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
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.
Prof. Dr. Adem ELGÜN
Selçuk Üniversitesi, Ziraat Fakültesi, Gıda Mühendisliği Bölümü Emekli Öğretim Üyesi, Konya aelgun@selcuk.edu.tr
Özet
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.
Abstract
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.
“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.
Definition
• 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.
• 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
cerevisiae
Industrial solvents,
beverages
Glycerol Saccharomyces
cerevisiae
Production of
explosives
Lactic acid Lactobacillus
bulgaricus
Food and
pharmaceutical
Acetone and
butanol
Clostridium
acetobutylicum
Solvents
-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
Microorganisms
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
C6H12O6
2CH3CHOHCOOH
Glucose Lactic acid
Lactic Acid Heterofermentation
C6H12O6 + H2O
Glucose
2CH3CHOHCOOH+CH3COOH+C2H5OH+2CO2 +2H2
Lactic acid Acetic acid Ethanol
Propionic Acid Fermentation
C6H12O6 2CH3CHOHCOOH
Glucose Lactic acid
2CH3CH2COOH+CH3COOH
Propionic acid Acetic acid
Diacetyl and 2,3 Butylene Glycol
Fermentation
CH2COOHHOCOOH 2CH3COCOOH CH3COCHOHCH3+2CO2
Citric acid Pyruvic acid Acetylmethycarbinol
CH3COCOCH3
Diacetyl
CH3CHOHCHOHCH3
2,3 Butylene glycol
Alcoholic Fermentation
C6H12O6 2CH2H5OH +2CO2
Glucose Ethyl alcohol
Butyric Acid Fermentation
C6H12O6
CH3COOH+ CH3CH2CH2COOH
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)
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
ABSTRACT:
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.
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
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.
Bu çalışma, İstanbul Üniversitesi Araştırma Projeleri Yürütücü Sekreterliği (proje no:T-515 /21102004) ve TÜBİTAK (proje no: 105 O 691) tarafından desteklenmiştir.
ABSTRACT
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.
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