FFT FERMENTATION AND SUGAR PRESERVATION

fermentation

Involves creating an environment where naturally occurring beneficial bacteria (like lactic acid bacteria) or added starter cultures break down carbohydrates in the food into acids, gases, or alcohol.

Microbial Activity: Relies heavily on active microbial fermentation, which not only preserves but also enriches the food with probiotics. Flavors: Leads to complex, often tangy, and umami-rich flavors due to the metabolic activity of the microbes.

lactic acid or alcohol

preservation agent in fermentation

Saccharomyces cerevisiae

able to concentrate large quantities of thiamin, nicotinic acid, and biotin

Sorghum beer

contains high levels of riboflavin and nicotinic acid. Pellagra (vitamin deficiency in high maize diets) is unusual in communities in which _____ is consumed. Even children benefit from consuming the dregs which contain relatively little alcohol but are rich in vitamins

palm wine

high in Vitamin B12, which is helpful for people with low meat intake and who subsist primarily on a vegetarian diet

Idli

– a rice cake originated from India made from fermented black lentils and is high in thiamine and riboflavin.

cellulases

Microorganisms contain certain enzymes, such as ____, which are incapable of being synthesized by humans.

hydrolyze cellulose into sugars which are then readily digestible by humans.

alcoholic fermentation

The result of yeast action on the simple sugar called ‘hexose’ converting this into alcohol and carbon dioxide.

Air is excluded from the product to avoid the action of aerobic microorganisms, such as the acetobacter.

ethanol + co2

Hexose + Oxygen = _______

C2H5OH + CO2

C6H12O6 + O2 =

alcohol

vinegar fermentation

Takes place after alcohol fermentation. Acetobacter converts alcohol to acetic acid in the presence of excess oxygen

CH3 COOH+H2O

C2H5OH+O2 =

vinegar

Acetic Acid + Water

Ethanol + Oxygen =

lactic acid fermentation

takes place due to the presence of two types of bacteria: homofermenters and heterofermenters.

homofermenters; Embden–Meyerhof

produce mainly lactic acid, via the glycolytic (_____pathway).

The fermentation of 1 mol of glucose yields two moles of lactic acid.

Lactobacillaceae

the most important bacteria in desirable food fermentations, have the ability to produce lactic acid from carbohydrates

heterofermenters

produce lactic acid plus appreciable amounts of ethanol, acetate, and carbon dioxide, via the 6-phosphogluconate/phosphoketolase pathway

The fermentation of 1 mol of glucose yields 1 mol each of lactic acid, ethanol, and carbon dioxide

Acetobacter species

acetic acid-producing bacteria that are also important in the fermentation of fruits and vegetables

Saccharomyces

The most beneficial yeast in terms of food fermentation are from the______ family, especially S. Cerevisiae aka Baker’s Yeast or Brewer’s Yeast

Aspergillus species

responsible for the undesirable changes in foods (mould)

Penicillium

associated in the ripening and flavoring of cheese

molds

are aerobic, and they have the greatest array of enzymes, and can

colonize and grow on most type of foods.

They do not play a significant role in the desirable fermentation of fruits and vegetables.

enzymes

The changes that occur during fermentation of foods are the result of _____ activity.

They are complex proteins produced by living cells, to carry out specific biochemical reactions.

Aka as catalysts since their role is to initiate and control reactions, rather than being used in a reaction.

They are sensitive to fluctuations in temperature, pH, moisture content, etc. Extremes of temperature and pH will denature the protein and destroy ____ activity.

Microbial _____ play a role in the fermentation of fruits and vegetables.

