows the bacteria to grow and form a thick slime coating over it.

It fitted with devices that allows the liquid to past through the shaving to access the acetic acid bacteria.

Holes at the bottom of the generator allows air to be added so that the bacteria can oxidize the alcohol.

The rate of acetification in this process is dependent on the amount of oxygen available.

Therefore if there is less oxygen the amount of acetic acid produced is less at a low temperature

Where as in abundant oxygen, extra acetic acid is produced at a higher temperature, therefore the temperature and oxygen concentration in this process needs to be controlled. Diagram of Generator

The Submerged Fermentation Process

This process takes place in production plants These plants are filled with large stainless steel tanks called

acetators. The acetators are fitted with centrifugal pumps in the bottom that

pump air bubbles into the tank. As the pump stirs the mixture nutrients are added to it. The addition of nutrients encourages the growth of Acetobacters

on the oxygen. At a temperature range of 26-38°C the alcohol is converted to

vinegar. The vinegar is then extracted and piped to a plate-and-frame

filtering machine then to the dilution station.

Factors Affecting Bacterial Growth

Ethanol : Depending on the species of bacteria the concentration of ethanol varies:-

 6-7 % ethanol    Acetobacter oxydans, A. xylinium  9-11 % ethanol   A. aceti, A. pasteurionum 11-13 % ethanol   A. schutzenbachi   Oxygen :For every gram of ethanol used its oxidation process

requires 0.49 L of oxygen, that is, 2.4 L of air Temperature :Optimum temperature for the growth of acetic

acid bacteria is 28 – 34° C Other nutrients :Generally mineral and nitrogen sources is

needed. Vinegar production from cider requires 100 g ammonium sulfate for every 1000 L produced. 

Acetic acid :Microorganisms can only tolerate acid at a certain concentration, that is, 0-55 parts acetate from 100 parts sugar. Likewise 1.26 g acetate per 1.0 g ethanol

Rye Bread Production

Rye Bread

Rye bread commonly known as sour dough is bread made from rye flour.

Sourdough is a dough containing a Lactobacillus culture (Lactic acid bacteria (LAB)), usually in symbiotic combination with yeasts. The Lactobacillus is much greater in proportion to the yeast. 

In comparison with yeast-based breads, sourdough produces a distinctively tangy or sour taste, mainly because of the lactic acid produced by the lactobacilli.

Lactococcus lactisWeissella confusa Lactobacillus

plantarum Lactobacillus brevis

,

Commercial strains Lactobacillus

plantarum Lactobacillus

brevis, Lactobacillus

helveticus Kluyveromyces

marxianus

Bacteria Used in Rye Bread Production

Biochemistry

Two most important enzymes in the flour are protease and diastase.

Protease conditions the gluten, improving its elasticity and its ability to retain the gas produced during fermentation.

Diastase changes some of the starch in flour to dextrins and maltose sugar

Rye bread differs from others due to differing amylases, Amylase is the enzyme responsible for the breakdown of starch

into sugar. Rye amylase remains active at substantially higher temperatures.

Since rye gluten is not particularly strong, rye dough structure is based on complex polysaccharides, including rye starch and pentoses.

As a result, amylases in rye flour can break down dough structure, inhibiting it from rising.

Biochemistry cont’d

Chemical differences in the proteins and enzymes found in rye present differences in how rye flour behaves when mixed with water to make dough, and these differences impact the use of pre-ferments, mixing, fermentation and baking when there is more rye than wheat flour in the dough.

The starch amylase is needed to form the structure of the crumb, and if too much starch is split up, the texture of the bread suffers and becomes gummy.

To combat this a fermentation process is applied. This fermentation process involves the removal of phytates and enzyme

inhibitors. Traditionally, this is prevented by acidifying the rye dough, which slows

down the action of amylases. This is why breads with a high percentage of rye flour are made with rye sour (rye-based sourdough starter), even if commercial yeast is added.

Acidification of rye dough has other nutritional advantages specific to rye bread which may also be of interest to the home baker, as well as the advantages that also apply to wheat-based sourdoughs.

Dough Making

Fermented bread is made by mixing flour, with a definite quantity of water, milk, salt, and a ferment. Sugar is usually added to hasten fermentation. Dough is kneaded to incorporated all the ingredients, covered, and allowed to rise in a temperature of 68° F, until dough has doubled its bulk.

In order to make the dough rise, dough acidification can be done to impede the function of rye amylases.

The lower pH, however, compromises the use of relatively acid-intolerant Saccharomyces cerevisiae-based "baker's yeast".

Instead, naturally acidic Lactobacillus "sourdough" cultures is added to lower the bread pH

It provides an acid-tolerant yeast strain, and helps gelatinize starches in the dough matrix.

This approach produces lighter breads.

Baking of Bread

Bread is baked;(1) To kill the ferment, (2) to make the starch soluble, (3) to drive off alcohol and carbon dioxide, and (4) to form brown crust of pleasant flavor.

Benefits of Rye Bread

Increases beneficial lactic acid-The longer rise time needed for sourdough increases the lactic acid and creates an ideal pH for the enzyme phytase. This enzyme breaks down phytates more effectively than in yeast breads. Sourdough rye has the least amount of phytates making it a healthier bread.

Predigestion of starches-The bacteria and yeast in the sourdough culture work to predigest the starches in the grains, thus making it more easily digestible to the consumer.

Breakdown of gluten-The longer soaking and rising times in the preparation of sourdough breaks the protein gluten into amino acids, making it more digestible.

Preservation-The acetic acid which is produced along with lactic acid, helps preserve the bread by inhibiting the growth of mold.

Better blood glucose regulation-research suggests that sourdough bread — sourdough white bread — showed positive physiological responses. It lowers blood glucose levels when compared to whole wheat, whole wheat with barley and plain white bread. Interestingly, the subjects tested after eating whole wheat bread fared the worse — with spiking blood glucose levels.

References

Freud, W. (2003). Production of Baked Goods from Wheat and Rye Flour- Methods and Analysis of Faults. 22-1 Bread Production System. http://www.agmrc.org/media/cms/bushuk_c8b79bab55bb0.pdf

ITDI. Acetator Vinegar Production. Industrial Technology Development Institute. Philippines. http://www.itdi.dost.gov.ph/index.php?option=com_content&task=view&id=84&Itemid=186

Lefevbe, M. (1924). Making Vinegar in the Home and on the Farm. U. S. Department Agriculture Farmers’ Bulletin No.1424. http://webcache.googleusercontent.com/search?q=cache:IOH9I4UwxgMJ:naldc.nal.usda.gov/download/ORC00000397/PDF+production+of+vinegar+pdf&cd=9&hl=en&ct=clnk&gl=gy

Rollán, G., Gerez1, C.L., Dallagnol, A. M., Torino, M.I. and Font, G. (2010). Update in Bread Fermentation by Lactic Acid Bacteria. Technology and Education Topics in Applied Microbiology and Microbial Biotechnology. www.formatex.info/microbiology2/1168-1174.pdf

Tan, C.F. (2005). VINEGAR FERMENTATION-A Thesis. Mechanical Engineering, University of Louisiana at Lafayette. http://etd.lsu.edu/docs/available/etd-11092005-152334/unrestricted/Tan_thesis.pdf