Please enable JavaScript.
Coggle requires JavaScript to display documents.
Fermented milk products, Lactose = Glu-Gal - Coggle Diagram
Fermented milk products
Yogurt
From
- Bovine milk
- Higher fat content: Goat, sheep
- Lower fat: horse
Process
- Natural fermentation possible - Temp dependent
- No rennet (set of enzymes in stomach of ruminant animals)
- Bacterial proteolysis and acidification -> thickening
- Industry: heat treated milk + starter cultures
Initial steps
- Filtration of milk
- Check antibiotics
- Affect bacterial activity during fermentation
- Fat adjustment
Standardization - SNF
- Elevation Solids not fat = other than fat and water
- Protein, carbohydrates, minerals
- Gel strong enough for consumer appeal / withstand stirring
- Adjust with skim milk powder to skim milk -> 11-15%
Homogenization
- Size reduction + equal distribution of milk fat globules
- High-pressure homogenization
- Pressing through small orifice -> size 1-2um
- Prevent cream separation
Heat treatment
Physicochemical properties
- Denature whey protein
- β-lactoglobulin -> attach to casein micelles -> texture + viscosity
- Free amino acids for MO
-
-
Starter cultures
- Streptococcus thermophilus
- Lactobacillus bulgaricus
Fermentation
- Temp 42C
- Enzymes: Lactose permease + B-galactosidase
- Glucose -> pyruvate + lactate
- Galactose expelled
Aggregation of casein micelles
- pH drop -> 4.6 = pl of casein
- Neg. charge decreases -> less repulsion + hydrophobic interactions -> casein micelles aggregate -> gel
Protocooperation - strains
- Grow + acidification : Better together
- Streptococcus -> formate, pyruvate + CO2 -> stimulate Lactobacillus
Key flavor compounds
- Acetaldehyde
- Pyruvate -> Acetyl-CoA -> Acetaldehyde
- Threonine -> Glycine + Acetaldehyde
- Small diacetyl
Final processing
- Cooling
- Packaging
- Slow acid formation
Safety consideration
- Low pH inhibits pathogens
- Spoilage: acid-tolerant yeasts or molds.
Acidophilus milk
General
- Lactobacillus acidophilus = natural human microflora
- Colonize gut -> health benefts
- Longer fermentation than yogurt - low competitiveness
Process
- UHT processing - high temp, short time
Homogenization
Cooling
Fermentation
- 37–40°C
- Acidity reaching 0.7% in 24 hour
Features
- Sour taste
- 1 week shelf life
Kefir- blomkål
-
Starter culture
- Added as kefir grains
- Water soluble polysaccharide - Kefiran sheet
Microorganism
- LAB (Lactobacillus kefir etc.) on the surface
- Yeasts like Saccharomyces cerevisiae in the interior
Production
Traditional
- Inoculated milk in sealed goatskin leather bag
- Ferment room temp
Nowadays
- Containers fermented in dark rooms
Fermentation
- Lactose hydrolyzed, glucose -> lactate, EtOH, CO2
- Lactose -> kefiran -> break up intograins
- Products: lactate, acetate, acetaldehyde, diacetyl
- Low lactose end conc
Koumiss
Milk
- Traditionally horse milk
- Now cow milk
Casein and whey ratio
- In cow vs horse milk
- Solution: Membrane ultrafiltration method
- Concentrate whey protein
- Added sucrose
Fermentation
Starter cultures
- Lactobacillus delbrueckii and yeasts like Candida spp
- Incubation at ~26–28°C
- Acidity (~0.8%) and alcohol (0.7–2.5%) levels
- Highly viable: Lactic acid and alcohol
Category
- Mild, medium, and strong
- Differentiated by acidity and alcohol content
Buttermilk
Milk
- Traditionally: by-product of butter churning
- Now fermented skimmed milk.
Starter cultures
- LAB : Leuconostoc mesenteroides
- Aroma- and acid-producing strains
- Products: lactic acid, CO2, acetaldehyde and diacetyl
- Diacetyl = buttery flavor
Fermentation
- 21–24°C for 12–16 hours -> 0.8 - 0.9% lactic acid
- Pyruvate -> diacetyl + acetoin
- Milk citrate declines in storage -> supplementation sodium citrate -> diacetyl formation
-