Etiket Arşivleri: Fermentation

Food Preservation Method ( Dr. Salih KARASU )

Food Preservation Method

Dr. Salih KARASU

Preservation Chemicals and Microorganism


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



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

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.


Alkollü İçkiler ve Gıdalarda Alkol ( Prof. Dr. Adem ELGÜN )


Prof. Dr. Adem ELGÜN
Selçuk Üniversitesi, Ziraat Fakültesi, Gıda Mühendisliği Bölümü Emekli Öğretim Üyesi, Konya


Etil alkol her ne kadar kimyasal bir madde olsa da, insan diyetinde yer aldığında sarhoşluk verici ve sağlık üzerine olumsuz etkilerinden dolayı hem tıbbi, sosyal ve dini açıdan önemli gündem maddelerinden birini oluşturmaktadır. Aslında karbonhidratların şeker formunun alkol fermantasyonu yoluyla oluşmakta, besleyici özellik insanın mental, fizyolojik ve sosyal aktivitelerini etkiler duruma dönüştürmektedir. Bu sebeple alkolün keyif verici içeceklerde ve gıda maddelerindeki mevcudiyetleri, etkisi ve kontrolü önemli denetim konularından biridir. Bu derlemede etil alkolün kimyasal konumu ve özellikleri, sağlık ve sosyal yapı bakımından etki boyutları, elde edilişi, içki, içecek ve gıda maddelerinde bulunuşu ve miktarları ile alkollü ürünlerin mevzuat boyutu incelenmiş, alkolle ilgili meselelere yönelik önerilerde bulunulmuştur.

Anahtar kelimeler: Etil alkol, fermantasyon, alkolün zararları, alkollü içki ve gıdalar.


Even though ethyl alcohol is to be a chemical substance, when take place in the human menu it has been the most important subject of the medical, social and religious agendas due to its detrimental and drunken effects. Actually, it becomes as a result of alcoholic fermentation of the sugar forms of carbohydrates, and the nutritional property is changed to negative effect on mental, physiological and social activities of human. By the way, it is a main subject of the governance at the control of presence, amounts and effects of ethyl alcohol in the beverages and foodstuff. In this review, the chemical situation and properties of ethyl alcohol, the dimensions of its effect on health and social structure, its production methods, its presence and amounts in beverages (soft and alcoholic) and foods and the legislative properties are summarized. And some suggestions are given on the problematic subjects in relation to the alcohol involvement.

Keywords: Ethyl alcohol, fermentation, detrimental effect of alcohol, alcohol in beverage.


Basic Principles of Food Fermentations

Basic Principles of Food Fermentation

• Introduction

• Fermentation and Fermenting Microorganisms

A)Food Fermentation

B)Fermented Foods: An ancient Tradition

C)Factors Influencing Fermentation

D)Biological Agents Responsible in Food


“fermentation, far from being a lifeless phenomenon, is a living process…”

– Louis Pasteur

The Chemistry of Fermentation

– Aerobic & Anaerobic Cellular Respiration

– Glycolysis

– Alcoholic Fermentation

– Lactic Acid Fermentation

Aerobic Cellular Respiration

• Aerobic means “with air”. This type of respiration needs oxygen for it to occur so it is called aerobic respiration.

Glucose + Oxygen -> Carbon dioxide + Water + Energy

• The chemical equation is:

C6H12O6 + 6O2 -> 6CO2 + 6H2O + 2900 kj

• 3 stages: -glycolysis

-citric acid cycle

-electron transport chain

Stages of Aerobic Cellular Respiration

• In glycolysis, a net of 2 molecules of ATP, or chemical energy, are produced.

• The citric acid cycle produces another 2 molecules of ATP

• The electron transport chain produces 28 molecules of ATP.

• Oxygen is used in aerobic cellular respiration as the final electron acceptor in the electron transport chain, which is part of why it’s able to create so much ATP. But what happens whenoxygen doesn’t exist?

Anaerobic Cellular Respiration

• In anaerobic cellular respiration, the only step of

this process that occurs is glycolysis.

