Food Preservation Method ( Dr. Salih KARASU )

Food Preservation Method

Dr. Salih KARASU

Preservation Chemicals and Microorganism

Fermantation

Fermentation could be described as a process in which microorganisms change the sensory (flavor, odor, etc.) and functional properties of a food to produce an end product that is desirable to the consumer.

Fermentation, along with salting, cooking, smoking, and sun drying, is one of the earliest ancient traditions developed by cultures all around the world to extend the possible storage time of foods.

Fermentation as a Preservation Method

As new preservation techniques have been developed, the importance of fermentation processes for food preservation has declined. Yet fermentation can be effective at extending the shelf life of foods and can often be carried out with relatively inexpensive, basic equipment.

The chemical composition of most foods is relatively stable; therefore, generally preservation is based on eliminating microorganisms or controlling their growth and the overall composition of the microflora

To reduce or prevent microbial spoilage of food, four basic principles can be applied:

1. Minimize the level of microbial contamination onto the food, particularly from “high-risk” sources (asepsis)

2. Inhibit the growth of the contaminating microflora

3. Kill the contaminating microorganisms

4. Remove the contaminating microorganisms

Fermentations use a combination of the first three principles. Fermentations should not be expected to sterilize substandard raw products, but rather should use high-quality substrates

Microorganisms can improve their own competitiveness by changing the environment so that it becomes inhibitory or lethal to other organisms while stimulating their own growth, and this selection is the basis for preservation by fermentation.

A number of different bacteriocidal and bacteriostatic factors that can be produced by lactic acid bacteria (LAB), acetik acid bacteria, yeast and moulds.

Preservation agent produced by LAB

Low pH

Organic acids, e.g., lactic acid, acetic acid, and formic acid

Low redox potential

Nutrient depletion

Accumulation of inhibitors, e.g., toxins, bacteriocins , antibiotics, lactococcins, nisin, natamycin, hydrogen peroxide

Ethanol

Diacetyl

Carbon dioxide

Microorganisms Used in Food Fermentations

Lactic Acid Bacteria —> Lactic acid

Acetic acid bacteria —> Acetic acid

Yeast —> Alcohol and CO2

Molds —> Enzyme

Natural Antimicrobials for Food Preservation

There is a rapidly growing demand for environment-friendly, safe preservatives to be used for mild food preservation. For a long time, chemical preservatives such as sorbate and benzoate have been used as reliable preservative factors to control a number of microbial
hazards.

However, such compounds do not satisfy the concept of “natural” and “healthy” food that consumers prefer and that the food industry, consequently, needs to manufacture.

Nature is well known to contain many different types of antimicrobial compounds that play an important role in the natural defense or competition systems of all kinds of living organisms, ranging from microorganisms to insects, animals, and plants.

Kaynak: http://avesis.yildiz.edu.tr/skarasu/dokumanlar

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