Yeast, a single cell fungus is one of the important processing aids in foods and beverages. The diversity of foods in which, yeasts predominate ranges from alcoholic beverages (wine, beer, whisky, etc.), cereal-based leavened products (sourdough, Kimchi, Tofu, idli, etc.), milk products (cheese, Curd, Yogurt), and condiments such as soy sauce and papas.

What is the process by which this tiny microbe can make super foods?

Fermentation: – Fermentation is a metabolic process that consumes sugar in the absence of oxygen to produce products like organic acids, gases, or alcohol. The science of fermentation is known as zymology. In microorganisms, fermentation is the primary means of producing ATP by the degradation of organic nutrients anaerobically. Fermentation is one of the oldest methods for preserving foods. It is becoming increasingly popular since the fermentation increases the nutritional value of foods and that consumers perceive it as natural and free of food additives.

What does a yeast cell need for successful Fermentation and Why?

Yeast nutrition is an essential factor in the overall health and success of fermentation. Managing nutrient requirements not only allows for regular and complete fermentation but enhances sensory quality.

Yeast nutrition is widely divided into three categories (Macronutrients, Micronutrients, and energy source) which includes different carbon sources, nitrogen sources, vitamins, trace elements, etc.
Figure 1.

Some important nutritional elements and their roles are listed below: –

Elements	Function
Carbon	Contribute to organic cell material
Nitrogen	A major part of proteins, nucleic acids, and coenzymes
Oxygen	Electron acceptor in the respiration of aerobes
Sodium	Principal extracellular cation
Magnesium	Important divalent cellular cation, an inorganic cofactor for many enzymatic reactions, incl. those involving ATP; actions in binding enzymes to substrates
Phosphorus	The constituent of phospholipids, coenzymes, and nucleic acids
Sulphur	Act as building element for cysteine, cystine, methionine, and proteins as well as some coenzymes as CoA and carboxylase
Chlorine	Principal intracellular and extracellular anion
Potassium	Principal intracellular cation, the cofactor for some enzymes
Calcium	Important cellular cation, the cofactor for enzymes as proteinases
Manganese	Inorganic cofactor cation, the cofactor for enzymes as proteinases
Iron	Constituent of cytochromes and other harm or non-herm proteins, cofactor for several enzymes
Cobalt	The constituent of vitamin B and its coenzyme derivatives
Zinc	Act as a cofactor for many enzymes and required for the structural stability of zinc finger proteins, many of which exert important controls on cellular metabolic processes
Molybdenum	Inorganic constituents of special enzymes

 

What Happens to the yeast due to less or non-availability of Nutrients?

The problems connected with development and nutrition are numerous and are very important. The requirement of nutrition in these small cells is not lesser than in animals and humans. The deficiency of a single nutrient during the growth phase of the cell may lead to the death of the cell and a huge economic loss to the industry. Some of the possibilities which may occur in lack of nutrients are listed below: –

• Deficiency of nutrients may reduce yeast growth, slow down fermentation, and promote the accumulation of pyruvic acid and acetaldehyde, components responsible for oxidation and binding SO2.
• Low levels of sterols, oxygen, and/or unsaturated fatty acids may shut down sugar consumption (stuck fermentation) and increase volatile acidity.
• Without proper nutrition introduced at the right stage in their growth cycle, yeast can come under stress and produce undesirable characteristics: off-flavors (hydrogen sulfide, oxidation…), high bound SO2, stuck or sluggish fermentation.
• Loss of viability during alcoholic fermentation is usually attributed to the non-availability of lipids, specifically sterols or unsaturated fatty acids, that are required to maintain cell membrane integrity, and deficiency in these compounds lead to altering cell resistance to ethanol.
• Lack of nitrogenous compounds breaks down asparagine with the final production of malic acid and this acts as a poison, suppressing and finally inhibiting reproduction as soon as its acid concentration reaches a certain limit.
• In lack of nutrients, cells start to shrink and, in the end, lose their viability. Figure 2.

Essentially all nutrients can limit the fermentation rate by being present in concentrations that are either too low or too high. At low concentrations, the growth rate is roughly proportional to concentration, but as the concentration increases, the growth rate rises rapidly to a maximum value, which is maintained until the nutrient concentration reaches an inhibitory level, at which point the growth rate begins to fall again and it is very important to keep a check on the availability of nutrient during the fermentation process to avoid any miss function and loss.

What Happens to yeast due to less or non-availability of Nutrients?

The problems connected with development and nutrition are numerous and are very important. The requirement of nutrition in these small cells are not lesser than in animals and humans. Deficiency of a single nutrient during the growth phase of the cell may lead to death of the cell and a huge economic loss to the industry. Some of the possibilities which may occur in lack of nutrients are listed below: –

• Deficiency of nutrient may reduce yeast growth, slowdown fermentation and promote the accumulation of pyruvic acid and acetaldehyde, components responsible for oxidation and binding SO2.
• Low levels of sterols, oxygen and/or unsaturated fatty acids may shut down sugar consumption (stuck fermentation) and increase volatile acidity.
• Without proper nutrition introduced at the right stage in their growth cycle, yeast can come under stress and produce undesirable characteristics: off-flavors (hydrogen sulfide, oxidation…), high bound SO₂, stuck or sluggish fermentation.
• Loss of viability during alcoholic fermentation is usually attributed to non-availability of lipids, specifically sterols or unsaturated fatty acids, that are required to maintain cell membrane integrity and deficiency in these compounds lead to alter cell resistance to ethanol.
• Lack of nitrogenous compounds breaks down asparagine with final production of malic acid and this acts as poison, suppressing and finally inhibiting reproduction as soon as its acid concentration reaches certain limit.
• In lack of nutrients cells start to shrink and at the end lose their viability. Figure 2.

Essentially all nutrients can limit the fermentation rate by being present in concentrations that are either too low or too high. At low concentrations, the growth rate is roughly proportional to concentration, but as the concentration increases, the growth rate rises rapidly to a maximum value, which is maintained until the nutrient concentration reaches an inhibitory level, at which point the growth rate begins to fall again and it is very important to keep a check on the availability of nutrient during the fermentation process to avoid any miss function and loss.

Figure 1.

Figure 2.