What is fermentation?

• Derived from the Latin verb ‘fervere’ meaning ‘to boil’

What is fermentation?

• It is a process by which the living cell is able to obtain energy through the breakdown of glucose and other simple sugar molecules without requiring oxygen.

• Fermentation results in the production of energy in the form of two ATP molecules, and produces less energy than the aerobic process of cellular respiration .

• Louis Pasteur in the 19th century used the term fermentation in a narrow sense to describe the changes brought about by yeasts and other microorganisms growing in the absence of air (anaerobically);

• he also recognized that ethyl alcohol and carbon dioxide are not the only products of fermentation.


• Fermentation is the metabolic process in which carbohydrates and related compounds are oxidized with release of energy in the absence of external electron acceptors under anaerobic conditions.

Microbial cell (Biomass) Yeast

Microbial enzymes Glucose isomerase

Microbial metabolites Penicillin

Food products Cheese, yoghurt, vinegar

Vitamins B12, riboflavin

Products of Fermentation

Fermentation products include:

• Food products: from milk (yogurt, kefir, fresh and ripened cheeses), fruits (wine, vinegar), vegetables (pickles, sauerkraut, soy sauce), meat (fermented sausages, salami)

• Industrial chemicals: (solvents: acetone, butanol, ethanol, enzymes, amino acids)

• Specialty chemicals (vitamins, pharmaceuticals) Products of Fermentation

Most commercially useful fermentations may be classified as Solid state fermentation Submerged fermentation surface (solid state) submersion techniques.

• microorganisms cultivated on the surface of a liquid or solid substrate.

• complicated and rarely used in industry.

• Mushroom, bread, cocoa, tempeh

microorganisms grow in a liquid medium.

(biomass, protein, antibiotics, enzymes and sewage treatment) are carried out by submersion processes. 19

Some important fermentation products

Product Organism Use

Ethanol Saccharomyces


Industrial solvents,


Glycerol Saccharomyces


Production of


Lactic acid Lactobacillus


Food and


Acetone and





-amylase Bacillus subtilis Starch hydrolysis Fermentor is the basic equipment used for fermentation.

contains the media to carry out fermentation, and creates environment for fermentation at large scale.

 Pure culture: organism, quantity, physiological state

 Sterilised medium: for microorganism growth

 Seed fermenter: inoculum to initiate process

 Production fermenter: large model

 Equipment

i) drawing the culture medium

ii) cell separation iii) collection of cell

iv) product purification v) effluent treatment.

II. Fermentation and Fermenting


A)Food Fermentation

The food is metabolized as a result of anaerobic fermentation which produces a mixture of organic wastes including organic acids (e.g. Formic acid, propionic acid, acetic acid and lactic acids).Intrinsic and extrinsic factors are critical to fermentation process.

Table 2.1 Major types of fermentation

via pyruvate as a key compound

1. Lactic acid homofermentation

2. Lactic acid heterofermentation

3. Propionic acid fermentation

4. Diacetyl and 2,3-Butylene glycol fermentation

5. Alcoholic fermentation

6. Butyric acid fermentation

Lactic acid homofermentation



Glucose Lactic acid

Lactic Acid Heterofermentation

C6H12O6 + H2O



Lactic acid Acetic acid Ethanol

Propionic Acid Fermentation


Glucose Lactic acid


Propionic acid Acetic acid

Diacetyl and 2,3 Butylene Glycol



Citric acid Pyruvic acid Acetylmethycarbinol




2,3 Butylene glycol

Alcoholic Fermentation

C6H12O6 2CH2H5OH +2CO2

Glucose Ethyl alcohol

Butyric Acid Fermentation



Lactic acid Acetic acid Butyric acid

Fermented Foods:An ancient Tradition

Human beings are known to have made fermented foods since Neolithic times. The earliest types were beer, wine, and leavened bread (made primarily by yeasts) and cheeses (made by bacteria and molds). These were soon followed by East Asian fermented foods, yogurt and other fermented milk products, pickles, sauerkraut, vinegar (soured wine), butter, and a host of traditional alcoholic beverages. More recently molds have been used in industrial fermentation to make vitamins B-2 (riboflavin) and B-12, textured protein products (from Fusarium and Rhizopus in Europe) antibiotics (such as penicillin), citric acid, and gluconic acid. Bacteria are now used to make the amino acids lysine and glutamic acid. Single-celled protein foods such as nutritional yeast and microalgae (spirulina, chlorella) are also made in modern industrial fermentations.

