Fermentation in Food Products
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Questions and Answers

What is the oldest known method of food preservation?

Fermentation

What does the fermentation process involve the breakdown of?

Carbohydrates (CHO)

What are some of the products produced by fermentation?

Acids, alcohols, aldehydes, ketones, and flavorings

Fermentation products help to preserve food against microbial degradation.

<p>True</p> Signup and view all the answers

What is a starter culture?

<p>A concentrated number of microorganisms desired to start the fermentation</p> Signup and view all the answers

What is glycolysis?

<p>The oxidation of glucose to generate pyruvate and energy</p> Signup and view all the answers

Which of these are industrial products produced by fermentation?

<p>Cheese, Sauerkraut, Yogurt, Pickles</p> Signup and view all the answers

The fermentation of glucose under anaerobic conditions produces ______ and carbon dioxide.

<p>ethanol</p> Signup and view all the answers

What is one benefit of fermentation in food production?

<p>Preservation due to acid production</p> Signup and view all the answers

Besides preservation, what other positive effects can fermentation have on food?

<p>Add flavors, change chemical properties, increase nutritional value, and make food easier to digest</p> Signup and view all the answers

How can we control the fermentation process?

<p>By controlling pH, salt content, and temperature</p> Signup and view all the answers

How does salt concentration in fermented vegetables affect the fermentation process?

<p>Salt concentration affects the types of bacteria that can survive and thrive.</p> Signup and view all the answers

What is the name given to salt in solution?

<p>Brine</p> Signup and view all the answers

Temperature is a crucial factor in the fermentation process.

<p>True</p> Signup and view all the answers

What types of microorganisms dominate the fermentation of sauerkraut?

<p>Three types of microorganisms</p> Signup and view all the answers

Starch and carbohydrates in vegetables are converted into ______ by lactic acid producing bacteria.

<p>lactic acid</p> Signup and view all the answers

What are the two types of lactic acid bacteria that are important in vegetable fermentation?

<p>Homofermentative and heterofermentative</p> Signup and view all the answers

What is a key step in preparing sauerkraut?

<p>Shredding the cabbage</p> Signup and view all the answers

What is the typical salt concentration used in sauerkraut?

<p>2.25%</p> Signup and view all the answers

What is the typical sugar concentration in sauerkraut?

<p>3-6%</p> Signup and view all the answers

What is the preferred temperature range for sauerkraut fermentation?

<p>18-22°C</p> Signup and view all the answers

Which lactic acid bacterium is initially responsible for converting sugar in sauerkraut to lactic acid?

<p>Leuconostoc mesenteroides</p> Signup and view all the answers

What is the final acidity level of sauerkraut?

<p>Not less than 1.5% (as lactic)</p> Signup and view all the answers

What is the primary difference between the fermentation of sauerkraut and brine-salted vegetables?

<p>Concentration of salt</p> Signup and view all the answers

What is the preferred salt concentration for brine-salted vegetables?

<p>15-20%</p> Signup and view all the answers

What is the minimum salt concentration required for brine-salted vegetables?

<p>12%</p> Signup and view all the answers

The fermentation process for brine-salted vegetables relies heavily on the fast colonization of lactic acid bacteria.

<p>True</p> Signup and view all the answers

How long does the fermentation process for brine-salted vegetables typically take?

<p>12 days at 30°C</p> Signup and view all the answers

What is the purpose of adding acetic acid to cucumbers during pickle fermentation?

<p>To contribute to the characteristic flavor</p> Signup and view all the answers

What is the typical salt concentration range used for pickle fermentation?

<p>11.25-15.90%</p> Signup and view all the answers

The same lactic acid bacteria used for sauerkraut fermentation are also used for pickle fermentation.

<p>True</p> Signup and view all the answers

What is the approximate final acidity level of pickles?

<p>0.6-1.2% (as lactic)</p> Signup and view all the answers

What is the first step in the process of fermenting olives?

<p>Soaking the olives in lye solution</p> Signup and view all the answers

What is the typical final acidity level of fermented olives?

<p>0.18-1.27% (as lactic)</p> Signup and view all the answers

What is the minimum acidity level required for olives to achieve a desirable flavor?

<p>0.6%</p> Signup and view all the answers

What is one of the advantages of fermenting vegetables?