Bound water

present within the tissue and is vital to all the physiological processes within the cell

Free water

exists in and around the tissues and can be removed from cells without seriously interfering with the vital process

Water activity

the amount of water available for microorganisms

1.0

Pure water aw

0.6

Almost ALL microbialactivity can be inhibited below aw

0.7

Fungi can be inhibited below aw

0.8

Yeasts can be inhibited below aw

0.9

Bacteria can be inhibited below aw

redox potential

Free atmospheric oxygen is utilized by some groups of microorganisms, while others are able to metabolize the oxygen which is bound to other compounds such as carbohydrates. This bound oxygen is in a reduced form.

below 4.6

high acid or acid food, which will not permit growth of bacterial spores

above 4.6

low acid will not inhibit the growth of bacterial spores

Lactobacillus and Streptococcus species

bacteria that can survive acidic environment

7.0

ph where bacteria can survive

4-4.5

ph where yeast can survive

2-8.5

ph where molds can survive

S. cerevisiae

properly applied only to ale yeasts.

Saccharomyces pastorianus

Lager yeasts are properly termed _______, representing as they do organisms with a 50% larger genome and tracing their pedigree to a joint of S. cerevisiae with Saccharomyces bayanus.

yeast

reproduces by budding. A single cell may bud up to 20 times each time leaving a scar, the counting of which indicating how senile the cell has become

sugar

basic substrate

Yeast can ferment ___ into alcohol and carbon dioxide in the absence of air but require oxygen for growth.

Excess oxygen – (and in the presence of acetobacter) can be oxidized to form acetic acid

0-50C; 20-30C

(yeast temp) ___ Celsius, with an optimum temperature range of ____deg Celsius

4-4.5

(yeast) pH near neutral point ____ but prefer acidic

0.85

aw for yeast

88%

relative humidity for yeast

40%

yeast grows well at __ sugar solution

osmophilic

yeasts can tolerate concentrations higher than 40%

Debaromyces

yeast – high salt concentrations

Zygosaccharomyces rouxii

yeast - high salt concentration and low water activity

microaerophillic

theyrequireoxygentosurvive,butonlyinverysmall amounts (microbial fermentation)

non motile gram-positive rods

All lactic acid producers are _____ that need complex carbohydrates as a source of energy.

Streptococcus and Leuconostoc

produce the least acid

intermediate

Heterofermentative species of Lactobacillus and Pediococcus – ______ amounts of acid

brine

is used for vegetables that incoherently contain less moisture.

20% salometer

ideal for fermentation

brien solution

prepared by dissolving the salt in water (15 to 20% salt solution)

nonsalted

Relies on the rapid colonization of the food by lactic acid producing bacteria, which lower the pH and make the environment unsuitable for the growth of microorganisms.

gundruk and sinki

acetobacter

 A second group of bacteria of importance in food fermentations are the acetic acid producers from the ____ Species.

important in the production of vinegar (acetic acid) from fruit juices and alcohols

The same reaction occurs in wine, oxygen permitting, where ____ can cause undesirable changes – the oxidation of alcohol to acetic acid.

acetic acid fermentation

raw material that will undergo alcoholic fermentation – Apples, pears, grapes, honey, cereals, hydrolyzed starches, beer, wine

yeast and bacteria

microbes in acetic acid fermentation

10-13

% alcohol concentration in acetic acid fermentation

acetaldehyde

intermediate product in the conversion of sugar from fruit juice into acetic acid or vinegar.

needs oxygen to be converted to acetic acid

Bacillus

A third group of bacteria of importance in food fermentations are those which bring about alkaline fermentation

bacillus subtilis

Causes the hydrolysis of protein to amino acids and peptides and releasing ammonia, which increases the alkalinity and makes the substrate unsuitable for the growth of spoilage microorganisms.

dominant species

alkaline fermentation

More common with protein rich foods such as soybeans and other legumes.

 Ogiri in Nigeria – watermelon seeds

 Ogiri-Saro in Sierra Leone – sesame seeds

 Semayi in Indonesia – coconut

 Kawal in Sudan – leaf proteins

 They are important in that they provide protein rich, low-cost condiments from leaves, seeds, and beans which contribute to the diet of millions of people in Africa and Asia

pickling

Process: Involves submerging food in an acidic solution, usually vinegar, combined with water, salt, and often spices.

Preservation Agent: Acid (like vinegar) is the key preservative that prevents spoilage and bacterial growth.