Fermentation is relatively efficient, low energy preservation process which increases the shelf life and decreases the need for refrigeration or other form of food preservation.

Factors Influencing Fermentation

• Temperature

• pH

• Nature and composition of medium

• Dissolved oxygen

• Dissolved carbon dioxide

• Operation system(batch,fed-batch,continuous)

• Feeding with precursors

• Mixing and shear rates in fermenter

Factors influencing fermentation may affect;

The rate of fermentation

The product spectrum and yield

The organoleptic properties of the product(appearance, taste, smell and texture)

The generation of toxins

Nutritional quality

Other physicochemical properties

Medium Formulation

The formulation of fermentation medium affects

The yield rate and product profile. The medium must provide the necessary amount of carbon,nitrogen ,trace elements and micronutrients(e.g. Vitamins for microorganisms)

Specific types of carbon and nitrogen sources may be required And carbon:nitrogen ratio may have to be controlled. Some trace elements may have to be avoided, for example minute amounts of iron reduce yields in citric acid production by A. niger.

Fermentation medium

• Define medium ; nutritional, hormonal, and substratum requirement of cells

• In most cases, the medium is independent of the bioreactor design and process parameters

• The type: complex and synthetic medium (mineral medium)

• Even small modifications in the medium could change cell line stability, product quality, yield, operational parameters, and downstream processing.

Medium composition

Fermentation medium consists of:

• Macronutrients (C, H, N, S, P, Mg sources water, sugars, lipid, amino acids, salt minerals)

• Micronutrients (trace elements/ metals, vitamins)

• Additional factors: growth factors, attachment proteins, transport proteins, etc) For aerobic culture, oxygen is sparged


Benefits of Fermenting Foods ( Dr. Çisem Bulut ALBAYRAK )

1.Improving Food Security

a) Food Preservation

b) Salvaging waste foods

c) Removal of anti-nutritional factors

d) Antimicrobial activities

Organic acids


Hydrogen peroxide



2.Increasing income and employment

3.Health benefits

a) İmproving nutrition

b) Vitamin

c) Digestibility

d) Lactose intolerance

e) Probiotics

f) Cholestrol

g) Anticancer effects

h) Stimulation of immunological system

ı) Medicinal benefits.

j) Other

4.Improving cultural and social well being

5.Malolactic fermentation

Siyah Sarımsak ( Selen AKAN )

Anahtar kelimeler: Siyah sarımsak, taze sarımsak, fermantasyon, besin, antioksidan, anti kanserojen

Keywords: Black garlic, raw garlic, fermentation, diet, antioxidant, anti-carcinogenic

Biyoteknolojik Yollarla Aroma Maddelerinin Üretimi ( Murat YILMAZTEKİN )


Dünya gıda katkı maddeleri pazarının % 25’ini oluşturan aroma maddeleri yıllık 7 milyar dolar civarında bir pazar  payına sahiptir. Aroma maddeleri önceden beri bitkilerden elde edilmiş, ancak bitkilerde düşük miktarlarda bulundukları için  saflaştırılmaları  zor  ve  pahalı  olmuştur.  Kimyasal  yolla  sentezlenen  sentetik  aroma  maddelerinin  üretimi  ucuzdur,  ancak  sağlık açısından zararlı etkileri ve tüketicilerde doğal ürünlere olan talebin artması nedeniyle tercih edilmemektedirler. Bu  nedenle,  son  dönemlerde  alternatif  olarak  biyoteknolojik  yöntemler  üzerinde  durulmaktad›r.  Bu  derlemede,  aroma  maddelerinin üretiminde kullanılan fermantasyon ve biyodönüşüm yöntemleri ile bu yöntemlerle vanilin, benzaldehit, lakton  ve ester aromalarının üretimi ele alınmıştır.