<p>Extending the product shelf life</p> Signup and view all the answers

Fermented vegetables are generally easier to digest than non-fermented vegetables.

<p>True</p> Signup and view all the answers

Fermenting vegetables involves cooking them.

<p>False</p> Signup and view all the answers

What positive impact can fermentation have on the safety of vegetables?

<p>Makes the food safer to be consumed</p> Signup and view all the answers

Besides preservation and nutritional benefits, what is another advantage of fermenting vegetables?

<p>Add variety to table</p> Signup and view all the answers

What is the first step in making yogurt?

<p>Standardizing the milk to the correct solids content</p> Signup and view all the answers

What is the temperature used to heat the milk during yogurt production?

<p>90°C</p> Signup and view all the answers

What is the temperature used to cool the milk after heating during yogurt production?

<p>40-45°C</p> Signup and view all the answers

What are the two starter cultures used in yogurt production?

<p>Streptococcus thermophilus and Lactobacillus bulgaricus</p> Signup and view all the answers

What is the incubation temperature for yogurt fermentation?

<p>42°C</p> Signup and view all the answers

What temperature is used to stop the fermentation process in yogurt production?

<p>5-10°C</p> Signup and view all the answers

What is the typical final acidity level of yogurt?

<p>0.9-1.2% (as lactic)</p> Signup and view all the answers

What is the approximate pH level of yogurt?

<p>4.4</p> Signup and view all the answers

What are the two starter cultures used in the production of Swiss cheese?

<p>Regular lactic culture plus propionic acid bacteria (Propionibacterium sp) and Streptococcus thermophilus</p> Signup and view all the answers

What is the key starter culture used in the production of blue-veined cheese?

<p>Regular lactic culture plus dried spores of the mold, Penicillium roqueforti</p> Signup and view all the answers

What are the two major categories of Italian cheese?

<p>Soft, unripened cheese and hard cheeses</p> Signup and view all the answers

What are the starter cultures used in the production of Italian cheese?

<p>Regular lactic culture plus S. thermophilus and L bulgaricus</p> Signup and view all the answers

What is the most common type of Latin American white cheese?

<p>Queso Blanco</p> Signup and view all the answers

What alternative methods are used to form curds in Latin American white cheese?

<p>Natural microflora or organic acids (vinegar, lemon juice, or glacial acetic acid) in conjunction with rennet</p> Signup and view all the answers

How is vinegar produced?

<p>By an alcoholic fermentation followed by oxidation of the alcohol to acetic acid</p> Signup and view all the answers

Vinegar can be produced only from grapes.

<p>False</p> Signup and view all the answers

What are the two types of microorganisms primarily involved in bread making?

<p>Yeast and bacteria</p> Signup and view all the answers

Which type of yeast is commonly used to leaven bread?

<p>Saccharomyces cerevisiae</p> Signup and view all the answers

What is the primary function of yeast in bread making?

<p>To perform the leavening function by producing carbon dioxide</p> Signup and view all the answers

What are some of the additional benefits of yeast in bread making?

<p>Yeast also produces flavor compounds, changes dough physical properties, develops structure and texture, and enhances nutritive value.</p> Signup and view all the answers

Specifically, what type of bacteria is mainly involved in bread making?

<p>Lactic acid bacteria, specifically Leuconostoc mesenteroides</p> Signup and view all the answers

What are the two main functions of lactic acid bacteria in bread making?

<p>Produce lactic acid and flavor compounds</p> Signup and view all the answers

What is dough conditioning?

<p>Improving dough characteristics (quality)</p> Signup and view all the answers

What is the primary factor that contributes to dough conditioning during fermentation?

<p>The action of proteolytic enzymes and low pH.</p> Signup and view all the answers

Why and how does dough conditioning shorten kneading time?

<p>The enzymes and low pH soften the dough, requiring less effort and time for kneading</p> Signup and view all the answers

What is one type of dough conditioner?

<p>Ammonium salt, such as ammonium sulfate</p> Signup and view all the answers

What is another type of dough conditioner?

<p>Sugars</p> Signup and view all the answers

Gas production during the formation of dough is increased with an increase in yeast activity.

<p>True</p> Signup and view all the answers

What else, besides yeast activity, can increase the level of gas production in dough?

