three types of food fermentation
DESCRIPTION
THREE TYPES OF FOOD FERMENTATION. Alcohol Acetic Acid Lactic Acid - Largest of all Homofermentative Heterofermentative. Bacteria lactic acid bacteria acetic acid bacteria food bioprocessing food biopreservation Probiotic. FOOD FERMENTATIONS. Lactic Acid Bacteria Vegetables and Fruits. - PowerPoint PPT PresentationTRANSCRIPT
THREE TYPES OF FOOD FERMENTATION
•Alcohol•Acetic Acid•Lactic Acid - Largest of all
– Homofermentative– Heterofermentative
Bacteria
lactic acid bacteriaacetic acid bacteria
food bioprocessingfood biopreservation
Probiotic
FOOD FERMENTATIONS
Lactic Acid Bacteria– Vegetables and Fruits
SWEET PICKLES
Lactobacillus helveticus Lactobacillus delbrueckii sub. bulgaricus
Lactobacillus lactis
Fermented Milks
• majority of fermented milk products rely on lactic acid bacteria belonging to the genera Lactobacillus, Lactococcus, Leuconostoc, and Streptococcus– gram-positives that tolerate acidic
conditions, are non-spore forming, and are aerotolerant with a strictly fermentative metabolism
Fermented Milks…• mesophilic
– Lactobacillus and Lactococcus– buttermilk and sour cream
• thermophilic – Lactobacillus and Streptococcus– yogurt
• probiotics– Lactobacillus and Bifidobacterium– addition of microbes to the diet to improve
health beyond basic nutritive value
FOOD FERMENTATIONS
Lactic Acid Bacteria– Meats
FOOD FERMENTATIONS
Lactic Acid Bacteria– Dairy Products
FOOD FERMENTATIONS
Lactic acid with other microbesDairy Products
• With other bacteria• With yeasts• With molds
Vegetable Products
Lactic acid bacteria (LAB)
• G+, non-spore forming cocci or rods• Microaerophilic or anaerobic• Metabolize carbohydrates through
fermentative pathways– Acid production as the major end-product
• Common genera– Lactococcus, Lactobacillus, Leuconostoc,
Pediococcus, Streptococcus, Oenococcus
Lactic Acid BacteriaLactic Acid Bacteria
• Gram (+) rods (Lactobacillus) and cocci (Streptococcus, Lactococcus, Leuconostoc)
• Produce large amount of lactic acid• Aerotolerant anaerobes: grow
fermentatively• Require many growth factors (vitamins
and amino acids)• Found in nutrient-rich environments
(decomposition)
Lactic Acid BacteriaLactic Acid Bacteria
• Used to ferment or culture foods for 4000 years• Used in fermenting yogurt, cheese, butter, kefir
and in pickling vegetables• Lactose (milk sugar) converted to lactic acid; low
pH precipitates protein, causing curdling• Low pH also inhibits growth of other bacteria• Give tart taste to fermented milks• Growth is self-limiting (build up of waste products)• Used in probiotics (presence in livestock feed
inhibits E. coli)• Also produce bacteriocins (antimicrobial agents)
Lactic Acid BacteriaLactic Acid Bacteria
• Produce large amount of lactic acid, lowering pH
• Can grow at < pH 5• Predominate in acidic environment if
it:– Is anaerobic– Is rich in nutrients– Contains a fermentable carbohydrate
Lactic Acid Bacteria: Divisions
• Group I: Strict homofermenters
• Group II: Facultative heterofermenters
• Group III: Strict heterofermenters
Homofermentative Metabolism
85% of Glucose Lactic acid
Glucose Pyruvate via glycolytic pathway
HO-C-C-CH3 Pyruvate
HO-C-CH-CH3 Lactate
O O
O OH
NADH2
NAD+
Heterofermentative Metabolism
Organisms metabolize glucose via the pentose phosphate pathway.
End products can vary depending upon level of aeration and presence of other proton and electron acceptors. Acetyl-phosphate can be converted to acetate and ATP or reduced to ethanol without ATP production.
Pentose Phosphate Pathway
Lactic Acid Bacteria can also metabolize pentoses such as ribose, arabinose and xylose, via the pentose phosphate pathway.
Acetyl-phosphate leads to the generation of acetate and ATP exclusively in pentose metabolism.
Pentose Phosphate Pathway
Glucose Phospho-6-gluconate
Ribulose 5-phosphate
Xylulose 5-phosphate
CO2
Glyceraldehyde 3- phosphate
Pyruate
Lactate
Acetyl-phosphate
Acetate Acetaldehyde
Ethanol
(glycolysis)
NADP+
NADPH
NADP+
NADPH
NADH
NAD+
NADH
NAD+ADP
ATP
ADP
ATP
ATP ADP
Lactic Acid Bacteria: Genera
• Oenococcus
• Pediococcus
• Lactobacillus
• Leuconostoc
Lactobacillus
Homolactic on hexoses
• L. bavaricus• L. casei• L. homohoichii• L. curvatus• L. saki• L. plantarum
Heterolactic on hexoses
• L. fermentum• L. brevis• L. buchneri• L. fructovorans• L. hilgardii
Bacteriocins
• Antimicrobial peptides produced by some bacteria that inhibit closely related species
• Membrane-active agents that form pores in cytoplasmic membrane and dissipate proton-motive force
• Significant in food safety to control pathogens– Lactococcus lactis subsp. lactis and NISIN
Nisin
• Class I bacteriocin: lantibiotic, <5 KDa
• Producer: Lactococcus lactis subsp. lactis
• Active against G+ bacteria (Clostridium botulinum, Listeria monocytogenes, LAB)
• Commercially available
• Cheese and dairy products, canned foods, mayonnaise
• Only bacteriocin approved for use in U.S.