FE308- Fermentation Technology Spring Lecture 1-2 Basic Principles of Food Fermentations Lecturer:Dr. Çisem Bulut Albayrak

Transcription

1 FE308- Fermentation Technology Spring 2016 Lecture 1-2 Basic Principles of Food Fermentations Lecturer:Dr. Çisem Bulut Albayrak

2 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

3 fermentation, far from being a lifeless phenomenon, is a living process - Louis Pasteur

4 The Chemistry of Fermentation - Aerobic & Anaerobic Cellular Respiration - Glycolysis - Alcoholic Fermentation - Lactic Acid Fermentation

5 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: C 6 H 12 O 6 + 6O 2 -> 6CO 2 + 6H 2 O kj 3 stages: -glycolysis -citric acid cycle -electron transport chain

6 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.

7 But what happens when oxygen doesn't exist?

8 Anaerobic Cellular Respiration In anaerobic cellular respiration, the only step of this process that occurs is glycolysis.

9 What is fermentation? Derived from the Latin verb fervere meaning to boil

10 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.

11 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.

12 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.

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14 Microbial cell (Biomass) Microbial enzymes Microbial metabolites Food products Vitamins Yeast Glucose isomerase Penicillin Cheese, yoghurt, vinegar B12, riboflavin

15 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)

16 Products of Fermentation

17 Most commercially useful fermentations may be classified as Solid state fermentation Submerged fermentation

18 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 Glycerol Lactic acid Acetone and butanol Saccharomyces cerevisiae Saccharomyces cerevisiae Lactobacillus bulgaricus Clostridium acetobutylicum Industrial solvents, beverages Production of explosives Food and pharmaceutical Solvents -amylase Bacillus subtilis Starch hydrolysis 19

20 Fermentor is the basic equipment used for fermentation. contains the media to carry out fermentation, and creates environment for fermentation at large scale.

21 Pure culture: organism, quantity, physiological state Sterilised medium: for microorganism growth Seed fermenter: inoculum to initiate process Production fermenter: Equipment ii) cell separation iv) product purification large model i) drawing the culture medium iii) collection of cell v) effluent treatment.

22 II. Fermentation and Fermenting A)Food Fermentation Microorganisms 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.

23 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

24 Lactic acid homofermentation C 6 H 12 O 6 2CH 3 CHOHCOOH Glucose Lactic acid

25 Lactic Acid Heterofermentation C 6 H 12 O 6 + H 2 O Glucose 2CH 3 CHOHCOOH+CH 3 COOH+C 2 H 5 OH+2CO 2 +2H 2 Lactic acid Acetic acid Ethanol

26 Propionic Acid Fermentation C 6 H 12 O 6 2CH 3 CHOHCOOH Glucose Lactic acid 2CH 3 CH 2 COOH+CH 3 COOH Propionic acid Acetic acid

27 Diacetyl and 2,3 Butylene Glycol Fermentation CH 3 COCOCH 3 Diacetyl CH 2 COOHHOCOOH 2CH 3 COCOOH CH 3 COCHOHCH 3 +2CO 2 Citric acid Pyruvic acid Acetylmethycarbinol CH 3 CHOHCHOHCH 3 2,3 Butylene glycol

28 Alcoholic Fermentation C 6 H 12 O 6 2CH 2 H 5 OH +2CO 2 Glucose Ethyl alcohol

29 Butyric Acid Fermentation C 6 H 12 O 6 CH 3 COOH+ CH 3 CH 2 CH 2 COOH Lactic acid Acetic acid Butyric acid

30 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.

31 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.

32 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

33 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

34 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.

35 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.

36 Medium composition Fermentation medium consists of: Macronutrients (C, H, N, S, P, Mg sources sugars, lipid, amino acids, salt minerals) water, Micronutrients (trace elements/ metals, vitamins) Additional factors: growth factors, attachment proteins, transport proteins, etc) For aerobic culture, oxygen is sparged

37 End