<p>Adding sugars and amylase.</p> Signup and view all the answers

What factors can decrease gas production in dough?

<p>Low amount of yeast, high and low temperatures, and salt addition</p> Signup and view all the answers

What is the flesh (muscle tissue) of warm-blooded animals called?

<p>Meat</p> Signup and view all the answers

Fermented specialties from poultry are not available.

<p>False</p> Signup and view all the answers

What is the defining characteristic of a fermented sausage?

<p>A pH below 5.6 and a D-lactic acid content above 0.2%</p> Signup and view all the answers

In addition to pH and lactic acid content, what other characteristics define a fermented sausage?

<p>Heat-stable color, crumbly texture is no longer present, a typical aroma, lactic acid bacteria predominate and Enterobacteriaceae counts are low.</p> Signup and view all the answers

Match the different categories of fermented sausages with their key characteristics and examples.

<p>Dry, mould-ripened = Ripening times &lt;4 weeks, final water activity &lt;0.90, smoke application during fermentation, genuine Hungarian salami Dry, no mould growth = Ripening times &lt;4 weeks, final water activity &lt;0.90, smoke application yes or no, German katenrauch, auerwurst Semi-dry mould-ripened = Ripening times &lt;4 weeks, final water activity 0.90-0.95, no smoke application, Various French and Spanish raw sausages Semi-dry, no mould growth = Ripening times &lt;4 weeks, final water activity 0.90-0.95, smoke application yes with exception, Most fermented sausages in Germany, The Netherlands, Scandinavia, USA etc Undried, spread-able = Ripening times 2 days to 2 weeks, final water activity 0.94-0.97, smoke application yes or no, German, Mettwurst Teewurst, Spanish, Sobrasada</p> Signup and view all the answers

What are the two main types of fermentation processes?

<p>Foods from a comminuted matrix and whole meat products.</p> Signup and view all the answers

What are the key variables that affect the fermentation of a comminuted meat matrix?

<p>Particle size, selection of additives, temperature/humidity, diameter of the sausages, casings used for smoking, heating after fermentation, antifungal preparations, and pH.</p> Signup and view all the answers

What is the typical particle size range for the meat and fatty tissue used in comminuted sausage production?

<p>1 to 30mm</p> Signup and view all the answers

What are some examples of additives used in sausage production?

<p>Curing salt, nitrate, ascorbic acid, sodium glutamate, and glucono-δ-lactone</p> Signup and view all the answers

What is the typical temperature range used during the fermentation of sausage?

<p>20°C to 28°C</p> Signup and view all the answers

What are the three main types of microorganisms used in meat starter cultures?

<p>Bacteria, fungi, and yeasts</p> Signup and view all the answers

What is one example of a lactic acid bacteria commonly used in meat starter cultures?

<p>Lactobacillus acidophilus.</p> Signup and view all the answers

What is one example of a fungi commonly used in meat starter cultures?

<p>Penicillium camemberti</p> Signup and view all the answers

What is one example of a yeast commonly used in meat starter cultures?

<p>Debaryomyces hansenii</p> Signup and view all the answers

What is a key benefit of using probiotic bacteria in sausage production?

<p>Probiotic bacteria support survival and metabolic activity in the intestinal tract.</p> Signup and view all the answers

What are two examples of probiotic strains that have been used in sausage production?

<p>Lactobacilli and bifidobacteria</p> Signup and view all the answers

What specific lactic acid bacteria is used for the production of moist-type fermented sausages?

<p>Lactobacillus paracasei</p> Signup and view all the answers

What are some of the factors that can damage or kill probiotic bacteria in sausages?

<p>Large reduction of pH, extended ripening, drying, and excessive heating.</p> Signup and view all the answers

Study Notes

Fermentation in Food Products

  • Fermentation is the oldest food preservation method.
  • Fermentation involves the breakdown of carbohydrates (CHO) by bacteria and yeast. This produces acids, alcohols, and some flavor compounds. The process occurs under anaerobic (no oxygen) conditions.
  • Fermentation preserves food by preventing microbial degradation.
  • Starter cultures are concentrated organisms used to initiate fermentation. These cultures contain specific organisms needed for the desired fermentation process.

