KBP Fermented Food Products

Fermented Food Products

Products from Microorganisms

Food and food related products

• Whole cells products 
• Cheese and yogurt
• Fermented fruits and vegetables 
• Organic acids
• Alcoholic beverages
• Flavoring agents: amino acids and nucleotides

Non-food products

• Enzyme
• Vitamins
• Antibiotics
• Biotech drugs

Fermented Foods

• Foods that have been subjected to the action of micro-organisms or enzymes, in order to bring about a desirable change. 
• Numerous food products owe their production and characteristics to the fermentative activities of microorganisms. 
• Fermented foods originated many thousands of years ago when presumably micro-organism contaminated local foods.
• Micro-organisms cause changes in the foods which:

–Help to preserve the food,

–Extend shelf-life considerably over that of the raw materials from which they are made,

–Improve aroma and flavour characteristics,

–Increase its  vitamin content or its digestibility compared to the raw materials.

ISTN Snack Bar

 

What are fermented foods?

Foods or food ingredients that rely on microbial growth as part of their processing or production

Food Fermentation

•Metabolic activities occur during fermentation that:

–Extend shelf life by producing acids

–Change flavor and texture by producing certain compounds such as alcohol

–Improve the nutritive value of the product by:

•Microorganisms can synthesize vitamins

•Breakdown indigestible materials to release nutrients, 

 i.e., bound nutrients 

Fermented Foods

 

•Foods fermented by yeast

–MaltàBeer

–Fruit (grapes) à Wine

–Rice à Saki

–Bread dough à Bread

•Foods fermented by mold

–Soybeans à Soy sauce

–Cheese à Swiss cheese

•Foods fermented by bacteria

–Cucumbers à Dill pickles

–Cabbage à Sauerkraut

–Cream à Sour cream

–Milk à  Yogurt

Food Fermentations – Definition
•Anaerobic breakdown of an organic substrate by an enzyme system in which the final hydrogen acceptor is an organic compound

–Example:

•Biological processes that occur in the dark and that do not involve respiratory chains with oxygen or nitrate as electron acceptors


Food Fermentations – Biochemistry

Sugars … Acids … Alcohols, Aldehydes

Proteins … Amino acids … Alcohols, Aldehydes

Lipids … Free fatty acids … Ketones

Table 1  History and origins of some fermented foods
Food	Approximate year of introduction	Region
Mushrooms	4000 BC	China
Soy sauce	3000 BC	China, Korea, Japan
Wine	3000 BC	North Africa, Europe
Fermented milk	3000 BC	Middle East
Cheese	2000 BC	Middle East
Beer	2000 BC	North Africa, China
Bread	1500 BC	Egypt, Europe
Fermented Meats	1500 BC	Middle East
Sourdough bread	1000 BC	Europe
Fish sauce	1000 BC	Southeast Asia, North Africa
Pickled vegetables	1000 BC	China, Europe
Tea	200 BC	China

Fermented Foods

•The term “biological ennoblement” has been used to describe the nutritional benefits of fermented foods.

•Fermented foods comprise about one-third of the world wide consumption of food and 20- 40 % (by weight) of individual diets.

 

Table 2   Worldwide production of some fermented foods
Food	Quantity (t)	Beverage	Quantity (hl)
Cheese	15 million	Beer	1000 million
Yoghurt	3 million	Wine	350 million
Mushrooms	1.5 million
Fish sauce	300 000
Dried stockfish	250 000

Table 3   Individual consumption of some fermented foods: average per person per year
Food	Country	Annual consumption
Beer (I)	Germany	130
Wine (I)	Italy, Portugal	90
	Argentina	70
Yoghurt (I)	Finland	40
	Netherlands	25
Kimchi (kg)	Korea	22
Tempeh (kg)	Indonesia	18
Soy sauce (I)	Japan	10
Cheese (kg)	UK	10
Miso (kg)	Japan	7

