FS 101: Test 3

significance of 9000 BCE in fermentation history

evidence of rice fermentation

heating process for yogurt

heating to 85 C, then cooled to 42 C and LAB is added, and it ferments for 4-12 hours

significance of 5000 BCE in fermentation history

evidence of beer and wine production in mesopotamia and egypt

significance of 500 BCE in fermentation history

evidence of vegetable fermentation in china

environment needed for fermentation

anaerobic

glycolysis

initial breakdown of glucose into pyruvate

lag stage of fermentation

introduction of fermentation conditions to product

initial growth phase of fermentation

rapid growth and consumption

stationary/stabilization phase

by-products accumulate, inhibiting further growth

decline phase of fermentation

deterioration of product overtime

lactic acid bacteria function

converts sugars into lactic acid

yeasts function

converts sugars into alcohol and CO2

molds function

production of soy and dairy products

nutritional benefits of fermentation include

• breaks down antinutrients

• increases availability of nutritional factors

• probiotic contents (lactobacillus and bifidobacterium)

• gut health support

• microbiome diversity

nutritional risks of fermentation

excessive salt intake, and contamination risks in processing

yogurt production process

pasteurized milk + LAB cultures + fermentation at 42-45 C → coagulation of proteins → cooling and packaging

cheese production process

pasteurized milk + rennet + LAB → curdling → draining of whey → aging

sauerkraut production process

cabbage + salt → anaerobic conditions → LAB sugar to Lactic Acid

kimchi

cabbage + radish + garlic + spices + salt → LAB sugar to Lactic Acid

bread production process

yeast ferments sugars in dough → CO2 → rising

sourdough vs commercial bread

sourdough uses wild yeast and a longer fermentation process leading to tangy flavor

beer production process

malted grains + yeasts + fermentation → conversion sugar to alcohol + CO2 → filter and processing

how fermentation time effects the alcohol content

longer fermentation time leads to higher alcohol content

food deterioration

the process in which food undergoes changes that make it unsuitable for consumption

salmonella symptoms

diarrhea, fever, gastroenteritis

salmonella common locations

raw poultry, eggs, dairy, contaminated vegetables

E.coli (Escherichia coli) common locations

undercooked beef, unpasteurized milk

E.coli (Escherichia coli) symptoms

stomach cramps, bloody diarrhea, vomiting

Listeria monocytogenes common locations

ready-to-eat meat, unpasteurized dairy, smoked seafood

Listeria monocytogenes symptons

diarrhea, nausea, vomiting

norovirus common locations

water and shellfish

norovirus symptoms

nausea, diarrhea, stomach pain

temperature danger zone

40 F - 140 F

virus transmission

cannot grow on food, transmitted through contaminated water, or food

virus reproduction

require living host to reproduce and then operate

intrinsic factors effecting microbial growth

• water activity

• pH

• nutrient content

• redox potential: oxygen availability

extrinsic factors effecting microbial growth

• temperature

• humidity

• gaseous environment

  
  

dehydration

removing moisture from food to extend shelf life

importance of dehydration

reduces AW, prevent spoilage, storage efficiency, preserved food quality

evaportation

removal of moisture from food surface

diffusion

migration of moisture from inside to surface

equilibrium moisture constant

point where food no longer loses moisture in drying process

mass transfer

movement of mass in the form of water from inside the food to the surface to then the air

heat transfer

process of exchanging thermal energy between different systems or objects due to change in temperature

conduction

heat through surface without moving the material itself

convection

heat through gas/liquid medium through circulation “convection currents”

radiation

heat through electromagnetic waves, doesn’t require a medium

challenges of dehydration

• uniformity

• energy consumption

• quality retention, different flavor, color, texture

• loss of nutrients

• varying rehydration quality

sun drying

• oldest method

• low cost

• unreliable, potentially unclean

air drying

• faster

• loss of heat sensitive compounds

tray drying

• industrial, small scale

• batch method

• easier to control airflow

• leads to case hardening

spray drying

• liquid sprayed into chamber with hot air

• rapid, good for heat-sensitive products

• energy consumption, expensive

freeze drying

• sublimation via vacuum of frozen products

• expensive

drum drying

• slurry or puree applied as thin layer onto revolving drums

• dried as revolving drums are exposed to hot air

fluidized bed drying

• food suspended and dried by hot air

microwave drying

• uses electromagnetic waves to dry

• fast, and retains nutrients

infrared drying

drying by exposure to infrared light

thermal processing

using heat to treat or prepare food, beverages, or other substances

importance of thermal processing

• extension shelf life

• destruction of microorganisms

• improved safety

• improved quality

• convenience

significance of mid 19th century in thermal processing

pasteurization created

significance of late 19th century in thermal processing

microbiology and technology increases, commercial canning industry booms

significance of mid 20th century in thermal processing

sterilization and pressure cooking invented

significance of late 20th century in thermal processing

microwave and sous vide cooking invented

relationship between temperature and processing time

higher temperatures lead to shorter processing times

factors effecting thermal processing

temperature, time, pH, moisture, food composition, microbial characteristics, packaging, agitation, equipment

D-value

time needed to decrease population of microbes by 90% at a certain temperature, measures sensitivity to heat

Z-value

temperature change needed to alter D by a factor of 10, measures sensitivity to change in temperature

F-value

cumulative lethality, measures equivalent time at a reference point that achieves same microbial destruction as process progresses at a variable temperature

pasteurization

mild heat treatment to kill pathogens without affecting food quality

HTST

high temperature, short time pasteurization

LTLT

low temperature, long time pasteurization

sterilization

severe heat treatment to kill all life forms

commercial sterilization

heat treatment to kill all microbes able to reproduce under typical storage

UHT sterilization

heating to temperatures above 135 C before packaging

in-container sterilization

heating of product after sealing

blanching

short heat treatment used to inactivate snzymes and prepare food for further processing

examples of heat processes

retorting, pressure cooking, aseptic processing, blanching, dehydration, baking, cooking, frying

frying

submerging foods in hot oil

retorting

method that used heat and pressure to sterilize foods

aseptic processing

commercially sterilized products are packaged in sterilized containers under sterile conditions

overprocessing in heat processing

excessive heat leads to quality, flavor, and nutrition degradation

under processing in heat processing

insufficient heat leads to food safety risks

heat distribution challenges in thermal processing

uneven heat distribution can cause under or overprocessing

energy consumption challenges in thermal processing

high energy required for most thermal processes, which can impact sustainability, costs, etc.

fading in thermal processing

pigment degradation in fruits and vegetables when heated