Fermentation Process

  • Glycolysis is the oxidation of glucose to create pyruvate and energy. This is a key step in many fermentations.
  • Fermentation processes use various microorganisms, including Saccharomyces (yeast), Lactobacillus, and Clostridium.
  • Fermentation produces different products depending on the specific microorganisms present. Products can include lactic acid, ethanol, carbon dioxide, butanol, acetone, etc.
  • These products can be used in industrial processes to create various goods such as wine, beer, fuel, and pharmaceuticals.

Benefits of Fermentation

  • Fermentation produces acids, like lactic acid, which preserves food.
  • Fermentation adds desirable flavors. (Soy sauce is an example.)
  • Fermentation changes food's chemical properties, like converting sugars to alcohol and then to acetic acid.
  • Fermented foods can be more nutritious due to vitamins produced by fermentation microorganisms.
  • Fermentation can break down complex molecules (like cellulose) into simpler, more digestible sugars.

Controlling Fermentation

  • pH: Adding or increasing acid helps prevent undesired microorganisms from growing.
  • Salt: Salt tolerance varies. Lactic acid bacteria often tolerate higher salt concentrations than other microorganisms.
  • Temperature: Different microorganisms thrive at different temperatures. The optimal temperature impacts the outcome of the fermentation process. Brine (salt water) is used as a preservation method in many processes to prevent the growth of microorganisms that do not grow as well in high salt concentrations..

Uses of Fermentation

  • Various foods are produced using fermentation, including vegetables (like sauerkraut and pickles), fruits, dairy products (like yogurt), and meats (like sausages).

Vegetable Fermentation

  • Starch and CHO in vegetables are converted into lactic acid by lactic acid bacteria present on the surface of the vegetables.
  • Some lactobacilli are homo-fermentative leading to the production of 2 moles of lactic acid, while others are hetero-fermentative producing a combination of lactic acid, ethanol, and carbon dioxide.
  • Sauerkraut production involves washing and shredding cabbage, then adding salt and brine. The amount of sugar in the brine affects the final acidity. Optimal temperatures are typically around 18-22°C.
  • Types of lactic bacteria involved vary but can include Leuconostoc mesenteroides, Lactobacillus brevis and Pediococcus cerevisiae, and Lactobacillus plantarum. The fermentation process develops acidity and flavor.

Brine-Salted Vegetables

  • These processes resemble sauerkraut fermentation using brine (salt solution) to preserve vegetables.
  • Salt concentrations generally range from 15-20%, but the lowest concentration must remain at 12% to allow the intended microorganisms to grow well.
  • The fermentation process for these typically takes about 12 days at 30°C, with the salt being the primary preservative in this case (not lactic acid.)

Cucumber Pickles

  • Fresh cucumbers are used and are packed with acetic acid (0.6%).
  • Spices add flavor.
  • The salt concentration ranges from 11.25% to 15.90%.
  • Microorganisms are lactic bacteria (similar to sauerkraut).
  • The final acidity level is typically between 0.6% and 1.2% (as lactic acid) and takes about 7-14 days to develop.

Olives

  • Olives are brined similarly to cucumbers.
  • Olives are initially soaked in a 1.25%-2.0% lye solution to remove their bitter taste.
  • Lactic bacteria are used.
  • The final acidity is 0.18%-1.27% and needs to reach a minimum of 0.6% for optimal flavor.

Advantages of Vegetable Fermentation

  • Extended shelf life (preservation).
  • Easier digestion.
  • More nutritious because the process doesn’t involve cooking.
  • Safer to eat.
  • Adds variety to food options.

Yogurt

  • Milk is standardized (10.5-11.5% solids), heated (90°C), then cooled (40-45°C).
  • Mixed culture of Streptococcus thermophilus and Lactobacillus bulgaricus is introduced.
  • The inoculated milk is incubated at 42°C for 3-6 hours.
  • The milk is cooled to 5-10°C to stop fermentation.
  • Final acidity is 0.9-1.2% (as lactic acid), with a pH of about 4.4.

Swiss Cheese

  • Starter culture combines regular lactic culture with propionic acid bacteria (Propionibacterium sp.) and Streptococcus thermophilus.

Blue-Veined Cheese

  • Starter culture is regular lactic culture plus dried spores of the mold, Penicillium roqueforti.

Italian Cheese

  • Includes mozzarella, Romano, Provolone, and Parmesan (Grana).
  • Starter cultures typically use Streptococcus thermophilus and Lactobacillus bulgaricus.