Table 4   Benefits of fermentation
Benefit	Raw material	Fermented food
Preservation	Milk	Yoghurt, cheese
	(Most materials
Enhancement of safety
Acid production	Fruit	Vinegar
Acid and alcohol production	Barley	Beer
	Grapes	Wine
Production of bacteriocins	Meat	Salami
Removal of toxic components	Cassava	Gari, polviho azedo
	Soybean	Soy sauce
Enhancement of nutritional value
Improved digestibility	Wheat	Bread
Retention of micronutrients	Leafy veges.	Kimchi, sauerkraut
Increased fibre content	Coconut	Nata de coco
Synthesis of probiotic compounds	Milk	Bifidus milk, Yakult,
		Acidophilus yoghurt
Improvement of flavour	Coffee beans	Coffee
	Grapes	Wine

Cassava

•Fresh cassava contains cyanhydric acid (HCN) that should be eliminated from any product originating from cassava to render it fit for human consumption. Depending on the production method (particularly traditional methods) gari could contains up to 20 mg / kg of HCN - against 43 mg / kg for fresh peeled cassava.

•Gari is a fermented, gelled and dehydrated food produced from fresh cassava. It is a popular diet in Nigeria, Benin, Togo, Ghana and in other West Africa's countries. The consumption area even expands to Central Africa: Gabon, Cameroon, Congo Brazzaville and Angola.

•Polvilho is a fine tapioca/manioc/cassava flour. it can be found at latino markets in california as "sour starch" (polvilho azedo) or "sweet starch" (polvilho doce)

Nata de Coco

•A high fiber, zero fat Philippino dessert.

•A chewy, translucent, jelly-like food product produced by the bacterial fermentation of coconut milk. 

•Commonly sweetened as a candy or dessert, and can accompany many things including pickles, drinks, ice cream, and fruit mixes.

•Highly regarded for its high dietary fiber, and its zero fat and cholesterol content. 

•It is produced through a series of steps ranging from milk extraction, mixing, fermentation, separating, cleaning, cutting to packaging.


Lactic Acid Bacteria 

•Major group of Fermentative organisms. 

•This group is comprised of 11 genera of gram-positive bacteria: 

•Carnobacterium, Oenococcus, Enterococcus, Pediococcus, Lactococcus, Streptococcus, Lactobacillus, Vagococcus, Lactosphaera, Weissells and Lecconostoc 

•Related to this group are genera such as Aerococcus, Microbacterium, and Propionbacterium. 

•While this is a loosely defined group with no precise boundaries all members share the property of producing lactic acid from hexoses. 

•As fermenting organisms, they lack functional heme-linked electron transport systems or cytochromes, they do not have a functional Krebs cycle. 

•Energy is obtained by substrate-level phosphorylation while oxidising carbohydrates. 

•The lactic acid bacteria can be divided into two groups based on the end products of glucose metabolism. 

•Those that produce lactic acid as the major or sole product of glucose fermentation are designated homofermentative. 

•Those that produce equal amounts of lactic acid, ethanol and CO2 are termed heterofermentative. 

•The homolactics are able to extract about twice as much energy from a given quantity of glucose as the heterolactics. 

•All members of Pediococcus, Lactococcus, Streptococcus, Vagococcus, along with some lactobacilli are homofermenters. 

•Carnobacterium, Oenococcus, Enterococcus, Lactosphaera, Weissells and Lecconostoc and some Lactobacilli are heterofermenters.

•The heterolactics are more important than the homolactics in producing flavour and aroma components such as acetylaldehyde and diacetyl.


Lactic Acid Bacteria - Growth

•The lactic acid bacteria are mesophiles:

–they generally grow over a temperature range of about 10 to 40oC,

–an optimum between 25 and 35oC.

–Some can grow below 5 and as high as 45 oC. 

•Most can grow in the pH range from 4 to 8.  Though some as low as 3.2 and as high as 9.6.

Starter Cultures
•Traditionally the fermenting organisms came from the natural microflora or a portion of the previous fermentation. 