Microbial Activity: It does not rely on live microbes for preservation. The acidic environment directly halts microbial activity.

Flavors: Typically results in tangy, sharp flavors due to the vinegar.

jam

made from ground or mashed whole-cooked fruit.

jellies

made from the juice of cooked fruit, with added sugar and pectin. For a clear __, the juice is first strained.

marmalades

contain juice with thin slices of fruit and rind, especially citrus fruits.

conserves

made from a mixture of fruits (usually citrus or at least with some

citrus) to which nuts and raisins, but no sugar, are generally added.

preserves

made from whole fruit, halves, or chunks

fruit preserves

these thick and smooth fruit preserves are made from sieved, long- cooked fruit; are usually less sweet than jams and jellies; and do not keep as well as other fruit spread forms.

sucrose

used in sugar preservation as it is hydrophobic

In high concentrations, acts as a preservative due to osmosis.

Sugar attracts all available water.

Must be a concentration of 68 % or more.

40 68 .5-.6 1

fruit content, sugar, acid, and pectin in jams

0.75-1kg

sugar for every 1kg extract in jellies

fruit bar or leather

Fruit pulp is taken, and its total soluble solids (TSS) content is raised to 30°Brix by adding sugar.

This pulp is then spread on stainless steel trays smeared with fat which are dried in a mechanical dehydrator at 60±5°C for 2 hours.

Potassium metabisulphite is added at the rate of 0.2 percent in the fruit pulp. A thin layer of pulp is dried on a pre-greased stainless steel or aluminum tray, followed by a second layer.

fruit toffees

Made by mixing fruit pulp with other ingredients like glucose, milk powder and edible fat.

• For one kilo gram of concentrated pulp, 160 g of glucose, 320 g of milk powder and 200 g of edible fat is added.

• This mixture is further heated to a thick consistency (75- 80°Brix) followed by spreading it as a sheet of one cm thickness on a fat smeared flat tray and allowed to cool.

candied fruits

are first soaked in cane sugar or glucose syrup and subsequently drained free of syrup and dried.

• These must be plump, tender and have highly flavored sweet taste without any stickiness.

glazed fruits

Candied fruits covered with a thin transparent coating of sugar, which imparts them a glossy appearance, are known as ____.

pectin; 0.5-1

makes fruit spreads gel.

• Naturally found in fruits but concentrations vary according to the fruit.

• ___ concentration is needed for fruit to gel.

• Commercial ___ can also be added if the fruit doesn’t contain sufficient amount

sugar

A natural preservative

• At least 50% granulated white sugar

• osmotically pulls water from the cells of the microorganisms.

• Maintains firmness of fruits, contributes flavor, and makes gelling possible.

• Adds calories.

• Can be reduced by using alternative sweeteners and pectin that relies on Calcium ions

acid

Provides both flavor and gel formation.

pH is between 2.8 and 3.4 and an optimal pH of 3.2.

Fruit spreads are somewhat —-.

Without __, fruit spreads lack flavor and gel strength.

If the fruit mix is too sweet, 1 tbsp of lemon juice, 1 tbsp of vinegar, or 1⁄8 tbsp of citric acid can be added for every 8-ounce cup of juice.

50:45

parts of cane sugar (sucrose) is used for every _ parts of fruit for preparation of jam.

3.1

The pH of the mixture of fruit juice and pectin should be ___ before sugar is added.

citric, tartaric, malic

___, ___ or ___ acid are used to supplement the acidity of the fruit for jam making.

68.5

After addition of sugar, the mixture is boiled to concentrate the soluble solids to about ___percent and also to allow the necessary degree of inversion of the sugar.

boils at 105C

jelmeter test

The end point can be determined by carrying out a __

40ppm

If jam is prepared from fresh, unsulfited fruit pulp then it is advisable to add about ____ppm of sulfur dioxide in the form of potassium meta-bisulfite to the jam, which is permitted by law.

1 60-65 1 33-38

pectin, sugar, fruit acid, and water in jellies