Latin American White Cheese

  • Queso Blanco is the most common unripened, soft cheese.
  • Natural microflora or organic acids (vinegar, lemon juice, or glacial acetic acid) can be used for curd formation along with rennet in some cases.

Vinegar

  • Vinegar is made through alcoholic fermentation followed by oxidation of the alcohol to acetic acid.
  • Yeast ferments food into ethanol.
  • Air and Acetobacter bacteria are added to the ethanol to produce acetic acid.

Bread Making

  • Fermentation in bread involves yeast (Saccharomyces cerevisiae).
  • Yeast produces carbon dioxide, which makes the dough rise.
  • Bacteria can also play a role, primarily in flavor development. Leuconostoc mesenteroids are one example of such a type of bacteria present in bread.
  • Chemical changes in the dough help provide volume, structure, and texture, as well as impacting flavor.
  • Dough conditioners like ammonium sulfate and sugars are added to stimulate yeast.
  • Gas production is affected by yeast activity, sugar, amylase, temperature, and salt levels.

Fermented Meat

  • Fermented meat generally has a pH below 5.6 and high D-lactic acid.
  • Meat products (e.g., sausages) can be fermented, with a range of types using various processes and levels of ripening.
  • Fermented meats utilize a variety of LAB types.
  • Various methods are used, with different levels of ripening and moisture that impact the final product and flavors.
  • Fermentation processes can also affect and reduce food poisoning risks through lactic acid production and low moisture levels, particularly with some types of bacteria.

Fermentation of a Comminuted Meat Matrix

  • Particle size, additives (salt, nitrate, ascorbic acid, glucono-d-lactone), temperature, humidity, sausage diameter, casings, and heating/antifungal dipping play a role during production.

Fermentation of Whole Meat Products (e.g., ham)

  • Curing by salting is a primary method, possibly along with nitrite and/or nitrate.
  • Salt diffusion is assisted/increased by low temperatures.
  • The process helps prevent Clostridium botulinum contamination.
  • After salt and flavor development, the temperature is increased to aid ripening.
  • Ripening time is often 6-18 months.

Composition Changes During Fermentation

  • Microorganisms (LAB) cause acidification.
  • Nitrates can be reduced to nitrites and nitrosomyoglobin.
  • Proteins and lipids are degraded, and dehydration occurs.

Acidification, Dehydration, Microbial Antagonism

  • Protein isoelectric points (pH 5.3-5.4) are affected.
  • Salt strength is increased, with lactic acid and sodium chloride contributing to the taste profiles.
  • Acidification and drying inhibit pathogens.
  • Lactic and acetic acids are key fermentation products, influencing moisture and flavor development.
  • Various properties are influenced by the ripening process and the level of salt and moisture in the finished product.

Proteolytic and Lipolytic Degradation During Fermentation

  • Accumulation of peptides and amino acids (about 1% of dry matter).
  • These peptides and amino acids can affect flavor.
  • Excess proteolysis can lead to bitter off-flavors.
  • Amino acids and peptides are used by microorganisms creating some flavor characteristics
  • Fat content can range from 40-60% dry matter.
  • Fatty acids are released from triglycerides and phospholipids.
  • Free fatty acids constitute about 5% in most fermented products, including meat products.
  • Polyunsaturated fatty acids tend to exceed saturated fatty acids.

Generation of Flavor Volatiles

  • Lipolysis and hydrolysis of phospholipids followed by fatty acid oxidation are common pathways.
  • Microorganisms produce organic acids and modify the products for flavor development (by producing certain alcohols, aldehydes, and other substances).
  • Flavor is also affected by additions like spices, smoking, or ripening with yeasts or molds.

Mechanisms for Generation Flavor Compounds

  • Carbohydrates, proteins, fats, peptides, and amino acids contribute to flavor in different ways.
  • Taste compounds are affected by bacteria and other microorganisms.
  • Flavor compounds can develop through microbial actions, or as a result of additions such as smoking or spices.

Product Diversity and Sensory Properties

  • Lactic acid production, breakdown of lipids, and degradation of peptides/amino acids influence the flavor/taste profile of fermented meats.
  • Oxygen consumption, nitrate reduction, and protein degradation by microorganisms, also effect.

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