•In many cases the natural microflora is either inefficient, uncontrollable, and unpredictable, or is destroyed during preparation of the sample prior to fermentation (eg pasteurisation). 

•A starter culture can provide particular characteristics in a more controlled and predictable fermentation. 

•Lactic starters always include bacteria that convert sugars to lactic acid, usually:

– Lactococcus lactis subsp. lactis,

–Lactococcus lactis subsp. cremoris or

–Lactococccus lactis subsp. lactis biovar diacetylactis.

• Where flavour and aroma compounds such as diacetyl are desired the lactic acid starter will include heterofermentative organisms such as:

– Leuconostoc citrovorum or

–Leuconostoc dextranicum.

•The primary function of lactic starters is the production of lactic acid from sugars 

• Other functions of starter cultures may include the following:

•flavour, aroma, and alcohol production

•proteolytic and lipolytic activities

•inhibition of undesirable organisms

 

A good starter CULTURE  will:

•Convert most of the sugars to lactic acid 

•Increase the lactic acid concentration to 0.8 to 1.2 % (Titratable acidity) 

•Drop the pH to between 4.3 to 4.5 

•Food scientists frequently use the ability of bacterial cells to grow and form colonies on solid media to:

–isolate bacteria from foods,

–to determine what types and

–how many bacteria are present.

•  Streak plates
 
                                                      A single bacterial colony






The streak plate technique

•Bacteria are “streaked”over the surface of an agar plate so as to obtain single colonies. 

•Obtaining single colonies is important as it enables;

– the size,

–shape and

–colour of the individual colonies to be examined. 

–It can also highlight the presence of contaminating micro-organisms

 

When conditions are right bacteria can double in number every 20 minutes

"I wish you'd learn to put the lid on your Petri dish, Harry..!!  We came here with four kids, and now it looks like we've got twenty million...!!"

Microscopic examination

•Can provide information on the size and shape of the bacteria

–Rods (1)

–Cocci (2)

–Spiral (3)

•It cannot provide enough information to enable bacteria to be identified

Microscopic views of stained bacteria

What is Yogurt 

A semi-solid casein gel formed by the action of specific lactic acid bacteria on milk

Fermented milk

 

Microbes used in Yoghurt Involved

• ØLactobacillus bulgaricus and/or acidophilus 
• ØStreptococcus thermophilus

They work better together than they do separately because…. 

• ØAcid production rate is much higher
• ØFormation of typical yogurt flavour and texture

 

Ingredients and Function 

• ØLactose is partial converted to lactic acid, which  makes digestion easier for lactose-intolerant people.  
• ØContaining higher amino acid than milk. 
• ØLactic acid causes the milk proteins (casein) to coagulate into a semisolid curd and also restricts spoilage bacteria. 
• ØFreshly prepared yogurt contains 10,000,000,000 (109) bactria per gram.

Main Families of Lactic Bacteria

Yogurt Production

Milk Selection==>Dry Matter Standardization==>Homogenization==>Heat Treatment (Deaeration, terilization, Denaturing protein)==>Cooling to 42-45℃==>Inoculation

Yogurt variations 

1. Set yogurt ：pouring the inoculated milk into pots and fermenting it, normally consumed by use of a spoon or sold into customers’ containers. 
2. Stirred yogurt:  fermented in bulk, stirred and then dispensed into pots.

Two types of yogurt

Inoculation
1. Flavoring, Fill Retail Container, Ferment, Cool/Store ==> Set yogurt
2. Ferment, Break, Stir/Cool, Fill ==> Stirred yogurt

 thickened milk
heat 65 C to kill dengerous microbes
add streptococus thermophilus Produces lactic acid
add lactococcus bulgarius flavour and aroma
ferment at 45 C for several hours
yogurt

Cone Bottom Processor

Basic Cheese-making Steps

1. Collect/deliver milk
2. Pasteurize milk
3. Add starter culture
4. Add rennet and CaCl2
5. Cut the curd and Heat
6. Separate curd from whey
7. Salt the curd (dry salt)
8. Package and ripen cheese