Anahtar kelimeler:  Biyoteknoloji, fermantasyon, biyodönüşüm, doğal aroma maddeleri


Flavour compounds represent 25 % of the total additives market on the world and have an annual value of  about 7 billion US dollars. For a long time, plants were the sole source of flavour compounds. However, they are often  present at low concentrations and thus their isolation is difficult and expensive. Even though, production of synthetic flavours   is  cheap,  they  do  not  prefered because  of  harmful  effects  to  the  health  and increasing  demand  to  natural  products  by  consumers. Therefore, in recent years an alternative route is the utilisation of biotechnological processes on the production  of flavour compounds. In this review, production of flavour compounds via fermentation and bioconversion techniques and   the production of vanillin, benzaldehyde, lactons and esters by these techniques were discussed.

Keywords :  Biotechnology, fermentation, bioconversion, natural flavour compounds

Malolactic and Other Fermentations

Webster defines fermentation as “a chemical change accompanied by effervescence.” Beginning winemakers often think the transformation of sugar into ethyl alcohol is the only fermentation process occurring in wine, but many other fermentations are possible in wine. Although the alcohol content and the high acidity makes wine a hostile environment for many microorganisms, several yeasts and

Kefir Kültürü ile Fermente Sucuk Üretimi ( Doktora Tezi – Beyza Hatice ULUSOY )


Ulusoy B. H. (2007). Kefir Kültürü ile Fermente Sucuk Üretimi. İstanbul Üniversitesi Sağlık Bilimleri Enstitüsü, Besin Hijyeni ve Teknolojisi ABD. Doktora Tezi. İstanbul. Bu çalışmada, fermente sucuk üretiminde, kefir kültürünün ve çeşitli oranlarda klasik sucuk kültürüyle kombinasyonun starter kültür olarak kullanılmasının mikrobiyolojik ve kalite yönünden uygunluğu araştırılmıştır. Bu amaçla, sucuk hamuru hazırlandıktanve 10’ar kg’lik gruplara ayrıldıktan sonra A (kültürsüz, kontrol), B (109 kob/ml’lik kefir kültürü stok solusyonundan 100 ml), C (109 kob/ml’lik sucuk kültürü stok solusyonundan 100 ml), D (Kefir kültürü stok solusyonundan 10 ml + sucuk kültürü stok solusyonundan 90 ml) ve E grubu (Kefir kültürü stok solusyonundan 90 ml + sucuk kültürü stok solusyonundan 10 ml) olmak üzere 5 gruba ayrılmıştır. Deneysel sucuk örneklerine 6 günlük olgunlaştırma ve 30 günlük +4˚ C’de muhafaza süresi boyunca mikrobiyolojik (toplam mezofil aerob bakteri, toplam aerob psikrofil bakteri, koliform ve Escherichia coli, sülfit indirgeyen anaerob bakteri, laktik asit bakterileri, Enterokoklar, stafilokok-mikrokok grubu bakteriler, Staphylococcus aureus, küf-maya sayımı), fiziko-kimyasal (pH, su aktivitesi, rutubet) ve duyusal analizler yapılmıştır. Elde edilen sonuçlara göre, fiziko-kimyasal analizlerden pH sonuçları, tüm grupların hamurlarında 5,80 civarında tespit edilirken, olgunlaşma dönemi boyunca pH düşmüş ve muhafaza sırasında gruplara göre değişen günlerde yükselmeye başlamıştır. Muhafazanın son gününde A grubu 5,55 ve diğer gruplar ise 5,18-5,26 arasında pH değerine sahip olmuştur. Deneysel sucuk gruplarının hamurlarında 0,97 civarında olan su aktivitesi değeri bütün gruplarda olgunlaştırma ve muhafaza dönemi boyunca düşüş göstermiş, 30. günün sonunda A grubunda 0,86 ve diğer gruplarda 0,85 civarında su aktivitesi değeri tespit edilmiştir. 30 günlük muhafaza sonunda A grubu % 37,0 rutubet oranına sahip olurken, B, C, D ve E gruplarında bu oran % 36 civarında tespit edilmiştir. Mikrobiyolojik analiz sonuçlarına göre, Staphylococcus aureus, Escherichia coli, sülfit indirgeyen anaerob bakteri ve koliform bakteriler gibi ürün hijyeni ve halk sağlığı açısından risk taşıyan bakterilerin kefirle üretilen sucuk gruplarında diğer gruplara kıyasla muhafazanın daha erken dönemlerinde inhibe olduğu tespit edilmiştir. Muhafazanın son gününde A, B, C, D ve E gruplarında küf-maya sayıları 5,30 ile 7,84 log10 kob/g arasında değişmiştir. Kefir kültürü ile üretilen fermente sucuklar, duyusal özellikler bakımından da panelistlerden beğeni toplamıştır. Sonuç olarak fermente sucuklara kefir kültürü ilavesi mikrobiyolojik kaliteyi olumlu yönde etkilerken tad ve aroma bakımından da kabul edilebilir düzeyde olduğu tespit edilmiştir.

