FT 114 - Dairy Products Technology | Jan Isobel Hidalgo | SY 14-15

MICROBIOLOGY QUICK REVIEW

Important microbes in food?

Bacteria

Fungi

Mold

Yeast

Bacteria

Single-celled microorganisms

Can transform into spores

Reproduce by binary fission

FT 114 - Dairy Products Technology | Jan Isobel Hidalgo | SY 14-15

FUNGI: Molds

Multi-cellular colonies that form intertwined and branching hyphae or

filament

Grows best in moist warm temperatures

Requires less moisture than bacteria and yeast

Reproduce by means of spores

FUNGI: Yeast

Single-celled fungi

Larger cell size than bacteria

Grow in numbers by dividing (budding or fission)

FT 114 - Dairy Products Technology | Jan Isobel Hidalgo | SY 14-15

Most are not pathogenic

Used in bread making, alcohol fermentation

Microbial Growth

Nutrient requirement

Water

Energy source

Carbon/nitrogen source

Vitamins and minerals

Moisture

Two types of water

Bound

Free water (aw)

Preferred aw = 0.99

Needed aw > 0.91

Spoilage bacteria aw > 0.90

Yeast and molds can grow @ aw of 0.80.

Most fungi aw > 0.70

FT 114 - Dairy Products Technology | Jan Isobel Hidalgo | SY 14-15

Temperature Requirements

Classification Minimum C

OptimumC

Maximum C

Thermophiles 40 to 45 55 to 75 60 to 90

Mesophiles 5 to 15 30 to 37 45

Psychrophiles -5 to 5 12 to 15 15 to 27

Psychrothrops -5 to 5 30 - 37 45

pH needs and microbes

Neutrophiles

Acidophiles

Alkalinophiles

Oxygen

Aerobic

Anaerobic

Facultative anaerobe

FT 114 - Dairy Products Technology | Jan Isobel Hidalgo | SY 14-15

Next Meeting

QUIZ

Main Sources of contamination

Microorganisms in Milk