Anahtar kelimeler: Kefir kültürü, fermente sucuk, starter kültür, fermentasyon

Bu çalışma, İstanbul Üniversitesi Araştırma Projeleri Yürütücü Sekreterliği (proje no:T-515 /21102004) ve TÜBİTAK (proje no: 105 O 691) tarafından desteklenmiştir.


Ulusoy B. H. (2007). Production of Fermented Sausage with Kefir Starter Culture. İstanbul University, Institute of Health Science, Department of Food Hygiene and Technology. Doctorate thesis . İstanbul. In this study, inoculation of kefir culture and its combinations were studied. After preparation of fermented sausage mixture, it was divided into 5 parts 10 kg dough and each part was inoculated with different ratio of kefir and classical fermented sausage culture and named as group A (no starter culture, control), group B (100 ml from kefir 9 culture stock solution with 10 cfu/ml viable cell), group C (100 ml from sausage 9 culture stock solution with 10 cfu/ml viable cell) group D (10 ml from kefir culture 9 stock solution with 10 cfu/ml viable cell+90 ml from sausage culture stock solution with 109 cfu/ml viable cell) and group E (90 ml from kefir culture stock solution with 9 9 10 cfu/ml viable cell+100 ml from sausage culture stock solution with 10 cfu/ml viable cell). Microbiological (total mesophyl aerob bacteria, total psycrophyl aerob bacteria, coliform ve Escherichia coli, sulfite reductating anaerob bacteria, lactic acid bacteria, enterococcus, micrococcus/staphylococcus, Staphylococcus aureus, yeast and mould), physico-chemical (pH, water activity, moisture) and sensorial analysis were performed during 6 days of ripening and 30 days of storage at +4˚ C. According to the results that obtained; pH of all groups were about 5,80 and decreased during ripening in all groups and started to increase at different days of storage. At the end of storage, ph values were 5,55 in group A and between 5,18-5,26 in the other groups. Water activity was about 0,97 in the dough of all groups and decreased to 0,85-0,86 at the end of storage. Moisture percentage of the experimental sausage dough was about 36-37% at the end of the storage period. According to the results of microbiological analysis it was seen that, the bacteria that concern public health such as Escherichia coli, coliform, sulfite reductating anaerob bacteria, Staphylococcus aureus were inhibited in the earlier stages of ripening or storage in the groups that inoculated kefir culture than the ones with no kefir. Yeast an mould counts of A, B, C, D ve E groups were changed amoung 5,30 and 7,84 log10 cfu/g. On the other hand, the groups with kefir culture were given higher scores than the other groups by panelists in the sensorial evaluation.

Key Words: Kefir cultur, fermented sausage, starter culture, fermentation

The present work was supported by the Research Fund of Istanbul University (Project No. T-515 /21102004) and TÜBİTAK (Project No. 105 O 691)